Front Axle centering (in wheel well)

We just finished an EVO coilover install on a 2008 JKUR. It's got 37's with ram assist and a draglink flip. We utilized some existing Teraflex bump stops (will most likely get swapped out later).

On a recent trip to the Winterfest 4x4 2017 in Hurricane, Utah, we found a couple of issues, one that is leading me to post this question.

First some background. This JKUR has had a full teraflex LCG long arm kit on it since 2010. We swapped the existing shocks and springs to the Evo coil overs and at the same time, did the drag link flip on it. It had been aligned and was driving very nicely prior to this work.

After the CO install, drive-ability was not impacted, it still drove nice, ride was better (as expected). From stock CO's we are set at 1" of preload in the rear and with 1" in the front we were a little light there (it just had an LS3 install) so we increased the front to 2" of preload as measured from the shock mount top to the near side of the preload ring. The rears were installed with a heavier spring and we have no issues on the rear.

I should also say that to meet the minum wheel width in the front, we had to go to 1.25 inch spacers with the raceline wheels that we have which have a backspace of 4.75 inches.

IMG_20170121_150208-small.jpg

Ok, so here is the issue we are trying to understand how best to address.

At full flex the tires rub on the rear inside of the wheel wells (body). We have trimmed a little and yet, there was a couple of times at full flex where we rubbed pretty hard with the body on the inside top of the tire. Also at full flex, and full turn, we are rubbing the tire on the frame to the point where we have rubbed about 3 inches smooth. We don't hit any other place inside the front wheel well, so the bumpstops are doing their job.

On a recent alignment, the caster was set to 4.2 degrees, but I've noticed that the axle pucks and the frame bumpstops are not very aligned. At drive height, they are off by about 1/2 the puck diameter (approx hockey puck sized). I know that the axle pivots on the long arms and that it should be more forward the more compressed the suspension is, but I'm just wondering how I go about determining if with all the changes the axle has be positioned further aft than it might need to be. E.g. The CO's are almost exactly vertical when at parked ride height.

Is there any way to take a set of measurements to axle center that might tell us if we are in the ballpark or if we need to move the axle forward (which I'm assuming you'd do by adjusting both top and bottom control arms out). Or is this one of those get in line, everyone has this issue with larger tires, kind of things?

As it relates to the frame rubbing, I think this may have to do with the offset being too deep on the wheels...
Racelines don't have much availability with offset spacing and I think there was a compromise there when the wheels were ordered. While we accounted for some of that with spacers, it still probably isn't ideal. (this may also effect where the tires rub on the body).

Anyway, figured I'd see what opinions might be offered to help us identify if we have a wheel well, centering issue and how to address it?

Thanks in advance. If anyone wants a panoramic image for multiple monitors, you'll have to live with those jeeps in the image, but here you go... we are the 3rd from the left in the row :)... - https://dl.dropboxusercontent.com/u/6730484/PANO_20170121_150016.jpg
 
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This is unrelated but curious about those 0.75" spacers you're running. They bolt to the axle and then have new studs your wheels go on? I didn't think you get ones that thin without using ones that don't actually bolt to the axle.
 
With 37s I was never even close to hitting the body. Looks like you have 37s.

At full compression are the bump stops centered on the landing? How much clearance do you have between coilover and tower towards front of vehicle again at full compression? You probably need to push axle forward assuming both of those items leave room to do so. And assuming you have enough adjustability in your arms.

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This is unrelated but curious about those 0.75" spacers you're running. They bolt to the axle and then have new studs your wheels go on? I didn't think you get ones that thin without using ones that don't actually bolt to the axle.

I might need to check that, they may be 1.25" spacers... I know that the stock bolts just fit with no protrusion. But they weren't very thick.
 
With 37s I was never even close to hitting the body. Looks like you have 37s.

