Discuss 90' Fox body chassis question. on AllFordMustangs.com, the place for Mustang enthusiasts.
Welcome to our Mustang forums where Mustangers come together to hang out, discuss and enjoy their favorite Mustang hobby with fellow Mustang enthusiasts. We invite everyone to read, post, and enjoy our Mustang forum as well as the many other sections of our site.
You are currently viewing our forums as a guest. By joining our community you gain access to post topics, communicate with members, upload your photos and access many other special features. Registration is fast, simple and free so why wait, join our Mustang community today! If you have any problems with registration or your account login, please contact support.
I have a 90' LX 5.0, 5-spd, 3:55, when I bought the car the struts and shocks were really worn out and the car was a handfull to drive. I have replaced the struts and shocks and the car is much better, however I feel something in the floor board when I hit bumps that acts like the control arm bushings are shot. Visual inspections lead me to believe that the bushings are ok.
The car "walks" in corners and on rougher roads, is this "walking" feeling possably an indication that the rack is worn out or something. This car was also used on the strip and I have been told that if it did not have chassis stiffeners on it then possably the problems that I have are a result of "a used up car!"
Welcome to the Fox chassis. The uni-body and flimsy rear control arms are a big part of the problem. Get a set of sub-frame connectors to fix the uni-body flex, makes a huge improvement. A set of aftermarket upper and lower rear control arms with poly bushings will also make a huge difference.
If the car was drag raced alot you need to check the torque boxes where the upper control arms mount. They are spot welded at the factory, and subject to being damaged in drag style launches. An easy fix is to this weakness is to have them fully welded when replacing upper control arms, thats what I did.
These two items will tighten the car up in rear dramaticly. The next step is to add a panhard bar to keep the rearend under the car when cornering hard, but not really needed for most driving situations, mainly just for guys like me who try to drive more on the sides of their tires than the bottoms.
The front end is pretty hard to pinpoint without actually seeing it but it could be an aged rack and pinion. I replaced mine not to long ago because I got tired of what you described. My new one is much stiffer and I dont have to worry about a floating steering ride.
I would also check out the condition of your ball joints also.
I was just rereading your post and noticed something I missed the first time. Something to check if you are feeling a thump in the floor pan is your transmission mount and crossmember just to be sure you don't have a problem there.
I didn't address the front end because like GhostDog said, too many things come into play when trying to find the cause of bump-steer. You will just have to check all the bushings up front, including control arm, strut, and steering rack. Also the ball joints, and tie rod ends, and it makes a big difference if the car has lower spring height. Tires alone can even cause bump-steer, especially those with directional tread designs or deep tread grooves.
definitely could be the tranny mount, however if it saw alot of track time definitely check the torque boxes, buy a set of battle boxes from wild rides, bolt them in or weld them in, its a must
__________________
NMRA FS #10
1985 Mustang Hatchback
1987 Mustang Convertible
2007 Mustang Coupe
Too many mods and parts to list.....
Thanks to: Ed Curtis @ FTI; Larry's Auto Machine; DeCordre Automotive and Performance
If the car steers with throttle input and you are hearing clunks, your torque boxes are shot out. The rear end is actually sterring your car. If you have ever been on a forklift, you will know how small inputs in the rear steering make big moves up front. Let us know what you find out.
My friends car did this, I spend a whole weekend welding new metal into the torque boxes, the problem disappeared.
Thanks for all of the reply's.. mm.racing, I think you hit the nail on the head! Your description of the rear end steering the front is right on. Off the line you would get the feeling that the car wants to go left, put the clutch in and the car wants to go right. The torque boxes were probably the culprit, however I am sure that the car probably just needs a good rebuilding in the front end!
When I explain the car to my boys the phrase "rode hard and put up wet" does a good job of describing the car.
Ironically shortly after posting my question I was approached by an individual who made an offer to buy the car and I have since sold the car.
Again I thank everyone for their responses and we may look for another Mustang to buy!
90' Fox body chassis question. 
