Overdrive Servo/Spring Replacement,
MLPS, Shift/EPC/TCC Solenoid Replacement,
Valve Body R&R
2002 Crown Vic HPP

I had noticed that the shift from 3rd gear to overdrive was getting a little "lazy" so I decided to do a little maintenance and upgrade work on the 4R70W in my 2002 Crown Vic HPP (80,000 miles on a regularly maintained vehicle). What this process describes is generally everything that can be done without actually dropping and disassembling the transmission, and it assumes that the OD band itself is still in reasonably good shape. The OD band is definitely a weak link in this transmission, as it is not very wide nor thick considering the work that it has to do. Compared with the reverse band, which will probably last way beyond the normal life of the average 4R70W, the OD band is somewhat scrawny.

In my case, I had done the infamous J-mod when I bought the car at 59,000 miles, but the OD servo/return spring and the spool valves in the valve body and various solenoids had been left alone. 1-2 and 2-3 shifts were quick and firm thanks to the J-mod, but the shift from 3 to "4" (not a gear, but the application of the OD band) seemed to be fairly soft and somewhat drawn out, especially when compared with the prior gear nice firm shifts. There was also a bit of hunting between 3-OD-3 at very light throttle application and low mph. I decided to invest some time and a few bucks to install some replacement parts to see if they would help firm up the shift into overdrive. If I do need to come back at some point to rebuild this transmission, the majority of these parts can be re-used, barring some sort of converter or internal component meltdown that spreads debris throughout the entire system. In that case, better figure on ALL parts being replaced and don't forget to completely flush the radiator cooler, or replace if it's the thermostatically controlled version on the newer cars.

Bear in mind that the transmission pressure and shift characteristics are controlled by the PCM, so there is a limit to what can be done by simply replacing parts or doing a J-mod. There is some "softness" (overlap) that is designed into the factory tune for the average drivers comfort, so there will always be an inherent limitation to the shift pattern no matter what you do to the mechanical/electrical components. Aftermarket tunes are designed to allow you to tweak the shift parameters, but remember that to get the best impact from any changes, the internal components need to be in good shape. At this time, my car has only the stock factory tune and all I am doing is replacing some components that can be accessed without transmission disassembly to ensure that they are all in the best shape that they can be.

It should be noted that converter lock-up was fine and operated as designed, so this was not a TCC solenoid related issue, although I did replace it as well. You will also find that I replaced some parts that were not perhaps 100% related to the overdrive hydraulic circuit - this replacement was done as maintenance since the pan and valve body needed to come off anyway. Also note that if your transmission is just plain worn out, this work will do nothing but highlight that a rebuild is in order. It is not a replacement for worn clutches, bad piston seals, worn bushings, etc.

I had also decided to replace the MLPS (commonly called neutral safety switch) as well. It is essentially a resistor that takes a reference voltage, then drops that voltage based upon what gear is selected. The PCM will read the voltage changes along with TPS and other sensor inputs as a verification of how to control the shifting. In my case, the transmission would occasionally hunt a bit in and out from OD to 3rd, so I included a new MLPS in my parts list. They can fail but they can also get a bit of corrosion that can sometimes cause intermittent strange shifts so I wanted to be sure I covered all the bases in obtaining the best possible non-reprogrammed shifts.

Finally, I am not a transmission expert, so use your own common sense in deciding what you may or may not want to tackle. This is as good a guide as I can come up with, but it is intended as a general guide and is not foolproof. It assumes that you have good basic mechanical skills, but read it completely before you decide to do anything. If you are unsure of what's going on, either use a good local shop or contact one of the resident cv.net experts. There's nothing worse than having to go back and figure out why the transmission is suddenly not working right and wishing you had never touched it - been there, done that. Also, I am not responsible for your personal safety working underneath a vehicle - be careful and use the right equipment to support and stabilize the car. WORK SAFE.

Parts List for 2002 4R70W:
  1. 2.7" OD Servo F7AZ-7H188-AA
  2. Stock return spring for 2.7" OD servo F87Z-7F201-AA or
  3. "Hi-performance" spring for 2.7" OD servo F2VY-7F201-A
  4. EPC Solenoid F6AZ-7G383-AA (96+)
  5. Shift Solenoid Pack F7AP-7G484-AA
  6. TCC Solenoid F7AP-7G136-AA (96+)
  7. 1-2 Piston/Accumulator F7AZ-7F251-AA
  8. 2-3 Piston/Accumulator F7AP-7H292-AA
  9. Valve Body Separator Plate Upper Gasket (96+)
  10. Valve Body Separator Plate Lower Gasket (01+)
  11. Valve Body Cover Plate Gasket (96+)
  12. Filter (96+) (FT105)
  13. Molded Rubber Pan Gasket F2VY-7A191-A
  14. Sonnax 76948-09 Main Pressure Regulator Valve (96+)
  15. Sonnax 76948-29K OD Servo Regulator Valve & Sleeve (01+)
  16. Manual Lever Sea
  17. MLPS Switch (Neutral Safety Switch) F8AZ7F293A
  18. Mercon V transmission fluid - 12 qts (I used 10)

You can get the shift solenoids from either bulkpart.com or transmissionpartsusa.com. I have found that they typically supply Borg-Warner electrical parts which are fine, may even be OEM supplier for all I know. Gaskets are TransTec brand, which are fine to use as well, never had a problem with them. I recommend that you get the MLPS and molded rubber pan gasket from Ford however.

