Highway speed vibration ('57 Thunderbird)

[KULTULZ]

I'm having a little difficulty with this thread, so please bear with me ...

... we had a reputable driveshaft shop check it out and install Spicer universal joints.

You sent out the shaft to a driveshaft shop to replace the joints and not ask to check the balance?

[dmsfrr]

Originally Posted by yblock57

I have heard good things about Diamondback. Went through 2 sets of 'Coker Classic' bias-plys and finally went with the Silvertowns as we had good luck with several sets in the past.

Call me stubborn, but I like the pie crust sidewalls on the bias-ply tires vs the more modern radials. ...

yblock57, Diamondback sells a classic style radial with the pie crust edges.

https://dbtires.com/product/auburn-d...l-15-16-sizes/

.

[yblock57]

Originally Posted by KULTULZ

I'm having a little difficulty with this thread, so please bear with me ...

You sent out the shaft to a driveshaft shop to replace the joints and not ask to check the balance?

This is my dad's car. He handled that part. Happened several years ago. He's old. He can't remember what he told them. Can't find receipt. Going on 2nd hand info here. Sorry for the confusion.

[KULTULZ]

Originally Posted by yblock57

This is my dad's car. He handled that part. Happened several years ago. He's old. He can't remember what he told them.

Can't find receipt. Going on 2nd hand info here. Sorry for the confusion.

Not your fault and now I understand. I thought you had it in a shop going through all of this (I am an old fart too).

If switching tires does not solve it, maybe take the shaft and have the balance checked.

Funny things can happen when putting radial tires on an early steel wheel that was not designed for the increased load.

[yblock57]

I ran the car on stands up to 70 and didn’t feel what I feel on the road. Minimal vibration from the drivetrain spinning up that fast. I guess that rules out driveshaft, mounts, etc.

What I do see are very wobbly rear tires and questionable rims. Hard to determine if both are at fault. YouTube video below. FYI they’re turning at about 15 mph… can only imagine what they look like at 70!

https://youtu.be/E2q_aya7AkI

Thoughts?

[Anteek29]

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Based on the video I just don't see sufficient variation to be a concern. The rims seem fine. Must look elsewhere.

[dmsfrr]

It's easy to notice the whitewalls aren't centered too well but that shouldn't matter.
One of the wheels (LR?) has a bit more run-out than the other, not sure it's enough to be a problem.
In the video there were a few moments the tires showed a little more wobble than I was expecting to see.

Have you tried swapping those tires & wheels with the ones from the Fairlane?
That should give you something else to compare to the ones currently on the T-Bird.
.

[yblock57]

Originally Posted by dmsfrr

It's easy to notice the whitewalls aren't centered too well but that shouldn't matter.
One of the wheels (LR?) has a bit more run-out than the other, not sure it's enough to be a problem.
In the video there were a few moments the tires showed a little more wobble than I was expecting to see.

Have you tried swapping those tires & wheels with the ones from the Fairlane?
That should give you something else to compare to the ones currently on the T-Bird.
.

I haven't had the chance to swap wheels yet. Fairlane is 3 hours away at Dad's place so logistics will take a while.

In the meantime I'm going to swap fronts to back and see how they act. Also going to verify axle runout.

[yblock57]

Eye-yi-yi … so much for wheels/tires. Upon checking for axle run out, a heck of a noise/vibration started. Does not do this in park. Only in reverse/drive. Double checked U-bolts. Can feel a small amount of slack in the yoke going into tail shaft of transmission. I have just replaced the bushing inside the tail shaft. Looks like it’s already leaking after putting a couple hundred miles on it. Doesn’t make sense that it would make that much noise and vibration at approx 15 mph in the video. Sounds/feels like it’s coming from inside the trans. What the heck?!?

Thoughts?

https://youtu.be/UMRg6J2dwVo

[KULTULZ]

Exactly where is the banging coming from, the front or rear joint or both?

You have checked both trans and rear fluid level? Are the u-joints grease-able or sealed? If that drive-shaft is vibrating it will eat a rear bushing/seal in no time.

[yblock57]

Originally Posted by KULTULZ

Exactly where is the banging coming from, the front or rear joint or both?

You have checked both trans and rear fluid level? Are the u-joints grease-able or sealed? If that drive-shaft is vibrating it will eat a rear bushing/seal in no time.

Trans & rear are both full. Universal joints are the spicer sealed variety.

Sounds like it’s coming from up front. Hard to tell for sure since the shaft makes it reverberate.

