Issue or Not Centering Rear Bump Stops?

[rows]

So my rear bump stops look like they need to come forward roughly an 1” to be centered and I only have a 1/2” of available threads on my lowers. With my tires on at full stuff the tires look pretty much centered in the wells. Are the stops good to go how they’re set? Or am I just looking for problem and leave them alone? Is the bump stop misalignment caused by my pinion angle from my lift and tuck and why relocating the spring perched is done?

Little backstory 06” LJ Rubicon with 35s. I just installed a new 4” RockJock lift with a Savvy tummy tuck. Working on getting it close enough to drive to the alignment shop. Lowers are set to the recommended starting pointing of 15 3/4” and there is only an 1/8” between each side measured axle to the center skid bolt hole. Pinion is set 1* degree under the driveshaft which is 18*.

 

[KennethS]

Working on getting it close enough to drive to the alignment shop.

If you’re gonna drive on a paved road to the shop it’ll probably be OK.
If there’s some rock crawling between the house and the alignment shop then I dunno.

 

[jjvw]

It's fine. If you sized the shocks correctly, they are the final limit to travel. The Currie bumps only exist to slow down the final ~3/4“ of shaft speed before full shock compression.

You fix this by moving the upper spring seats within the frame arch. But it's a good amount of work for not much benefit without also doing a shock outboard.

As far as pushing the axle back further, you are limited by either the tires digging into the rear of the wheel opening. This can be resolved by trimming the body. Or the diff cover will smash into the gas tank skid at full shock compression. There isn't much you can do about that without a huge amount of work.

Or don't worry about the bumps not lining up.

 

[jjvw]

If you’re gonna drive on a paved road to the shop it’ll probably be OK.
If there’s some rock crawling between the house and the alignment shop then I dunno.

Full shock compression during rock crawling is typically a slow speed event. There isn't much need for bump stops to begin with in that scenario. We are far more likely to hit hard on pavement going to the grocery store.

 

[rows]

It's fine. If you sized the shocks correctly, they are the final limit to travel. The Currie bumps only exist to slow down the final ~3/4“ of shaft speed before full shock compression.

You fix this by moving the upper spring seats within the frame arch. But it's a good amount of work for not much benefit without also doing a shock outboard.

As far as pushing the axle back further, you are limited by either the tires digging into the rear of the wheel opening. This can be resolved by trimming the body. Or the diff cover will smash into the gas tank skid at full shock compression. There isn't much you can do about that without a huge amount of work.

Or don't worry about the bumps not lining up.

Thanks that was what I was looking for and after I thought about for a bit I figured it was related to the pinion angle with lift and tuck and this was one of the reasons people move the spring perch. I’m pretty new to tinkering with Jeeps so I appreciate the explanation. I can be guilty of overthinking things sometimes.

I think my shocks are probably perfect because in the picture of the bump stops touching, the shocks only had about a 1/4” or so of travel left. Everything else clears my Savvy gas tank skid with stops touching except my tracbar. It is barely contacting the front lip of the mounting bracket. I marked it on the skid and will clearance it a little when I drop my tank fix the overflow plunger I buggered up.

Another question though…. The axles being 1/8” out of square to the center skid bolt hole. Is this something a competent 4x4 shop will take care of if I take it for an alignment or do I need to sort that out before taking it to them? Or will a guy even notice the 1/8”?

 

[jjvw]

Thanks that was what I was looking for and after I thought about for a bit I figured it was related to the pinion angle with lift and tuck and this was one of the reasons people move the spring perch. I’m pretty new to tinkering with Jeeps so I appreciate the explanation. I can be guilty of overthinking things sometimes.

I think my shocks are probably perfect because in the picture of the bump stops touching, the shocks only had about a 1/4” or so of travel left. Everything else clears my Savvy gas tank skid with stops touching except my tracbar. It is barely contacting the front lip of the mounting bracket. I marked it on the skid and will clearance it a little when I drop my tank fix the overflow plunger I buggered up.
...

Somewhere in the Currie literature, they recommend about 3/4" of shock shaft showing at first contact at the bumps. That's what I set mine up for.

...

Another question though…. The axles being 1/8” out of square to the center skid bolt hole. Is this something a competent 4x4 shop will take care of if I take it for an alignment or do I need to sort that out before taking it to them? Or will a guy even notice the 1/8”?

I can't imagine any shop knowing how to properly set and square an axle. Never mind even knowing to use the center skid bolts as a reference.

