Vibration Saga

[ROKuberski]

My '57 Fairlane 500 has suffered from a vibration that only happens between about 65 - 75 MPH.  Recently, I have gone after this problem with a vengeance.  I have completely rebuilt the front end, new wheel bearings, new upper and lower control arm bushings, new upper control arm shafts, new upper/lower ball joints and tie rod ends.  Front end aligned.  All 4 wheels and tires checked for radial and axial runout and tires balanced with a machine that puts them under a 700# load (tires are new radials with about 3K miles on them.)  Drive shaft straightened and balanced (was not all that far out.)  New front yoke, new bushing in the transmission tail shaft and new front and rear u-joints on the driveshaft. 

Many of the parts mentioned above were original and worn, so much of this needed to be done.  But, I still have the vibration.  Next, I am going to replace the rear axle bearings.  If that does not do it, I guess the last moving parts are in the differential, so those bearings will get replaced.

I have driven the car at 70 MPH and shifted into neutral to see if the vibration stops, it does not.  I put the transmission into low gear and got up to about 35 MPH to get the engine turning at highway speed, no vibration.

What a lot of fun I'm having, sort of.  If anyone can think of something that I have overlooked, I'd sure like to know what it is.

Rich

[Frankenstein57]

Rich, by the list of items you replaced it sounds like you felt it in the front end or steering wheel. My ranchero has a vibration from 50 to 65, but I feel it in the seat, like its behind me. When my summer returns to normal, I plan to pull the axles out. I recall that when I was going through the drive train, one of the bearings seemed to growl a bit when spinning them. I was at an all Ford show and bought two large bearings with retainers for $40, I think that's a good price. Let us know if you find it, Mark

[RICH MUISE]

Rich...if you're a hamb member do a search there. Not too long ago I read a lengthy thread on what they were calling "that pesky 65mph vibration"..many noting that vibrations are frequently noticed at that speed. Lots of good suggestions and cures. If your not a hamb member, let me know and I'll try to find it and post a thread.
I know your drivetrain is stock..can't remember if anything was done to the suspension that would alter rideheight and pinion angle??   flexplate/torque converter out of balance?

[ROKuberski]

My drive train is completely stock.  No changes in ride height.  After having no success with the front end work making any difference, I jacked up the rear end and ran each wheel independently.  By doing this, I got each rear wheel up to highway speed and each side shows some vibration, about equal on each side.  This is when I decided to have the drive shaft checked.  At this time, I also noticed some play at the point where the yoke goes into the tail shaft on the transmission.  There was some minor wear on the yoke and the rear bushing was only $15 so I put it in.  I can tell that this connection is a little tighter, but when I measured the thickness of the new bushing against the original, it was about .001" thicker, that's not much wear in 105k miles.  While the drive shaft was slightly out of alignment and balance, the guy that did the work said it was not all that bad.  Since I had it at the shop I figured that I might as well get the work done too.

Replacing axle bearings is not too tough or too expensive, so I may do that myself.  I've never worked on a differential before, but this may be the time.  I think there are about 5 bearings in there.  I may get a few quotes on this part of the job just in case the axle bearings don't solve the problem.  I can't believe that the vibration is inherent in the design.  Too much shaking for this to be normal.

Since have run the engine at high speed with the car in low gear, I think that I have eliminated the engine as a source of vibration, however, I suppose there could be transmission components that are the culprit.

No, I am not a member of the HAMB site, but I have looked at it before.

Rich     

[RICH MUISE]

Let me see if I can transfer these links...
http://www.jalopyjournal.com/forum/showthread.php?t=802546&highlight=vibration

http://www.jalopyjournal.com/forum/showthread.php?t=808131&highlight=vibration

[lowrider]

Like was mentioned before if you feel it in the steering wheel its usually front end related. If you feel it in the seat look at the driveline for the vibration. Sounds like you've covered all the bases but I would also check the driveline angle too.
Along with the diff bearings I have run across ring & pinions that vibrate also. Those were mostly newer cars though. Just one more thing to look at.

