Strange Noise !!!!!!!
Thread Starter
Instructor
Joined: Mar 2007
Posts: 183
Likes: 0
From: Corpus TX
Strange Noise !!!!!!!
I was wondering if somone can point me in the right direction as were to look ? I have a knocking noise coming from the rear and it only does it when im moving slowly forward or backwards ! I jacked the rear up and put it in drive and reverse and no noise ! When im moving say about ten miles or faster no noise ! Iv looked for the obvious but no luck .
Le Mans Master
Joined: Apr 2005
Posts: 6,355
Likes: 425
From: Seattle Area WA
A knocking noise with weight on wheels or under a load..hmmm. Have you checked all the U-joints? Check the half shaft ones with the car on the ground since their geometry changes with the car lifted.
Maybe the differential posi pack?? Does it seem to shudder while doing it too? A wheel bearing sounds a bit like a grinding noise.
Maybe the differential posi pack?? Does it seem to shudder while doing it too? A wheel bearing sounds a bit like a grinding noise.
Thread Starter
Instructor
Joined: Mar 2007
Posts: 183
Likes: 0
From: Corpus TX
I have checked the u-joints visualy , but dont see anything my only thought is since the rear is totaly out of wack and is in need of an alienment realy bad is that the shfts are sum how binding a bit . I mean it is realy noticable when you look at the rear wheels the top slants inward !
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Never jack up the rear and let the wheels hang and put it in gear. It will bind the shafts up big time. This is a sure way to bust up some parts.
The noise can be a lot of things from ujoints to bearings to a bad posi unit. If the ujoints have not been replaced in the last 40K miles they should probably be replaced anyway. How many miles on the car or rear bearings. They could be bad. There is a lot going on back there and a lot of parts to wear out.
The noise can be a lot of things from ujoints to bearings to a bad posi unit. If the ujoints have not been replaced in the last 40K miles they should probably be replaced anyway. How many miles on the car or rear bearings. They could be bad. There is a lot going on back there and a lot of parts to wear out.
Melting Slicks
Joined: Dec 2000
Posts: 3,363
Likes: 303
From: Lansdale 19446 PA
2024 C3 of the Year Finalist- Unmodified
St. Jude Donor '10-'11, '15, '19
Are the top of the wheels in or the bottom of the wheels out?
If the bottom of the wheels are out, it could be the side yokes in the rear. Check to see how much play you have on each yoke side to side.
If the rear spring is weak - it can cause the bottom of the rear wheels to kick out at the bottom. That could cause a strain on the U-Joints if they are marginal.
Not sure either of these would create a "knocking" noise at low speed though.
If it is a single knock, it could be the rubber differiential mount in front of the rear.
If the bottom of the wheels are out, it could be the side yokes in the rear. Check to see how much play you have on each yoke side to side.
If the rear spring is weak - it can cause the bottom of the rear wheels to kick out at the bottom. That could cause a strain on the U-Joints if they are marginal.
Not sure either of these would create a "knocking" noise at low speed though.
If it is a single knock, it could be the rubber differiential mount in front of the rear.
Thread Starter
Instructor
Joined: Mar 2007
Posts: 183
Likes: 0
From: Corpus TX
Im not sure what all has been done to the rear end but i do know that it has been upgraded with new shocks and sum sort of new suspension from VB thats why it needs an alienment realy bad and no there is no play in the wheel side to side ! The noise is definately a knocking sound and if im bearly moving say not even a full rotation of the wheel it will knock several times !
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Racer
Joined: Mar 2006
Posts: 276
Likes: 1
From: Pistoia PT (ITALY)
Your noise is present when you make a very short radius turn...... at very low speed..... ???
That can be the time to change differential oil and to add some antilock additive!
If the noise is present allways, may your problem can be in the u-joint.
Did you check if the noise is sincronised with the wheel speed?
I mean...... 1 "clang" = 1 turn ????
That can be the time to change differential oil and to add some antilock additive!
If the noise is present allways, may your problem can be in the u-joint.
Did you check if the noise is sincronised with the wheel speed?
I mean...... 1 "clang" = 1 turn ????
