Topic: Suspension question for those who have adjusted pinion angles

[stan98tj]

Just wanted to get some ideas about a little bit of an issue I'm having with my rear suspension.
I'm running an 8.8 in the rear. We set the spring plates and brackets for 2-3inches of lift. I'm running 2-2.5" suspension and 1" BL (not that it counts in this instance).
I've got MML, sye, and high clearance skid. I adjusted my pinion for all of that. But when I was done, I noticed my rear springs had bent into a curve from the pinion adjustment. Now when I drive, I get a lot of bounce from the rear end. I have the rear bumper off, but it doesn't weigh that much, and I do plan on installing the LOD bumper at some point which does weigh significantly more. My springs were purposefully bought with a little more stiffness in them to handle added weight, but since the recent pinion adjustments it feels like the rear end bounces a bunch.
Have any of you experienced this? Is the solution to cut the spring pad off and reweld it? Or cut the top piece and move it back? I assume, you'd want the spring straight up and down, right now it has a slight curve at the bottom.
Also, could the bounce in the rear be unrelated to the curve in the spring? Maybe the springs are just too stiff?

[stan98tj]

meant to say "coils" not springs

[Jeffy]

So I'd imagine your control arms are out of whack as well?  I think you'd be better off removing all the brackets, rotate the housing to where it needs to be then putting the brackets back on the right locations.

[stan98tj]

So I'd imagine your control arms are out of whack as well?  I think you'd be better off removing all the brackets, rotate the housing to where it needs to be then putting the brackets back on the right locations.

The arms are adjustable, they were what I used to adjust the pinion angle. Should I cut the coil perch at the bottom and slide it back? I'm inclined to think I should prob cut the top (frame side) and move it back. The coil would then be up and down.

[sharpxmen]

4 things i could think of
 1. what is the current pinion angle in relation to d/s (that's when i was getting bounces)
 2. is the coil seat lined up properly for (the line between the centers of the upper/lower seats should be perpendicular to the seat plane itself (what Jeffy and you basically said).
 3. how good are the bushings on the suspension arms
 4. did you account for the intersection point after adjusting the length (what i mean is that after this geometry change the torque from the rear axle thru the suspension arms is rotating the vehicle CG upwards then it might result in a bounce). what i'm thinking is something similar to what drag racers to when they adjust susp arm geometry to reduce wheelies, I don't know if the change you made is as extreme but you might need to relocate the upper mounts to prevent the momentum arm due to rear axle torque to push the CG upwards, i think it's related to the intersection point but i'm not an expert with this - Art or Bounty might have better insight for this particular issue if this is the case. Basically (as I understand it) the longer the resulting momentum arm at the imaginary intersection for the upper susp arms to the lowers the easier the torque at the rear axle to lift the CG of the vehicle, the shorter the harder and resulting in less bounce. Hope someone can clarify this further if this is the case and how to prevent it.

[Bounty Hunter]

Likely need to move the upper coil bucket rearward, straightening out the coil.  The bent coil is reducing the effectiveness of the spring, making the ride harsh and bouncy.  Many have luck relocating the stock upper bucket, or you can go aftermarket.

http://www.genright.com/ProductInfo.aspx?productid=RSM2100#.UtDQSfRDv0c

http://www.superlift.com/media/bulletins/s185.pdf

http://www.tntcustoms.com/Jeep_wrangler/coil_spring_relocators.aspx

[dwtaylorpdx]

if your setup will do it, you might be able to lengthen or shorten the suspension rods enough to get the spring straight.
often the heims get threaded in too far or not enough and it pulls or pushes the spring at the bottom.

Dave

[Jeffy]

if your setup will do it, you might be able to lengthen or shorten the suspension rods enough to get the spring straight.
often the heims get threaded in too far or not enough and it pulls or pushes the spring at the bottom.

Dave

The problem is he's using the control arms to set the pinion angle.

I'm wondering if rotating the housing is going to affect the geometry of the suspension and cause binding though.  The track bar mount isn't going to be centered either.  As you rotate the housing the distance between the upper and lower control arms is reduced.

[dwtaylorpdx]

:) Well put, that's where I was headed, you have to get the arm lengths in the correct geometry, It may mean modifying the brackets to get the pinion angle to a correct position..

 

[aw12345]

Just wanted to get some ideas about a little bit of an issue I'm having with my rear suspension.
I'm running an 8.8 in the rear. We set the spring plates and brackets for 2-3inches of lift. I'm running 2-2.5" suspension and 1" BL (not that it counts in this instance).
I've got MML, sye, and high clearance skid. I adjusted my pinion for all of that. But when I was done, I noticed my rear springs had bent into a curve from the pinion adjustment. Now when I drive, I get a lot of bounce from the rear end. I have the rear bumper off, but it doesn't weigh that much, and I do plan on installing the LOD bumper at some point which does weigh significantly more. My springs were purposefully bought with a little more stiffness in them to handle added weight, but since the recent pinion adjustments it feels like the rear end bounces a bunch.
Have any of you experienced this? Is the solution to cut the spring pad off and reweld it? Or cut the top piece and move it back? I assume, you'd want the spring straight up and down, right now it has a slight curve at the bottom.
Also, could the bounce in the rear be unrelated to the curve in the spring? Maybe the springs are just too stiff?

Less weight and developing bouncing means the shocks are to stiff. Bowed coil spring will not cause that about every lifted TJ on the road has bowed rear coil springs with very little if any ill effects. Find some shocks that are adjustable like the Rancho 9000's and dial them and be happy

[stan98tj]

Less weight and developing bouncing means the shocks are to stiff. Bowed coil spring will not cause that about every lifted TJ on the road has bowed rear coil springs with very little if any ill effects. Find some shocks that are adjustable like the Rancho 9000's and dial them and be happy

I know DPG set me up a bit stiff as we figured id be carrying a bit more weight with the rear bumper. maybe the shocks they sent are a bit too stiff. I just find it a bit strange it seemed to develop after these recent adjustments. Guess I can swap to less stiff shocks. would you recommend even adjusting the upper (frame side) bucket to line up with the rear, Art?