Need help cycling suspension for track bar, full bump

97' 4 Popper

Opened a Can of Worms
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I am currently in the process of cycling for Rancho RS5000x RS55239, 2-3 inch lift shocks, in conjunction with Currie TJS bar and 32s.

As I wanted to test the fitment before drilling, I have the axle side in with the factory bolt and flag nut, and I have the frame side ziptied in. I am wondering how much my measurements will be affected after having the track bar fitted tightly in, as I'm dealing with some major interference at the diff cover at full bump.

It's not the cover itself that's the problem, but the bracket that extends from the back side of the Currie bar hitting a diff bolt. If this bracket could be cut out the bar would probably clear at full bump.

When jacking up only one side at a time there are no clearance issues. With only one shock in at a time I measure 1.625 inches of additional bump stop needed, this is not including the 3/8ths factory weld on stop that the Rubicons apparently(?) came with.

With both shocks in at the same time, jacking up the driver side results in 1.625 inches additional bump stop needed, passenger side 1.875.

The scary part is when I try to full bump it. I jacked up from the center of the axle tube right next to the diff, the passenger shock bottoms out with 1.5 inches between the cup and pad. Then I try to get the driver side to do the same, however before that can happen the track bar interferes, with 1.25-1.37 inches of driver shaft left. If I were to set the bumpstops for this interference point, it would require 2.875 inches of stop on top of the 3/8ths already there. This cannot possibly be right, or an ideal setup to say the least.

I wouldn't think jacking up from the diff would be the right way to check full bump as it's not centered, but I tried it anyways. When I try to jack from diff neither shock bottoms out before track bar hits the diff bolts. Measuring the disance cup to pad, 2.25 inches of bumpstop needed for the bar, with .75 inches of driver shaft still showing.

So what should I do? Cut the tab off the track bar? Or drill the mounts and restart the process with track bar bolted in?
 
By tab, do you mean the little gusset at the frame side Johnny Joint?

If you plan to run the axle side without the zip tie, then you should put the bolt in for your cycling.
 
By tab, do you mean the little gusset at the frame side Johnny Joint?

If you plan to run the axle side without the zip tie, then you should put the bolt in for your cycling.

I don't know the technical term but I believe that is what it is. I mean it has to be there for a reason so I hesitate to cut it without trying the other options.

As for installing a bolt unfortunately my favorite local business hardware store has been closed all weekend, tomorrow I need to make a run there anyways so maybe I can push a 1/2 inch diameter bolt through to do a mock up test one more time before drilling. I'm not sure if anyone else uses zipties or if that is a reliable method, but I was in a pinch.

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Grind down the gusset or pull the axle backwards. Also, verify that the axle is centered at ride height. All of this will affect where the final limit to up is. My Currie track bar is ground and reshaped quite a bit to make it not be an iterference to my shock travel.

The other question is surrounding the shock length. The ultimate goal is 50/50 travel from ride height, or close to that. Use the shocks as the final limits to travel. Extend the bump stops to make the jounces perform at the last bit of up travel.

Where it sits right now, what is the up and down travel from ride height?
 
Grind down the gusset or pull the axle backwards. Also, verify that the axle is centered at ride height. All of this will affect where the final limit to up is. My Currie track bar is ground and reshaped quite a bit to make it not be an iterference to my shock travel.

The other question is surrounding the shock length. The ultimate goal is 50/50 travel from ride height, or close to that. Use the shocks as the final limits to travel. Extend the bump stops to make the jounces perform at the last bit of up travel.

Where it sits right now, what is the up and down travel from ride height?

This is my first time cycling as previously I did a build with 31s and shorter shocks that didn't need to be cycled. My questions might be stupid so bear with me. :) What do you mean by pull the axle backwards? How would I verify it is centered now that everything is disconnected, by centered at ride height do you mean center the axle with the track bar? Is there a reference point that I can measure from, or do I have to drop the jeep back on the ground and center it out? I had a stock track bar with 2 inch lift before so the axle was off center to start. The Currie isn't adjusted properly, it's just fitted in there however I could to reach the holes.

