My on going story of trying to find my vibration may have just taken a new turn. My 1965 Skylark GS (Bucamino) has a vibration at 55 + mph. Tonight I put it up on the lift and had a buddy watch the rear wheels as I ran it through the gears. In third gear around 40 mph it started to shake and did the same thing in fourth gear. My buddy says that one rear wheel would bounce up and down and then the other side would do the same. This is a non-posi rear end. Drive shaft has been balanced. My other buddy, who was also watching, thinks I have a bent rear axle. Anyone with experience with a bent axle or other problem that would cause the shake? If I need to change the rear end I have a shorty wagon that is a three on the tree that I could swap with. Any ideas appreciated.
Do you have enough equipment available to measure rim and hub runout as the axle is rotating? A bent hub can casue this and having you chase your tail to track it down. A curb or bad pothole can cause this fairly easily, unfortunately. Drum balance can be a culprit, too. Devon
are your rear axle bearings still ok ? i've also got the same problem with another car with a solid rear axle ou: Greetz Lennard
Update: I am going to borrow an on the car wheel balancer to check the brake drum balance. At the same time I will check the rear wheel bearings, I assume by grabbing the top and bottom of the tire and trying to move the tire up and down? Seems like I should have gear oil running out of the seals if the bearings are bad enough to shake the car??? Wouldn't bad bearings make a lot of noise??? All help appreciated.
A vibration a 45 and again at 70 is a tire issue. Either it's out of balance or seperated. I"d start there. -Josh
if it is a tire/wheel issue, find a shop with a Hunter 9700 RFV road force variance machine and let them check the wheels/tires, IF you are still using the OEM style drive shaft with the rubber insert 3/4 the way down the shaft( look carefully) the rubber falls apart and the shaft turns within itself,even if you had it balanced... good luck, vibrations suck....
This weekend I had to clean out our garage and move a bunch of stuff into my shop until I can sort through it, hopefully this week. A friend of mine loaned me an old Hunter balancer that balances the tires on the car, so I will try that later this week or next weekend. The search goes on.....
I had the same problem with my `65 Skylark and I know this is going to sound wayyyyy too simple but before you spend a lot of time and money on other things, try unbolting the driveshft at the rear yoke and rotating it 180 degrees. The first thing I tried was having the rear tires re-balanced. I even watched them do it and they were out of round, so I bought new rear wheels and tires. Cost: $600. It didn't help. Next I had a completely new driveshaft built and balanced. Another $300, it didn't help. I also had the rear trans bushing replaced. Cost:$50. No change in the vibration. Then I bought a set of adjustable upper control arms, shimmed the trans and adjusted the pinion angle so I had a perfect 0 plane between the trans and pinion and a 2 degree driveshaft angle. The result was the vibration now started at 65mph instead of 60mph. Cost: $200 plus shipping. Then I rotated the driveshaft 180 degrees. Bingo, it's gone. Cost: 5 minutes of my time. It may not work for you but it can't hurt to try it. Let us know how you come out. Bill
You're right, with an rpm vibration. I did that with a `68 GTO years ago. Went 120 and it got worse, then another 120 and it went away. My Buick driveline vibration was a speed related. I could put it in neutral at 65mph and it was still there. This is certainly something to keep in mind, though. Bill
I haven't had time to try any of these ideas, but I appreciate them and keep them coming because I will get back into the shop soon, and I will need good suggestions and ideas to explore. (I have been installing storage cabinets for my wife which has kept me away from the shop)
Except in this particular case, it's a 4 speed. The nailhead flywheel has an index hole that must match up with the index hole in the crank. If it's not lined up, it throws the engine balance way off. It has been posted that a bad water pump or out-of balance fan can cause vibrations. But in your case, it sounds like to narrowed in down to something in the rear.
Would the pinion bearing cause a vibration like that? I can get a little movement up and down on at the rear u-joint.
I'd say you found the problem! There should not be any up/down movement in the pinion bearing. Was the pinion nut ever taken off...is it possible it is just loose? If it's not a loose pinion nut, you most likely have a bad bearing.
