Driveline vibration
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,369
Likes: 103
From: Centerville Louisiana
Driveline vibration
Any help on tracking down what seems like a light vibration in driveline? Looking for ways to isolate area. Transmission recent rebuild, rebuilt Trailing arms about 3500 miles.I also sent rear dif out for rebuild at 3500 miles. Rear end Brairs, trailing arms VTech. So I’m pretty confident these two were done correctly.
Safety Car
Joined: May 2001
Posts: 4,757
Likes: 1,647
From: Fairfax Virginia
How about the outer bolts that secure the rear spring? Are they shorter than the original bolts?
A Chevrolet dealer rebuilt my posi-trac unit for me and when they put it back together they installed shorter bolts on the outer spring mounts and this jacked up the rear of the C3 and caused Drive-line vibration. It took me a while to learn that the bolts were the only thing they did wrong. VBP was the one who told me about the solution. It turns out a lot of people replace the put new shorter bolts in place of the originals. The shorter bolts forced my rear up to the point where it was visible in the rear view mirror and the car looked high in the rear. When I pointed this out the dealer suggested that the spring needed to "re-seat" itself. Hog wash....
Just be sure that your half shafts are running parallel to the ground and are fairly level.
A Chevrolet dealer rebuilt my posi-trac unit for me and when they put it back together they installed shorter bolts on the outer spring mounts and this jacked up the rear of the C3 and caused Drive-line vibration. It took me a while to learn that the bolts were the only thing they did wrong. VBP was the one who told me about the solution. It turns out a lot of people replace the put new shorter bolts in place of the originals. The shorter bolts forced my rear up to the point where it was visible in the rear view mirror and the car looked high in the rear. When I pointed this out the dealer suggested that the spring needed to "re-seat" itself. Hog wash....
Just be sure that your half shafts are running parallel to the ground and are fairly level.
Burning Brakes
Joined: Nov 2004
Posts: 1,193
Likes: 176
From: Hillsborough NC
Is the vibration felt in the shifter? If it is, I would check your driveline angles. With all of the replacements/rebuilds you list (Transmission, rear), I would assume you replaced the mounts for these as well. While you would assume that if you replace the mounts, everything should line up as it was from the factory, sometimes this is true, sometimes it is not 
A driveline issue usually manifests itself with a vibration that only occurs at certain speeds and is felt through the shift handle.
The key is to make sure that the angle of the transmission is equal and opposite to the angle of the rear end.
If these are your symptoms, there are plenty of good articles on how to check the angles. In the C3, the common way to adjust the angle of the rear is to trim the rubber on the front mount, that will alter the tilt.
Good luck, vibrations are a bear to find sometimes....
A driveline issue usually manifests itself with a vibration that only occurs at certain speeds and is felt through the shift handle.The key is to make sure that the angle of the transmission is equal and opposite to the angle of the rear end.
If these are your symptoms, there are plenty of good articles on how to check the angles. In the C3, the common way to adjust the angle of the rear is to trim the rubber on the front mount, that will alter the tilt.
Good luck, vibrations are a bear to find sometimes....
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,369
Likes: 103
From: Centerville Louisiana
It seems to have gotten worse since Transmission rebuild. My plan as of now jack it up inspect all bolts , exhaust hangers, put weight on shocks mounts and run it slowly
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
But....if it is worse since the trans rebuild.....you probably put a new mount in it.......buy or make some shims to add phase to the drive shaft.....and test. Maybe the new mount doesn't like your pinion angle...you can shim the snubber as well at the rearend.
The halfshafts need to have a little phase in them too.....not much but some......
The other thing to check is to make sure all six U-joints are centered in the ends of each shaft......your driveshaft is new but check it anyway.......
Most drivetrain vibrations are due to insufficient phasing of the shafts....
