Has anybody experienced wheel vibration from the rear end. I have had the wheels balanced twice and have mounted another set of tires/ wheels and still get a vibration around 40 to 50 mph. I have installed new shocks, but I did remove some leaves from the springs, first and third spring. Using ideas from mid fifty's and it does ride a lot smother.

This next week I am taking the truck to a shop that balances tires for drag race cars $30 each sure hope this works. I guess if it still persist the only thing to do is new tires and do something with the springs.

dennis

 

Have you checked your U-joints? It may also be a driveshaft phasing or pinion angle problem, too. What changes or modifications have you done to your truck? What kind of truck is it? If you've swapped tires and wheels in the back, and experienced the same problems, it's pretty likely spending another $60 on balancing will be a waste of money.

 

More information Please. What engine, trans, rear end? If you changed all these and did not reset you pinion angle to trans you are getting drive shaft vibration.
Just my 2cents

Vern

 

The truck is a 55 F100.
just installed a volare suspension. Moved the motor to the pass side around two inches and them moved the trany so they would be parallel with the frame. I have checked the pinion and it is 3 degrees up and the tranny is 3 degrees down. I dont get a drive shaft type of vibraton.
the faster I go the less vibration I seem to have. And at other times is seems kind of like a harmonic type of vibration. When it get to the wheel hop speed i have put the trenny in nutral and it is still there.
Any ideas

Dennis

 

I forgot to add, its a ford 302, c6 tranny and a 9 inch rear end

 

Is the drive shaft balanced? As 52merc mentioned, check the u-joints.

 

Had it on a rack a couple of days ago and we spun the wheels and the drive shaft looked good as did the wheels. They pu an indicator on the drive shaft and the round out was around .002 so that should be well within tolerance. We have a drive shaft shop close by and will stop by and see what they think.

 

I'm at a loss. Hopefully someone will find your problem.

 

Six degrees of difference in Pinion angle is too much. 3 degrees max with the set up you have.

PLUS, if you moved your motor, you may have introduced lateral pinion angles. IE if your motor is not pointing straight back, instead it is pointing toward the rear end, it will have a high lateral pinion angle difference. If that one is 3 degrees off you are at 12 degrees. And compounded they are worse for vibration.

Plus, they have to be close to level and at the same angles - not with in 6 degrees of total angle with differential pointing up and transmission pointing down.

I just had new springs put on my truck and both of those angles were off making a compound angle over 15 degrees off. When corrected, it completely went away.

I have a 390 C6 and 9 3/8 rear. When I would drive it would start out ok then at about 30-32 it would start to shake as though something was eccentric. This would quiet out significantly at about 38 but never completely go away. As I increased speed, it would seem to lessen and I thought go away (not until I had it corrected did I realize just how bat it was).

There ar anumber of things that will cause this type of problem in the rear. As mentioned, U-joints bad, tires out of ballance (which will get progressively worse with speed btw) a bent wheel; a drive shaft out of balance.

But also with the 9" rear end harmonic vibration is typical of a bad rear wheel bearing. The 66 shop manual I have states that this vibration will occure at about 25-30 mph and continue up to about 35 mph. BUT, it will usually be accompanied by a grinding or sqeaking noise when truning the truck away from the side the bad bearing is on.

From your description, this sounds exactly, (and I mean exactly) like what I just cured by correcting the pinion angle.

Here is an excellent artical on Pinion Angle by Jon Niolon - I'd bet ya about 70-30% that's your problem.

http://www.clubfte.com/users/jniolon...nephasing.html

 

Ok, I see what you mean. I did check and the engine is pointing straight back. I think I am offset to the passenger side about 2 inches, but when i last measured it I was parallel with the frame. I don't know what the difference is between the engine center line and the rear end. Will have to measure that to see what that angle is.

As far as the engine angle, it is tilled down 3 degrees (nothing I can do about that angle now). I have a 3 degree wedge between the spring and rear end, which is pointing the rear end up, maybe I could try and remove the wedge and see what angle I have. like I said I will be going to the drive line shop this week and have them check it out on there rack.

the vibration that i have starts around 40-45 and is fine when I get up to 50-55. The truck seams to get a harmonic vibration at times when i am at highway speeds. I will check the wheel bearings. The passenger side is new but never checked drivers side.

thanks again for all the ideas

Dennis

 

Yep, let them "protract" those angles. The centerline of your Harmonic balance nut, and the center of your transmission output shaft should be exactly the same distance out from your frame (measured on a level lateral). Being offset won't hurt anything if it's straight. Jon's got some good pictures in that write up that show all this better.

On mine, the 30-35 MPH vibration always happened. But the severity varied. Also the high speed Vibration (which was very subtle) was not consistent - some days a little more and some days you couldn't hardly feel it.

The wheel bearings I was speaking of are the REAR bearings!

Question, did this do this before you moved your engine?

 

Well yes and no. At times it would vibrate but I allways thought it was flat spots on the tires and would get smoother with time on the road. With the truck on a rack it will be easyer to recheck all the angles. Don't know what I can do with any lateral angle. Just have to live with that.

thanks
Dennis

 

It could be a combination of a couple of things too. Everytime I fixed something on my truck, things got better. But this last pinion angle thing was significant.

And yes, buying new tires made a substantial difference too.

But just FYI - these trucks are NEVER going to ride like a modern car or truck!

 

Amen to that sister !!!.

But just FYI - these trucks are NEVER going to ride like a modern car or truck![/quote]