I had 2 inch lift springs that measured 14 at ride height, now I'm going to about 3 inches of lift but not sure how much I'll get until it's back on the ground. I had OME 2933 and now I want to use 2934 with 10mm spacers. My shocks were OME 60047 which I'm getting rid of.

If I simulate the spring height at 15 inches, the shock shaft has 4.5 inches up, and roughly 4.5-5 down at full droop.

Also good to know that I can grind down the gusset if I have to. I think it would have to have almost half of it cut out.

Last thing- I forgot my steering stabilizer has been out this whole time. Do I have to put it back in before cycling?
 
Center the axle with the track bar. There are many ways to measure. I like to measure center between frame rails at two points hang two plumb bobs with magnets from the engine and somewhere further back. Then find center of the axle and make a mark. Line up all three points at ride height.

The track bar needs to be adjusted because it affects where, what and if things collide, such as that gusset.

Pull the axle backwards with adjustable control arms. This requires adjustable control arms.

Ride height is the height of the Jeep as it sits normally on the ground with the springs installed. Do not simulate ride height until you know what ride height really is. It may or may not be 15" of spring height.

The steering damper does not need to be installed during cycling unless you are not using the stock mounting locations.

Once you get roughly 50/50 shock travel from ride height without hard things crashing into other hard things, then call it good. It seems like you are close to that.

Extend the bumps enough to make the jounces squish almost all the way into the cups. Let the shocks be the final limit to travel.
 
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Center the axle with the track bar. There are many ways to measure. I like to measure center between frame rails at two points hang two plumb bobs with magnets from the engine and somewhere further back. Then find center of the axle and make a mark. Line up all three points at ride height.

The track bar needs to be adjusted because it affects where, what and if things collide, such as that gusset.

Pull the axle backwards with adjustable control arms. This requires adjustable control arms.

Ride height is the height of the Jeep as it sits normally on the ground with the springs installed. Do not simulate ride height until you know what ride height really is. It may or may not be 15" of spring height.

The steering damper does not need to be installed during cycling unless you are not using the stock mounting locations.

Once you get roughly 50/50 shock travel from ride height without hard things crashing into other hard things, then call it good. It seems like you are close to that.

Extend the bumps enough to make the jounces squish almost all the way into the cups. Let the shocks be the final limit to travel.

Okay, I think I get it. Hang the magnetic plumb bobs from two points between the frame rail that don't change, like the motor mounts maybe. Then find the center of axle and get it equally between the two plumb bobs.

However I have no idea what my ride height will be. So am I better off just starting the whole thing over with all my new components put in, springs, shocks etc, taking ride height measurement and getting the axle centered with the track bar by driving back and forth a couple feet. Then taking the suspension apart again. When I'm ready to cycle I could then just install my track bar at the adjustment point it was at previously when the axle was centered?
 
I end up with one bob hanging from the crank pulley and another can go on the rear bumper. The magnets are just a way of sticking the string to the Jeep. All you care about is getting two centered reference points with some distance between that you can see at the same as your axle center mark. There is no need to drive around to center the axle. The track bar is a hard link.

You need to know the ride height to center the axle and to know what the shock travel bias is. You can jump on the bumper to settle the springs. The last thing you do is extend the bump stops.
 
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I end up with one bob hanging from the crank pulley and another can go on the rear bumper. The magnets are just a way of sticking the string to the Jeep. All you care about is getting two centered reference points with some distance between that you can see at the same as your axle center mark. There is no need to drive around to center the axle. The track bar is a hard link.

You need to know the ride height to center the axle and to know what the shock travel bias is. You can jump on the bumper to settle the springs. The last thing you do is extend the bump stops.

