I have a bad vibration I only notice it crusing down the interstate at 75 in the 6th gear. The vibration goes away when I accelerate, or slow down. I have it when i Just maintain a speed with the throttle or when i Shift in neutral. I recently had a Torsen Hd Posi, new axles and 4.10s put in the rear. I didnt do anything to the drivline or u Joints. What Should I do first

 

maybe its the lubricant in the rear end?

 

Im using richmond gear oil GL6

 

Have the driveshaft balanced and replace the u-joints. If it is at a certain rpm(as you notice at 75mph), it is most likely driveshaft related.

 

with a posi rear you are supposed to use limited slip additive, maybe this will help, though if it only happens at high speeds it's probably the drive shaft-mine did that in my now stolen '85 Z28

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei
'95 3.23 rearend
hotchkis rear suspension

 

I am running a higher drivline speed. 3.08-4.10 Ill replace the ujoints and have it balanced again

thanks