When I changed that bushing, it fit nice and snug on the input yoke. I guess it’s worth having it spun and checked for balance before another bushing goes in.

Thanks

[yblock57]

Update — driveshaft balanced with new universal joints and slip-yoke. Wrong yoke had been in there for a long time. New correct yoke for the Fordomatic was over 2" longer than the one that came out. Suspect it was for a 3 speed. Anyway, with that solved a new output shaft bushing & seal got everything wrapped up. No more noise!

Did some crude measuring with a stand and caliper measuring on the outer lip just inside where wheel weights go. Runout is as follows:
LF — .026”
LR — .079”
RF — .027”
RR — .025”

Obviously that left rear is the most concerning. I made a video of the inside of the wheel showing some concerning brake drum movement. If you watch closely, the inside lip of the drum appears to be moving in & out. I checked the axle flanges with the drums removed and didn't notice any runout. Is it possible the drum is tweaked somehow and causing that excessive runout? Thoughts?

Video here

[KULTULZ]

Originally Posted by yblock57

Did some crude measuring with a stand and caliper measuring on the outer lip just inside where wheel weights go. Runout is as follows:
LF — .026”
LR — .079”
RF — .027”
RR — .025”

Obviously that left rear is the most concerning. I made a video of the inside of the wheel showing some concerning brake drum movement. If you watch closely, the inside lip of the drum appears to be moving in & out. I checked the axle flanges with the drums removed and didn't notice any runout. Is it possible the drum is tweaked somehow and causing that excessive runout? Thoughts?

Video here

A steel wheel rim is stamped then formed into a circle and welded at that joining seam. Depending on the age of the wheel, it was not an exact science. The plate will have varying thickness.

The drum may be warped. It needs to go on a brake lathe to confirm concentric/out of round.

Has this been mentioned, the tire may be out of spec.

[yblock57]

Originally Posted by KULTULZ

A steel wheel rim is stamped then formed into a circle and welded at that joining seam. Depending on the age of the wheel, it was not an exact science. The plate will have varying thickness.

The drum may be warped. It needs to go on a brake lathe to confirm concentric/out of round.

Has this been mentioned, the tire may be out of spec.

Thanks, Kultulz. I’ll be talking a close look at all the above. Brake lathe is a great idea. Appreciate it [emoji1303]

[Gene F]

I used to work for a professional drag racer. (super stock). He once found a rear brake drum that threw a weight. confirmed it when he put it on a bubble balancer. You know, like you'd balance a tire with. The thing flopped completly over....

[Pete]

This would be a long shot for you since you have checked so many things already. This is fairly easy to check.
I have had two 9 inch rear end cars in the shop in the last 20 years that had the same symptoms as you and I went through many of the checks you have already done.
In both cases here it was the flange yoke on the rear end that was hammered out and would not hold the cups tight side to side.

[yblock57]

Originally Posted by Gene F

I used to work for a professional drag racer. (super stock). He once found a rear brake drum that threw a weight. confirmed it when he put it on a bubble balancer. You know, like you'd balance a tire with. The thing flopped completly over....

Neither of the rear drums have weights on them. Don't see any evidence they ever had any attached. I need to go have them turned and give them a close look on the lathe.

Thanks for the tip.

[yblock57]

Originally Posted by Pete

This would be a long shot for you since you have checked so many things already. This is fairly easy to check.
I have had two 9 inch rear end cars in the shop in the last 20 years that had the same symptoms as you and I went through many of the checks you have already done.
In both cases here it was the flange yoke on the rear end that was hammered out and would not hold the cups tight side to side.

The cups seem to be ice and tight in the yoke. I replaced the nuts & lock washers on the u-bolts. I'll give it another close look just to be sure.

When running the car in gear on jack stands, there isn't any vibration anymore, so it's making me lean towards rims/tires.

Appreciate it!

[yblock57]

Drums were put on a lathe and checked. Both are fine. Looks more and more like rims/tires are the issue here. Can see a slight up/down on the tread when spinning. Need to see what discount tire can do for me. Hopefully can replace as these have less than 500 miles on them.

[KULTULZ]

Are the wheels original to the car or a mis-match? Are the tires quality or EL CHEAPO's? The 57 BIRD used special KH wheels ($$$).

Tire run-out can be measured.

- https://evanstire.com/understanding-tire-runout/

Also SEARCH bent wheels and tire run-out.

What shape are the shocks in? Are the springs still springy? Bushings still bushy?

Is the car a driver or a restoration?