Vibe / shudder help?
Thread Starter
Instructor
Joined: Dec 2001
Posts: 196
Likes: 0
From: Dry Ridge Kentucky
Vibe / shudder help?
After 3+ years of work got the 72 back on the road. Now I'm trying to diagnose a bad shudder and vibration in the back at 45+ mph so its driveable every day.
Tires are balanced and alignment is mostly correct, although I'm taking it in again this weekend to a better alignment shop and to get the tire balance rechecked. At the previous shop we couldn't get the toe-in dead on and I found the rt trailing arm slightly bent from an accident so I replaced it.
During the rebuild, the only things I didn't replace were the differential and the rear spindles and rotors. So, naturally my worst fear is that the rear bearings are causing the shudder.
Any thoughts or possibilities? Hard to believe an out of balance tire could cause this much vibe. Thanks for any help.
Tires are balanced and alignment is mostly correct, although I'm taking it in again this weekend to a better alignment shop and to get the tire balance rechecked. At the previous shop we couldn't get the toe-in dead on and I found the rt trailing arm slightly bent from an accident so I replaced it.
During the rebuild, the only things I didn't replace were the differential and the rear spindles and rotors. So, naturally my worst fear is that the rear bearings are causing the shudder.
Any thoughts or possibilities? Hard to believe an out of balance tire could cause this much vibe. Thanks for any help.
Racer
Joined: Nov 2001
Posts: 478
Likes: 3
From: Huntsville AL
A out of balance tire can cause it. I bought two new tires during my resto two years ago. After the resto was complete this year I took it in for an allignment and balance and couldn't balance the two new tires. I had a real bad vib at 50 mph that was almost uncontrollable with the two new tires on the front. I ended up replacing all 4 tires with new ones and the vib was gone 
Lesson: Don't buy cheap tires, I now have two new tires that are useless to me!!! 
YBnormal...drive a vette
Lesson: Don't buy cheap tires, I now have two new tires that are useless to me!!! YBnormal...drive a vette
Thread Starter
Instructor
Joined: Dec 2001
Posts: 196
Likes: 0
From: Dry Ridge Kentucky
vibe / shudder help (2)
ttt
This went down the board so fast, thought I'd give it another shot. Any other advice on the situation below?
This went down the board so fast, thought I'd give it another shot. Any other advice on the situation below?
Originally Posted by keith72
After 3+ years of work got the 72 back on the road. Now I'm trying to diagnose a bad shudder and vibration in the back at 45+ mph so its driveable every day.
Tires are balanced and alignment is mostly correct, although I'm taking it in again this weekend to a better alignment shop and to get the tire balance rechecked. At the previous shop we couldn't get the toe-in dead on and I found the rt trailing arm slightly bent from an accident so I replaced it.
During the rebuild, the only things I didn't replace were the differential and the rear spindles and rotors. So, naturally my worst fear is that the rear bearings are causing the shudder.
Any thoughts or possibilities? Hard to believe an out of balance tire could cause this much vibe. Thanks for any help.
Tires are balanced and alignment is mostly correct, although I'm taking it in again this weekend to a better alignment shop and to get the tire balance rechecked. At the previous shop we couldn't get the toe-in dead on and I found the rt trailing arm slightly bent from an accident so I replaced it.
During the rebuild, the only things I didn't replace were the differential and the rear spindles and rotors. So, naturally my worst fear is that the rear bearings are causing the shudder.
Any thoughts or possibilities? Hard to believe an out of balance tire could cause this much vibe. Thanks for any help.
Burning Brakes
Joined: Jun 2002
Posts: 837
Likes: 3
From: Texas
I'd like to keep this discussion going a little longer also......in some cases people recommend checking U-joints and driveshaft/halfshaft balance........once a wheel balance problem has been ruled out.
Keith....a couple of questions....is the vibration more noticable during acceleration? If you throw it into neutral during the vibration does it stop or ease up at all??
Keith....a couple of questions....is the vibration more noticable during acceleration? If you throw it into neutral during the vibration does it stop or ease up at all??
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
what would rotor run out do????? by that i mean a rotor that wobbles?
you know now that i think about it, i drove a c5 for a friend that had a wierd rumble shudder only starting at 65mph below that it was fine... turned out to be a wheel bearing...
you know now that i think about it, i drove a c5 for a friend that had a wierd rumble shudder only starting at 65mph below that it was fine... turned out to be a wheel bearing...
Last edited by bobs77vet; Oct 28, 2004 at 09:52 PM.
Thread Starter
Instructor
Joined: Dec 2001
Posts: 196
Likes: 0
From: Dry Ridge Kentucky
No it doesn't change under acceleration loading, and neutral doesn't make any difference. And, it doesn't get any worse or better from 50-70 mph. (Haven't taken it past that yet).
That's why I'm thinking its probably not drive train, but something in the suspension. Unless its a shaft out of balance, but I just think that would be unusual to just "happen".
That's why I'm thinking its probably not drive train, but something in the suspension. Unless its a shaft out of balance, but I just think that would be unusual to just "happen".
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Instructor
Joined: May 2004
Posts: 199
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From: Santa Monica CA
Did you take your drive axle off the car while you were working on the rear end? Those things are balanced with counterweights, so if you put it on rotated in a different way than it was balanced, you would get exactly that symptom.
Dave
Dave
Burning Brakes
Joined: Jun 2002
Posts: 837
Likes: 3
From: Texas
Hmmm......seems like bearings bad enough to give you a vibration would give you some noise also. You mentioned it was possibly in a wreck (bent trailing arm).....any chance the spindle flange is bent? Maybe have someone drive along behind you and look for a wobble?? Just guessing.
Thread Starter
Instructor
Joined: Dec 2001
Posts: 196
Likes: 0
From: Dry Ridge Kentucky
Thanks for the replies.
Had the tires rebalanced today and yep, found a wheel bent. Balanced it as well as possible and put it on the back. Still vibrates but not near as bad.
Needed a reason to buy some TTII's anyway......
Had the tires rebalanced today and yep, found a wheel bent. Balanced it as well as possible and put it on the back. Still vibrates but not near as bad.
Needed a reason to buy some TTII's anyway......
Burning Brakes
Joined: Jun 2002
Posts: 837
Likes: 3
From: Texas
Interesting.....and thanks for the update....always good to hear how these things work out. How/where was the wheel bent? Did they just balance the wheel without the tire and then mount the tire and tweak it in?
Race Director
Joined: Oct 2002
Posts: 12,065
Likes: 2
From: Smalltownville Michigan
Cruise-In 5, 6 & 10 Veteran
St. Jude Donor '09
Originally Posted by keith72
Just balanced it with the wheel on. But, you can see the inner rim "bounce" when its on the balance machine.
you may try to rotate that wheel to the front for a test drive... sounds like a bent rim...