I get the first part of your post but not the second. There is a way to find ride height with the front end jacked up and just the springs in? If the axle is drooped how would I find the ride height? Do I lift up the axle until the frame is off the stands, and wouldn't that compress the springs somewhat?
 
I get the first part of your post but not the second. There is a way to find ride height with the front end jacked up and just the springs in? If the axle is drooped how would I find the ride height? Do I lift up the axle until the frame is off the stands, and wouldn't that compress the springs somewhat?

To determine the ride height of the springs, all you need is the full weight of the Jeep on the springs. There can be jack stands under the axle when you do this.
 
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To determine the ride height of the springs, all you need is the full weight of the Jeep on the springs. There can be jack stands under the axle when you do this.

Okay, sweet. So at this point my only issue is making sure I'm measuring for center correctly.

I measured between the two frame rails where the sway bar clamps would be (currently removed) and came up with the measurement 33.25 inches. I divided in half and found that 16.625 inches corresponded with the hole on the front body mount bracket, but not the body mount itself. It is roughly in the center of the middle slot of the grill. I then stuck a skinny 4ft steel tube into that hole (will get the plumbs soon). I measured the distance between sway bar link mount to mount, and got 39 inches. 19.5 inches away I put a masking tape on the axle tube, about .38125 inches away from diff. I then tried my best to line up the two marks with measuring tape, steel tube, whatever I could find. It appears as though the axle is slightly off to the driver side. Hopefully this is somewhat correct or heading in the right direction.
 
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Well, I'm at the point where I just about lost all that's left of my mental sanity.

Got the ride height measurement, I needed to put the rotors and tires on and drop the jeep to the ground with just springs in to get reliable measurement, came out to 3.75 and 3 and 5/8ths lift with the 10mm spacers. Too much lift, so I got rid of the spacers and subtracting the 3/8ths from the total puts my lift height at 3.25 inches, and 3 and 3/8. I then used the plumb bob to find the center of the jeep and line it with the center of axle at that ride height. I found that at 15.25 inches of coil height my track bar needed to be 1 and 3/8ths inches extended to center the axle.

To clarify I am cycling for full bump with track bar mounted with original flag nut and bolt, and with the frame side bolted in with a 1/2 bolt. i have not drilled out the holes yet. Shocks are fully tight. Drag link is hand tight at the steering knuckle. No sway bar links, no springs, no steering stabilizer, and driveshaft is off.

I was soo excited to see my gusset clearing that I failed to realize my track bar was hitting the diff. I could get the shocks to bottom out fully on both sides at full bump- but the track bar was grinding against the diff cover and popping over it in the process. In order to stop this I would have needed a massive 2 and 3/8ths bumpstop extension, on top of the 3/8ths already welded to the perch.

Then i decided to off center the axle to the passenger side to see if it made any difference. It didn't make any difference at all, and in fact when i went to droop my axle back down my entire axle was stuck on the diff because of the track bar. i had to jack it back up and down to get it to pop off.

I mean what the hell am i supposed to do at this point? i bought the best clearing track bar money could buy, I just spend 1300 dollars on 5 265/75/16 tires mount and balanced. If I knew this was going to happen I would have said to hell with the moab rims and swapped the 31/10.5/15s from my other jeep. I'm dying over here. I went through of all this just to get load c tires on moab rims. Ridiculous.
 
From ride height, how much upward travel is there before the track bar contacts the diff cover? From ride height, how much shock up travel is there? How much down from ride height?
 
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From ride height, how much upward travel is there before the track bar contacts the diff cover? From ride height, how much shock up travel is there? How much down from ride height?

Fully drooped I measured 8.5 inches of travel on passenger side and 9.5 on driver; the axle is tilted off towards the driver. It's probably 9 inches of travel if I jack up the driver a bit to even it out. From ride height, 15.25 inches coil height at passenger and 15 and 3/8ths on driver, I have 5 inches of uptravel, however I hit the track bar with roughly an inch and 1/8th of shaft left. At this point I would need 2.5 inches of additional bumpstop; a combined total of 2 and 7/8ths when including the weld on bump. If I continue to jack up until the track bar pops over the other side I can fully bottom out the shocks. For the shocks I only need 1 and 5/8ths inches of additional bumpstop.

