Mike_hawk

Have an 82 silverado lq4/4l60e, kept stock driveshaft and trans crossmember (relocated rearward) using dirty dingo mounts in stock sbc location. I have a vibration that starts around 50mph, nothing severe just noticeable, it didn't exist before my swap. I have 20" boss 338's on it before/after swap and recently had them balanced with weights on the inside only. Truck didn't drive for about 6 months during the swap. I recently checked the pinion angle trans is 4* down diff is 2.5* up. I feel the vibration in the seat, not the steering wheel so I think it's related to something in the rear. Could that 1.5* difference cause my vibration or should I try swapping wheels front to back? I'm sure I researched it but a 700r4 and 4l60e have the same output spline count right?

i r teh noobz

iTrader: (4)

I'd swap the tires first. Maybe a wheel weight got knocked off or something.

homemade87

Mike, I would go ahead and move the trans up to the 2.5* to match your pinion . You should have plenty of room in your 82 to shim the tranny mount . They say you can get by with 1* diffrence but its best they are equal to cancel . I would do this regardless.

If it had been sitting for 6 months your tires may have flat spotted. 20" wheels with a low profile tire , not much side wall to move. It will take some heat in the tires to get them back.

Just some things to think about. Good luck

rotor vs. piston

iTrader: (3)

What I was going to say about the flat spotting, happens to me a lot. Just have to drive some miles and so far has always smoothed out. One day I'll get smart and put them on stands when I know I wont be driving it for a while.

i r teh noobz

iTrader: (4)

Some say inflating the tires to the sidewall max helps minimize flat spotting.