Rear Axle Upper Control Arm Mount Relocation

[XCRN]

I am looking at relocating the upper control arm mounts on the rear axle to move them inboard enough to be able to be done with the trackbar. I took some rough measurements of a stock frame and axle and found the upper arm separation looking from above is approximately 30 degrees and it sounds like 40 degrees is minimum, 45 is optimal for enough triangulation to remove the track bar. I was thinking of moving the upper control arm mounts on the axle closer to the center about 1-1/2 to 2” both sides putting the rough angular spread around 43-45 degrees and keeping all of the other mounts in the same location.

I would like to avoid moving the uppers over the pumpkin to maintain my up-travel and to allow me to keep a decent sized muffler with exhaust still dumping out the back, not under the tub. I am thinking this should keep mostly the same stock ride characteristics, which is ideal as this is a go-fast sand dirt toy that is also my summer daily so this still needs to have great highway manners as well. I just want to be able to get more overall travel for when I end up airborne which happens a lot and the track bar is the main limit for travel in a few ways, so this seems like a simple(ish) solution and keeping within my constraints.

Any thoughts? Is this just a dumb idea, or am I not considering everything that would be detrimental?

 

[mrblaine]

I am looking at relocating the upper control arm mounts on the rear axle to move them inboard enough to be able to be done with the trackbar. I took some rough measurements of a stock frame and axle and found the upper arm separation looking from above is approximately 30 degrees and it sounds like 40 degrees is minimum, 45 is optimal for enough triangulation to remove the track bar. I was thinking of moving the upper control arm mounts on the axle closer to the center about 1-1/2 to 2” both sides putting the rough angular spread around 43-45 degrees and keeping all of the other mounts in the same location.

I would like to avoid moving the uppers over the pumpkin to maintain my up-travel and to allow me to keep a decent sized muffler with exhaust still dumping out the back, not under the tub. I am thinking this should keep mostly the same stock ride characteristics, which is ideal as this is a go-fast sand dirt toy that is also my summer daily so this still needs to have great highway manners as well. I just want to be able to get more overall travel for when I end up airborne which happens a lot and the track bar is the main limit for travel in a few ways, so this seems like a simple(ish) solution and keeping within my constraints.

Any thoughts? Is this just a dumb idea, or am I not considering everything that would be detrimental?

View attachment 565558

You won't limit uptravel generally with them on top of the diff. But, your challenge will be making the mounts strong enough to handle being triangulated uppers.

 

[XCRN]

You won't limit uptravel generally with them on top of the diff. But, your challenge will be making the mounts strong enough to handle being triangulated uppers.

I am going to use a blank slate with an 8.8 or an already stripped down Rubi Dana 44 I have lying around so I could just get a much thicker bracket on the axle and add some gussets.

I have seen some rear exit exhausts routed with pumpkin mounted UCA brackets so I am not too opposed to making that work with staying at the same uptravel. Currently I have 2in of bump stop extension and I would like to keep that as my max extension, and that is only because of the factory mounted shocks, when I outboard with 12in shocks, I would like to be able to take that down to 1in, but I can live with the same 2in BS extension because of the UCA mounts and just maybe get a 14in in there.