Good thing I bought a couple quarts of rustoleum because my diff is going to need to be touched up after this whole affair. :cry:
 
The total shock travel on the RS55239 is 9.41". From ride height, you are getting 5" of up travel before the track bar interference. And there is about 1.125" shaft left exposed and unusable. Math says there is about 3.285" of down travel from ride height.

Your shocks are too short. Correct?
 
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Understand that all of this is contingent on the accuracy of your measuring.

The rs55239 is 14.43" compressed. Your current setup leaves 1.125" of shaft exposed at the point of track bar interference.

Imagine if you had the rs55255 with a 15.69" compressed length and a 10.73" travel stroke. Now the shock reaches compression just before the track bar interference. And you end up really close to a 50/50 travel bias.

Do you see how the math works?
 
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The total shock travel on the RS55239 is 9.41". From ride height, you are getting 5" of up travel before the track bar interference. And there is about 1.125" shaft left exposed and unusable. Math says there is about 3.285" of down travel from ride height.

Your shocks are too short. Correct?

According to my measurements I had about 4 or 4.5 inches of down travel from ride height and only 3.87 up due to the track bar interference, not good. I really am not sure if the shocks are too short but if getting longer shocks will give me more up travel, split my travel closer to half, or reduce the amount of bump stop needed I'm all for it. I'm only using the rs55239 because everyone recommended them for 3+ inch lift saying they run long, and they've been sitting on my shelf since 2020. I was going to use them on another LJ but it turned out to have really bad frame rust.

Understand that all of this is contingent on the accuracy of your measuring.

The rs55239 is 14.43" compressed. Your current setup leaves 1.125" of shaft exposed at the point of track bar interference.

Imagine if you had the rs55255 with a 15.69" compressed length and a 10.73" travel stroke. Now the shock reaches compression just before the track bar interference. And you end up really close to a 50/50 travel bias.

Do you see how the math works?

I'm trying to do my best to be accurate with measurements but at the end of the day how precise can I really be with a tape measure and some eyeballing. I measure my coil spring height from the back of the spring, between the shock mounts and coil seating. It's really hard to measure from the front. When centering the track bar for ride height I even droop my driver side that extra 1/8th's inch for the taller OME "A" spring.

I haven't really heard of the RS55255 but then again I'm getting into lift amounts that are above my pay grade. I think perhaps I will order a set and if it doesn't work out I can return them.

I think a body lift might be in my future if it will reduce bumpstop but it's not something I want to get into right now. I know it sounds absurd but if it were up to me I would have brought the LJ back to it's original condition. However they don't make the 245/75/16 in load c anymore, and they don't make stock LJ height springs as you already know.

Thank you for taking the time to help me and steer me in the right direction, it makes a huge difference.
 
Stock control arms, correct? That keeps you from pulling the axle backwards.

Another option is to add more bend to the track bar using a shop press to clear the diff cover. I did this to mine for the same reasons, although the circumstances were very different.
 
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Stock control arms, correct? That keeps you from pulling the axle backwards.

Another option is to add more bend to the track bar using a shop press to clear the diff cover. I did this to mine for the same reasons, although the circumstances were very different.

Yes, all stock arms. I always thought people got adjustable arms to extend the length vs. stock. Would shortening the arms make the pinion angle worse?

I forgot about that second option, now that I think of it it was recommended by Blaine in one of the threads. I'll save that for the final last ditch effort.

I ordered the Rancho RS55255. I was never good at diagnosing problems, but I'm really good at firing off a parts cannon. 😲
 
Adjustable arms are for correcting pinion angles and axle positioning. Pulling your axle back a tiny amount would not create a problem for the pinion.
 
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