Drive shaft

[TC Chris]

For two weeks I've been driving around with two hose clamps in the truck. Why? Because I got a new drive shaft a couple weeks back, and it was off balance. The old one had a balancer ring that came adrift, and the new one did not have that ring. The truck shuddered and vibrated between 42 and 47 mph, just the speed for a lot of local driving. At first I tried to ignore it but it kept annoying me. Also, it was going to wreak havoc on the transmission's output bearing with all that shaking. I have to take the truck to the shop for a muffler soon and figured that I'd ask if they could exchange the shaky shaft, but my best guess was that I'd bear another set of installation charges at least. So it was off to Google. First of all I called the local machine shop that advertised driveshaft balancing. That used to be a common service but nope, they don't do it any more, nor anybody else around here. But the YouTube options... as usual, some clever people had devised work-arounds. The best video was a guy with a lift. He ran the car up on the lift, attached a bracket to the differential housing to hold a glass of water, and ran the car up to speed, wheels spinning in the air. He held a piece of chalk against the drive shaft to mark the high point--the heavy side--and then put two clamps on with the threaded sections (weights for this purpose) on the opposite side. Again up to speed; watch the water glass for an agitated surface that showed vibration. Stop, mark the position, and rotate the clamps slightly; try again. Over and over until the water surface stayed calm at speed.

My problem is that I do not have a lift so I cannot run the truck up to speed and mark the heavy side of the drive shaft. So I did other chores and projects instead for the next two weeks. But then my boat hauler came down with Covid and cancelled yesterday's haulout, so I had time on my hands that evening. I crawled under the truck and attached two pipe clamps. If we figure that there are 360 degrees in a circle, and if I'm aiming at getting the clamps within 3 degrees, I've got a 1 in 120 chance of guessing right. Even if we up the tolerance to 6 degrees, it's one in 60. Not great odds. But maybe I'll be lucky. I just guessed at a position. First time, I went off on a drive and there was no improvement at all. Back home, crawl under, mark the first position, rotate the clamps, and drive again. No luck. Head home and try again, marking 2nd position. On the 6th try I found the sweet spot. Yay, no vibration from 40 to 50 mph, or up to 65. We'll call it good. And maybe when the guys at the shop see the new shaft with pipe clamps on it for balance, they'll find a better solution. Or maybe I'll just add some Loctite to the tightening screws on the clamps and call it good.

Chris Campbell

[electra225]

Did you pay a shop to replace the driveshaft? If so, why not take it back to them? Take the hose clamps off so they won't know you tinkered with it. That in itself may void any warranty they might offer. If you didn't pay for a shaky driveshaft, you didn't get what you paid for. Give them the chance to make it right before you try to fix it yourself. I think the legal definition of that would be "not fit for intended purpose". The intended purpose being to propel the truck down the road with no shake.

[TC Chris]

I think the problem is that the drive shaft for a vehicle of this age is hard to come by. The new one does not have the balancer on it that the old one had. I don't know if it was new or refurb'd--I think the latter. It has the usual balance weights welded on. I will have a chat.

Chris Campbell

[electra225]

It shouldn't matter as a matter of professional conduct, whether the driveshaft was hard to come by or not. They accepted the job and took your money. You deserve a driveshaft that is satisfactory for what you paid for. You already had a driveshaft that shook, why pay extra for a new one that shakes?

[19&41]

You might see if you could borrow a pair of heavy jack stands to hold up your rear end while the driveline moves. Use a marker on a stick to mark the eccentric side.

[walyfd]

Cadillac shop manuals say when removing the shaft, mark front and back joints so it goes back in the way it should. Also, on cars with center bearing, not only mark it (if the bearing is bad and you need to separate the shafts) but mark the shims in the X.

my 57 had 2 big weights on the back end and it was balanced. I had a joint dry up and had to replace it but I didn't do the other one and it threw off the balance. Ended up replacing the other joint and the center bearing.

Apparently they were balanced at the factory.

[TC Chris]

You might see if you could borrow a pair of heavy jack stands to hold up your rear end while the driveline moves. Use a marker on a stick to mark the eccentric side.

That's what the guy did in the YouTube video. He used a lift, then jacked up the differential so the drive shaft was at the correct angle. Then he used chalk to mark the heavy side at speed. But he also had a device for setting the accelerator pedal for the right speed while checking.

Me, I just guessed and guessed again until I finally lucked out and found the position that worked. Took 6 tries, then a couple more to verify that it was dialed in.

Chris Campbell

[Ken Doyle]

There aren't as many driveline shops as there used to be, but you should be able to find one. They often specialize in truck driveshafts, and can easily balance a car drive shaft, or repair it if it's bent.

[TC Chris]

There aren't as many driveline shops as there used to be, but you should be able to find one. They often specialize in truck driveshafts, and can easily balance a car drive shaft, or repair it if it's bent.

My Google search was not effective, at least for this area, but I'll look again. The truck goes into the shop soon for a muffler. They will take a gander at the drive shaft then.

I gave up on finding an OEM exhaust system, and the pipes from 10 years ago are still intact, but I''ve masonry patching cement (no laughing, it's all I had) with a tin can stretched over it for temporary quiet.

I'm headed downstate for the weekend and will see how the hose-clamp balancing act works at highway speeds.

Chris Campbell

[TC Chris]

An update on the drive shaft problem. I had the red truck in the shop a couple weeks back for a stainless exhaust system. I can't stand "muffler shop" exhausts because they are basically a way of assuring regular returns to the muffler shop as their cheap crap rusts or corrodes out. I asked them to look at the drive shaft. They said they'd replace it as a warranty item.

So the new shaft arrived and the truck was there yesterday. They spent the day assessing and pondering and consulting and eventually concluded by the end of the day that they would go ahead and install the warranty replacement. So the truck went back today for the transplant. Lo and behold, it worked. I drove the truck up to about 70 mph and it's pretty vibration-free. Problem solved.

By the way, the hose-clamp solution actually worked pretty well. By the time they replaced the shaft again, either I had got used to the little rattle remaining or it had diminished for some other reason. If you have an old car and can't find a good drive shaft or a balancing shop, try hose clamps. I used two. Tried a third and it did not improve matters in my case. It was just trial and error: drive, stop, slide under the truck, move the clamps, and drive again. Repeat until you find the right position.

Chris Campbell