bad vibration

[jasonblinn]

i was wondering if anyone could help me out.im about to give up anytime.i just lowered my 1986 chev stepside,did an axle flip in the rear,and now i have a bad vibration in the truck.at 40 mph its more like it jumps more than a vibration.i already tried 3 driveshafts,all rusted or dented though,hard to find 1 around here for some reason.after i lowered it the stock driveshaft which was 27'' was too long,so i found out that 1 off a 4x4 long box is the same,around 55 1/2'' long.tried another set of wheels,it slowed the vibration so that told me it was my wheels.then put mine on another truck and no vibration at all.balanced my wheels 3 times already.had a bent axle,replaced that,still does the same thing.checked my rear drums cause it does it when i slow down or when i brake,rear drums were wharped,took them off,blocked my rear brakes off,went and tried it,still the same vibration.last night i put it on the hoist for the 100th time..lol..played with the pitch,seemed like it slowed it down at 1st,thought i had done something right but it started vibrating again.how do i check for that anyway??someone even suggested my shocks cause im still using the stock shocks,but took them off and it was still doing it.i know my rear end is more towards the passenger side,about 1/2'' for some reason,could it be that?seems like every thing i try it slows it down for a little ways down the road then it starts again.its really getting on my nerves,ive been trying to figure this out for almost 3 weeks now,every day i try something different with no luck at all.any info would be greatly appreciated

[old Rusty C10]

carrier bearing?

[jasonblinn]

im just about ready to change the whole rear end itself.but what i dont understand is that it wasn't doing this before i lowered it.i just bought the truck last summer,drove it back,it was a 4 hour drive,no vibration.i know when i replaced my axles,the bolt that holds the pin was broke,so i replaced it,and within a week i took it apart again and the bolt was broke again...frigg knows??

[sick454]

did you ever figure out your vibration? I have a vib that cycles when going down the road.

[jasonblinn]

never figured ity out..i ended up selling the truck

[68c10owner]

It was probably a incorrect pinion angle. When you lower the vehicle the pinion angle changes. That can cause vibrations because now the driveshaft is not inline like it should be. Pinion shims usually correct this problem.