81 vette vibration
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Instructor
Joined: Mar 2013
Posts: 108
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From: Georgia
81 vette vibration
I have new tires on the rear and new u-joints. All the rubber mounts are in very good shape.
When I get up around 60 MPH I feel a vibration in the rear. I haven't gotten above 60 since I noticed it.
I don't have history about the car. I bought it, put it on stands and started working on things. I had to put new output shaft seals in, a new trailing arm, u-joints, and tires and a few new rubber bushings was everything done to the car.
Any ideas
When I get up around 60 MPH I feel a vibration in the rear. I haven't gotten above 60 since I noticed it.
I don't have history about the car. I bought it, put it on stands and started working on things. I had to put new output shaft seals in, a new trailing arm, u-joints, and tires and a few new rubber bushings was everything done to the car.
Any ideas
Drifting
Joined: Aug 2010
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From: nassau co. new york
i bought a car with a similar vibration that you describe and it was not caused by a single part or adjustment.old tires,1 bad halfshaft u-joint,drive line not in phase,trailing arm bushings and 4 wheel alignment.car is a joy to drive now vibration free.
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From: Georgia
I never got it up 60 before. The car has 46000 miles on it and I bought it from the original owner for $6000. I did take it down the road for about 5 miles but I only got up to around 50. Then I roled it in the shop and started fixing all the leaks due to it setting so much. It feels kind of like a u-joint to me but all 6 are new and rotated good when I checked them.
I just I need to get it above 60 and see if it stops. That would lead me to think it was a tire not ballanced correctly.
I just I need to get it above 60 and see if it stops. That would lead me to think it was a tire not ballanced correctly.
Drifting
Joined: Aug 2010
Posts: 1,839
Likes: 45
From: nassau co. new york
i could not detect any roughness in my halfshaft when rotated.i just replaced them all and dicovered a few disintegrated needle bearings when removed.some driveline phasing information.http://www.classicchevy5speed.com/fi...roc_111606.pdf
Last edited by billcarson; May 1, 2013 at 12:40 PM.
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From: California
Thread Starter
Instructor
Joined: Mar 2013
Posts: 108
Likes: 1
From: Georgia
i got it up to 90 and the vibration just kind of stays there. No increase or decrease. I will go get a 4 wheel alignment and see if that fixes it. The guy I bought it from was not a mechanic. It has most likely not had an alignment in the past 15 years.
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Thread Starter
Instructor
Joined: Mar 2013
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From: Georgia
I did read it. I have put so many parts on the rearend suspension. I think I need to have it aligned anyway. It is also a little squirrelly when I go around corners.
I will check the motor alignment if this doesn't fix it.
Thanks
I will check the motor alignment if this doesn't fix it.
Thanks
Race Director
Joined: May 2003
Posts: 10,956
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From: California
if your still squirlley when you go around corners after the alignment (remember, we need both a front and rear end alignment), then I would look very closely at the trailing arms... bad bushings cracked trailing arms and the like will make it feel that way....
Also... our C3's are not the norm, especially the rears, and most alignment shops have no idea how to do the rear, much less have the shims needed to even do the job....
Also, go to VB&P web page and get there alignment specs to give to your alignment guy... p
Also... our C3's are not the norm, especially the rears, and most alignment shops have no idea how to do the rear, much less have the shims needed to even do the job....
Also, go to VB&P web page and get there alignment specs to give to your alignment guy... p
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From: Georgia
I dropped it off this afternoon. I am having them recheck the tires as well for ballancing. They just called me and said the lower ball joints are worn. I didn't motice any movement but they have worked on my company's trucks for the past 10 years.
They have been in business here for the past 30 years and said they have shims and all the specs.
I really hope it drives like a new one when I pick it up tomorrow.
They have been in business here for the past 30 years and said they have shims and all the specs.
I really hope it drives like a new one when I pick it up tomorrow.
Thread Starter
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From: Georgia
I picked it up. They had to change out one of the lower ball joints. He said it was very bad. I say, I never saw the wheel leaning. He said you may never see it on a bottom ball joint like you will on an upper one. I told him about the car being a little squirrely in cures. He said this is why.
Changed lower ball joint, 4 wheel alignment, balanced all tires. Very smooth up to 60 and very smooth from 80 up. Around 65 ~ 75 just a very small vibration. I can put it in neutral at 70 and it is as smooth as glass. I think this car should have the locking converter but mine isn't locking. If I get this fixed, it will be as smooth as I can ask for with 15" tires. I will start my next post about the converter. Thanks guys for all your help.
Changed lower ball joint, 4 wheel alignment, balanced all tires. Very smooth up to 60 and very smooth from 80 up. Around 65 ~ 75 just a very small vibration. I can put it in neutral at 70 and it is as smooth as glass. I think this car should have the locking converter but mine isn't locking. If I get this fixed, it will be as smooth as I can ask for with 15" tires. I will start my next post about the converter. Thanks guys for all your help.
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From: California
Around 65 ~ 75 just a very small vibration. I can put it in neutral at 70 and it is as smooth as glass.
this is typical of an out of alignment drive train. it shold NOT do this if aligned correctly.
this is typical of an out of alignment drive train. it shold NOT do this if aligned correctly.
Race Director
Joined: May 2003
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From: California
they go out of alignment when people change rear-ends, transmissions, clutches usually..... then they just put it all back together without paying attention to this important detail... as most mechanics are not even aware of this.
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From: Georgia
Well that explains it. I removed the rearend to replace the seals. But if I remimber right, on the 81s the complete rear cross member is part of the rearend and it is held in by a bolt on each end. The mount bolts had no movement to them just bushings where the bolts went through. How can it be trued up? There were no adjustments anywhere to do this.
Race Director
Joined: May 2003
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From: California
this adjustment is very fine... 1/8" can effect everything... and between your trans mount and rear end mounts and motor mounts you can get the proper adjustment..
go read the thread again... it shows it all..
go read the thread again... it shows it all..
Last edited by pauldana; May 2, 2013 at 01:54 PM.
Thread Starter
Instructor
Joined: Mar 2013
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From: Georgia
OK I will look at my alignment tonight. It would be great if that is all it is. I can do adjustments all day long. I just don't want to keep throwing money at it. When you finally fixed yours, was it as smooth as if it were new again?