Feel vibration around 50mph

B

Bullerman

Senior Member
50 model custom with Flathead V8. I can feel a vibration around 50 with motor under a load. When I let off on the gas it seems to go away. Haven't checked the universal joints. Is this a symptom of bad joints. It has probably been 25 years since I changed a set.
 
I’d check the u joints. Not just for tightness but pull the cap and look for a washboard pattern on the shaft of the joint
 
Do you happen to have new tires on it? Out of round tires start to "hop" at around 50-55 mph. If the tires are the same size front to back, swap them to see if it still happens.
 
Typically, a defective (worn) universal joint will vibrate around 30 - 35 mph.

I agree with Tim.
First thing, rotate the tires to see if there are any changes. Even if it still vibrates, that vibration should feel as if it moved.
If no change, inspect the front chassis very carefully.
 
Sounds familiar. If it sits for long periods of time, it could be flat spots on the tires. Go for a 10 or 15 mile drive on the highway and see if the vibration goes away.
 
Had that same thing on our 38 coupe years ago, changed all the bearings in rear end and drive shaft; also wheel bearings, no change, a friend and old ford guy said to balance my wheels, i did that and everything was smoothe
 
Thanks for all the suggestions. It was the universal joints. I had a bad one in the front and rear. Got them changed today. Hadn't did that in a while but that seemed to have fixed it.
Now I have to get my clutch fixed. Bad shudder when taking off. I believe it is either the pressure plate or the flywheel. At idle with the motor running With my foot on the clutch I can feel it pulsating. Don't think it should do that. It shifts ok and doesn't slip.
When I down shift from 3rd to 2nd with a little speed it shudders bad also. I talked to a guy about putting in pilot bearing, clutch disk, pressure plate and throw out bearing and having flywheel surfaced. He hasn't got back with me yet. Don't know what would be a decent price to have that done.
 
It took me about three times as long as it would a real mechanic but I got it.
I wish I could fix this clutch issue but I am afraid that's a little too much.
 
Excellent news about the DIY fix. If you can change the U-joints, I think you can tackle taking the motor out. I'm pretty sure you can rent a cherry picker if you don't have access to one.
 
Well I thought I had it fixed. After changing the universal I just drove up the road and back and it seemed ok. We took a good long drive yesterday.
I still feel a vibration but it is in the steering wheel. I don't feel anything in the seat or the floor. The steering wheel doesn't shake or move side to side. Just a vibration and what is strange is that it seems like it changes.
I will start with the tires. It does have a new set of radial tires on it. I my take it and have them balanced and rotated. It drives straight going down the road. I think I wasn't noticing this because of the universal joints.
Same way as with the universal joints you don't feel it until you get a little speed.
I haven't had a wheel bearing go bad in years but I don't think that's what it is. Doesn't sound like a grinding noise.
I know I need the clutch straightened out but would anything in the drive train cause the steering wheel to shake?
 
Bullerman said:
Thanks for all the suggestions. It was the universal joints. I had a bad one in the front and rear. Got them changed today. Hadn't did that in a while but that seemed to have fixed it.
Now I have to get my clutch fixed. Bad shudder when taking off. I believe it is either the pressure plate or the flywheel. At idle with the motor running With my foot on the clutch I can feel it pulsating. Don't think it should do that. It shifts ok and doesn't slip.
When I down shift from 3rd to 2nd with a little speed it shudders bad also. I talked to a guy about putting in pilot bearing, clutch disk, pressure plate and throw out bearing and having flywheel surfaced. He hasn't got back with me yet. Don't know what would be a decent price to have that done.
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Make sure that you have the presssure plate and flywheel balaanced
 
Tim Ayers said:
Excellent news about the DIY fix. If you can change the U-joints, I think you can tackle taking the motor out. I'm pretty sure you can rent a cherry picker if you don't have access to one.
Click to expand...

why do you need to pull the motor for a clutch job?
 
Out of balance tires will begin to shake at about 48 mph and get worse at higher speeds. Your experience may vary depending on other factors. Rotating radial tires should be same side front with back. Reversing rotation like in the old days is not recommended. Quality of rubber in tires these days is inferior causing delaminations, which may contribute to the problem.
 
Going in the morning to have the tires balanced. Wish that would fix it. We have a really good front end place here. I may just go there to start with.
 
Well I took the car to get the tires balanced. Got other bad news. Right front kingpin is wore out.you can move the wheel up and down and back and forth. Left front has a little slack. Went and talked to the frontend place about fixing it. He said he would check on the parts and let me know.Dont think I want to undertake that. Hadn't counted on that.
 
Bullerman said:
Well I took the car to get the tires balanced. Got other bad news. Right front kingpin is wore out.you can move the wheel up and down and back and forth. Left front has a little slack. Went and talked to the frontend place about fixing it. He said he would check on the parts and let me know.Dont think I want to undertake that. Hadn't counted on that.
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Not that complicated of a job. If you have a good front end place, they should be able to take care of it for you
 
I know the place I went can take care of. They are really good. A family business. Hauks Alignment here in Alexandria.
They are going to check on the parts and let me know. Should drive good when I get that fixed. Still have to deal with the clutch but I may get my wife's grandson to help me do it. He is a pretty good shade tree mechanic. I believe between the two of us can do it.
Believe I may get with Shoe Box Central today and see about ordering the parts. Should be the 9 1/2" clutch.
 
Thankx for the thread. I have the same dreaded 48mph vibration. My frontend might have 8500 miles so I know its good. About the same mileage on U-joints. Driveline angles aren't bad BUTT driveline was picked from the Chevrolet junk pile. I was debating to start there with a straighten and balance but thankx to your tread I think I'll do the tires 1st. My "shake" isn't in the steering wheel more in the butt seat. Keep us posted please.
One thing I would suggest it throw away the alignment specs. Put as much castor as turning in a parking lot would allow. More caster make for a good road car but a bear in the parking lot. I've got a 1/4 degree camber and about a heavy 1/8th toe in to take the slack out of all the moving parts. 225/60/14 radial tires.
 
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