3 rd gear vibration???? 4L 60

[95TAVert]

Needing a little expertise guys, put 2 no and 4 gear servos in my 4 th gen TA and poly Trans mount and torque arm mounts. Now I have a slight vibration in all gears, could even be considered road vibration which really didn't surprise me with the poly mounts. Except when it's in 3 rd gear the little vibration becomes a big vibration. Any I deas or suggestions. The tranny shift and feels awesome, shift quick. I installed one of Frank Cahall's valve body which also really helped. But now I have a vibration that was not there before. Thanks

[tleed]

Check your pinion angle and get rid of your poly transmission mount

[SSlowBoat]

Poly Trans mount will barely cause vibration IF you bought the right one. The regular gm universal part number causes vibration. There is a lt1 fbody specific mount that has an improved angle. Also, you do not use the shim with the Trans mount, the mount bolts straight to the trans

[shadowbandit]

What is that mount I'm trying to get one my self

[SSlowBoat]

3.1114g I believe. It's a little shorter and offset a little better. It cured my vibration on the 96 and the 94

[95TAVert]

Poly Trans mount will barely cause vibration IF you bought the right one. The regular gm universal part number causes vibration. There is a lt1 fbody specific mount that has an improved angle. Also, you do not use the shim with the Trans mount, the mount bolts straight to the trans
I bought the 95 specific from Summit. Sure don't remember using a shim. What do you think I should check now?

[SSlowBoat]

U joints

[SSlowBoat]

You have a steel or aluminum driveshaft? FYI the 3" aluminum I had from a 02 ss was too long and the yoke was buried in the tail shaft causing vibration. Check pinion angle as well.

[CPT]

You can't use the shim with the Energy Suspensions mount. Most poly mounts I've seen do tend to transfer more vibration. If you have worn u-joints, The poly mount will magnify them.

Frank

[95TAVert]

You have a steel or aluminum driveshaft? FYI the 3" aluminum I had from a 02 ss was too long and the yoke was buried in the tail shaft causing vibration. Check pinion angle as well.
The drive shaft is a 3 1/2 alluminum with 1350 solid joints, it only has a thousand miles on it. The rearend is a 9 in with 3.90s and the angle is a little over 3. I guess it must be the poly bushings sense I didn't have vibration prior to tranny removal and new mounting installed? Thanks for all input any other ideas would be appreciated.

[SSlowBoat]

Auto should be closer to -1-2

[95TAVert]

U joints
One day I had no vibration, pulled tranny and reinstalled now vibration is mainly in 3rd gear. But very noticeable,
Question, could the one to one 3 rd gear ratio have anything to do with it? And if so? How?

[SSlowBoat]

harmonics, pinion angle, etc could all play a factor, you dont have a nice rubber bushing soaking that up now. could even be gear noise. my firebird did that, only at 70mph on the highway it would vibrate like hell, thought it was the trans,then this, then that, here all along it was the gears harmonics coming thru the trans mount. gears ended up being shot

[95TAVert]

harmonics, pinion angle, etc could all play a factor, you dont have a nice rubber bushing soaking that up now. could even be gear noise. my firebird did that, only at 70mph on the highway it would vibrate like hell, thought it was the trans,then this, then that, here all along it was the gears harmonics coming thru the trans mount. gears ended up being shot
I definitely need to double check my angle and I think I pick up a rubber. Mount and install it to see. My 9 in only has maybe 500 miles on it so I don't want to destroy them. Thanks Tubby

[CPT]

Get the car running at a given RPM is 3rd and notice vibration. Then het it running the same RPMs on O/D. Is the vibration the same? Now try the same test using MPH and see if the vibration is the same between 3rd and O/D. Why did you have the trans out? It's very possible that you have the driveshaft 180 degrees out.

Frank

[95TAVert]

Get the car running at a given RPM is 3rd and notice vibration. Then het it running the same RPMs on O/D. Is the vibration the same? Now try the same test using MPH and see if the vibration is the same between 3rd and O/D. Why did you have the trans out? It's very possible that you have the driveshaft 180 degrees out.

Frank

i will check the speed and rpm's. I looked to see if the driveshaft was out of time, but I am not sure how to tell? I will find out. The tranny was out to install 2 and 4 gear sonnax billet servos, install went great and it shifts awesome.

[95TAVert]

Get the car running at a given RPM is 3rd and notice vibration. Then het it running the same RPMs on O/D. Is the vibration the same? Now try the same test using MPH and see if the vibration is the same between 3rd and O/D. Why did you have the trans out? It's very possible that you have the driveshaft 180 degrees out.

Frank

Hey Frank
i had tranny out putting servos in it. I turned shaft 180 but no change.
i tried the rpm and mph and the mph was it. At 45 mph was the worst.

[CPT]

Try a stock mount. It will atleast eliminate that variable. A new vibration after poly mount install is a VERY common complaint.

Frank