vibartion at 85mph.

[Street Fighter]

I have a 77camaro that have a vibration that can be felt through the floor of the car at 85.I rebuilt the trans about two months ago and I have noticed that a bad vibration is there. I believe that it was there at frist but maybe not so bad.(Question)1 if you rebuild a engine and do not have it balanced will it cause this problem?2 could the trans cause this? The car runs good up to this speed than it begains to vibrate the flood board.I am going to check the trans mount and see if it's bad and check the joints that's all I know to check. Hope to get some ideals from you all. Thanks for any and all replys.

[HASTINGSRJ]

try checking your drive shaft to see if its balanced. Also maybe the tail shaft bushing in your tranny went bad....you may want to check the rear end as well....

[ChevyThang]

It could be your rims. Did you put on different rims? If so you need hub centric rings

[05gtoautoX]

check your U-Joints that connect the driveline to rear-end, and driveline to transmission, while car is off and in park or in gear if it's a manual trans. get under the car and see if you can rotate the driveline and visually check the caps on the u-joints, if OK, check and see if your motor mounts are loose, still ok? see if your harmonic balancer bolted to the front of the crank is loose/not on all the way etc. also check your: lug nuts, tires/wheel banced?, bent driveline, warped flywheel/ring gear. hope this helps