Help diagnose my trailing arm "clunk" [Video]
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
Help diagnose my trailing arm "clunk" [Video]
I've been hearing some clunking noise when going over rough roads. I got the rear end jacked up today and I was kind of shock at how much the rear tires (and trailing arms) move. The top of the tire moves in and out about 1/8". It also makes this clunking noise which I believe is coming from the yokes as they move in and out of the case slightly. Both sides move about the same amount.
Is this normal play or are the trailing arm bushings bad?
71 Coupe, 4 spd, 454.
I'm grabbing the tire at the top and bottom and lifting as well as pushing the top in.
Left Side:
Right Side:
Is this normal play or are the trailing arm bushings bad?
71 Coupe, 4 spd, 454.
I'm grabbing the tire at the top and bottom and lifting as well as pushing the top in.
Left Side:
Right Side:
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
It's hard to tell from the video, but it looks like the wheel bearings are loose. Do you get the play and noise when you grab the tire at 3 and 6 oclock? Are the diff yokes sliding in and out?
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
No, they're solid moving them that way. I can see the trailing arm moving in unison with the wheel, so it seems the bearings don't have excess play. It's like the whole assembly is pivoting at the lower strut rod connection point.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
'Repairing' pretty well comes down to a complete diff overhaul. Mostly likely the yokes have been worn that way for years and years, maybe 10K+ miles. I'd keep on looking for other sources for the 'clunk', the yokes don't unload on a straight road unless you've got the car in the air. 
Last edited by Mike Ward; Aug 19, 2011 at 10:02 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
There is end play in the yokes between the end of the yoke and the center pin. When you pick he wheel up as he is doing in the video and going down with it you will hear a clunk noise. If you watch the video closely you'll notice the clunck is on the down stroke. It is the yoke bottoming out on the snap ring at full travel.
Are you hearing any noise while driving?
If you suspect the bearings are the problem and before you dig all the way in, remove the 1/2 shaft and put a dial indicator on the bearings to check the end play.
Are you hearing any noise while driving?
If you suspect the bearings are the problem and before you dig all the way in, remove the 1/2 shaft and put a dial indicator on the bearings to check the end play.
Last edited by Willcox Corvette; Aug 20, 2011 at 05:57 PM.
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
I do on rough roads. It's deep rattling/clunk noise that coincides with the wheel movement and the number and frequency of any bumps. I'll do a thorough check of everything before tearing the rear end out. It only has 78K miles, so I wouldn't suspect the rear end being worn out.
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
Burning Brakes
Joined: Apr 2007
Posts: 1,186
Likes: 41
From: Pinecrest FL
2015 C3 of the Year Finalist
Have you swapped out the fluid in your rear? Could possibly be the posi fluid is toast and the clunking noise is coming from the rear end when one wheel is traveling at a slightly different speed than the other. You can vacuum out all of the fluid and do an exchange with 2 parts of posi lubricant to see if that takes care of the problem.
Melting Slicks
Joined: Jun 2004
Posts: 2,077
Likes: 0
From: westmoreland N.H.
I vote bad bearings. looks to be on the left side when you move the wheel up and down the half shaft stays put. not good. check your shims at the front of the trailing arm also .are they still there.
check your shims at the front of the trailing arm also .are they still there.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I'm not so sure it's bearings either. When you move the wheel up and down on a car with bad bearings the support won't move up and down and it appears as if both are moving. If they were that bad it would be obvious. Best way to check would be to remove the 1/2 shaft and then check the end play.
When bearings are out you'd have the same free play movement in all directions. So he could go check this pretty quickly by twisting the wheel in the same manner from the sides.
When bearings are out you'd have the same free play movement in all directions. So he could go check this pretty quickly by twisting the wheel in the same manner from the sides.
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
I'm not so sure it's bearings either. When you move the wheel up and down on a car with bad bearings the support won't move up and down and it appears as if both are moving. If they were that bad it would be obvious. Best way to check would be to remove the 1/2 shaft and then check the end play.
When bearings are out you'd have the same free play movement in all directions. So he could go check this pretty quickly by twisting the wheel in the same manner from the sides.
When bearings are out you'd have the same free play movement in all directions. So he could go check this pretty quickly by twisting the wheel in the same manner from the sides.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Wheel bearing will also give you a slight vibration at speed. Your rear view mirror will detect this as the cars behind will look like they are vibrating, at least that's what was the outcome for me 
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
Well! I found the source of the clunking. The left rear brake caliper bolts were loose. 
Glad I found that! Seems like the rear end might need some attention soon, but it drives and sounds solid now.
Glad I found that! Seems like the rear end might need some attention soon, but it drives and sounds solid now.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Just remember... the best way to check for a bearing problem and really the only true way is to use a dial caliper and check the run out of the bearings.
Thread Starter
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA