[BlueFlameFord]

QUESTION: how would YOU prep a road race 87 Fox Mustang?


we have a 1987 LX with a 2.3 in it. We are fine with the motor but need direction on handling/suspension.

we want to take it racing/competition (road course/autoX) and need to upgrade our suspension & handling.

So, for handling upgrades, Where would you start?

Do they have serious understeer? Sway bars (what model & years cheaply fit)? Do we lower it? coils? HD shocks?

Any advice appreciated.

We'll post pics of our progress.




EDIT: I know speed = $ (how fast do you wanna go means how muchg cash do you wanna waste)

Perhaps I should also mention "cheaply" and on the low-budget.

[battlr]

I know you said cheap. Someone else I'm sure could help you there. But I figure go with the best, do it right first, so you never have to do it again. Or take a chance at being disappointed for that matter. I feel the best suspension upgrade is going to be with a combination of Griggs and Koni. Griggs can be expensive. Packages range 3, 5, 7, and 13K. 13K for the world class package. But you can't beat it, its a track proven winner time and time again.

[J. Rhapsody]

I you dont know, fox chassis cars have snap oversteer. all you need is a rear sway bar and a 3link panhard bar or wattslink. I think 3links are better for road racing or TRuck arms like stock cars use. SFC's obviously. you want to know where to get parts from look at my sig. for a bit of fox body info. which expands to fox chassis cars including sn-95's. you'll eventually want an 8.8 axle which only v8's have.

[MJ91GT]

You didn't mention your experience level, if you're a beginner, I'd say do everything you need to so that the car is safe for the track. This means good suspension bushings, good brakes, and good tires. Don't forget that this driving puts a huge strain on everything, on my first day, the car overheated because the original stock radiator couldn't handle it, check the small stuff, tune up, radiator, alternator, hoses, etc.

Once the car is safe to drive at the limit, get some seat time.

Don't make the mistake of throwing a bunch of parts on the car that don't help you because you don't know how to drive, take some training classes or get an instructor from the club you're running with to show you the ropes. Your driving will be the thing that makes the most difference.

The first thing I'd upgrade on these cars is the brakes (assuming your suspension bushings and tires are sound). You'll find the stock V8 brakes will fade almost instantly, the 4 cyl brakes will be worse. Grab a set of brakes from a '94 or newer car from a jy or get a decent brake kit (you'll probably have to upgrade to an 8.8" rear end- you can get that from a donor car too). Here's a site that covers the upgrades: Sn95 Brake upgrades

To answer your question, yes these cars understeer, the 4cyl probably not as bad as the V8 but still. If you're going suspension, get some rear control arms from a reputable company (I recommend maximum motorsports) and a panhard bar. Those will make a big difference along with a good set of springs and shocks, maximum motorsports, griggs, steeda, and probably a list of other companies will have great recommendations to give you over the phone or via e-mail. Get in touch with them.

[billf]

I have raced Fox chassis in SCCA ITB for many years. The best, least expensive set up would look something like this.

GT sway bars, cut down stock springs (optional to use GT springs, depending on track surface), Sensitrack struts (Monroe), hard durometer bushings in the front A arms, home-made K member lower brace, brake ducting to front calipers, steel braided flex brake lines, 3.45:1 differential gears, with welded differential. We preferred to use 14X6 steel wheels, with lots of offset. A better idea is 13X6 wheels (very light), with offset that will clear the brake rotors. I am a believer in low rotational mass concepts.

Linkage in the rear is the secret of Fox (M3), and M4 chassis' handling. Many add-on pieces exist to cure the inherent ills of the four link designs, but there are other things that can be done, especially for the budget minded. Understanding of the actual problem is needed, first. Best reference is the Mathias book on Mustang...the second one deals with chassis, and solutions for various types of applications (street, drag, road racing, etc). A must read, in my opinion. However...

The essence of the "handling problems in the rear of the Fox" is this: A four link suspension that has to locate both laterally and longitudinally uses arms that are not in the same plane. Both uppers and lowers are set in rubber, and when the car is cornering that rubber is forced into angles not consistant with the opposing arms. Therefore, it creats a progressive spring rate (rubber is a spring, here) that approaches infinity (engineering term meaning higher, and higher rates). In the rear, when the spring rate approaches infinity, the car will oversteer. It happens quickly in the Fox, and is frequently referred to as "snap oversteer". Above is the problem, below is only one of the many solutions.

In the rear we initially used replacement medium durometer bushings on the upper arm rear bushings, with new upper arms from Racer Walsh. For a race/track car, a better solution is the upper arm rear bushing replacement from Walsh, with spherical bearings (fits the large cast eye on the differential housing). A better solution (more money, tho) is to use complete upper adjustable arm with spherical bearings in front, and then use Walsh rear spherical bearing replacements in the rear. Note: these upper arms may be questionably legal in IT.

I do have positive feelings for them relative to legality, and I can make arguments for legality. Not all will agree, however, so I won't discuss that here. You decide after reading the rules yourself.

These will not change the basic geometry (which is not the basic problem), but will attack the snap oversteer problem.

Incidentally, the 7.5 rear works very well in IT. (Also, the 8.8 is ILLEGAL in IT...car was never produced with it, and you are not allowed to create a new model.)

I hope this gives you some insight. Powertrain ideas were not included, but I can share them also if you are interested.

Good racing.

Bill