5 speed swap vibrations! please help
 

Well at the junkyard I got my self a 5 speed out of a 79 that seemed in good condition to replace the 4 speed in mine. Well I've swapped it out and now I have a bunch of vibrations!

the most noticable one is between 74-85mph it's a really harsh but constant vibration. it's not a rumble tho. and it doesn't matter if the clutch is in or not, it's still there and it kinda gets worse if the clutch is in.

the driveshaft is in good condition, new u-joints.

Tires are brand new and I had them balanced at both high and low speed.

Also I drove the car to run to pepboys to get some gear fuild and the vibrations weren't there.

So what could it be, because I'm scared to drive the car as to damging something else.

What should I do, swap the 4 spd in, find another 5 spd at the yard (there are a two other SA's I can check and a bunch of FB's) or should I have it rebuilt and just drive the 4 spd for a bit again?

If I end up going to the junkyard again what should I look for in the tranny?

all experts please help me out.

thanks,
matt

My 85 GSL wibrates around those same speeds...I dont know why though :)

~T.J.

mine two when i slow down from 80-85 to 70 it buzzzzzz
as soon as i step on the gas even just to maintain speed it stops