A word about transmission fluid - it is recommended that Mercon V be used in all 4R70W transmissions, even the earlier AODE models that initially used Mercon. Mercon V is a synthetic based fluid, more expensive that Mercon, but with a better additive pack and also able to withstand higher temperatures longer. Ford recommends the use of Mercon V to address torque converter shudder as well. Using Mercon V in a Mercon transmission just means draining as much of the Mercon out as possible, then re-filling with Mercon V. A little blending of the two fluids will not hurt anything. Do not use a universal application fluid - use only fluid specifically labeled Mercon V, any major brand is fine. Personally, I use Castrol and/or Pennzoil brands because they are locally available and yes, I have blended them together with no harmful effects. I do generally try to stay with one brand though.

I saw Castrol bottles labeled as replacement suitable for Mercon/Mercon V when I was getting fluid for my parts installation. The counter guy was pretty insistent that this would be fine and perhaps it would be, but I was more comfortable with getting the bottles that were specifically marked Mercon V. In my opinion the universal fluids have an overabundance of additives that allow then to be labeled as fit for GM/Ford/etc, but I prefer a specific factory recommended fluid, at least for as long as it's available.

Parts sources that I used:
  • www.fordgenuinepartsonline.com
  • www.bulkpart.com
  • www.transmissionpartsusa.com

Great on-line info:
  • http://www.mn12performance.com/mn12-techinfo/trans-tech/4r70w_rebuild.html
  • http://fordfuelinjection.com/files/Ford_MLPS.pdf
  • http://www.tccoa.com/articles/tranny/index.html
  • http://www.sonnax.com

If you are curious about the inner bits and pieces of the 4R70W and want to know more, this is an excellent resource - it is a 4R70W Rebuild Diary from my friend Glacier991 on the Ford Explorer forums:

NOTE - in some cases, I have used (and identified) reference pictures from a recent 1995 4R70W rebuild where the item to be viewed was essentially the same as the 2002 4R70W that is the subject of this write-up. Since I already had the pictures there was no need to duplicate them.

First of all, get yourself a nice clean work area, and then get some plastic and/or cardboard laid down so that you won't make a mess everywhere. Do not support the car with only a jack. I like to drive the car up on ramps and then raise the back end to rest on large solid wooden blocks under the rear wheels. I made the blocks to be the same height as the ramps. This lets the car sit level and high enough to comfortably use a creeper under it, plus it's actually enough space to get the entire transmission out if needed. Personally, I find that if I take the time to set up a clean work area and get the car where I want it, it seems to help me do a better job. I also have a ton of empty baby-wipe plastic containers (don't laugh) that are great for keeping parts separated instead of just dumping them all into a single container. Do this as you remove parts and toss a little label in there - it will make re-assembly much easier.

Disconnect the battery. This will allow the computer to re-learn shifting parameters within the factory parameters after your installation has been completed and will avoid any possible unpleasantries as you remove connectors. Remember that there is a limit to the computer re-learning short of adding an aftermarket tune (program) so don't expect miracles.

Drain the transmission, either by using the drain plug if the pan has one, or by loosening the 10mm pan bolts and allowing the fluid to drain out. Get a nice big catch-pan to catch the fluid. If you loosen the bolts on one side more than the other sides, the pan will dip a bit and tend to drain in that direction, but bear in mind you may still get fluid down your arm at some point. Leave a bolt loosened on opposite sides of the pan to hold it up but also letting it tip. When the fluid has stopped draining, hold the pan and remove the remaining bolts and set them aside. Lower the pan and tip it so that the remaining fluid in the pan drains into the catch-pan. The transmission will continue to drip into the pan. Now you can look at the stuff you are going to be removing, but also look in the pan before you clean it.

If you see some debris that is generally the consistency of sand, that's pretty normal (as long as there's not piles of it). You will also see a round magnet that will have various crud stuck to it - you can just pull that out and clean it but remember to put it back after you clean the pan. As long as there are not pieces of clutch lining (dark brown) or metal fragments laying in there and the transmission is working normally, chances are that it is in decent shape. If you see chunks of stuff in the pan, then chances are a rebuild may be in the future at some point. Remember that those chunks are not only in the pan, they are throughout the hydraulic system as well, trying to plug up something somewhere and there�s obviously something inside that is deteriorating. You may also find a ball looking thingy laying in the pan - not to worry, that is the plug that the factory puts into the dipstick hole until the dipstick is installed, which then pushes it down into the pan. Finding it usually indicates that you are the first person to have dropped the pan since the car left the factory. That could be good if the car has moderate miles or not so good if it's a higher mileage vehicle. In my case, the plug was still there at 59,000 miles so it was a good thing I did maintenance as soon as I bought it - that's getting a little borderline in my opinion.

You will also find that the pan gasket should be a factory rubber molded gasket that is reusable - it's really a good piece. I will re-use these a time or two, but my comfort level is to replace it with the same type if I have any doubts - it's well worth the extra cost over a cheapie cork gasket that will soon start to seep. Now go ahead and clean the pan (put the magnet back in) and the pan bolts so they will be ready later. Take a small flat hammer and tap around the bolt holes in the pan (use a block of wood under the pan rail) to get the surface of the pan flat. Don't beat it to death, just enough to take out the little warpage that the tightened bolts put into the pan.

I also like to get a general measure of how much fluid has drained - that lets me get into the ballpark right away when it's time for new fluid. I have some empty oil containers that I pour into, so if I have drained 8 quarts for example, I will know that's approximately what I will be putting back in. Of course, you need to verify final fill level, but that eliminates guessing - I know I can easily pour in 4-6 quarts before I ever start the car, then slowly add until full.

OK, back underneath the car. By now the transmission dripping should have slowed down but not stopped. Be prepared that when you get remove the filter and valve body, you will have more fluid that drains each time.

Let's look at the pictures and you can see the various parts identified as we go along. This is a 1995 model with the wiring harness, note the flat filter.

And this is a 2002 model with the plastic harness, note the filter with extension.

