Driveline Vibration

[John L.]

I have a 1964 Factory Air, Powerglide Coupe with PS and PB, 327-300HP...at about 50 MPH a vibration starts that is a low growling sound you can hear and feel a strong vobration in the drivers seat bottom. Its far less noticible in the passenger seat. Also much more notible under accelertaion, less when you let off...but still there. Nothing felt in stearing wheel. I have checked tires and wheels for balancing issues...it's not that, had transmission checked, taken apart, and all was fine. One more clue...I recently insatlled an NOS harmonic balancer...but didn't notice any vibration at the time. Several monts later this vibration just started. Now that I am really listening it seems like it may be there all the time...but really noticble between 50 and 60...then smooths out and appears to go away??? Ideas?

[Timothy B.]

Re: Driveline Vibration

John,

You will get lots of suggestions so here is mine, consider a bad front wheel bearing. These vibrations usually start at higher speeds and will ceace if you turn the wheel one way or the other depending on how the bearing gets loaded when the wheel is turned.

Vibrations also seem to stop and go depending on light throttle or acceleration but the tele tale will be turning the steering wheel one way or the other at speed.

[Harry S.]

Re: Driveline Vibration

John, I fought the same problem with my 63 for years. Each time I fixed/replace a component it get better but never went away.

I swapped wheels and tires with a smooth running 65 and the problem still existed.

Because of the way I replace the components I know each one was worn or failed.

I replaced the front wheel bearings, drums, shocks, idler arm and had all wheels balanced several times. One bearing was shot, the shocks were gone and the idler arm was well worn.

I pulled the body, restored the frame and replaced all the control arm bushings, sway bar and bushings, motor mounts and anything else that moved with rubber in it. Put the body back on, went for a drive and the problem was still there. Now what?

I borrowed a set of aluminum knock-off wheels with new tires and then the problem was gone. My original 63 wheels had severe run-out as well as the tires.

Summary, the problem was all of the components I mentioned failing together. It was an expensive fix, but at least I now have a restored frame and suspension and it drives just fine with a set of aluminum wheels and tires I purchased.

Good luck!

[Jim T.]

Re: Driveline Vibration

John you mentioning of the replaced balancer makes me wonder about your vibration. Reason is way back in early 1969 I rebuilt the engine in my 1964 327/300HP 4-speed. The engine did not really need a rebuild, only had 60+ thousand miles on it but I wanted to install a Crower mild hydraulic cam.
I installed a new balancer also. The new balancer actually came off although I had to pound it on.
I had the local Chevrolet dealership check it out and the mechanic told me I had the wrong balancer. The one he installed made a west coast to east coast trip a few months later and half way back west to Dallas with no problems.
I still have the balancer that came off that I installed.

[Tom H.]

Re: Driveline Vibration

Can you make the vibration appear with the car in park and raising the RPM's or does the car have to be moving to create the vibration ??

[Michael W.]

Re: Driveline Vibration

Can you make the vibration appear with the car in park and raising the RPM's or does the car have to be moving to create the vibration ??

That's a big clue.

Try letting off the gas and selecting neutral while at highway speed. If the vibration still exists but at a decreasing amplitude, suspect bad u-joints.

[Rob M.]

Re: Driveline Vibration

You might want to check if the drive shaft (the axle from the gearbox to the differential) is still in balance...

[Harry S.]

Re: Driveline Vibration

I did what everyone is suggesting, check and verify all the easy, inexpensive and least labor intensive things first. If you fix it, great, else it's time for Big $$$.

[Paul J.]

Re: Driveline Vibration

John, everyone's giving you some good advice, and Harry summed it up pretty well. I hope you did'nt go into the transmission looking for this.

Let's look at a couple of things.

When you had the tires and wheels checked, were they dynamic balanced?

Are your tires round and not flat spotted?

The vibration is in the seat/floor/body/frame and not the steering wheel, so forget about the front tires, wheel bearings, and suspension for now.

Push in the clutch at 50 like Michael said and if it continues then you can eliminate the engine. You've probably also eliminated the transmission.

Put the front tires and wheels on the back.

The growling says bearing and the vibration says u-joint.

U-joints go "squeak, squeak, squeak" when they are about to fail. Roll the car about 2-3 mph beside a masonry wall and listen, or have someone walk along with or squat beside of the car and listen. Check to see if there is any play in the joints. How many miles are on these?

Wheel bearings and axle bearings go "crunch, crunch, crunch" and sometimes "grrrrrrrrrrrrr" (or roar) at higher speeds. Once again, check for play. Mileage?

I doubt that your problem is tires or wheels. My guess is either a bearing or a u-joint, but it's only a guess from behind this computer.

We can talk about the rear end later.

Paul

[John L.]

Re: Driveline Vibration

Thanks to all for the replies. I am meeting with the mechanic (which I am not) tomorrow morning with all the replies for discussion as to where we go from here. This will give us a great road map hopefully to PV! Thanks again to all...and any other ideas or thoughts, please send! I'll post the solution when we find it. Don't forget my car is a 300hp powerglide.