Low RPM Vibration?

[lotzagoodstuff]

Two weeks ago, I changed all the fluids in my truck per the posting on this forum (thanks to all who contributed to both types and capacities as it made the job super easy at the parts store ), and at that time I changed the the wheels and tires to 285/75R16s. I noticed an immediate low speed vibration in the cab, kind of shakes the whole thing including the seats/dash/steering wheel. Today I loaded up a car hauler and headed up to Seattle to pick up a car (427 Windsor powered Pinto, pics to come ) and I noticed it was a little worse under the additional load.

It almost seems like something rubbing but I have looked everywhere and there is no sign of any friction on externally moving parts. Whatever it is, it seems to be worse in the lower gears at lower rpm and goes away at highway speeds. I would have sworn that it was something rubbing when the truck was squatting during take off, but I don't think it would happen in the first three forward gears .

I am guessing it might be my dual mass clutch, but no stink of burning friction material.

Any thoughts anybody ?

Thanks

R. J.

 

[Mr_Roboto]

Your new tires are not running true. Road force balancing may help some as the process match mates the tires and wheels for reduced runout.

 

[lotzagoodstuff]

I think you are correct, thanks for the tip. Will a simple alignment make this go away?

Again, good to hear from somebody back East. Although I have seen a lot of sports coverage on the Indians and Cavs lately, it's not like being back there.

Take care, and again thanks for the insight.

R. J.

 

[reklund]

a simple balance job should take care of your issue. An alignment doesn't correct for out of balance tires, just out of alignment suspension components.

Are your tires and wheels brand new, or used? Are they the proper lug-centric wheels for the truck, and are you using the proper acorn nuts?

Typically, an out of balance tire is more noticeable at high speed, but an out of round tire or off-center/bent wheel will be noticed at low speed. You might try rotating the tires front to back to see if maybe you have a bent wheel installed on the front axle where it would be more noticable...


Ryan

 

[lotzagoodstuff]

Defintely not tire balance as there's no harmonic with vehicle speed. It's defintely a low RPM vibration, especially in the lower gears, more pronounced with a trailer in tow.

 

[towcat]

how are the U-joints and center support bearings doing?

 

[lotzagoodstuff]

Mr. Roboto got this one :

I put the "tape measure" alignment on her today after work and it reduced the vibration tremendously, however, the true test will be pulling the trailer with the race car next week.

Thanks for all the input which saved me chasing my tail over a simple alignment issue.

R. J.