Remove the old filter by simply wiggling it and pulling it down - be aware that there is an o-ring seal that goes around the neck of the filter and often gets a bit stuck up in the valve body. Be sure that you remove the old seal - the new filter will come with a new seal, otherwise the new filter won't install correctly. If you have an older model flat filter and pan you can upgrade to the newer deeper pan and filter if you prefer.

Remove wire harness. On newer models this is a hard plastic assembly, on the older models, this is an actual wiring harness. Be careful and try not to break the retention tabs on the plastic connectors when you disconnect them from the various solenoids. The retention tabs can be GENTLY pried up slightly with a small thin blade screwdriver but be aware that they can break easily. Fortunately, replacement harnesses are available from the sources I noted at the beginning of this guide and they are not that expensive.

You are now looking at the bottom of the valve body. Before we remove it let's cover some very basic items. Valve bodies are aluminum and with heat and time they can warp slightly. You want to exercise some care with removal and reinstallation. There are many cases where a perfectly good valve body was damaged by some ham-fisted installer making sure it was really "torqued" down. Correct torque is 90-120 in/lbs which is no more than 10 ft/lbs. It's not that easy to gauge what that is by feel. I've tried a direct comparison and when I checked what I thought was right, it was off by quite a bit. Do yourself a favor and get an in/lb torque wrench in order to re-install the valve body correctly and with all bolts to a consistent tightness. There is also a bolt sequence that should be followed for both loosening and tightening.

Let's also look at the components as well as the relationship of the manual valve to the shift linkage before we remove the valve body. Looking at the earlier pictures above you can see the thermal sensor, the shift solenoid pack, the EPC solenoid, and the TCC solenoid pack. The thermal sensor lets the PCM know the temp of the transmission fluid, the shift solenoid pack controls the 1-2 and 2-3 shifts, and the TCC is the torque converter control (lockup) solenoid. Note that the separate thermal sensor is on the earlier models - later models have it incorporated into the plastic harness. What you can't see yet is the EPC (electronic pressure control) solenoid - it's above the valve body and we will first need to remove the valve body, MLPS switch, and shift linkage to replace it. Note that the first (#25) bolt (bolt sequence chart) that will be removed also attaches the EPC bracket to the valve body. Be sure to re-install the bracket since it keeps the EPC solenoid in place. Be aware that 92-95 and 96-up transmissions use different TCC and EPC solenoids, but that the shift solenoid part number above will fit all models. 92-95 TCC is F2VY-7G136-A. The retaining brackets for the older/newer EPC solenoids are different as well - they need to match the correct year application. 92-95 EPC solenoid is F5AZ-7G383-AA with F5AZ-7H111-A bracket. 96+ EPC uses F6AZ-7H111-A bracket.

The manual valve is extremely important - it provides the primary hydraulic routing control to the entire valve body. Note how the shift linkage fits into the manual valve. This is sometimes missed when re-installing the valve body and can possibly damage the linkage or valve if it's incorrectly installed.

Following the bolt sequence (work backwards, start with bolt #25) break the smaller 8mm bolts loose first. These are the ones that actually attach the valve body to the case. The larger 10mm bolts are for the attachment of the cover plate to the valve body. You can break these loose, but leave the cover on until you have the valve body on the workbench. There are also two 10mm bolts that are actually guidepins, they can be loosened and also left in place. Some fluid will probably start to seep out between the gaskets. Now go around and loosen/remove the 8mm bolts, leaving a couple finger tight in the middle of the valve body to hold it up. When you are ready to drop the valve body, remove these last couple of bolts and lower the valve body - try to keep it level since it has fluid in it. Note that the perimeter bolts are shorter in length than the ones that go through the cover plate.

Also note that bolt #11 retains the shift solenoid bracket, bolt #9 retains the rooster comb spring, and bolt #25 retains the EPC bracket. Don't forget to re-install these items at re-assembly.

Be also aware that, depending on the model year, you may have a small round or larger oval screen fall out as you remove the valve body. The locations of the screens are shown in the pictures below - be sure to re-install them before the valve body is re-installed.

Incidentally, here's what the various pistons/accumulators and servos look like. In the picture below you can see the basic factory setup of the 1-2 and 2-3 pistons/accumulators and the reverse servo. The reason that I say "basic factory setup" is that the 1-2 and 2-3 shift characteristics are often changed by replacing the springs with others of different rates or sometimes eliminating some of them. Different spring colors = different spring rates. I have modified the shift characteristics on both of my cars by changing the 1-2 springs and removing the 2-3 spring. This is a different topic, so I won't get into it here, but here is a link to more info:

The 1-2 piston is of special note - this is what the one in your car should look like, it's the updated version (second design). If you have a 97 or older unit, then chances are that it may have the first design aluminum/o-ring version which should be replaced. The first design tends to score the bore and results in leakage. Also, look at all the pistons, covers, and servos - what do they all have in common? Rubber edge seals! These seals get brittle with heat and age. I like to replace them at about the 80-100K mile range, especially since these parts are really not that expensive. Good seals are very important to good shifting. It-s up to you if you want to replace the reverse and/or 2-3 piston/accumulator while the valve body is out, but I would certainly recommend it if you have some miles on the transmission. The 1-2 piston/accumulator is the only one that can be replaced with the valve body in place. In my case, I had already replaced the 1-2 and 2-3 piston/accumulators with the prior J-mod work, but I have included the part numbers as a reference. The 2-3 accumulator cover is very easy to remove - it is retained by 3 small tabs. As with any internal parts, lube them beforehand and install with a slight turn and wiggle to ensure that they are properly inserted into the bore.

