I have a slight vibration at around 65-72 mph and was wondering what can be done to fix it. It fells like it might be the rearend?
Any suggestions are appreciated.
Thanks,
Simon

 

The three things I would look at first are...in this order...

Rear wheels/tires for obvious defects and for balancing
Pinion angle if you have done any height mods on your truck
Drive shaft...have a dealer check to see that it is properly balanced.


Rocks

 

I do have drop shackles. How do you make the pinion angle equal to stock?

 

It is fairly easy to fix. Go to:
http://www.djmsuspension.com/Product...inionShims.htm

If all you've done is the drop shackles, the lowest angle should fix the problem. Some of the Lightnings, like the 2003 and 2004's come with a shim as a part of the pring pack.

 

I flipped the shims but it still vibrates

 

I thought only the 03s & 04s have shims not an 01.Try putting the stock shackles back in. If that solves the problem then you need to get different shims.

 

You are correct. You only need to shim the 03/04 with the "revised" rear suspension, not the model years before that.

 

The August issue of Hot Rod magazine page 142 talks about Driveshaf u-joint angles.


For general street use, the sum of the trans ouput-shaft angle and rearend pinion-shaft angle should total 180 degrees (+ or - 2 degrees), and on high-speed automotive driveshafts, the angle of offset between the driveshaft and U-joints needs to be between 1 and 5 degrees. Shim the engine/trans mounts or slighty rotate the rearend pinion nose as needed to accomplish this.

Good vibrations is no vibrations

 

My truck does the same thing and its all stock.

 

I suppose I got lucky. My 2003 didn't need any pinion adjustment.
I only did the 2" shackles...maybe that was not enough to create problems.

Here is a link to a thread I found pretty informative about pinion angles.

http://www.nloc.net/forum/showthread...t=pinion+angle






Rocks

 

Does anyone know the correct pinion angle for the 04 lihgtnings?
Thanks,
Simon

 

Here...check out this one. http://www.nloc.net/forum/showthread...t=pinion+angle

I am not trying to be a smart **** here, but doing a search on pinion angles at NLOC turned up a butt load of info.


Rocks

 

So should I buy different shims and use them and see what happens?
Thanks,
Simon

 

You should measure your pinion angles to see if that is even the problem.

Have you clicked on the links I posted?????? All the learning you need is in them.

The last link I posted has some excellent info.........

 

I did read them, and from what I read the pinion angle should be 5.7 degrees. So when I measure it and find out what it is I will post my results.
Thanks,
Simon