rear end ? help please

[snowman23]

Hi all,
I have a 90 GT convertible. Last year I had the rear endrebuilt / 373's installed. The tranny rebuilt(auto) with a shift kit and the rear shock as well as upper/lower control arms replaced. I went with Mustangs Unlimited direct replacement kit with urethane bushings. Now when the car shifts its weight, I get a "clunky squeak" from the rear area. It is definitely not the tranny (althought the weight transfer in the car with a gear shift will cause it). I also had the u-joints , etc in the rear checked and they don't appear to be it.
I had the rear end taken back apart and all is well (backlash,etc). I also changed to synthetic gear oil at this point. The shop now thinks its coming b/c the urethane bushings are so stiff/tight that there is absolutely no play in the rear suspension and therefore nothing to absorb it. they suggested changing to factory replacement control arms with rubber bushings, but the only place i can find these is at FORD and they are ridiculously pricey. I also cannot find just the bushings in rubber as urethane should be better.

I was wondering if anyone had a problem similar to this and /or any suggestions for me. I need all the help I can get at this point.

 

[873Stang]

i think energy suspension has a special grease that you can put on the bushing to keep them from squeaking, its clear. if it were me i would buy that grease and try it out before buying stock bushings. you may im not sure, but be able to use white lithieum grease

 

[RYC CUKR]

See if you can get the grease 873stang was talking about. Ungreased urethane bushings will squeak, just kinda the way they are.

I have a set of MM adjustables on my 93 with a spherical bearing on the axle end and a 3 piece bushing on the chassis end and they have a provision for being able to grease them. Once they are greased they are quiet. I know that you don't have that provision on the stockers but if you can get some grease on them they should quiet down.

 

[lang williams]

I had a nosie in the rear of my car i swore was in the suspension an it was a misadjusted tv cable...when it shifted it clunked an it sounded like it was in the rear end....wouldn't hurt to check it.

 

[krallman]

ill trade you.

 

[Mustang78]

same here i got 3 sets of stock control arms..do you drag race? it could be your torque boxes..

~Mark~

 

[snowman23]

thanks for the advice. I called the shop that has the car and suggested that they try greasing anything and everything that they could. they are closed today so it will be Monday before anything is done.

I also suggested the tv cable.

If it comes to having to swap them out (which I really dont want to b/c of the MUCH improved handling) then I would be interested in trading. I will keep you all posted.

THANKS AGAIN

 

[snowman23]

p.s.

no i don't drag race and I really dont beat on the car. the previous owners were an older couple and a ford mechanic in his 30's so I would hope that they did not either

 

[snowman23]

UPDATE

Well i got the car back and everything is great except this rear end sound. I have isolated it to the point that i know it only happens when the tranny is close to shifting (its an auto) and I let off of the gas before it can. It then seems to shift (but not under the load that keeping on the gas would give it) and this is when I hear and feel the sound. It originates in the rear and feels like it travels up to the front.

The shop is insisting it is the polyurethane bushings in my new rear control arms still, but I am not 100% sure nor do I really want to go back to stock.

ANY FURTHER THOUGHTS???

 

[93 LX]

here is something else you may want to look at.

Bad U-Joints or Drive shaft Yoke bushing in the tranny.

I know more fuel to the fire but what the hey sometimes you have to think in a wider scope when the obvious doesnt seem to fis the problem.

Allen

 

[88mouse]

did you replace the bushing in the rear end housing(where the upper control arms bolt in) it self.They are bad about going bad and make the clunking sound you are talking about.

 

[snowman23]

Thanks. The bushing in the rear end seems to theoretically make sense since all this started after replacing the c/arms. I already had the U joints checked and they are ok. The tranny was rebuilt last year by the same shop so hopefully they would have checked the yoke bushing, but I will bring it up.


I am going to pass these suggestions along to the shop since they have to take the car back since it is now leaking more oil than it was before the oil pan gasket, valve cover gaskets, and intake plenum gasket were replaced.


Couple this with the rear clunk, and the fact that I bought an 03 Explorer on Tuesday of last week and proceeded to scratch the rear tailgate door on Friday, I am not having a good car week

 

[snowman23]

Alright,

Well both Ujoints are now new, re-greased all the rear C/A's. And still, let off the gas as the RPMs increase before the tranny shifts and it shifts NOT under load and BANG! there is a clunk/slam/whatever from the rear that you hear and feel right through the car. (I also noticed its worse when going uphill.)

2 different shops have checked the rear gears, backlash, etc and said its all good. The shop that did the ujoints said maybe the tranny crossmember????


WHAT ELSE CAN I CHECK? I feel like this is a wild goose chase OR it has to be in the rearend and both shops missed it.

 

[snowman23]

UPDATE-- GOOD NEWS

I just wanted to share that the shifting/rear end gremlin is finally gone!!

It took 2 years, some wasted money and a few parts I probably did not need, but I am ready to DRIVE in peace!!!!

I had the rear end rechecked and the posi-carrier was replaced with a new one and the ring / pinion backlash was re-adjusted. This stopped 1/2 the noise. I then had the tranny shop that did most of the work at the start of this mess and they replaced the valve body (and in turn removed the shift kit that I had previously installed). Now it shifts smoothly, with NO CLUNK, and NO REAR NOISE!!!!

The car is in the shop getting a custom roll bar installed (the result of my totalling another car in Jan when a guy ran a stop sign and hit me) for a little piece of mind. I cannot wait for the nice weather....

 

[Deleted member 87397]

I'm glad it's solved, but i was going to suggest that because the trans is shifting harder now are getting the clunk from where the driveshaft hooks up in the rear. I have and IS with a 5 speed and when I really get on it and am shifting hard it makes the exact noise you described. I also used to have an AOD in my mustang and when I had it rebuilt with a nasty manual valve body from Art Carr it made the same noise. Sometimes the price you pay for performance is a sacrifice in sound quality, ride quality, comfort etc. Glad you got it fixed though.

 

[snowman23]

thanks. I knew that there is always a trade off with performance vs. everyday comforts. However, the annoyance of the "clunk" was far larger than the gain that I had from the shift kit. That coupled with a screwed up rear end made for a car I love that I hated to drive. Being that it is a covertible that I built for street cruising with my wife and kids I am now happy to be able to enjoy it. I am eagerly awaiting the call from the roll bar shop to say "come and get it"!