Most likely the overdrive band.

I'm sorry this thread has gotten so long.

My basic questions at this point are:

Should I take the car in to have them check out the transmission-is there any point in it?

I drove it yesterday for 200 miles at 55-70mph with no slip. Should I just let it go--wait until it fails if it's going to.

Is there perhaps something that can be fixed without taking the transmission out? I don't have much knowledge on how they work or how bands do.

Thanks for looking. Scott.

My 2001 with 140,000 miles also does this. I am going to try adding some SeaFoam Trans Tune. My fluid level is correct and the fluid looks and smells fine. I put on 100 - 200 miles per day. I will let you know the results tomorrow.

If i put my car in 2nd gear at a dead stop and i go WOT the tranny slips and shudders really bad. car has 140,000 and is a p71. not sure if the filter has been replaced the fluid is a brown / redish color and needs to be flushed. I have the filter and fluid (mercon 5), plan on doing the filter and fluid when I get time to do the J-mod but i need to get the sep plt gasket. Do you think the slipage and shuddering will go away if I do this? it only slips and shudders in 2nd gear. If it doesnt what will need to be replaced?

Here is some info that may be of help. It was all written by JohnG on 12/31/05. I just cut and paste it here:

Allow me to clarify:

ALL domestic OEs program their "lock-up" TCs to slip some. Not JUST during "steady state" cruise, but ALL the time. The reason is VERY simple: Misfire diagnostics.

Disabeling OD will NOT change wether the TC slips or not, it is in lock-up in every gear but 1st (when it is hydraulicaly prevented from locking up).

Wether the TC shudders in lockup has much less to do with friction modifiers than it does to absorbed calsium by the friction elements. This is also what "takes out" your friction elements in the clutch packs (excessive calsium).

Calsium is absorbed both over time (normal wear), and most importantly with HEATand PRESSURE. The more HEAT (or pressure) you have in the trans, the more calsium is absorbed by the friction elements (clutches). As calsium is absorbed from the ATF, the ATF get MORE "grippy". With PCM controlled shift strategies, the PCM will reduce line-pressure DURING shifting to maintain good shift feel (as the ATF wears - depletes calsium etc). When you change OLD (burned or very old) ATF you suddenly DROP the grip of the ATF (old = very grippy, new = normal). The shifts get VERY soft almost instantly, and if the PCM is not "reset", or the vehicle is used to tow (or haul heavy loads) before the PCM corrects it's strategies, your clutches burn up from excessive slippage - soon.

The smaller 11.25" TC (PI and HPP) is WORSE for shudder than the larger 12" (standard) because both the clutch AREA and RADIUS are smaller.

The PCM attempts to maintain a "slip" of *about* 32 RPM during ALL lock-up conditions (2nd-4th gears, any speed). Obviously, as the friction material gets glazed from wear or heat you need more TCC pressure to maintain the same Tq throughput. Also, with old/worn ATF which is very grippy, the TC will have a much harder time slipping smoothly that with newer less-grippy ATF.

As most anyone can figure out, the greater the vehicle's LOAD (either carried or towed) the more pressure the TCC sol will need to apply to maintain the slip rate during any given situation. Downshifting one gear can help, but is is NOT a solution. Shudder is also less likely on vehicles with steeper gearing (larger ratios) like 3.55 or 3.73 because the Tq demand of the engine is less for the same wheel Tq. That means the Tq that the TC must "pass" to the wheels is less, making the TCC pressure less to attain the same slip rate. This is one reason that towing package equipped vehicles have deeper RARs (typically 3.73 or 4.10).

When shudder occurs you generate LOTS of heat in the TCC friction area. If left to shudder for any significant length of time, the clutch will be perminantly damaged, and the ATF will locally overheat very badly. When this happens (heat and pressure) will force even more calsium into the friction elements. Once calsium is in, it NEVER comes out. When you change ATF, you have that slippery calsium glazed onto the clutches, and new less grippy ATF on top. You get VERY smooth TCC lock-up, but it takes a LOT of TCC pressure to maintain the correct slippage. This again overheats the ATF and friction material, and now the TC is done for. If you are lucky, all you need is a new TC. But if the ATF got too hot or for too long, the friction elements in the trans will be damaged as well.

The TCC solenoid is an "on/off" type solenoid. It controls the TCC pressure by the PCM varying the DUTY CYCLE of the solenoid (on/off time). You MUST NOT mess with it.

The folks at SCT are VERY well aware of the TC slippage problem. JW suggested YEARS ago that you change your ATF often, and use ONLY Mercon V fluid. This was before Ford was even saying it "officially" as I recall. He also knows (and NO "tooners" even have a clue) that when you change the TCC slippage to "zero", you must also adjust the misfire detection alogrythms to make them less sensative, or you will get false MILs for engine misfire. SCT allows the TCC duty cycle to be set to it's maximum, to reduce slippage to very near zero under most conditions. This keeps your ATF COOLER, that is a good thing.

Why is this done? Simple. If you have a M/T, your clutch has "dampner springs" between the input shaft of the trans, and the clutch itself. These springs absorb the radial vibrations of the trans and driveline (or engine) from the other component (engine/drivelne). With a lock-up TC clutch, ther are NO dampener springs. In fact, the connection from the tires all the way to the crank is 100% solid. ANY vibrations in the drive line will be transmitted directly to the engine via the crankshaft. Misfire detection is based on the waveform of either the crank (most cases) or cam sensors. So, any external vibrations transmitted to the crank can show as a misfire. Solution: allow *some* slippage of the TCC to "absorb" those small vibrations.

This applies to ALL of the current Ford ATs: RWD, FWD, AWD including: AODE, 4R70/75W, 4R100 (not E4OD), 5R555, Tq Shift (5R100) and all FWD transmissions.

The ONLY ATs that MUST NOT use Mercon V ATF are: E4OD, 4R100, 5R100 (Tq Shift). You WILL fail them w/Mercon V. In fact, if Mercon V is ANYWHERE on the bottle, even if Mercon is listed as well, DO NOT USE IT in one of these: E4OD, 4R100, 5R100!


Edited by JohnG (12/31/05 09:26 AM)

So I guess what I got from this is I shoukd get a tune to get rid of the slipage and alow the TC to be in lock up 24/7? Im still changing the fluid and draining the TC. Ill use mercon V and use the friction modifier that you use to put in the 8.8 trac lok diffs.