[BWhitmore]

If the pinion angle of the differential is not correct a vibration will occur.  This is a simple check that your rear end or front end shop should be able to check with a magnetic angle finder.

[ROKuberski]

I've covered about every base that I can think of on this issue.  However, I don't know where to find out what the correct pinion angle is.  I do have the "stuff" to check it with.

Today, I had to run an errand, so I took the Fairlane.  About 4 miles from my home I hit the interstate and zoomed up to 65 MPH to check out the vibration.  Still there.  About a 15 mile drive to destination.  Car sat abut 5 minutes then turned around to head home.  It was about 5 miles down the interstate before I could get up to 65 again, but once there, ZERO vibration, had clear sailing so went up to 80 MPH, still no vibration, then had to slow down for a while, then back up to 70 MPH and some minor vibration. 

Figure that out, I can't.

Rich

[Ford Blue blood]

However, I don't know where to find out what the correct pinion angle is.  I do have the "stuff" to check it with.
Rich

With the car sitting level put an angle finder on the valve cover (runs parrallel to the crank), it should be in the 3 - 4 degree down range, next put the angle indicator on the pinion yoke, it should read the same number of degrees but up.  Given you have a stock drive train and it has not been modified I'm betting all is well with the relationship between the engine angle and rear angle.  If it checks out my next move would be to put both rear tires on the front and run it.  The fact that it went away and came back different says a "soft" issue, not a hard mechanical issue.

[BWhitmore]

Given that the driveline has not been modified and IF the pinion angles do not check out you might want to suspect motor mounts and/or transmission mount. 

[ROKuberski]

This morning I checked the drive line angles.  They are within 1 degree, close enough for me.

I also made a video of each of the rear wheels running from idle up to a wheel speed of 100 MPH.  (Wheel speed is double the indicated speed when only one wheel is allowed to spin.)  Watch the video and you can see the results.  http://youtu.be/PXLfUEchc4Y

I could feel about 1/4" of in and out play on the real axle.  I don't know if that is too much or not.  I know the transmission mount is good and I will check the engine mounts later on today.

You will be able to see some vibration in the video, but what is too much?  I don't know.  The steel wheels are all within spec and there are no defects in the tires.  The tires have all been balanced on a high tech machine within the last 100 miles on the car.

Rich

[BWhitmore]

The movement of the leaf springs is interesting.  As we all know the purpose of the shock absorbers is to control the oscillations of the springs, however, I have never heard of bad shocks causing a vibration.  Maybe someone can comment on whether or not the shocks can control the spring oscillations when the wheel is off the ground.

I would guess that a 1/4" movement in the rear axles is within tolerance.  The only other suggestion might be to run the car on a chassis dyno.  Most big towns have a shop that specializes in diagnosing vibration problems.  You might want to try a big rig truck shop and ask them to go on a ride with you. 

[ROKuberski]

The shocks are new Monroe coil over shocks, I don't think that there are any problems with them.

We are heading to Europe in a couple of weeks, so any more work on the car will have to wait until we return.

However, I am inclined to replace the rear wheel bearings.  They are 56 years old and have about 106k miles on them.  They are cheap and easy to do. 

In my video, the engine is under very low load, so I don't think the motor mounts are the problem either, but they too are 56 years old. Perhaps I'll just replace them because of their age. 

Soon, I will be out of things to replace.  If there is still a vibration then, I guess I will just keep it under 65 MPH. 

Rich

[ROKuberski]

This morning I installed new rear axle bearings and new seals.  The left rear axle bearing had a little wobble in it and the right one seemed very tight.  On a test drive I would say that I have reduced the vibration by at least half, but it's still there.

I have access to a large press at the Colorado Railroad Museum where I am a volunteer.  That made the removal and reinstallation of the bearing an easy job.  I did borrow a bearing clamp ( I guess that is what's it's called) it mounts under the bearing when you press it off and on top of the bearing when you press it back on.  All in all, it was about a 90 minute job, not too bad. 

As to my next step, I don't know what it will be.  Likely nothing for a while.

Rich