Tranny making funny sound PLEASE read

[HO5POINTO1990]

ok im driving my stock engine, stock car, 1990 manual mustang gt 5.0 yesterday... and im at about 2,400 rpms in my car, and i let go of the gas to slow down, and hear this clunking sound coming from the rear end... maybe the differentiable ???? so I put it into third gear and do it at about the same rpm's and it makes the same sound... same in fourth... only from about 2,100 rpms and higher when i let go of the throttle it makes this clunking sound. I thought maybe my engine was knocking, but it's coming from the rear end? does anybody know what this might be? I did just put in a new clutch about 3,000 miles ago, and it wasn't professionally done, but it was done by a few of my friends who are pretty good mechanics... do u think maybe the tranny isn't placed correctly or something? they had to completely take it out to get to the tranny. But if u have any ideas please post. it would be appreciative. Usually u are all really helpful. thanks

 

[HO93LX302]

So it deffinitly only happens at those rpms?? not at any time you hit the gas?? It could be a loose rear control bolt, or maybe sway bar endlink or bolt.. I'd check over everything specially if you hear it coming from the rear of the car.. Don't forget the tranny is right under you you'd probably hear the noise right under you if it was the tranny.. Also check to make sure all the driveshaft bolts are there and tight..

 

[HO5POINTO1990]

it is definately coming from right under me... And the sound is only being made noise when i let off throttle after 2100 rpm's, nothing less... if it's more than 2100 rpm's and i completely let go of gas it makes this sound... so i'll do a once over tomorrow, because for now i gotta drive it and ignore it. ok thanks

 

[Schlodes]

it is definately coming from right under me... And the sound is only being made noise when i let off throttle after 2100 rpm's, nothing less... if it's more than 2100 rpm's and i completely let go of gas it makes this sound... so i'll do a once over tomorrow, because for now i gotta drive it and ignore it. ok thanks

I would get the car up on stands.

Inspect the crossmember.. and make sure the two mount bolts are tight, and the rubber bushings are nice condition still. Next I would check the transmission mount to crossmember retaining bolts to make sure they are tight or worse yet still there.. If that checks out, make sure the trasnsmission to bellhousing [them 4 bolts] bolts are tight. If they are, make sure the bellhousing to block bolts are all tight. Like the others said, check the driveshaft bolts too.. seen them come loose a few different times if the guys didnt use loctite on the bolts [I use the blue stuff].

Also, seeing as how the exhaust all has to come out to do such a job. Get under the car [on stands] and with a bit of finesse grab the exhuast system and pull down and then push up real hard to simulate a load on the motor, then an unloading... [like letting off at 2100 RPMs] and listen for a bang.. or clunk... Maybe the exahust isnt sitting exactly the same as it did before the clutch job or has come loose...

Good luck.

 

[custom90GT]

heh, well when you check the cross member, make sure its the right way. I did my moms clutch in her 94 a long time ago and put the crossmember in the opposite way it should go (doh!) and it would make a loud clunk like that when you let off the gas...

 

[HO5POINTO1990]

how will i for sure know it's the wrong way? will it look obvious, because i remember them taking off the cross member, but don't remember exactly what way they put it back on. lol. And I noticed that the sound is also heard when i go over speed bumps in the rear end... Do u think it's just something isn't tightened or on right? ok, i'm looking today if i have time. thanks guys

 

[UnderPressureGT]

I had a similar problem as you.. except, it did it when you hit the gas to accelerate too.. Turned out that my u joints in the driveshaft were shot.. 20 bucks later, my car ran smooth as a babys ass again...

Do you have any vibrations going on around them rpm?? If soo, i put my money on bad U joints