The picture below shows the locations of the various pistons and servos as well as the linkage retaining pin and a small round screen that slips up into the case. The linkage (roll) pin is removed by simply pulling it out with a set of pliers, but note that it sticks up just a bit - don't try to hammer it down flush when you re-install it. The screen is there to trap debris and can fall out - be sure to re-install it, tab end faces down when installed. You can use a little assembly lube or Vaseline to keep it in place. Note that this picture shows the screen in a 1995 model - my 2002 had a different screen located in a different spot, so be aware that you may have one or the other.

Here is the screen in my 2002.

OK, now that the valve body is removed (and the transmission continues to drip) we can do some cleaning and install the Sonnax replacement parts. You will see that that separator plate is still held on by the 2 or 3 round reinforcement plates and an extra 10mm bolt as well. Earlier years had the 3 plates, more recent years have 2 plates. The picture shows an earlier year so you can see the orientation of all the plates - note that the upper gasket that goes between the plate and the transmission case has been removed for clarity. Incidentally, this is a J-modded separator plate which means some of the fluid passage holes have been drilled larger.

Before removing the separator plate, turn the valve body over and remove the cover plate/gasket that is held in place by the 10mm bolts. Remove the 10mm guidepin bolts as well. Note - guidepins are different in earlier and later year models. The earlier versions are a larger diameter. You can use a newer year valve body in an older 94-95 model, but since the guidepins are a smaller diameter in the newer years you will also need to use a couple of small round spacers in order to align the valve body correctly into the case. You may find that someone before you has done this, so if a couple of very small little spacers fall out of somewhere don't panic, they simply go around each guidepin into the case. You do want to be sure that they seat properly and don't hang up, otherwise the valve body will not seal and can be damaged when being tightened. Thoroughly clean and dry the cover plate.

Now turn the valve body back over and remove the round reinforcement plates and the extra bolt and carefully lift off the separator plate/gasket. Don't force it, it should come right up, you do not want to bend it! Thoroughly clean and dry the separator plate.

The picture below shows the valve body with the separator plate removed. You can see the locations of the 8 check balls as well as a small internal screen and a round check valve. These will all fall out as you clean the valve body so remove them first and keep them in a safe place. Be very sure to re-install every one of the check balls into the right location! They can be held in place with a dab of Vaseline or transmission re-assembly lube until the separator plate has been re-installed. The manual valve is shown for reference. Looks like a real spaghetti bowl, but the channels are there simply to route fluid to various components. If you think about it, you can see why good gasket sealing is critical to the valve body. There is a lot of hydraulic pressure in these channels, even a slight gasket leak can cause a problem and of course a warped valve body will affect proper sealing. That's why we wanted to make sure the valve body was as straight as possible. ALWAYS install new valve body gaskets when replacing a valve body, even if they were almost new. Don't monkey around saving a few bucks on gaskets. Also be very careful when re-installing the valve body - the gasket between the separator plate and the case can sometimes get a little hung up and torn. I typically get several sets at time, just to have some extras on hand.

Here is what you may find inside the valve body - in this case (taken from another transmission) the debris was a bit more excessive due to a broken thrust bearing in the torque converter, but you get the idea. The best way to thoroughly clean a valve body is to remove all of the spool valves and then clean the empty valve body using a tank or some type of pressure cleaner. I usually tank clean it, then follow with a pressure washer, compressed air, then spray it lightly with transmission fluid to keep all the surfaces lightly oiled. Going somewhere and getting a solvent flush cannot get to the debris that is trapped in the valve body; in fact it may dislodge it and move it to a worse place, like one of the spool valve bores. Getting a fluid flush if the unit is operating normally is OK, except that you should include a filter change as well.

Now it's time to remove all the spool valves in order to get everything nice and clean. This may seem daunting, but if you stay organized and take your time, it's not that bad. As a help, you can take the valve body and lay it onto a large piece of cardboard, then trace the outline on the cardboard. This will enable you to get the valves back into the right places for re-assembly. You can also take some photos before and during removal if that helps you remember. Digital cameras are wonderful things.

The valves are held in the valve body by a series of retainer clips and/or end plugs and they also have internal springs. In order to remove each valve, you need to push in on the valve slightly, then pull the clip/end plug out of the valve body. Sequencing is critical, what I do is remove the clips/valves/springs, then take a picture so I will remember where everything goes. Some of the valve shapes and parts are different from earlier and later years, so if your parts vary a bit, don't worry - the main thing is to re-install everything in order. As you remove each valve, lay it out in order on the cardboard next to the bore that it came out of. Here is a website that can also help you to see the valves and the order of the parts:

Some of the valves will also have what look like end plugs - don't try to pry them out! There is a threaded hole in the plug, just thread an 8mm bolt in the plug and you can them pull it straight out after the retaining clip has been removed first.

Now that everything is out of the valve body, we first want to ensure that it is as straight as possible. As we have mentioned, these are aluminum and can warp over time. First do a minimum cleaning to get rid of any remaining transmission fluid, then dry the valve body. Compressed air is your friend here. Now take a metal straightedge and lay it across the separator plate side of the valve body and see if there are any gaps between the straightedge and the valve body. Do this diagonally and across the valve body as well. If there are gaps, this indicates some warpage of the valve body. Sometimes the gasket can compensate, but while it's out you can take some reasonable action to even it out a bit.

You will need a smooth and level surface - my workbench has a laminate top that works well. Take a couple of sheets of 400 grit sand paper and tape or glue them down to your level surface and GENTLY run the valve body over the paper. The idea is to just get the high spots down, not to grind the valve body into nothing, so don't get carried away. Check your progress often with the straightedge, it won't take that much.

