So as may of you know, I'm racing my P7 in 24 hours of Lemons, and we were actually pretty successful our first time out. (50 out of 132 overall and 21 out of 62 in our Class)

Our suspension, which is stock, was very much a limiting factor. I have set out researching what will work best for our needs.

In about a week I (as soon as my trans is all back together) I am having the car corner weighed so I know what our front/rear distribution is. My rough estimate says 3700LBS, with about 53% over the front, but we'll see.

Our priorities are as follows:
1) Has to be a durable and reliable as stock. We were successful in our first race because nothing broke. We want to maintain that reliability.
2) Needs to make the handling more neutral. We had quite a bit of understeer, although not as much as you would think. I think taking 200+ pounds off the nose helped a lot.
3) Need to stiffen up the front, and make the rear less squirrelly under hard deceleration. (Our brakes are far too good for our current suspension.) We had a ton of nose dive and rear wheel lift under hard brakes.
4) All springs, front and back, MUST be linear. Progressive rate does not work well in racing.

Based on my rough measurements so far, we are probably going to need about a 600lb front spring. Not sure about the back yet.

It also seems, based on my research, switching out the rear upper and lower control arms seems to be of great help. The MDEC set up seems interesting, but I had a conversation with Maximum Motorsports, and they had this thought....

"Just like the 1979-2004 Mustang rear suspension, the P71 rear suspension is overconstrained. Given this, do not install polyurethane bushings or bearings in all eight rear control arm locations. If you do that, the ride and handling will be terrible. You must leave at least four of these bushings with rubber or very soft polyurethane material."

I'm open to suggestions, and feedback on what you guys use, your experience, and things you have used and would not use again.

Thanks,

Chuck

Totally agree with Maximum. The suspension will bind. There are some that think the flatter feel that comes from them is better handling. It's just the suspension can't move any further But that's applies to the trianglated 4 link. If you have a later model with panhard bar the action is different.


What year? Going to 600 sounds like an 03 and up model.

Adding stiffer to the front will induce even more understeer. So you need stiffen the back even more. With springs or swaybar or both. I've run some 200 lbs in the rear of the 91 caprice. But it would be too big of a diameter for a panhard set up i think.

I guess I should have mentioned it’s a 2011. Yes, binding is bad, definitely want to avoid that.

When we go lower, I know that will induce a little negative camber, which for us is a good thing.

I’m having a tough time figuring out rear spring rate, because estimating weight is a guess at best. Once I know our actual rate, it’ll be easier to sort it.

It does seem for the rear, upper and lower control arms, are a must. The CHE Performance arms seem robust, appear well made, and are a little cheaper than the Heinous. Of course the Heinous are aluminum and likely lighter, which of course is a good thing.

Lowering will 'automatically' add negative camber. That's what it's supposed to do in a turn when that side compresses. Issue at least with b-bodies, lowering you change the camber curve. When the lower arm is parallel to the ground, you've achieved max negative camber. If you're parallel at rest you have max neg. As you push down more like in a hard turn, it now starts loosing camber rather than gaining. But the uppers come into play to as to what the top of the spindle change is. Not sure how the vics arm are relative to each other. Caprices actually can handle better at near stock height. A tad lower to help center of gravity is about it. Real low is more for looks than handling.

If you don't mind spending the bucks, last set i just got for the other caprice is the moog cvpi replacement, 81479. 82 bucks shipped and tax from amazon. Rockauto have at like 65 but then add shipping.

They work out to almost impala ss height in a caprice. These have a 160 rate. Which is one of the numbers i've heard for stock pi springs. With them as a know, you already know how to proceed figuring out what you want.

Thanks for the info. I’m actually having an email conversation with Chris over at ADTR. We’re kind of spitballing a game plan.

Cool. Would love to hear their thoughts if you don't mind sharing.
Racing stuff tends to be secretive so would understand if not.

A little history for the younger viewers. Carroll Shelby for his first gen Shelby Mustangs dropped the pivot point on the upper control arms to increase the negative camber rate. It was the hot ticket for regular Mustangs to do the same by drilling new holes 1" lower in the shock tower than the original holes for the arms.

The factory rear end setup will accept 2.5" coil springs so getting different rates and lengths isnt a huge deal.

I'm going to try out 3.1 degree of negative camber at our next luckydog race, as we had issues with understeer. Although its an aero it might help you with some setup ideas. We are running 2012 boss 302 rear springs and shocks, cut springs upfront with p71 shocks. 1/16 toe in and 5 degree of caster. 275/35/18 RS4 18x9.5 et10 rim and 12mm spacers. Poly bushings everywhere upfront and almost nothing left in the car. Doors are just skins, trunk is just a skin and pin on, next to go are teh wipers, hvac is all gone, interior wiring is all gone. Shedding weight should help with the understeer.