 

[rows]

Somewhere in the Currie literature, they recommend about 3/4" of shock shaft showing at first contact at the bumps. That's what I set mine up for.



I can't imagine any shop knowing how to properly set and square an axle. Never mind even knowing to use the center skid bolts as a reference.

I don’t remember seeing anything the instructions that I printed out. But it makes sense, I’ll double check though. I did have to trim down the rubber spring isolators a little to get the bolts in the top stops started, maybe a 1/4”, the bolts were too short and would not start. I probably lost a little there but not 3/4”.

In regards to square the axle. Where’s the best place to reference from? Is the center skid bolt hole adequate? Here’s two threads, one TjDave and posts #12 & #13 from mrblaine, that I’m using for reference while sorting this out.

https://wranglertjforum.com/threads...-control-arms-on-a-jeep-wrangler-tj-lj.17062/

https://wranglertjforum.com/threads/double-adjustable-control-arm-install-tips.17061/

 

[jjvw]

I don’t remember seeing anything the instructions that I printed out. But it makes sense, I’ll double check though. I did have to trim down the rubber spring isolators a little to get the bolts in the top stops started, it seemed the bolts were too short.

In regards to square the axle. Where’s the best place to reference from? Is the center skid bolt hole adequate? Here’s two threads, one TjDave and posts #12 & #13 from mrblaine, that I’m using for reference while sorting this out.

https://wranglertjforum.com/threads...-control-arms-on-a-jeep-wrangler-tj-lj.17062/

https://wranglertjforum.com/threads/double-adjustable-control-arm-install-tips.17061/

The center skid bolts are a great reference point. Absolutely do it how Blaine does it. Especially the part with the framing square and extending the skid bolts with longer bolts to measure from.

My point point is that I can't remember ever seeing signs of a shop that I would trust to setup a rig comparable to what is available here for a DIYer.

 

[rows]

The center skid bolts are a great reference point. Absolutely do it how Blaine does it. Especially the part with the framing square and extending the skid bolts with longer bolts to measure from.

My point point is that I can't remember ever seeing signs of a shop that I would trust to setup a rig comparable to what is available here for a DIYer.

Thank you. I’m going to spend some more time with it and get it setup closer than what it is. I really appreciate it.

 

[LONGJP2]

Somewhere in the Currie literature, they recommend about 3/4" of shock shaft showing at first contact at the bumps. That's what I set mine up for.

Wouldn't that only apply to the stock (collapsible) bump stops?
His look solid.

 

[LONGJP2]

Thank you. I’m going to spend some more time with it and get it setup closer than what it is. I really appreciate it.

Remember, the only thing an alignment shop will adjust is toe.
And they're probably just going to set it to factory spec without taking your lift into consideration.
You may end up having to go back and adjust camber yourself.

 

[jjvw]

Wouldn't that only apply to the stock (collapsible) bump stops?
His look solid.

I have the same bump stops. They squish, despite being harder than stock. Stock bump stops squish all the way into the steel cup. Which is why you want cup to axle pad contact to closely match the collapsed shock and not before. The shock is the hard limit to up travel. Currie/RockJock has no hard stop, so you do about 3/4" of shaft at first contact. Again, the shock is the hard limit to up travel.

 

[rows]

I have the same bump stops. They squish, despite being harder than stock. Stock bump stops squish all the way into the steel cup. Which is why you want cup to axle pad contact to closely match the collapsed shock and not before. The shock is the hard limit to up travel. Currie/RockJock has no hard stop, so you do about 3/4" of shaft at first contact. Again, the shock is the hard limit to up travel.

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I used the lower shock brackets from RockJock also. I didn’t measure how much was left with shocks at bump, just look at them, it could have been a bit more room too. I’m wondering if those brackets might have raised the lower mount a little and in combination with trimming down the spring isolators a little, that enough to loose the half or so that I seem to be missing. I probably should get a longer bolt for the top spring retainers and new isolators pads then install them and see where that puts it.

 

[jjvw]

I used the lower shock brackets from RockJock also. I didn’t measure how much was left with shocks at bump, just look at them, it could have been a bit more room too. I’m wondering if those brackets might have raised the lower mount a little and in combination with trimming down the spring isolators a little, that enough to loose the half or so that I seem to be missing. I probably should get a longer bolt for the top spring retainers and new isolators pads then install them and see where that puts it.

The answer is to remove the springs and bring the axle up to full shock compression.