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Fox street setup

3K views 12 replies 10 participants last post by  SuperChicken 
#1 ·
I have a 92 coupe with springs, struts, subframes. I recently picked up an ISF, and very impressed with how stable the car feels in all around driving. I don’t autocross or anything like that and have limited experience driving newer vehicles. So my question is can I upgrade the fox to feel that good? Is it a matter of going to coilovers?
 
#3 ·
Lexus?

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#9 ·
For those that only bleed blue, the OP is referring to a Lexus ISF with a 5.0L Japanese V8 that debuted in 2008. It's a great performance compact sedan for its time. Behind the wheels, it feels light years ahead of a stock Foxbody for sure. My wife likes it for the size and I love it for the motor and trans.

I also happen to have a '90 Fox convertible with a complete MM suspension, minus their adjustable rear sway bar. I feel confident driving both vehicles hard into the corner. The ISF provides more of a refined feeling and it tends to give you more false confidence to keep on pushing it harder. The Fox is more raw, from the steering to the suspension, you're getting feedback from the car in every angle.

Both are a blast to drive, but they provide 2 totally difference driving experience. My suggestion is to look into doing a complete MM suspension setup. Do that with some upgraded brakes and you'll wonder why you never did it sooner.

Many moons ago, Jack Hidley provided some solid advice on MM spring rates. I've been happy ever since!
 
#10 ·
Stangin, this is exactly the feedback I was hoping to hear. For those asking, sorry, I didn't respond back until now. Yes, the ISF is a Lexus IS model sedan but setup for the track right from the factory. 416hp V8, 8 speed auto, 14" brakes, IRS, 9" / 9.5" wheels. Its a great package in my opinion. Could be a little larger in the back seat for passengers, but not any less room than the stang. What year ISF do you have?

I had the stang out this past weekend, and on back roads coming out of turn, it gets a little squirrely in the rear. The 363 makes 435 rwtq at 4300 with 3.73 gears which makes for interesting driving if you keep your foot into it. Has me wondering if this can be cured with IRS or PHB/TA combo(?)

The ISF on the other hand has me spoiled since its my daily driver. Of course it makes no where near that power to tire, but pulls up top and feels great into 140+. In fact it really does such a great job, I have to look down to realized how fast I'm actually going. In the stang, you really have to be a better driver.

Stangin, it shows you have a coyote in your signature, so your car is def making some power. Do you have any issues with putting the power to ground with your setup? From 0-60 or spirited back road driving? From the 0-60 there's no way my stang could keep with the F ( without slicks or something ). The F sticks, and goes, and you don't have to think about it too much-- just focus on driving. Mustang takes a lot more skill to get it moving and then not blow the tires off. The dual friction mcleod clutch is also very grabby, which doesn't help when driving around town. I'm guessing the coyote doesn't make as much torque so maybe that's a bit easier(?)

You def nailed it about the stang just feeling a lot more raw, unrefined feel. And with the power to weight, it accelerates quickly ( when you have traction ).
 
#12 ·
Assuming the Fox has a stock rear suspension, then yes the oversteer you feel can be corrected. But not using the stock parts. This is because the upper control arms tend to bind at the limit causing unpredictable outcomes (i.e., snap oversteer). There are four ways to go:

1. Remove the DS upper leaving what is called a Poor Mans 3 Link (PM3L). Here you have to add a PHB or Watts Link to control lateral movement. Stiffer rear springs will also be needed now that most of the bind is removed. The remaining upper merely controls axle roll on acceleration and braking. The down-side is that there is a lot of stress on the one upper's chassis side mounts which tend to tear. I used an upper with rod-ends on both ends. This causes a lot of NVH transfer into the cabin. I've read but not experienced that some floor tearing has been attributed to the use of rod-end uppers. Ride quality is improved. Stock exhaust can be used.

2. T/A - this replaces the uppers entirely with the T/A. You also need the same PHB or Watts Link to control lateral movement and use stiffer rear springs. This set-up completely re-engineers the rear suspension geometry and works very well. Ride quality is improved. Stock exhaust can be used but may need to be slightly moved. Ultimately, I put the entire MM works on my 86. Huge improvement.

3. Steeda 5-link. This replaces both the lowers and the uppers with Steeda designed pieces, and also uses a PHB. The "5" link is the two lowers, the two uppers and the PHB. I've read good things about this kit but it does limit exhaust routing.

4. Cobra IRS. Many have done this swap. The cost of entry is high and then you generally need to upgrade the IRS pieces to make it work well. You will need the iRS specific springs and shocks (Fox pieces are not valved correctly or the correct rate). For a non-track daily the upgrades many not be needed. I did like the ride quality of my 01 Cobra but the rear was not very stable when cornering or upon hard launches. Ride quality is improved. IRS specific exhaust is required. New wheels with offset consideration to fit the wider track.

A very cheap huge bang for the buck improvement is doing the PM3L. The DIY element is pretty easy; if you can do control arms and springs. Not much to remove. And, some of the pieces can be reused if you go with the T/A. The others are not complicated but require additional skills, some welding, rerouting the exhaust and more money.
 
#13 ·
Yes, you absolutely can have a mustang that rides and corners as competent as a modern car. The only catch is you have to completely remove and replace ALL of the original Mustang suspension parts. Basically the MM max grip box will get you there.

And for $5g's it's an absolute bargain considering how expensive modern cars are.
 
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