Okay it's driveline set up time after my 351W/C4 swap, DJM beams and lowering shackles and hangers. At the trans I've got 4 degrees down. At the rearend I've got 12 degrees up. The front hanger lowers quite a bit more than the shackle so it's caused a lot of pointing up. My question is, is it feasible to change the rearend the required 8 degrees using shims? or am I looking at the more labor intensive job of relocating the perches?

 

What was the rear pinion angle before shackles & hangers?

 

I knew that was coming.

 

Ya know it!

And I am curious to know because DJM shackles and hangers shouldn't require shimming per se. It is supposed to be a kit.

 

I respectfully disagree. The rear shackle only lowers slightly because of clearance to the box it can only go up so much. The front hanger accomplishes most of the drop and that causes the increase in upward tilt. I did not measure the pinion angle before the hanger mod. Not sure what that would accomplish since I was swapping the motor and trans. I'm not trying to get it back to what it was, I'm trying to match it to the motor/trans.

 

OK... I dig it.

Summit carries 8° shims: http://www.summitracing.com/search/p...2%2B4294820969

 

Right on. A little costly. Also until I get the front body clip and truck box back on I won't know final ride height. The front hanger has some adjustment to move the back height a bit. Pinion angle will change if I move it and I'll be buying more shims, lol.

 

I just went through this over the summer with mu DJM lowering kit. I tried shims, and they ended up 'shifting' under power. If you've got a stock engine, you may be OK. I ended up having to cut my spring perches off the rear-end and re-weld them at the proper angle. I haven't had a problem since, but I also added Cal-Tracs to my rear suspension too. You may have better luck than me, I sincerely hope you do!

 

Did you use the slide in shims with the slot? Or the ones with the hole in the middle. You can get aluminum or steel. If one was to use steel it could be tack welded a bit to the perch.

 

I used the aluminum ones with the hole in the middle. I had to use two(2) four degree shims on each side to get the 8 degrees I needed. The centre bolt in the middle of the leaf spring was not long enough to protrude through, and properly locate the shims, and rear-end under the springs. That's how I ended up with some shifting. If you can get a steel shim and weld it in place, then I would think you'd be OK?

 

I ended up buying some 6 degree shims from DJM. I now have 4 degrees down on the trans and 6 degrees up on the rear. My rationale was that once the box is put back on the truck, it might bring the back trans angle down slightly. At any rate they say I you're within 2 degrees you're doing pretty good. When the truck is done I'll recheck.


I should add that the aluminum shims that I got from DJM came with new bolts and a couple of bushings that make the head of the bolts stick out longer in order to go all the way through the shim and well into the perch.

 

Adding weight to the truck will not affect engine/trans angle as it relates to the pinion angle.

 

Wouldn't it? The motor and trans are fixed in the frame. When the rear frame comes down it tips the back of the trans down but the rear diff always remains on the same place. No? Anyways I'm not going to worry to much until I'm at final ride height.

 

But the driveline angle remains the same in relation to the pinion angle.