Fox T-Bird/Cougar Forums

On my 87 T-bird the left rear of the car sags 1-1/4" compared to the right rear. I've disassembled the entire rear suspension and have found no visible damage or other problem. I've even switched rear springs side to side. Did this thinking that if the left rear spring was weak then when switched the right rear would sag. After the switch there was no difference in the measurements. So I've taken the car to a professional mechanic and he raised the car in the air on his hoist to get a better look under the car. Only thing the mechanic found was that maybe the right front lower control arm was twisted. But he was not really sure since the spring pocket on the left control arm protruded about 1/4" more beyond the under side of the control arm than the left front control arm. The twist he also found was by using a Level and placing it on the on the under side of the control arms and parallel to the tires. The result was the under side of the left control arm was level with the ground with the spring cup was just barely lower that the lips of the control arm. On the right front control arm it was far from being level to the ground and the spring cup protruded about 1/4" lower than that of the left control arm.

My question is there a difference in the shapes of the front lower control arms on an 87 T-bird or is this right control arm twisted or damaged some how?

Check the front springs, they're known to break in the spring cup.

A problem in front that would effect the rear by 1¼" should be obvious...

Jack up the LF and see how much you have to raise it to lower the RR by 1¼"...

Aren't the Turbo Coupe front control arms different from the standard control arms?  Could someone have replaced and mixed/matched parts?

No difference.

I agree, busted spring. If there was a pothole or other contact hard enough to tweak a c/a, there's going to be lots of other broken stuff.

One question....any rust on the car? ANY rust?

The front springs are notorious for rusting and breaking...causes all sorts of silly shiznit..

Good suggestion!

Made the following measurements with the car at a normal rest on level ground going from the wheel well lip down past the center of the wheel to the ground.
Results were:
LF = 27.50"  RF = 27.50"
LR = 27.25"  RR = 28.75"  rear side to side difference = 1.50"

Then placed jack under LF control arm spring pocket and proceed to raise LF of car.
Results were:
LF = 30.75"  RF = 28.75"  front side to side difference = 1.50"
LR = 28.00"  RR = 28.00"

From these measurements does the LR sag or is the RR to high?

I'm the original owner of the car as are the front control arms are original and frt springs. I don't recall ever hitting a pothole.

If front spring was broken there would likely be a noticable difference between RF& LF...


I want to say the 27.5" is approx correct but can't remember height of mine, I know it's approx 1/4"-3/8" lower in front than one with orig engine...

I believe I've posted height of my Bird in past, maybe a search will find that info...

I'm wondering if the rear end axle housing could be bent? You could check by hanging some string lines across the back and the top or bottom from hub to hub. Check dimensions from the string line to the axle tubes at various locations. If they are not consistent, that could be where the problem lies.

So this is a very common problem in the Fox Mustangs so we can learn a lot from them being the chassis are very similar.  There was a TSB on the Mustangs addressing this pointing to the driver side front spring softening and requiring replacement.  I know a lot of guys that replaced all four springs and the problem persisted but thought the TSB was interesting so here it is:

90ford47
 SPRINGS - VEHICLE LEAN - APPLICATION CHARTS - EXCLUDES "SALEEN" MODELS
 Article No. 90-26-3
 FORD: 1989-90 MUSTANG
 ISSUE: Vehicles may have a tendency to lean to the left because the location of the battery, windshield washer bottle, radiator expansion bottle and engine accessory drive may cause a weight bias on the left front side. This lean condition most often appears as a lean in the rear of the vehicle rather than the front.

ACTION: Check the wheel lip measurement and, if required, install a new left front spring to restore the vehicle to a more level attitude. The front spring is to be changed, even if the lean is greater in the rear of the vehicle. Refer to the following procedure for service details.
 Figure 1

 1. Place the vehicle on level ground.

 2. Take all measurements from the ground to the body wheel lips as close to the axle center line as possible, Figure 1.

 3. Determine the difference of the front wheel lip measurements by substracting the low from the high measurement. Using the following Wheel Lip Measurement Chart. select the correct spring load change (i.e. plus 1. plus 2) within the rate group.

 4. After determining the correct spring change (i.e. plus 1 or plus 2) find the three letter tape code located on the front spring of the side that exhibits the lean and select the replacement spring using the following charts.


 The following 1989-1990 Mustang Rear Spring Chart is provided for general informational purposes only. Generally, the rear springs will not have to be replaced unless there is damage or structural concerns.

 (*) Code is also in Parts Book.

 5. Remeasure the vehicle as described in Steps 1 and 2. Confirm that the vehicle is in specification per the Wheel Lip Measurement Chart. If the vehicle is not to specification (0.00" +/- 0.20"), repeat Step 3 through 5.

Within a rate group, installing a high load spring will increase the vehicle ride height. Conversely, a lower load spring will decrease the vehicle ride height. The following Spring Change Bumper Effect Chart indicates an approximate change in bumper-to-ground height for each increment of spring change.

