Ls1 driveshaft upgrade vibration

[95 GA/TA]

I installed 4.10 gears in my trans am and was getting the vibration from the steel drive shaft.I bought a used ls1 aluminum drive shaft and put it in about 600 miles ago.The problem was solved.Well now the vibration has came back and its about as bad as it was before, 70-80 mph and when the rpms are around 4k-5k i feel a vibration from the driveshaft.I havent done anything different to the car , i have installed a centerforce clutch about 200 miles ago but the vibration was happening before i installed the clutch so i dont think its related.I havent got to get back under the car to check it out but if anyone has any ideas let me know.

[raroZ28]

Did you have the gears installed, or did you do them yourself?

[DeWynter]

tripple check to make sure non of your wheel weights have fallen off, Many shakes can be atributed to that, make sure you always get your wheels balanced at a place that has the "roadmaster" balancer machine, way better balance. I can give the full explination why but I dont want to type that much, if you want the particulars I can give them too you just ask. Ihad the same kind of problem and could swear up and down it was the driveshaft, but it turned out it was on wheel on the back.

[94 formula]

Also check you u-joints just to make sure. I had them go bad in my wrangler before and it picked up a vibration anywhere from 50-60 but then stopped above that.

[Joe 1320]

Also check you u-joints just to make sure.

That's what I was thinking. It doesn't take much slop in the bearings to force the shaft into a non concertric spin. As speed increases, so will the vibration. Also check for any damage to the yoke.

[95 GA/TA]

Im hoping it is the u-joints.The ls1 shaft was used but when i installed it the u-joints felt good so maybe something has happened there.Me and a friend installed the gears.We had all the tools to do it,it turned out ok but i get some whine in 4th-6th.I dont think its in the gears because when i changed to the aluminum shaft the vibration went away.The problem seems to be worsening too so im hoping u-joints.The 4.10 gears are nice but have been a little trouble, im changing to 3.73 since i am supercharged, maybe that will slow the driveshaft down a little because with the 3.23 ratio i originally had never gave any problems or vibrations.Thanks for all the ideas,ill also ck the weights too on the wheels.Any more ideas will be appreciated,im tryin to fix it without havin to take it to someone if possible.