Jebby
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Drifting
Joined: Dec 2011
Posts: 1,743
Likes: 289
From: Chardon Ohio
I had an issue where I had a vibration and it turned out to be one of the U joints in one of the half shafts which was improperly installed. Possibly not seated fully or something. All at once it let go. Not good.
https://www.corvetteforum.com/forums...a-flatbed.html
Jim
https://www.corvetteforum.com/forums...a-flatbed.html
Jim
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,369
Likes: 103
From: Centerville Louisiana
I had an issue where I had a vibration and it turned out to be one of the U joints in one of the half shafts which was improperly installed. Possibly not seated fully or something. All at once it let go. Not good.
https://www.corvetteforum.com/forums...a-flatbed.html
Jim
https://www.corvetteforum.com/forums...a-flatbed.html
Jim
Pro
Joined: Feb 2017
Posts: 518
Likes: 365
From: San Diego
2023 C3 of the Year Finalist - Modified
Try the elimination method.
Get it to vibrate then eliminate the engine/clutch as a source. If auto, change gear.
Get it to vibrate and eliminate alignment and bushings by finding a road where you can load the tires in a turn when the vibration is present.
Then you are down to drive shaft and half shafts. Take them apart and inspect them. Double check your engine, tranny and Diff mounts. Align the driveshaft again.
Get it to vibrate then eliminate the engine/clutch as a source. If auto, change gear.
Get it to vibrate and eliminate alignment and bushings by finding a road where you can load the tires in a turn when the vibration is present.
Then you are down to drive shaft and half shafts. Take them apart and inspect them. Double check your engine, tranny and Diff mounts. Align the driveshaft again.
Melting Slicks
Joined: Mar 2010
Posts: 2,270
Likes: 375
From: Randolph nj
someone once said they had the same problem and he brought his car to a oldschool shop and the mechanic loosened the trans and motor mounts and took the car around the block and tightend everything up and the problem went away ,,, It was on here about 6-7 years ago maybe others can chime in
Last edited by forman; Feb 16, 2022 at 08:51 PM.
Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 492
From: Salmon Arm, BC
Those pics you posted point to an issue that should be fixed, but that's likely not the issue. I like what FORMAN posted above as a possible solution for a fix. The most likely cause is the u-joint angles at the transmission and the rearend....as said before, they need to be the same, but opposite angles. Check this using a magnetic angle finder on the flats spots of the u-joint ends....using a nut as a spacer to clear the stepped end of the yolks.
Hope that makes sense....
EDIT: Adjust the angles using a spacer shims at the tranny mount.
Hope that makes sense....
EDIT: Adjust the angles using a spacer shims at the tranny mount.
Last edited by OMF; Feb 18, 2022 at 12:25 PM.
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
Those pics you posted point to an issue that should be fixed, but that's likely not the issue. I like what FORMAN posted above as a possible solution for a fix. The most likely cause is the u-joint angles at the transmission and the rearend....as said before, they need to be the same, but opposite angles. Check this using a magnetic angle finder on the flats spots of the u-joint ends....using a nut as a spacer to clear the stepped end of the yolks.
Hope that makes sense....
Hope that makes sense....
Race Director
Joined: Mar 2016
Posts: 14,399
Likes: 8,204
From: Napa Valley California
I didn't see in the posts if you have an auto or manual trans.
There has been several threads where members have reported vibrations when using a CenterForce clutch.
After they swapped the clutch with another manufacturer, their vibration disappeared.
There has been several threads where members have reported vibrations when using a CenterForce clutch.
After they swapped the clutch with another manufacturer, their vibration disappeared.
Heel & Toe
Joined: Jul 2020
Posts: 23
Likes: 6
From: Australia
My experience with chasing a vibration on my 81 was to send the driveshaft for balancing. It was heavily pitted all over the surface. I replaced it with a new shaft and universals. Problem resolved after chasing it for many years.
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,369
Likes: 103
From: Centerville Louisiana
Not saying it’s not the problem but it’s a new shaft and spicers I got from Fort Wayne driveshaft. Tomorrow’s my day off so I’ll pull it and give it a once over. They have a big truck driveline shop kinda close but I don’t believe they can high speed balance it