 OTHER APPLICABLE ARTICLES: None

 WARRANTY STATUS: Eligible Under Basic Warranty Coverage
 OPERATION DESCRIPTION TIME
 902603A Replace Spring 1.2 Hr.
 DEALER CODING
 BASIC PART NO. CONDITION CODE
 5310 63
 OASIS CODES: 304000

Wanted to break this up into a couple of posts as that TSB is long.  Other issue found were worn control arm bushings both front and rear, tweaked chassis (this was a bitch if you had already welded in SFC's), tweaked control arms, bent axle housing, etc.  One guy completely rebuilt the suspension in his Fox Mustang and had the chassis checked on a frame machine and still had about 1/2" or so of sag.  He ended up adjusting it out with the coil overs on the car.  Needless to say these cars were not built with the tolerances we have now and that is still not saying much.

So check the basics and if they are all good then it may need to go to a body shop and up on a frame machine.

From my earlier investigations I knew that both of the KYB front struts had lost gas pressure. They may even be worn out since they both slowly collapse under the weight of the upper strut mount when they were unbolted from the strut tower. So after removing the brake caliper and rotor and with the sun shinning at just the right angle today I could see that the LF spring was indeed broken. Had a heck of a time removing the two lower bolts on both of the struts. I guess the heat from the Ft brakes really seizes those bolts. Anyway both front springs were broken. LF was broken at about 7/8 of a coil and remainder of spring measured 14-3/8" long. RF was broken at about 3/4 of a coil and remainder of spring measured 14-5/8" long. With both Ft springs broken at roughly the same length that would explain why there was no visible lean observed on the front of the car. Another side benefit of the broken springs is this had the same effect as having  lowering springs in the front. This would also explained why the Ft fender/tire gap measurements on my car is roughly the same as other T-Birds which have lowering springs.

But, even with the car supported by jack stands under the front frame rails at the same point from side-to-side and with the RR shock disconnected ( thinking that its gas pressure was raising the RR ) the RR was still much higher than the LR. So the chassis is probably twisted and in my case it's 1-1/4" to 1-1/2". So I'll have to get my local body guy to measure the frame when car is back together.

I have a question about the reliability of these broken Ft springs. If I was to square-off the ends of both springs so they'd be the same length. Could I use these springs the same as if I were to buy new lowering springs? I'm guessing the only reason why the Ft springs break on these Fox Body cars is because of the way the Ft control arms are designed. The same could happen to new replacement springs.



From this TSB I guess you could tweak the frame measurements. That is if you still had the Tag codes and if you could buy just the right spring.

This is the cars original LF spring now broken.

And this is the cars original RF spring also now broken.

Perfect excuse to lower on SN-95 springs.

The reason those springs broke is that they are not made well. Swap over to the SN95 springs and get some quality dampers on all four corners. Check all of the control arm bushings, sway bar frame mounts & end links, and ball joints.

If you install the new springs I would highly recommend you get the Maximum Motorsporte caster camber plates. Once you have installed all the new parts and have an alignment done see where you are at with the gangster lean in the rear. Let the springs settle a day or so before getting the alignment.

If you replace the front lower control arm bushings remember to torque the bolts only with the suspension fully loaded or you will preload them and they will prematurely wear out and cause the front of the car to be higher than it should be. Also, the strut mount bolts to the spindle have crimped nuts which make them difficult to get off.

Any updates on this fix, 87tbird?  My car has this same issue, so I am interested to hear if you found a solution.

UPDATE.



I don't think the steel that Ford had spec'd for the springs was of a lesser quality. I think the way the Ft Springs were designed to fit into the Crtl Arm spring cup caused the springs to break. Stress on the springs was about the same since they both broke at roughly the same length.

Due to parts being lost in shipping, impending winter weather and working out in the open I was not able to get new springs installed. So I cut both of the broken springs to the same length 14.25" then installed them along with new Crtl Arm bushings and new spring isolators. Result was more of a front end suspension drop. Fender lip to ground now measures 26.25" and there's a 1.25" fender/tire gap. The rear of the car still has the same twist. When I get some time I'll take the car to the repair shop.

My 86 Elan sags to the drivers side in the rear when sitting on level pavement. Hopefully I'll eliminate it when I install my new 8.8 rear and four new springs.

I regard to Ford springs, while they weren't T-Birds, BOTH my 86 and 00 Taurus's broke springs. Ford even issued a recall to put sleeves on the fronts, as they would puncture the front tires when they broke!

Was the car ever hit in the driver side rear? The bumper alignment with the quarter panel looks a bit off.

The other thing that can cause the springs to have an issue is the weep hole in the lower control arm spring pocket to get plugged and rust becomes an issue.  This is especially hard on cars up north where salt is used quite a bit.