Yep, we’re all stripped out like you. I’m actually having the car weighed soon to see what rates we need for our springs.

We’re going to slowly move to all Polly bushings.
Chris is actually recommending the Massive Traction system for the rear. (It’s very similar to the MEDC system posted here)
I’m not 100% comfortable with the idea of no bushings in the rear, My gut says this is going to put too much stress on the mounting points.

Our first step is new front and rear sway bars.
I’m leaning towards the Heinous billet upper and lower arms and watt link.
We’re likely going to do coil overs at some point.

Thanks for the alignment recommendations.

You can always beef up the rear suspension mounting points, thats not really a big problem.

We had huge problems with rolling over the tire due at the first race due to stock tire sizes, and stock everything upfront. 3.1 of camber might be a little too much, most seem to end up in the upper 2.x range but its a start since 3.5 is possible with the stock aero adjusters at our ride height. Depending on how it handles im going to add sway bars. Im hesitant without testing what we have, it has the 29mm ( i think) up front and a rear bar already. We have changed so much and im trying not to add another variable to the mix.

I will also end up on coilovers but im slowly fixing bigger problems. The p71 front shocks/cut springs were cheap and boss302 rears/springs were free so we will try them out.

Im going to try heim joints on both ends of the lower rear control arms and poly bushings up top on the factory arms. If it binds i will switch to a Jimmy Joint on one end of the lower. The triangulated 4 link isnt great but its what i have at the moment.

I'm not well versed in the pre-2003 cars, because I don't have one. But our buddies are running an 01 (I think it's the same or similar suspension to yours. They run these springs from speedway motors.

Tru-Coil 5x13 Oval Track Racing Rear Coil Spring 175 lb Rate
252513-175
Eibach 1100.550.1100 Front Coil Spring, 5.50 O.D. X 11 Inch, 900 Lbs 330115-900

I am not sure which shocks they run with them. They are in a manual conversion car. They sit low, corner flat, and move VERY fast. Especially on a stock, rebuilt, junk yard motor.

The boss 302 rear spring we have is 185lbs Do you know their ride height with those front springs? I may be inclined to buy it if its close to the same as what we have. Coilovers are optimal but we have other things that need attention first. Sway bars are probably next, im going to see how it does at VIR this sunday.

Get a second set of rear control arms and watts link and weld them back to back, should reduce flexing. You can solve your understeer with a 26mm civvie front sway bar or 21mm rear sway bar from a marauder or HPP cars. Use new cop shocks and springs. The biggest trick will honestly be wider rubber and possibly better brakes, easiest way to achieve is probably used Cobra or GT500 wheels with a 275/?/17/18 tire. It isn’t perfect but it should help a lot for Lemons in terms of staying in budget and still improving your handling.

WE took our 1996 out to a hpde at VIR in preperation for our next Luckydog race at CMP

The changes flat out worked, it has grip for days and honestly needed more speed since it really couldnt get fast enough to have to brake in a lot of the corners.

The understeer seemed to be gone, it didnt have enough power to oversteer, so all in all it did great.

It liked the 3.1 degrees of camber up front, the stock sway bars didnt really seem to hinder us at all. 275/35/18 hankook rs4 are amazing, as well as gutting the entire car had to help. If i had to guess we are sub 3200lbs. We definetly need a bigger trans cooler since we saw 200+ degrees trans temp, and we are making the old trans cooler the power steering cooler. It would whine a little bit until it cooled off. Its a late model P71 pump.


I bought a containment seat since the regular kirkey wasnt my favorite. That should help with the lateral g's we can pull now, im sure its over 1.0

Sorry it took so long to respond...The 01 Vic sits low. I’m not sure how low, but low. If I had to guess 2-3” lower than stock. Here is a photo.

https://24hoursoflemons.smugmug.com/Race/Sears-Pointless-at-Sonoma-Raceway-April-2021/i-n2xLxLm

On a side note, we had the same trans issue as you. We ran as high as 264 on a mild (73 degree day) with the average operating temp of about 240-250.

We have taken a number of steps (guided by Eric 88GrandMarq)

There is a discussion about it here, with photos and a step by step of what we did. We’ll find out at the end of May if it all worked.

https://www.crownvic.net/ubbthreads/ubbt...;gonew=1#UNREAD

That is definetly lower than our cut stock springs and the boss 302 rear springs. My only hesitation with going lower is that the pitiful front shock is probably going to have almost no travel.

I think a fuel cell is our next upgrade then coil overs. We cant make 1 hr 55 minutes on the stock 20 gallon tank. Luckydog has a 2 hour maximum stint with a 5 minute minimum pit time. the max capacity is 24 gallons, that extra 4 gallons should get us there. We did find out that the stock tank will starve at roughly 3 gallons left in the tank, that is also roughly when the fuel light comes on. I really dont think going after those 3 gallons with a hydramat setup is going to get us to our goal.