neverenuff#1

I have a 2000 t/a with a 6.0 liter engine, 4l60e tranny, stock 10 bolt with 4.10 gears. I took the car to the track and broke the ring and pinion. I had the rear end all rebuilt with new bearing seals, and gear set. It seems to work good with no whine at all. But when you get it up to 70 80 mph and let off the throttle it has a bad vibration, step back on the throttle and it goes away. Any body have any ideas on what to look at on this. I had the bushing in the rear of the tranny replaced because the driveshaft had a little play in it but this didnt help any.

O2Form

Try this 1st, mark the drive shaft to the yoke at the rear. Then remove the straps and rotate it 180 reinstall the straps. If that doesn't help you have a drive shaft angle problem. What trans mount are you using? The stock one or after market? Also be sure the pinion is tight and has no up and down play when you have the DS off. The pinion gets forced foreward when you are on the gas and gets pulled back towards the rear as you let off, If its not set up tight enough it could cause a vibration. Another thing I've noticed some of these cars has a slight vibration letting off the gas at certain speeds. It has to do with the trans- rear angles and body.

neverenuff#1

Thanks ,I have already rotated the driveshaft 180, It has the torque arm relocated to the tranny cross member but I dont no what brand it is, There is isnt any slop in the pinion. And If this was a slight vibration it would be fine..lol. ITS REALLY BAD LIKE SOMTHINGS GETTING READY TO GO SOUTH.

neverenuff#1

I got under the car today and looked at the tranny mount. Its a poly urethane energy supesion mount. Will this mount cause vibration? I read some post on another site where guys said it made there cars vibrate. Also my car has a steel drive shaft. Did it come with this or is it suppose to be aluminum?

Camaro Junky

Yes it will. Poly mounts will add vibration. Do a search for OEM transmission mounts. They are under older firebird numbers at the Auto parts store. So did you just add the poly mounts during the rebuild?

neverenuff#1

The polly mounts have been on it a while. Its always had a slight vibration but now it has gotten worse.

speed_demon24

iTrader: (6)

Loose pinion nut.

neverenuff#1

Thanks but Its not a loose pinion nut. Sombody else told me to tighten it up and that caused me to get a new front pinion bearing and crush sleeve when the other one burnt up from being to tight. Its setup right the problem is somthing else.

Camaro Junky

I had the poly trans mount and hated it. I have the OEM 97 ish Firebird rubber job and works just fine. I am also going to replace my poly motor mounts back to rubber as well.

}Anti_Ricer_X{

iTrader: (1)

Just going suggest cuz I had the same problem And it turned out to be my LCA's try moving them side to side if there is slack the bushings on your LCA's are bad not sure if that's your problem but you have the exact same symptoms I had I replaced LCA's and it helped. Good luck

neverenuff#1

thanks for the input. I will definitley be checking those LCA'S out. I hadnt thought of that. Also gonna shed the poly mounts for stock ones. Thanks

neverenuff#1

I got my vibration fixed today!! It was my drive shaft, it some how got twisted. I put in a new aluminum and wah la its fixed!!