95 Suburban drive line vibration

How about a drive shaft weight? Could one of them fallen off?

Could be a U-joint not seated or centered in the output shaft on the transmission or pinion shaft on the rear end. Check that or try rotating the driveshaft 180* at one of the u-joints. Could also be a bent wheel or mabey a problem with the front suspension. Any tire wear problems? If I couldn't find the problem myself,I would have a shop do a test drive.

The first thing I would do is move the left rear wheel and tire to the right front. If nothing changes then its got to be in the drive axle, if it changes then since you say new tires get a good used rim. If it doesn't change the next thing I would do is swap the brake drums side to side, and see if that changes things. Those drums usually have balance weights on them, What happens at 65 mph when you hit the brakes? At low speeds as coming to a stop? I wouldn't think a miss-centered drive shaft if you have been driving any time like that, as the vibration would really be ungodly, and it would crack the tail shaft on the tranny(Don't ask it was really ugly a Muncie bit the dust, lessoned learned don't trust friends) . Now then if you have a three piece drive shaft, I would suspect the carrier bearing/ center support assy. also if the when you tighten the straps that hold the u-joint to the yoke on the diff its real easy, this could be an issue as another posted suggested. I never liked the straps, prefer good old fashioned u-bolts my self.

Whitelightning

Thanks for the advice.

Regarding your questions, I have replaced the drums (throwing more money at it). It has a one pieve, aluminum drive shaft about a mile long, but I have not tried to have that checked/balanced.

When I het the brakes at 65, the truck slows down. No special or increased vibration. I recently put new U joints in the drive shaft with no noticable change. Drive shaft is tight in the yokes at both ends.

I'm actually thinking it may be a slightly bent axle, although with the center clips, you would think that this would be difficult to get them back on as the bending would tend to shorten the axle.

If I put the tires/rims on the front, they are as smooth as float glass, but whatever goes on the rear still shakes.

I must say I'm stumped but really appreciate everyone's post. Please leep the ideas coming!

regards

Thanks Bill,

I think I'll take the drive shaft out and run it down to a local guy in town that balances drive shafts. It can't be more than $50 or so for a re-balance.

regards

I have seen the flange area of the axle get bent, but usually you get a hurley gurly kinda feeling out of the rear, like a tire with a belt separation.. If you have access to a ball joint dial indicator gauge, or a Rotor run put gauge you can check it that way, Make sure you clean any rust from the flange face where the gauge will ride, and turn the axle by hand slow and steady. If someone has been getting on it hard, I've seen axles get twisted, but the place that rebuilt the diff should have seen that if it was the case., and with a non posi trac spool, I really wouldn't think that.

Shocks look good? Springs in tact? Bushings in the spring eyes good?

Whitelightning

Going to try the axle run out tomorrow while the weather's warm here on the EC. I have a straight dial indicator and one of those little bendy clamp sort of stand to clamp it in so I can check the run out.

I've been getting on it, all it's life without mercy. Seems like a warped flange would make the whole tire wobble somewhat and I had them flip the axles when they redid the rear end.

It is not an open axle though, a limited slip/positive traction (whichever Spicer calls it). Eveything works fine there. If I'm on a slippey boat ramp and one tire even acts like it's going to spin, they both kick in. Tried it in some slippery mud after the re-do and everything pulled correctly.

I'll let you know if I find anything and thanks again. You seem to have a lot of experience in the Chevy realm.

regards