Commeeche

Hey guys. I recently bought a ground force drop shackles kit. It didn't have any instructions in it. O know it's straight forward for install. But with the shims, I would think that the fat part goes towards the front of the truck but people are saying it goes towards the rear. Which doesn't make sense since it will point the pumpkin down . I thought it would want to be pointed up. Any help would be much appreciated before u get into this project.

1NiceHarley

My thoughts on this, and I could be completely wrong, is that you put the flat (thick) part forward because when you put on the drop shackles that rear of the spring goes up forcing the pumpkin down. So you put the thick part of the shim forward so that the pumpkin is close to level again.

Commeeche

That's what I thought. But I've read that it's the opposite. Which would point the pumpkin down further. Which doesn't make sense to me

1NiceHarley

Oh. I miss read your first post. We did say the same thing. Sorry about that. I have no clue why they would say put the thick part of the shim to the back of the truck.

LTNBOLT

It depends on whether the axle is over or under the leaf spring. If the axle is over the spring the thick part of the shim would go to the front. If the axle is under the spring the thick part of the shim goes to the back.

Commeeche

Okay. Ya my leafs are not on top I didn't do a axle flip. Just seems weird that pinion is gonna be pointing so far down now when I flip those shims. But I guess that what it wants. Cause I'm getting a vibration at 40kmh when I'm braking and at the same speed when I accelerate

RLXXI

The thick end to the rear is going to point the pinion up not down.
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Commeeche

Maybe I don't need to run shackles. With searching on here I read posts were guys said they never used them and had no issues. Just frustrating being the first time I'm lowering a vehicle and can't figure this out

Newport

The direction of the shims and final angle all depend on getting to an angle differential of approximately 1.5 to 2 degrees between the trans output shaft centerline and the pinion centerline. This is also referred to as pinion angle. My 17 needed about 1.5% to be happy.
Any more and it shook slightly at 25-27mph and any less and it shook around 40-45mph. Measure the angles and do the math and then you will know how much and which direction.