Suspension and caster question

[mgroeger]

Background:
2004 LJ, The lift is a 2” DPG Offroad TJ Super Ultimate Lift, contains the following:
-JKS Control J-Flex Adjustable Control Arms (All)
-Old Man Emu Springs
-Old Man Emu Shocks
-Old Man Emu Steering Stabilizer
-JKS Quick Sway Bar Disconnects
-JKS Front and Rear Adjustable track Bars

Here's the problem... the guy who put this kit on got a little crazy with pushing his caster out on the front axle to the point where the track bar hits the diff cover when I hit bumps. He added a VERY robust (total overkill) diff cover but after taking a side by side look at three other diff covers, including a stock Dana 44, it turns out they would all hit the track bar as well. The Jeep has the stance I want so putting spacers up front isn't an option. This is the cover: https://eastcoastgearsupply.com/i-130009-dana-44bent-steel-diff-cover.html

I called Dirk at DPG who put this kit together and he said that whoever put that kit on pushed the front axle way too far because he's used this combo and never had a problem.
His recommendation was to put all the JKS control arms (upper and lower) back to the factory length and then make only the front lower control arms 5/16" longer to add some caster to compensate for the lift.
He said even pushing that axle out an entire inch on an LJ is pointless, that I would never notice that from a stability standpoint.
All that being said, does this sound like a good approach? If so does anyone happen to have the center hole to center hole measurements for all four control arms? If this is a good plan I'm guessing it will be pretty straight forward and then I will need to get teh alignment checked afterward.

 

[Jerry Bransford]

Dirk's advice is sound.

 

[mgroeger]

Thanks!

 

[billiebob]

Best advice, first, follow the instructions. Second if you want to deviate from the instructions, consult the manufacturer.

I do this daily installing chimneys and wood burning appliances. The basics never change. If it is technical, follow the technical advice, design, instructions and consult the experts if you have a "better idea".:tiburon:

 

[ac_]

I am not sure what they are for JKS but I have this from Currie:

2) Currie control arms come preset for a TJ with a 4” lift, a transfer case slip yoke eliminator kit, and a CV driveshaft.
Front upper arms - 15” c-c
Rear upper arms - 13 1/2” c-c
All lower arms - 15 3/4” c-c

This is for a 4 inch though, but maybe help you guestimate a starting point?

 

[mgroeger]

Potentially dumb question... do the TJ and LJ use the same control arms? I'm guessing yes since I can't find any control arms designated for the LJ. Having a difficult time finding the hole to hole measurements on these suckers.

 

[mgroeger]

Found some info assuming I can use the ones for a TJ. On Quadratec's website they list the models it fits and one of the models is the 1999 Cherokee XJ which my daughter has so technically I could get a pretty good idea from under her Jeep.

 

[mgroeger]

OK, I keep answering some of my questions. It does appear that the TJ and LJ take the same control arms.
Still hunting down specs.

 

[Jerry Bransford]

Yes they use the exact same control arms.

 

[mgroeger]

Excellent. So that means they also share with the '99 XJ that my daughter has so I can get my measurements.

 

[Chris]

Don't pay attention to control arm length measurements, it doesn't matter at all. Put on one control arm at a time. Remove a stock one, put one on in place of it. Wherever it lands measurement wise is where it lands. Do this for all the arms, replacing one at a time.

After that's done, cycle the suspension and make sure the bump stop pad and jounce bumper are dead center on both sides. If not, adjust the arms out so that they do center up. Once that is done, put the wheels back on and use the upper arms to dial in the rear pinion angle (the front pinion angle shouldn't need to be changed from stock).

Make sure that when you're adjusting the upper arms (I pray you have double adjustable uppers to make it easier) that you adjust one of them first to set the pinion angle, then adjust the other so that there is zero bind in it and it sits perfectly eye-to-eye without having to jam the bolt in or anything.

Like I said, measurements don't matter, it's absolutely useless. Once you do control arms once or twice, it starts to make sense.

 

[mgroeger]

SO

Don't pay attention to control arm length measurements, it doesn't matter at all. Put on one control arm at a time. Remove a stock one, put one on in place of it. Wherever it lands measurement wise is where it lands. Do this for all the arms, replacing one at a time.

After that's done, cycle the suspension and make sure the bump stop pad and jounce bumper are dead center on both sides. If not, adjust the arms out so that they do center up. Once that is done, put the wheels back on and use the upper arms to dial in the rear pinion angle (the front pinion angle shouldn't need to be changed from stock).

Make sure that when you're adjusting the upper arms (I pray you have double adjustable uppers to make it easier) that you adjust one of them first to set the pinion angle, then adjust the other so that there is zero bind in it and it sits perfectly eye-to-eye without having to jam the bolt in or anything.