When you are happy with the surface, wash and clean the valve body very thoroughly. Be very sure that the interior passages and bores are spotless, then dry with compressed air. Remember that you will have basic operating gunk plus the metal particles from your sanding - you must get this part extremely clean. A rag can leave lint, so compressed air is better. Cover the valve body with something when you are not working on it as well. Clean, clean, clean - cannot be emphasized enough!

You will also need to be sure that all the valves themselves are clean as well. The best way is clean them one by one so you don't get everything mixed up. I like to take a green Scotchbrite pad and LIGHTLY run it over the valve before final rinsing just to be sure there is no minor debris left. Just a few passes is all it takes, then rinse, dry and set back in place around that cardboard template you made.

Now it's time to re-assemble your nice clean valve body, plus we can install the Sonnax updated parts. You can look up info on the Sonnax website, but in general I am using the Sonnax parts to ensure that line pressure to the OD servo is not compromised by a worn stock valve and that overall line pressure remains to factory specs. Installing a new EPC solenoid also helps to ensure good pressure control.

Take the valve body and either pour some fresh transmission fluid on it or place it into a pan full of fluid. Keep it in the same configuration as the outline on that piece of cardboard so that you know which bore each valve will be installed into. Now take each valve assembly, dip into transmission fluid and gently re-install each component into each bore. Don't force anything. Take your time and be very sure that each component is fully seated all the way into the bore, as the valve can get hung up passing through the various compartments. Once you have done that, install the end clip for each valve. Remember that one of bores has 2 valves in it and each has its own retaining clip. Note which components have been replaced with the Sonnax parts and remember that you must use the correct parts for your year of transmission if you have chosen to install the upgrade parts.

When you have installed all of the valves, install the small square screen, the round check valve, and all of the 8 check balls into their proper locations. Now carefully put the lower separator plate gasket in place, followed by the separator plate itself. Install the 2 or 3 round reinforcement plates and the additional 10mm bolt and torque to 90-120 in/lbs. Be aware that the round reinforcement plates must be installed in a certain position as they have fluid channels on the underside. Fortunately, the bolt hole locations are set up to help with proper alignment of the plates. Turn the valve body over, install the cover plate with gasket and torque to 90-120 in/lbs. Set the assembly aside for now, remember that you will also need the upper separator plate gasket when installing the valve body back into the transmission. I also installed the shift solenoid pack and TCC solenoid at this time, although they can be installed after the valve body has been re-installed - your preference. Lube the o-rings on the shift/TCC solenoids and gently push them into place. You will note that the TCC solenoid is installed first, with the shift solenoid bracket installed over it. There is a 10mm bolt that retains the shift/TCC solenoids, with one of the 8mm valve body bolts also acting as a second retainer for the shift solenoids.

Time now to get back to the transmission itself - hopefully most of the dripping has stopped by now.

We will first replace the EPC solenoid, which will require removal of the shift linkage. Remember that the EPC solenoid is specific to earlier or later model years, so be sure that you have the right one for your application.

First item is to unbolt the shift cable from the linkage - this is pretty straightforward. There is a little arm that extends towards the front of the car with a nut on a stud. Loosen the nut and pull the cable off of the arm. Now remove the 2 bolts retaining the MLPS switch and pull the switch off of the linkage shaft. In our case the MLPS will be replaced with a new one.

Now look inside the case and you will see a large nut retaining the linkage shaft. It is loosened in regular manner (loosens to the left), but it's tight quarters in there. As the nut unthreads, you can push the linkage out a little so it will have room to come off of the shaft. You can put a little wood block under the rooster comb to keep it from moving. After the nut has been removed you can grab the linkage shaft and pull it out of the case - as you do this the internal "rooster comb" and parking pawl assembly will come off of the end of the shaft. Note how it fits into the shaped end of the linkage shaft. The shaft should be a fairly tight fit to the seal so you may need some muscle and twisting motion to remove it. After the linkage is out the seal can then be removed - be careful not to scar the bore when removing. I suggest that you replace it now to avoid a lot of hassle later to replace a $1 leaking seal. Just wipe the bore clean and gently tap the new one in place. I like to use transmission assembly lube (fluid is fine) to grease the lip of the new seal before re-installing the linkage.

Now the EPC solenoid is accessible and easy to replace. Simply pull it gently out of the bore, wiggle it a little if needed. Be sure that the o-ring that is on the neck is intact and was not somehow stuck in the bore. Take the new EPC solenoid, lube the o-ring/neck, and carefully install it. It helps to slowly rotate and wiggle it a bit when re-installing. You absolutely do not want to damage the new-o-ring. Take a look at the screen on the end of the old EPC solenoid just to see how much debris there may have been on it - they can clog up sometimes if poor maintenance has been done or if there is an internal wear problem.
Re-install the shift linkage - it's helpful to lube the shaft before installing - and be sure that the rooster comb assembly is in the correct position and that that parking pawl is also correctly in place at each end. Install the retaining nut and tighten. I don't have a torque setting on this, I just get it tight. Be sure that as you are installing the shift linkage the little arm is towards the front of the car, then re-attach the shift cable to the arm in the same place as before so that indicator in dash will line up correctly.

Take the new MLPS and slide it onto the shift linkage, then install, but do not tighten the retaining bolts. The MLPS needs to be properly adjusted. To do this, the gear selector in the car first needs to be moved to the "N" (neutral) position - be sure the car is safely anchored in place. Now look for the small marks on the MLPS shaft and body - they both need to be lined up for proper adjustment. Do not confuse the small mark on the shaft with the large indents on the shaft, see the picture for the proper marks. When the marks are lined up, slowly tighten the MLPS retaining bolts and recheck that the alignment is good. For on-car service, I use a small mirror to see everything on cars with dual exhaust.