One last thing to try is to loosen the bolts on the upper and lower control arm on the rear end and then torque them with the suspension loaded and level.  This goes for the front lower control arms as well if you did not already to that when you put it back together.  Torqueing the bolts up without the suspension loaded and level can cause preload and get things all out of whack.

I too am struggling from this situation.  I was low in stock form with factory 16s and now I have a sn95 cradle with new factory sn95 springs.  My rear springs are factory height and now with 17x9s and 275 tires, I am about to cut my left rear tire!  Have tried all mentioned above.  I need to finish the car. I have a wheel lip roller so I don't cut the lip in the future but I am 1/2 lower than the other side.

Have you taken it to a body shop and put it on a frame machine?  Several of the Mustang folks suffer from this same issue and some of it was just the sloppy tolerances back in the day and if they all lined up it caused the car to be out of whack.  One of the guys worked at a body shop and put it up on the frame machine and it was horribly out of whack.

Not yet.

Repairs keep popping up. The battery disconnect switch that I'd installed several years ago went bad last month and killed the 11 year old car battery. Then yesterday when I was going to get the alignment checked one of the rack & pinion hydraulic transfer tubes failed. Spewed oil all over the underside of the engine bay.  I figure the tube got damaged when I had to move the Rack while changing the Ctrl Arm bushings. This is what brought me back to the forum today. I was searching to see if there was some place that sold inexpensive transfer tubes. Google search only turned up places that were selling both tubes for nearly $50. I hate to replace the still good original Ford rack & pinion for some reman unit. But when a new life time warranty reman unit can be bought for around $85 it don't make sense to buy just the tubes for $50. Then I'm going to have to buy new P/S hoses since they too are originals and then I'll also have to clean out the P/S pump. Would not want to contaminate a new rack. I'm thankful I can do these repairs myself otherwise I'd probably have to dish out over $300 bucks at some shop.

If anyone knows where to buy inexpensive rack & pinion transfer tubes feel free to respond.

Have you looked to see if you can get a rack from a salvage yard off a Fox or SN95 Mustang and use those tubes?  Someone on here might have a junker laying on the shop floor they can pull off send you but I would start another thread with that in the title to get some traction.

I have reman units in both cars and have only had an issue once so that may be the best way to go and use yours for the core.

I was just talking to my alignment guy about the sag issue, as my car has it, as well.  He suggested simply putting a spring spacer in one of the rear springs to even things out.  This seems like it would be an easy an effective fix, and avoid lots of labor and other expense.  Has anyone tried this with success, or have any reasons why this wouldn't be a bad idea?

Adjustable lower control arm, spacer, and coil overs have all been used.  One guy measured his wheel well to the ground and found that it was only an 1/8" difference but his bumper cover was over a 1/2" different.

These are a good bet: http://www.maximummotorsports.com/1983-88-Thunderbird-C429.aspx

I've got the extreme duty versions in my Thunderbird.

After 3 attempts in trying to get an undamaged rebuilt R&P unit I've finally got the R&P installed and have taken car to alignment shop. The alignment settings in the attached photo show camber is not as bad as I thought back -1.6L and -2.0R verses what I initially thought of -5.0. May have to get the adjustable caster/camber plates if these camber settings cause tires to wear. Caster changed a little, not as much as my prior alignment records on car indicated. Toe reading is from me reattaching the outer tie rod ends on the R&P unit and doing the best I could. Still have to take car back to body shop for them to see why car still tilts.

Don't know if there is something wrong with the R&P unit just installed. Engine drops some 200 to 400 RPMs at idle when turning the steering wheel. Something else for me to worry about.

WARNING to those who purchase a R&P and have it shipped to your home. It probably will come damaged. I purchased from Autozone and there was nothing in the R&P box to secure the unit from flopping around. Had 2 R&P's arrive which had a crushed or broken hydraulic transfer tube.

Typically you will notice a drop in rpm when turning the wheel at idle. Did you replace the pump? Did you flush the system before installing the new rack if you did not replace the pump? What fluid did you use?

The camber is far too negative and will wear the tires as well as cause poor cornering response with the lack of caster the car has. You need CC plates no question about it.

That camber will wear the shiznit out of your tires.  Ask me how I know.  Seriously, ask me.

Get the C/C plates, fix the camber to around -0.75 to -1.0, max out the positive caster you can get with them, I got around +4 to +4.5.  More positive caster will make the car feel more on center, and will help the car straighten out the steering after a turn.  It also greatly improves high speed stability.  Once you have the plates, install them and run back to the alignment rack.  Ask for stock camber and toe, but ask for at least 4 degrees positive caster, as recommended by the install sheet.  These cars don't specify and cross caster, so be sure to get them exactly the same, or as close as possible.  If possible, sit in the driver's seat during the alignment, if your shop doesn't allow it, ask for the seat to be ballasted with your approximate weight.