At full compression are the bump stops centered on the landing? How much clearance do you have between coilover and tower towards front of vehicle again at full compression? You probably need to push axle forward assuming both of those items leave room to do so. And assuming you have enough adjustability in your arms.

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kinda what I figured... I guess we are going to have to pull the spring(s) and see what full travel compression looks like with bumpstop alignment vs. puck.

If I remember right and I didn't look at the top control arms, the bottoms had a pretty good amount of the ball joint rod still inside the control arm. The could be moved out probably up to an inch with no issue (little of the thread was exposed with the locking nut tightened down).
 
I just did a custom axle swap. It required cycling the axle 4 times to get the bump stops set in the right location and I had to adjust the track bar 3 times to center the axle. My most recent issue was that the right upper control arm was rubbing on the inside of the frame whereas the left one had about 5/16 spacing. I ultimately centered the axle so that upper arm spacing was even. As far as bump stops, it's just trial and error of cycling the axle to make sure that you're in the correct spot. I would definitely check the upper arm spacing in relation to the frame just to make sure that the axle isn't favoring one side.
 
You need some 1.5" spacers to not rub

Thanks, we actually have some of those as well, but elected to not stress the lug bolts and went with the shorter ones.

At some point we'll do 60's on this and this will all have to repeat... but I don't know how far down the road that will be and I'd rather not tear up tires between now and then. :)
 
I just did a custom axle swap. It required cycling the axle 4 times to get the bump stops set in the right location and I had to adjust the track bar 3 times to center the axle. My most recent issue was that the right upper control arm was rubbing on the inside of the frame whereas the left one had about 5/16 spacing. I ultimately centered the axle so that upper arm spacing was even. As far as bump stops, it's just trial and error of cycling the axle to make sure that you're in the correct spot. I would definitely check the upper arm spacing in relation to the frame just to make sure that the axle isn't favoring one side.

I think you are referencing mostly the side to side spacing? We have that nailed. this is an issue with the fore/aft centering in the wheel well, and potentially a backspace issue with the racelines/spacers?
 
I think you are referencing mostly the side to side spacing? We have that nailed. this is an issue with the fore/aft centering in the wheel well, and potentially a backspace issue with the racelines/spacers?

I misread your post at first. Sorry about that. But I still would cycle the axle as far as looking at where the axle is rubbing. I am not familiar with coilovers at all, but if you're hitting in the rear wheel wells, it sounds like your lower arms may need to be extended, then recheck your caster. As far as rubbing on the inward frame rails, I bet the backspacing fixes that as mentioned.
 
I misread your post at first. Sorry about that. But I still would cycle the axle as far as looking at where the axle is rubbing. I am not familiar with coilovers at all, but if you're hitting in the rear wheel wells, it sounds like your lower arms may need to be extended, then recheck your caster. As far as rubbing on the inward frame rails, I bet the backspacing fixes that as mentioned.

Thanks for that, no problem, I created some confusion originally with the wrong spacer thickness.... No worries. And yes, you are probably right. I'm becoming more and more convinced that our axle is more aft than is should be. Now the questions are what to do that resolve that, is it just lower or both upper and lower that needs to be adjusted to push it forward and what does that do to our driveline length... sheesh, it's always something with these things...

But DANG it was sure fun wheeling in St. George this past weekend!!! :)
 
Thanks for that, no problem, I created some confusion originally with the wrong spacer thickness.... No worries. And yes, you are probably right. I'm becoming more and more convinced that our axle is more aft than is should be. Now the questions are what to do that resolve that, is it just lower or both upper and lower that needs to be adjusted to push it forward and what does that do to our driveline length... sheesh, it's always something with these things...

But DANG it was sure fun wheeling in St. George this past weekend!!! :)

Your lower arms should set the axle position in the wheel well and then your upper sets the caster. After you set the lowers, check the caster and see where you're at. I'm guessing that it won't take much to get the axle in the right spot. Did you already shorten the driveshaft due to a different axle or anything like that?
 
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