Vibrating at take off

[NorCalTurbos]

First I wanna say thanks for any input on this issue. I’m getting vibration taking off from dead stop partial throttle goes away when I get into it and 1-2 shift feels good like it wants to chirp the tires but the vibration is all you hear and feel.
If I shift through the gears manually from stop in first no vibration like when in drive. I’m thinking driveshaft or u joints or both

 

[xlr8ngn]

Check both engine mounts and your trans mount, the rubber breaks down over time. It's easy to drop the drive shaft and check your U joints. Probably not this, but check your harmonic balancer for any movement, and watch it while running with the engine running. Probably not this either, but check flex plate to torque converter bolts.

I bought a TTA with a weird vibration, and did everything I could think of. The crank broke in half finally between throws 1 and 2.

 

[NorCalTurbos]

Check both engine mounts and your trans mount, the rubber breaks down over time. It's easy to drop the drive shaft and check your U joints. Probably not this, but check your harmonic balancer for any movement, and watch it while running with the engine running. Probably not this either, but check flex plate to torque converter bolts.

I bought a TTA with a weird vibration, and did everything I could think of. The crank broke in half finally between throws 1 and 2.

 

[NorCalTurbos]

Engine and transmission mounts are new so I’m gonna check the drive shaft out next. The engine feels fine sm showing that it’s a lil lean but the vibration feels like it’s coming from the rear passenger side during take off 1-2 and 2-3 shift points.

 

[John Larkin]

The u-joints should have c clips that align it with the yoke. If its out of center, it will vibrate. Ask me how I know.

 

[1KWIKSIX]

The u-joints should have c clips that align it with the yoke. If its out of center, it will vibrate. Ask me how I know.

Yup, I found the same problem……only discovered it after chasing my tail for years!
After removing & installing new U joints (making sure these were centred / seated properly in the yoke) , shaft was found with a very slight bend in it , so had it straightened & rebalanced which finally resolved my vibration issues .

 

[xlr8ngn]

What kind of transmission mount did you use? A poly mount can allow a lot more vibration to pass through, but it would normally be localized. Also, if you might have changed the height/angle of the transmission, that will change the geometry of the trans/driveshaft/rear end and things can happen. Check your rear suspension upper and lower control arm bushings as well. Is your car stock height or lowered?

 

[1986 Buick GX1]

It was mentioned the vibration doesn’t happen when shifting manually.
It makes me think there might be something going on with the line pressure, but I’m no transmission expert. Just a thought.

 

[xlr8ngn]

You could also sit in the back seat while letting someone try and recreate the vibration, and see if you can narrow the origin down further.

 

[jfsram]

What is the pinion angle of the rear joint?

 

[NorCalTurbos]

What kind of transmission mount did you use? A poly mount can allow a lot more vibration to pass through, but it would normally be localized. Also, if you might have changed the height/angle of the transmission, that will change the geometry of the trans/driveshaft/rear end and things can happen. Check your rear suspension upper and lower control arm bushings as well. Is your car stock height or lowered?

Rubber mounts

 

[NorCalTurbos]

You could also sit in the back seat while letting someone try and recreate the vibration, and see if you can narrow the origin down further.

Feels like the center but I will have my daughter drive me around tomorrow to see if I can feel more precisely

 

[NorCalTurbos]

What kind of transmission mount did you use? A poly mount can allow a lot more vibration to pass through, but it would normally be localized. Also, if you might have changed the height/angle of the transmission, that will change the geometry of the trans/driveshaft/rear end and things can happen. Check your rear suspension upper and lower control arm bushings as well. Is your car stock height or lowered?

Rear body bushings are shot new set coming soon. Due to this I assume it’s sitting lower than stock, time to start checking before I start throwing parts at it… Again

 

[NorCalTurbos]

What is the pinion angle of the rear joint?

It’s probably going to the shop to find out I don’t have tools to check it

 

[jfsram]

Make sure the shop understands this happens during take off. So they can check the angle under load.
If the rear control arm bushings are shot, the axle housing will nose up during torque.

 

[Chuck Leeper]

Rear body bushings are shot new set coming soon. Due to this I assume it’s sitting lower than stock,

Body droop doesn't affect pinion angle.