Now on to the OD servo replacement. This can cause a lot of anxiety since you are in effect temporarily eliminating OD while you remove the OD servo from the case and where it is attached to the OD band. The anxiety part comes from knowing that the OD band is internal and can only be replaced by transmission disassembly, but even if you hear the band "drop" when the OD servo is removed, that's OK, you can still install the new servo and re-install the servo pin into the band. Many times, loss of OD has been experienced after replacing the servo because the band has dropped out of position and was not re-positioned prior to OD servo installation.

Before we go further, let's look at the components to get a basic understanding of how they work together. The picture shows a typical OD band along with a 2.7" OD servo and stock OEM return spring. I won't get into a discussion of the hydraulics, but the OD band is essentially a clamp that tightens or loosens around a rotating drum. The band is fixed into position at one end (note the anchors at each end of the band), with the OD servo pin engaged in the anchor at the opposite end. The pin is never loose from the band, it actually always maintains contact with the band anchor to keep some tension on the band.
The OD band tightens around the drum when hydraulic pressure is sent to the OD servo which in turn pushes the servo up into the band and then loosens when the pressure is released. The return spring helps to release the OD servo quickly and it also helps determine the rate of application of the servo onto the band. The stiffer stock spring helps to slow down the application, resulting in a smoother overall shift feel to OD. I want a firmer application, so I am installing the softer spring.

What can happen when the OD servo is re-installed is that since the OD band has some spring to it, it can fall away from the OD servo pin. Now OD has been lost since the servo pin cannot tighten the band around the drum. Problem is not found until first drive and panic often ensues.

Now that we can sort of see the basic operation we can go ahead and replace the OD servo. We have a couple of choices in regards to the band - we can let it fall loose when the servo is removed or we can try to keep it in place while we are replacing the servo. For our purposes, let's try to keep it in place.
I made a bracket to help compress the OD and reverse servos a bit in order to get the snap rings out, also works well for installation. It has a nut tacked to the upper side with a bolt threading through it and I used a couple of valve body bolts to attach it to the case. Tightening or loosening the center bolt either compresses or releases the servo.

I also used this funny looking setup that simply extends into the case to push against the band and keep it in place while I am replacing the servo. It's nothing more than a flat bladed bar (or screwdriver) sitting on a scissor jack - I'm sure that there are fancier setups but this works fine. I use the scissor jack to carefully apply ONLY enough pressure to keep the band in position - do NOT start trying to jack the car up, you will ruin the band. I just hand-tighten the jack, that's all that's needed. Note that there is an opening in the case that can be used for this purpose - if you happen to drop the band out of position, you can take a screwdriver and move it back into position through that same opening. After the new OD servo has been installed, be sure to always double-check to see that the band is in the right position. The diagram essentially shows what we are trying to do.

Ok, now we are ready to proceed. First item, before doing anything, is to make a couple of observations. Look into the opening in the case and see what the OD band looks like when it is in place. You can take a marker of some sort and put a mark on the band itself to verify that it is back in position when you are done. If you can see the mark, the band should be in the right position - if you can't see the mark, chances are it has dropped out of position.

Here's what you will see through the opening:

Also look in the bore of the OD servo and see where the snap ring is located. Some transmissions have 1 groove and some have 2 grooves. If the bore has 2 grooves, the snap ring will need to be re-installed in the deeper (upper) bore. My transmission only had the single groove.

After the high-tech "band retainer tool" is in position this is followed by installing the servo compressor bracket over the OD servo. As you tighten the bolt on the bracket you will see the servo being pushed up into the bore. Don't over-do it, just compress it enough to get pressure off of the snap ring. Be careful not to gouge the bore when you are removing the snap ring. I have a set of long needle-nose pliers with the tips ground to sharper points that I use for this particular snap ring.

Once the snap ring has been removed, start loosening the bolt on the bracket and you will see the OD servo moving downward. Remove the bracket and the servo will come out, along with some fluid. Verify that the return spring is in good shape - you can probably re-use it, or you can install a new one if you prefer. This brings me to my decision point about which return spring to use, but first some information on OD servos in general.

Depending on the year of your car/transmission, you may find that it was equipped with a smaller 2.5" OD servo and sleeve assembly and return spring. The sleeve is provided in order for the smaller servo to correctly fit into the bore in the case. The return spring is matched to this smaller servo and should not be used with the larger 2.7" servo. It is generally recommended to upgrade the smaller 2.5" OD servo with the larger 2.7" OD servo along with the appropriate return spring for the larger servo. The larger diameter servo is able to apply more torque to the OD band.

There are two return springs that Ford lists for the 2.7" OD servo. The stock F87Z-7F201-AA spring has a higher rating (stiffer) than the hi-performance F2VY-7F201-A spring. The lower rated (softer) hi-perf spring allows clamping power from the OD servo to be applied faster to the OD band, which should result in a firmer shift and less slippage, especially if you are running significant hp through the driveline. I spoke with a couple of local shops that have good reputations (no transmission repair chain stores please!) and that also do performance rebuilds. They recommended the hi-perf spring even in a stock driveline for a firmer (faster) shift so that's what I will install, especially since I already have the firmer 1-2 and 2-3 shifts from the J-mod and piston/accumulator spring changes that I have done. The idea is that since the hi-perf spring is softer, it offers less resistance to the OD servo when it is being pushed up against the OD band. The OD servo moves faster so that the shift into OD should be faster as well. What I am not sure of is how the softer spring will affect the 4-3 downshift as well as the 4-2 downshift (which you should try to avoid if possible, it's pretty hard on some of the internals). The only way to find out is to try it - the worst case is that I will have the hassle of getting back in there to install the stock OD servo return spring if I don't like the 3-OD-3 upshift/downshift with the hi-perf spring.

