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-   -   Steering Vibration Part 2 (http://www.hotrodders.com/forum/steering-vibration-part-2-a-206815.html)

1brewmaster1 10-09-2011 06:24 PM

Steering Vibration Part 2
 
Continuing from August 23, 2011...

PLEASE...Any and all help is appreciated.

1951 Chevy 3100 P-U that has been resto modded with 350/350, 700r4, 10 bolt rear end, Mustang II rack, 245-40-18 KMC wheels and Nitto tires and all of the other stuff to complete the job. In August after purchasing this truck I had a serious vibration that started about 62 MPH and lasted to about 68. Steering wheel shakes like hell and all kinds of noises come from the steering column. Since then, I and others have looked everywhere on the truck and and found the following defective and/or not right. First, the truck had its front end lowered with 2 inch drop spindles and was only a few inches off the ground. After some serious looking, we found that the lower control arms had a radical pitch upward because the wrong coil springs were installed. We changed the springs and the vibration was still there. Secondly we found that because the springs were wrong it put excessive pressure on the upper and lower ball joints and all four were totally destroyed. They were changed. Vibrations still there. Third, we replaced all four tires and wheels with 15 inch steel wheels and almost new tires to rule out my current set up. Vibration was still alive and well. Forth, we changed the drive shaft, checked all angles and installed new universal joints. The vibration is still there.

We have gone through the truck and looked at everything that we thought could cause this vibration and as a last resort, we put about 300 pounds in the bed of the truck over the axle and took it for a ride. The vibration was gone. Now I am told that the vibration is caused by harmonics. This is now out of my league and I don't know where to look to find the cause of the harmonics causing this steering wheel to jump all over the place.

If you have any idea please let me know. Thanks, Richard

bates_k 10-09-2011 10:40 PM

Sounds like it needs a center bearing in the drive shaft, but I'm betting it has something to do with the rake of the truck.

How much lower is the rear end with the weight in it??

1brewmaster1 10-10-2011 04:01 AM

Vibration Reply
 
Thanks for the reply Bates...

With the weight in the bed the back end fell about 1 1/2 inches. The angle on the pinion held at about two degrees as did the angle from the transmission.

Richard

cucumber1949 10-10-2011 04:58 AM

You didn't mention in this thread what the alignment specs are. Have you tried more positive caster on the front axle? What you describe sounds like what some call the 'death wobble' - steering wheel and front wheels oscillate strongly back and forth at certain speeds or after hitting an irregularity in the road. Some never get this completely solved with alignment changes, others fix it with a steering damper.

user151 10-10-2011 08:24 AM

death wobble is normally a low speed phenomenon, but checkin the alignment is a good suggestion.
Also - check that the R&P steering arms are aligned properly with the lower A arms on the truck.

Frisco 10-10-2011 08:53 AM

Your front end alignment is off.

When you lower the front end you change the geometry. Adding weight to the rear corrects that geometry by lowering the rear.

Get the front end aligned.

Frisco 10-10-2011 09:26 AM

Here is a link to check out. Scroll down to the heading for CASTER.

1brewmaster1 10-10-2011 04:47 PM

Vibration Reply
 
Thanks for the responses...

The steering arms are parallel to the ground as are the control arms.

As we speak, the truck is in for an alignment and the technician is aware of all the details with the vibration.

That link for alignment was very helpful as I did not believe a vibration could be related to alignment specs. Here's hoping!!

Thanks for all the responses and I will follow up when I get it back tomorrow.

Richard

user151 10-10-2011 06:54 PM

Quote:

Originally Posted by 1brewmaster1
Thanks for the responses...

The steering arms are parallel to the ground as are the control arms. ....

The alignment may very well solve your problem. But what I meant re the R&P arms was that they should be not only parallel to the lower A arms but the same length as them, and ideally their respective pivots would be vertically aligned.

The issue is somewhat like the issue with side steer where you want the drag link aligned with the wishbone.....


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