The Stovebolt Site Forums The Shop Area Engine Shop '79 GMC 1 ton 4x4 driveline shaking

Just bought this truck, on the way home at ~30 mph, hit some bumps and the transmission/transfer case levers started violently shaking and banging. I pulled over until it stopped, then took off again and it didn't repeat for 50 miles+. It has a two piece drive line, the spline joining the front to the rear drive lines looks worn. Could it be so worn that it's getting cocked and out of balance? I've never seen such a thing, but don't have any experience with this set up. Any ideas? Thanks,
Ray

Sounds more like a bad shock absorber somewhere. You go over a bump, and the suspension loses it. There might even be a resonating frequency that a good shock would normally dampen. Then you feel it through the entire driveline. I dunno, just an idea. Have someone drive next to you and see if you can get that to happen. Have him tell you if one of your wheels starts bouncing up and down real rapidly.

If that's not it, might want to give it a once over, make sure u-joints and driveshaft and everything is cool.

If that doesn't reveal anything either, Midas will troubleshoot it free of charge. They'll want a million bucks to fix it, but once you know what it is, you can go after it yourself probably.

Just a few ideas.

I would like to know what you find out. We had a 79 one ton tow truck that sounds like the same problem. It was called the death shake. Going along at 30 mph, hit a small bump and hold on. The whole truck shook. The steering wheel would turn back and forth really fast. You have to stop the truck to get it to quit. We checked everything underneath and could not find anything wrong. The truck is only used in the yard now, but would like to know what is wrong. :confused: :confused:

I've had the same problem on a couple of vehicles. In both of those cases it was the front end alignment & shocks.

Thanks a lot guys. What was weird about this shake was that it was just in the drive line and didn't really affect the front end/steering wheel. Pretty scary, glad it didn't happen at 65 mph on the freeway. I'll try to track it down and post if I figure it out. Shocks seem fairly new and steering seems fairly tight for a 4x4.
Ray

I talked to an aquaintance who does a lot of wrenching on Chevys. He suspects the same thing I did - the spline and bearing where the front and rear drive shafts come together. He said he had a car that did the same thing and replacing the bearing did the trick. I'll let you know what transpires.
Ray