Another comment about all the servos, pistons/accumulators - each has a fill and exhaust circuit that are controlled through the valve body. The fill circuit provides fluid to move the servo/piston forward (up), and the exhaust circuit allows that fluid to escape and allow the servo/piston to move back (down). There are holes in the separator plate that are modified (enlarged) by the J-mod to allow faster fill/exhaust - this creates less overlap between the shifts as well. This combination results in the faster/firmer shifts that you feel, which can be further tweaked by changing the various springs, such as what I have described for the OD servo. With this said, bear in mind that there is only so much change that can be done to the OD application without also modifying the separator plate to affect the fluid application to the OD servo itself, or by adding an aftermarket tune to the PCM. In my case, I am not modifying the separator plate any further than the J-mod changes nor am I installing a tune at this time.

Take the new OD servo and thoroughly lube the perimeter seal or dip it into some transmission fluid. Place the return spring onto the servo and gently push it up into the bore - you may want to wiggle/rotate it a bit to help. Be careful of that new seal! As you are doing that, check the position of the OD band - you should see it move just slightly as the OD servo pin makes contact with the band anchor. Now using the compressing tool/bracket, continue to push the OD servo up into the bore until the proper notch is visible. Don't get carried away and push it too far, just enough to expose the notch. Install the snap ring, being sure that it is fully seated all the way around on the groove. Now slowly release the pressure on the servo. Remove the band retaining tool and then AGAIN, check to see that OD band has not dropped out of position. You can try to push it a bit with a screwdriver to verify that it is not loose. If it's loose, you will know as it will generally flop around.

This is also the time to replace the reverse servo/cover and the 2-3 piston/accumulator if you wish, or do any spring mod/removal to the 2-3 piston/accumulator. I consider these as wear/maintenance items since they have rubber seals. You can use the compressor tool (or helper) on the reverse servo, but the 2-3 piston/accumulator is simply held in place by a 3-tab cover. It just pulls out. I have found that removing the spring entirely in the 2-3 piston/accumulator results in a firm but not harsh 2-3 shift. You can also replace the 1-2 piston/accumulator and/or do spring changes to it, but it is accessible with the valve body in place, so you can do that on a later fluid/filter change if you wish. My own preference is that if I am going to the trouble of removing a servo or piston/accumulator for any reason, I am going to replace it with a new one, just cheap insurance.

OK, our valve body is done and we have installed the new EPC solenoid and OD servo/spring. We are ready to re-install the valve body. Begin by getting all of the valve body bolts handy and remember to include the EPC solenoid bracket and the shift linkage rooster comb spring as well. Everything should be clean. Place the new upper separator plate gasket onto the separator plate - you can run a little assembly lube or transmission fluid onto it to help keep it place. If you have a newer year valve body in an older model, be sure you have the two little guide pin spacers installed. The guide pins will also help to keep the gasket aligned, but take a lot of care not to mis-align the gasket on something as you install the valve body. Remember to also install the small round screen or the rectangular screen back into the case if they have fallen out. I use some assembly lube to help keep them in place while I am installing the valve body.

As you put the valve body back into place, be sure that the shift linkage is properly located into the manual valve - very important! Just slide the manual valve back or forth to wherever it needs to be. You also want to be very sure that the top separator plate gasket does not get hung up or torn as you put the valve body into position.

Take a couple of the longer center 8mm bolts and hand-thread them into place to keep the valve body from falling on your head. Now begin to loosely install all of the valve body bolts, remembering that the longer bolts install through the cover plate, shorter bolts everywhere else. We want to install the bolts finger-tight to allow the valve body to shift slightly if needed to seat properly. Install the EPC solenoid bracket and the rooster comb spring in their proper positions. You will also need to install the shift solenoid pack as well as the TCC solenoid if you did not already install them and remember that the shift solenoid pack uses one of the 8mm valve body bolts as well as a separate 10mm bolt to retain it. As you did with the ECP solenoid, lube the o-rings on the shift/TCC solenoids and gently push them into place. You will note that the TCC solenoid is installed first, with the shift solenoid bracket installed over it.

At this point the valve body should be in place, solenoids in place, EPC bracket and rooster comb spring in place, shift linkage aligned in manual valve. Look all around the edge of the valve body to ensure that the gasket has not slipped somewhere, but be aware that it can slip on the inside somewhere - that's why we go slowly when installing. Using the bolt sequence chart, start at bolt #1 and snug it up, then follow the chart all of the way around. Tightening will be done in 3 steps. First step is to gently snug the bolts so that the valve body is resting against the case. Second step will be to go around again and torque to spec (90-120 in/lbs). Third step will be to wait a few minutes for gaskets to compress a bit and re-check the torque. Remember to also torque down the 10mm cover bolts if you have not already done so, sequence is from the center of the plate outwards.

An important note about proper torque - use an in/lb torque wrench! 90-120 in/lbs is no more that 10 ft/lbs on a ft/lb torque wrench, and on the average home mechanic wrench this low value is generally inaccurate. You don't need to spend a lot, but get the right tool to ensure that your work is not wasted by possibly warping the valve body by inconsistent and/or over-tightening. I've tried to guess at hand-tightening to this value and it's really hit-and-miss.

Before going further, check that the shift linkage is working properly by moving the gearshift selector through the entire gear range. You should hear/see an audible click as the shift linkage moves the manual valve back and forth. The click noise is from the rooster comb spring tension on the shift linkage. You also want to verify that the end of the parking pawl is in the proper position so that the transmission will be locked when Park is selected. You will be able to see it move back and forth as the linkage moves.

Next step is to re-install the temperature sensor and the wiring harness. The later year plastic assembly is pretty straightforward, but the earlier year harness is fairly simple as well since the lengths and plugs are set up for the specific components. Be very sure that everything is fully connected and that all tabs are locked together.

