ok heres the deal, my friends got a 91 rs..... was a 10 bolt 2.73's

when he bought the car it had a bad speed related vibe that would start about 65, the transmission blew up, so he since replaced it....

so the trans is new

new u-joints

new shocks, brakes bearings etc.....

changed the rear to a 9 bolt like mine w/ 3.27's


the vibration is still there, and it starts around 55 now due to the gears being taller and the driveshaft spinning faster

is this another bad third gen driveshaft or am i just overlooking things???
Luke

i would say driveshaft, mine vibes at 65-78 or so, after 80 its smooth as glass, strange, how i can be doing 95 and never know it, but 70 is rough

im putting an alum driveshaft in when i find one

2 things, either driveshaft out of balance or tires out of balance.

My driveshaft started to vibrate at 70 really bad. I was scared to go down the track. I replaced it with a aluminum 3 inch and have seen no problems since

Do the easy things first....Rebalance all four tires & wheels. If that dose not work try replacing the dr shaft with a Aluminum 3rd or 4th gen shaft.
I am guessing as my first choice you have a tire balance problem.

sweet guys thanks, i told him to order a new shaft as thats what i figured too i wanted you opinions first!!!

and he had the tires balanced too i forgot to mention it.... thanks y'all
LUKE