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Topic: Clunk From Rear on Clutch Release/Engagement (Read 1485 times) previous topic - next topic

Clunk From Rear on Clutch Release/Engagement

So I finally got tired of peg legging it and replaced the worn clutch packs in my TC rear end before I headed out from here in Illinois to Philadelphia Pa. I rightly assumed that the road trip would be much more enjoyable with the traction lock working and as a pleasant bonus the hitherto clunk on depressing the the clutch pedal had disappeared for the first hour of driving on the highway.

Great I thought, I've got two wheels spinning and without the clunk and slop this bird drives like a brand new car. Much to my chagrin however, the clunk quickly reappeared some time between that first hour and Indiana...

Keep in mind the clunk only happens when tension is let on or off of the drive train by way of the throttle (or more noticeably the clutch), and direction ( ie turning or going in a straight line) has no effect on worsening or altering the sound. There appears to be to my and my co pilots ears' no chattering from the clutch packs in the rear.

What bothers me is the fact that the clunk disappeared initially after installing new steels and clutches, but quickly reappeared after only a short time of only highway driving (and straight as straight here in Illinois). Maybe it's coincidental  that the clunk reappeared or a new one appeared after fixing the traction lock, but either way I'm open to suggestions so that before I tear into this thing I can dive in with some idea of what's going on.

The driveshaft is new as well as the ujoints, but that will be my first checkpoint. The posi is still working as I tested it out last night under "working" conditions on the road. There is no whurring sound and the ring gear did not raise any alarm bells upon dis-assembly of the center section, so yeah..
1987 Tbird 5.0 swap, go fast mods coming soon....

Clunk From Rear on Clutch Release/Engagement

Reply #1 –
I'm betting on motor mounts or u-joints. I replaced one with an autozone "gold" one. about 15k later and its getting a bit loose.

using stock third/cougar  motor mounts?
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Clunk From Rear on Clutch Release/Engagement

Reply #2 –
I've got Chuck w's mounts, up front and I'm running a brand new polyurethane transmission mount on a solid mounted transmission crossmember so yeah. I'm currently waiting for the garage to clear out so I can get the thing up
in the air and checked over with a fine tooth comb. Academically however I'm pretty stumped at the minute.
1987 Tbird 5.0 swap, go fast mods coming soon....

Clunk From Rear on Clutch Release/Engagement

Reply #3 –
With a clunk during drive and coast situations on a straight road that would eliminate the POSI in most situations. What is the BACK LASH? Are the spider gears OK normally with posi the spiders do not play a part in that as they are loaded with the clutches. BUT!!!! You said the NOISE was gone after you re-clutched it so i am thinking the spiders just mat be an issue. Without seeing them it is just a guess. If you have an 8.8 those posi units are cheap and i replace the entire unit when the clutches fail. I found that it is better than replacing the clutches.  Basically i would check the joints and the back lash. Also the trailing arms and bushings. Just something else not critical but what is the axle in and out clearance. Normally should be around a hundred!! But once again if the noise was eliminated after the rebuild i would say your issue is most likely in the posi unit but hard to figure!!! Good luck!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Clunk From Rear on Clutch Release/Engagement

Reply #4 –
Pinion bearing is taking a dive.

Clunk From Rear on Clutch Release/Engagement

Reply #5 –
Normally a pinion bearing does not CLUNK!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!
 

Clunk From Rear on Clutch Release/Engagement

Reply #6 –
No, but if the bearing is toasted it gives it enough slop to sound like the backlash is all out of whack. Not saying I'm right by any means, but if you're hunting for the problem check all angles. The 8.25 rear end in my 92 dakota had the same problem checked everything, pulled the driveshaft to check universals and the pinion had a ton of play in it.