After installing the rear shackles to lower the truck, is the pinion angle greater or less? I know Ground Force includes shims with their lowering shackles but others say they don't need them. Do the shims included with Ground Force, tilt the pinion up or down? In other words, are the shims thicker in the front or back when installed? I am just trying to figure out which way the differential is rotated when lowering.

John

 

I am guessing downward, so the shims would should be thicker in the front.

 

Superscrewed is right.Lifting the rear of the spring while leaving the front in the same position will point the front of the diff downward.Not very much though...Kevin

 

You are correct. I have the Ground Force shackles and the thicker end is towards the front.

 

Unless there are two diferent sets of instructions from Ground Force something isn't right- my instructions say the thicker part of the shim goes toward the rear of the vehicle,even shows a pic of them installed toward the rear.

 

I gotta agree with Mike on this one. If you lower the rear by extending the rear spring hanger, then the front of your pinion will be pointed more toward the ground. You need the fat part of the wedge to the rear in order to angle the pinion back up in line with the driveshaft and tranny.

 

I never looked at the rear DS in my F150, so I don't know what type of shaft is in it, but I am going to assume has a CV joint. Here's a few pictures that should answer your question.





In some cases it is nice to have the pinion just a little below the output of the t-case/tranny. This is becasue axel wrap on the rear spring will cause the pinion turn up when underload.

Hope this helps,

zman

 

I ordered my 2" DJM shackles from Stylin' Concepts this week. I asked the salesperson if shims were needed with the 2" lowering, and he assured me that I wouldn't need them.

 

I spoke with Ground Force before I installed my shackles,their tech said I didn't need the shims if I only lowered it 2 inches, but if I went the full 4(which actually only came out to be 3.5 inches) that I would need the shims for proper pinion angle.

 

WHAT ABOUT A FLIP KIT?

 

with a flip kit you elimate the need for shims. i have a flip kit and didnt have to use shims.

 

Well, I installed my DJM lowering shackles this weekend. I went for the full 2". It looks great! But....I now have a low speed vibe.

I called DJM and they said that they are starting to get alot of feedback with the same results. Evidentally these trucks are VERY sensitive to any pinion angle changes. They (DJM) are looking into it and will probably be coming out with a very slight shim to correct the vibe.

Until then, I'll have to live with it. Up until around 30 mph it feels like I'm on a slight washboard surface. Very frustrating.