Now install the new filter and remember to use the new gasket at the neck. Use assembly lube or transmission fluid to lube the gasket and push it up until it is fully seated. It will stay in place.

We are almost there, our next step is to re-install the clean pan (with magnet) and the new rubber molded pan gasket. No sealant is required for the gasket and it has spacers molded into the rubber to prevent over-tightening. Hand-tightening is OK, but don't get carried away - the gasket does not need a lot of pressure to seal properly. I also like to use some blue Locktite on the bolts just to ensure they don't loosen, but it's not really an issue.

Final step is to re-connect the battery and fill the transmission through the dipstick tube. BE SURE THE CAR IS SAFELY CHOCKED IN PLACE. If you have drained the torque converter as well (on units equipped with drain plug), you can start by adding about 4 qts, then start the engine for about 15 seconds to allow the fluid to be drawn into the converter. Repeat this step.

If you have not drained the converter, add a quart or two less than you initially drained and then start the engine. Yes, the transmission will be overfilled for a few seconds until the fluid is drawn into the internals, that's OK. Foot on brake, move the gearshift selector through the entire range several times, leaving it in each range for a few seconds. This allows the fluid to re-enter the empty valve body circuits. Initially you may not feel anything, but you should soon feel the transmission engage the various gears. Now put the selector in park and add fluid until the full range on the dipstick is reached and then go for a drive.

Driving - check in particular for clean up-and-down shifts and use the selector button to turn OD on/off to verify proper operation. Verify that downshifts are operating correctly - at about 50 mph, give enough gas to ensure that the transmission is coming out of OD into 3rd gear, then you can give it more gas to downshift to 2nd gear. You also want to feel that that torque converter is locking in at normal cruising. There is no need to immediately flog the car, just allow it to get to full operating temperature, then re-check the final fluid level. What you are trying to do is to verify proper operation for all the types of driving that you do. When you return from that first drive, double check the fluid level. Look below the car for any leaks as well, both immediately after parking and a few hours later.

My Driving Observations:

  • 2002 4R70W, 80,000 miles, with fresh Mercon V fluid and new filter
  • New 1-2/2-3 shift, TCC, and EPC solenoids
  • New OD servo and hi-perf (softer) return spring
  • J-mod (separator plate modification) done at 60,000 miles
  • 1-2 and 2-3 pistons/accumulators replaced at 60,000 miles
  • 2-3 piston/accumulator spring removed at 60,000 miles
  • 1-2 piston/accumulator purple (softer) lower spring, green (stock) upper spring done at 60,000 miles
  • New MLPS
  • New shifter linkage shaft seal
  • Valve body disassembled and cleaned
  • Sonnax Main Pressure Regulator Valve installed in valve body
  • Sonnax OD Servo Regulator Valve & Sleeve installed in valve body
  • New valve body/separator plate gaskets

  1. First order of business was to verify that all shifts were taking place and that there were no leaks or parts falling out of the car. This was to verify that the mechanical installation was properly done and that the OD band had not somehow fallen out of place. Everything seemed to function normally on a first careful drive
  2. I noticed that the first drive had somewhat softer shifts than subsequent drives. I attributed this to the PCM "re-learning" shift parameters as the shifts did indeed firm up over the next few days. Remember again that this is limited to factory overlap settings unless you use an aftermarket tune.
  3. 1-2 shift is firm under normal driving but has a good kick at higher throttle applications. I did notice that the timing of the 1-2 shift has changed at normal driving and that the shift occurs just a bit sooner. My opinion is that if the line pressure has increased slightly due to replaced and/or cleaned internals then the piston/accumulator may apply a little sooner. At any rate, it feels fine, not too early, perhaps I was used to the slightly delayed shift.
  4. 2-3 shift is unchanged and firm.
  5. 3-OD shift is much improved. Remember that I was wondering about using the softer (hi-perf) OD servo return spring but after actual experience I am happy with it. The application of the OD band is firmer and faster at all throttle positions. The OD-3 downshift is good too - there is no lurch or anything annoying about it. I'm very pleased with the net change in the OD band application which is what started this whole thing and would recommend the softer OD return spring even with stock driveline components and factory calibration, which is what my car has.
  6. MLPS setting appears to be fine, with no strange or intermittent shift characteristics observed.
  7. All in all, the transmission feels that it is more calibrated in regards to upshifts and downshifts, which I think is important to any vehicle, but especially to heavier cars like the Crown Vic. There is no hesitation or extended overlap where the car sort of wallows around waiting for a gear to be selected.

The original Microsoft Word Document version of this write-up can be viewed here: http://www.crownvic.net/bok/ODservo/ODservo.doc

A Power Point picture slide show of the pictures seen above with captions can be viewed here: http://www.crownvic.net/bok/ODservo/OD.ppt

1995 P71-SOLD
badgeless grille-tinted tails-Hrbacek whiteface gauges-Pioneer spkrs-12" sub-reworked tranny internals-Sonnax/jmod upgrades-ceramic pads-urethane swaybar bushings-new timing chains/guides/tensioners-Granatelli plenum-75mmTB-MZT-NGKTR6 plugs-180d thermo-Steeda UD's-BOC 93tune-Thrush mufflers-LED interior/door puddle lights-Projector HID retrofit-MM corners-LED signal mirrors-17x8 TorqThrust wheels-235/55/17 Contental ExtremeContact DWS tires
2003 LX Sport-SOLD Hrbacek whiteface gauges-Pioneer spkrs-12"sub-reworked tranny internals-Sonnax/jmod upgrades-urethane swaybar bushings-Thrush mufflers-ceramic pads-Steeda UDs-LED interior/trunk/door lights-rebuilt 3.27 axle
Current = 2011 Silverado, time for a change