ThirdBird

Do you mean axial play? I have checked for that, it's tight. If you mean up/down, front/back by lateral, I've checked that also. By hand though, not with indicators.

How about pinion angle?? The angle of the differential to the drive shaft. It's supposed to be like 2 degrees offset or some such number. We've tried to measure that with all sorts of stuff like magnetic angle finders. Very hard to reference off anything flat and square. From what I;ve read, the drive shaft/u-joints at the the diff. and at the tranny need to be at a small angle (not straight) and opposite each other. Any knowledge of this weird angle spec? I'm not sure I understand it.

Ted G

iTrader: (1)

Pinion angle should not be an issue with a stock height truck and I'll assume the u-joints were checked for alignment when the driveshaft was worked on. Does the truck have an auto 4wd setting and do you drive with it like that? Have you tried to run the truck with the frt driveshaft out?

Rippem

exactly

ThirdBird

Truck is stock height. I don't know if Universal Joint checked the joints for alignment to the shaft. I told them to check everything and replace the joints. The truck does not have an auto 4wd setting, it's the old style lever on the floor. We did run the truck with the front shaft removed, no change.

If one of the rear axles was bent at all, wouldn't I feel that at all speeds? And why then would it fade to almost nothing sometimes?

I also don't think it's a pinion angle issue either. We ran the truck on the lift with axle hanging, effectively worsening the pinion angle. Axle hopped pretty good. Then we compared that by running another truck on the lift with it's axle hanging. That truck's axle ran smooth as can be at all RPMs.

One more tid-bit I forgot to mention, the vibration is less severe when the boat is trailed or when there is a heavy load in the back.

Rippem

stop throwing in more tid-bits!!

though that is interesting...pondering...

it still points to chassis not driveline..

ThirdBird

I'm thinking NOT chassis. The reason is that the vibration was evident while on the lift. Chassis alignment issues causing vibrations would only be evident while all four wheels are on the ground and "fighting" each other due to the misalignment. While hung in the air, the chassis misalignment would not have any resistance to any thing.

Rippem

Ok smarty...

let me tell you if you have had a shuddering or out of balance convertor for the last 75K miles...it would have exploded along time ago.

and dont be so confident about chassis. it would still shake in the air if the axle was pushed to one side of the frame or cocked!

think about it!

ThirdBird

Appreciate your ideas Rip, but still not buying into the alignment thing. If it were an alignment issue, I'd have eaten these tires by now. The last set has about 15k on them, there should be some unusual wear evident from misalignment.

But, don't stop your input. It makes us think and analyze. There's got to be a culpret here someplace. After all, it's just nuts and bolts. And, by the way, when I get the chance to get it to a good body shop, I'll certainly have the frame checked.

Rippem

touche'

though how much would cause a vibe (only at higher speeds) and how much would show in tire wear? especially rears? I think there is a thin line there.

Rippem

BTW like my new avatar?