I have a clunk in the rear end when I put the tranny into reverse. Forward also but reverse is bad. I believe it to be the bushings on the brace on the front of the rear differential. I just replaced them with a now set of poly bushings. I have not driven the car yet so I do not know if it is fixed yet.

Couple questions.
1) Does anybody know what the torque is suppose to be on the bolt holding everything togeather?
2) The new lower polly bushing was only about 2/3 rds as thick as the old rubber one. Anyone know why. The old rubber bushing had a metal plate bonded to the bottom and the new poly one does not.

Just a comment : I think the clunk was worse when going into reverse because the top rubber bushing was really trashed.

 

Ever change the rear gear oil and put in the posi additive? Worked wonders for mine!!

Just a suggestion!! :yesnod:

 

65 ft lbs will tighten the mt bolt to spec.
The poly is more rigid than rubber. I doesn't compress as much, so it doesn't need to be as thick, or need suppt in form of a plate/washer.
Hope that fixes your prob! :chevy

 

I am having a clunk problem with my Formula, I jacked it up and found the tires will rotate about 1/4 to 1/2" in either direction, both u-joints and the tranny are nice a tight. Guessing the posi (ring gear backlash?) was not set up properly. :(

 

Thanks for the torque value. I don't have it near tight enough yet. I'll crawl under the beast again tomorrow and tighten it right.

I was planning to change the rear end fluid too. I did not notice any slop in the rear end or u-joints.

I noticed after the bushing change (not torqued enough yet) that the clunk was very reduced. Much improved. There still is some but partly becuase I can not get the idle below 1200 RPM. (Carb problem) That's my next project.

Thanks :seeya

 

Just a tip... you may already know this.

You say you have a high idle issue related to the carb. When I first got my car I had a similar issue. Idled at around 1200 and the idle set screw was all the way out. If I grabbed the throttle and pushed forced it in the shut direction the idle would drop. This made me think it was a carb issue.... It wasn't. It was a big freakin' vacuum leak. I would highly recommend pinching off vacuum lines before making any carb changes.

:cheers:

 

...Just a word of warning, I've replaced engine, tranny, and the front diff bushings with new poly bushings-- still clunking.
Same as you, clunk in fwd, clunk in reverse.
I've fiddled with this for about 2 years, and my next step is to remove ALL the ujoints and check them for binding. I also suspect the spindle flanges might be the culprit, the machinist had a heck of a time pressing the ujoints in there (the flange was warped, and I couldn't do it at home, and he had to use a vice and a hyd. press to get them in.)
My worst fear is that my rebulit diff has to much endplay between the ring and pinion.

BTW, if you hold it in 2nd, and go about 45ish, and hit the throttle hard, then let off immediately, and then stab the throttle again, does it clunk then too?? Well, mine does...
Good luck!

 

Hi guy's

I have a similar problem. Mine does not clunk but cliks :confused:
I have replaced all of my bushings a year ago. I brought my rearbearings to a local specialist, replaced one yoke in the diff and put in some new oil and additive. At first it was oke but within a month or so I heard a nuckling sound at the rearand a funny click cam also with it. I drove around with this sound for one year. This summer I was really sick of it and decided to do something about it. First I replaced the U-joints ans the sound was still there and a click came also back.
Then i decided to check the bearings again. I took off the rearbrake rotors and found out that the local specialist had made a mess of changing the bearings. The outer seal on both sides ran out and the grease was everywere.
I did the rearbearings myself this time, borrowed special tools here and there and changed the bearings. The end play was left 0.0016 and right 0.0017 so that was oke.
I found out that there was already a little play on the u-joints again and
ordered some new ones(real heavy duty ones) I've also tighten the bolts on the spndle plate where the driveshaft is mounted on the flange.
After a testdrive it was ok, no funny sounds really great!!!
After 300 miles or so the funny clicking sound came back.
Here is what happens,

If i'll put it in D and let the car roll over a short distance en stop. Then I'll put the car in R and let go of the brake, when I give a little bit of gas I hear a click (no klunk)in the rear. It looks like it comes from the wheel sides. Also when I' cruising and lift the throttle and give a little bit gas I hear the click again.

Anyone who knows what the problem is???

Bye Rene




[Modified by pace78, 2:54 PM 9/15/2003]