"clunking" ...rear-end?
Thread Starter
2nd Gear
Joined: May 2004
Posts: 2
Likes: 0
From: Irvine KY
"clunking" ...rear-end?
I bought my '73 about a month ago. The car runs and drives great BUT...after the car warms up when I slow to a stop I get this clunking in the rear of the car. With every clunk you can actually feel the car try to creep forward. I have checked the u-joints and everything seems solid. The driver side yoke is slightly worn, but I'm not sure that would cause this particular problem. Anyway, as soon as I accelerate, the clunking goes away. Anyone had the same experience? All suggestions greatly appreciated!
Drifting
Joined: Aug 2002
Posts: 1,731
Likes: 22
From: Marietta Ga.
Re: "clunking" ...rear-end? (73fan)
:seeya welcome to the forum.
Several causes for rear clunking, Yours sounds like Posi plates in rear end. since you just got thre car, I would suggest you change the rear end lube and add the GM posi treatment. The second most clunk causer is a shot front brushing on the differential. To check this, have some one sit in car and shift from foreward and reverse and get down so you can see the front of the diff. You will see it jump up if bushing is bad. I would suggest you gat a service manual and an assembly manual(AIM), as they will help a lot.
You can find more on the subject by the search function on the left.
Several causes for rear clunking, Yours sounds like Posi plates in rear end. since you just got thre car, I would suggest you change the rear end lube and add the GM posi treatment. The second most clunk causer is a shot front brushing on the differential. To check this, have some one sit in car and shift from foreward and reverse and get down so you can see the front of the diff. You will see it jump up if bushing is bad. I would suggest you gat a service manual and an assembly manual(AIM), as they will help a lot.
You can find more on the subject by the search function on the left.
Racer
Joined: Feb 2004
Posts: 253
Likes: 0
From: Athol NY
Re: "clunking" ...rear-end? (73fan)
Dropping the differential case really isn't too bad a job, but it is heavy. I was able to install new posi- clutch pack with a home made tool. One sure fire way of telling the posi-clutch is in trouble: if rearend seems to "chatter" when slowly leaving a stop while taking a turn. Supposedly you can "flush" and refill using the proper lube and posi additive, didn't work for me though, I had the pleasure of fixing it the hard way! :cheers: By the way '73's are awesome! :cheers:
Advanced
Joined: Jan 2001
Posts: 83
Likes: 0
From: Snellville, GA, USA
Re: "clunking" ...rear-end? (73fan)
73fan,
If this is your first vette, buy a good troubleshooting manual. Buy the assembly manual as well. Old vettes make all kinds of noises. Some of them are pretty serious and should be addressed, while others obviously are not.
Jack the car off the ground and support it at the frame. Rotate the wheels and listen for noises from the brake assy. Check for excessive movement from the wheel bearing. One of the guys suggested changing out the diff fluid. Thats a good thing to do, especially if you just got the car and you dont have any service records. Make sure to add the GM diff lube and the additive. Dont forget the additive. While the car is in the air, check and lube all ujoints. Everything should be tight. By the way, do not start the car and run the drive train with the wheels hanging. Not good on the ujoints. They are in their full down and flexed position.
If you dont find anything at this point. Have someone else drive your car. (a vette guy). Sometimes a 2nd opinion is helpful. My advice, is start easy, be system-matic and you will find the problem and probably a bunch of stuff you wernt looking for.
good luck.
steve :thumbs:
If this is your first vette, buy a good troubleshooting manual. Buy the assembly manual as well. Old vettes make all kinds of noises. Some of them are pretty serious and should be addressed, while others obviously are not.
Jack the car off the ground and support it at the frame. Rotate the wheels and listen for noises from the brake assy. Check for excessive movement from the wheel bearing. One of the guys suggested changing out the diff fluid. Thats a good thing to do, especially if you just got the car and you dont have any service records. Make sure to add the GM diff lube and the additive. Dont forget the additive. While the car is in the air, check and lube all ujoints. Everything should be tight. By the way, do not start the car and run the drive train with the wheels hanging. Not good on the ujoints. They are in their full down and flexed position.
If you dont find anything at this point. Have someone else drive your car. (a vette guy). Sometimes a 2nd opinion is helpful. My advice, is start easy, be system-matic and you will find the problem and probably a bunch of stuff you wernt looking for.
good luck.
steve :thumbs:
Thread Starter
2nd Gear
Joined: May 2004
Posts: 2
Likes: 0
From: Irvine KY
Re: "clunking" ...rear-end? (73fan)
Thanks guys, all of you have confirmed my suspicions about the posi. I will check it out ASAP. And thanks for the warm welcome...yeah, first Vette. Never thought I'd be able to own one, but I swore if I ever did it would be a '73. Like the chrome on the back and the clean front. Right place, right time, and the right $...now it's mine!! Thanks again for the advice.