Like I said, measurements don't matter, it's absolutely useless. Once you do control arms once or twice, it starts to make sense.

Thanks Chris. I get what you are saying but as it sits now, with adjustable control arms, the whole thing is WAY too far forward. My track bar and diff cover are hitting so the guy said put the arms back to stock length. That's been the dilemma... finding out stock length, but I believe I have it now. I understand what you are saying though.
Also from what I have read you could actually stick with stock arms on a 2" lift.

 

[tworley]

Don't pay attention to control arm length measurements, it doesn't matter at all. Put on one control arm at a time. Remove a stock one, put one on in place of it. Wherever it lands measurement wise is where it lands. Do this for all the arms, replacing one at a time.

After that's done, cycle the suspension and make sure the bump stop pad and jounce bumper are dead center on both sides. If not, adjust the arms out so that they do center up. Once that is done, put the wheels back on and use the upper arms to dial in the rear pinion angle (the front pinion angle shouldn't need to be changed from stock).

Make sure that when you're adjusting the upper arms (I pray you have double adjustable uppers to make it easier) that you adjust one of them first to set the pinion angle, then adjust the other so that there is zero bind in it and it sits perfectly eye-to-eye without having to jam the bolt in or anything.

Like I said, measurements don't matter, it's absolutely useless. Once you do control arms once or twice, it starts to make sense.

X2. If you want, start with the arms as short as possible. Cycle suspension and adjust as necessary.

 

[Chris]

SO


Thanks Chris. I get what you are saying but as it sits now, with adjustable control arms, the whole thing is WAY too far forward. My track bar and diff cover are hitting so the guy said put the arms back to stock length. That's been the dilemma... finding out stock length, but I believe I have it now. I understand what you are saying though.
Also from what I have read you could actually stick with stock arms on a 2" lift.

But even as it sits now with it way to far forward, you still don't need to pay attention to specific lengths of the control arm, that's the wrong way to do it. You need to shorten them until your front lower spring perch and the upper jounce bumper are dead center. That's how you will know the axle is centered. Whatever the control arm lengths end up being, that's absolutely irrelevant. What matters is that the axle is centered where it should be. If you go off a set measurement it may be right, or it may be close, or it may not be close at all. All I'm saying is forget the measurements and center the axle. If you're concerned with measurements, you can measure after you're done centering it.

I was once in your exact same situation, literally. I was so focused on figuring our control arm lengths, that I didn't understand why everyone else kept telling me that they didn't matter. Once I started playing around with it and trying to focus on centering the axle, it totally clicked in my head, why those stupid charts with control arm lengths are nothing more than a waste of time.

The only way to properly do this is to cycle the suspension and get things centered where they need to be.

I'm not trying to talk down to you, so don't take it that way. I'm just saying, I've been here before, and I learned my lesson.

Yes, you could use stock control arms on a 2" lift, most people do. At only 2", the arms don't need to be extended much (if any) at all.

 

[mgroeger]

Thanks Chris and everyone else. BTW... I took a hard hit on one of the control I believe and had it been stock I don't think i would have fared so well.

 

[Schwifty Rich]

But even as it sits now with it way to far forward, you still don't need to pay attention to specific lengths of the control arm, that's the wrong way to do it. You need to shorten them until your front lower spring perch and the upper jounce bumper are dead center. That's how you will know the axle is centered. Whatever the control arm lengths end up being, that's absolutely irrelevant. What matters is that the axle is centered where it should be. If you go off a set measurement it may be right, or it may be close, or it may not be close at all. All I'm saying is forget the measurements and center the axle. If you're concerned with measurements, you can measure after you're done centering it.

I was once in your exact same situation, literally. I was so focused on figuring our control arm lengths, that I didn't understand why everyone else kept telling me that they didn't matter. Once I started playing around with it and trying to focus on centering the axle, it totally clicked in my head, why those stupid charts with control arm lengths are nothing more than a waste of time.

The only way to properly do this is to cycle the suspension and get things centered where they need to be.

I'm not trying to talk down to you, so don't take it that way. I'm just saying, I've been here before, and I learned my lesson.

Yes, you could use stock control arms on a 2" lift, most people do. At only 2", the arms don't need to be extended much (if any) at all.

This really helped me realize what to focus on and what not to focus on.

So when I have my shocks and springs out at full bump all I’m trying to do is center my bump stops. From what I can tell there are three things that effect my bumps stops and their position on the jounce pad. 1st my upper control arms, 2nd my lower control arms, and 3rd my track bar.

I am lengthening/shortening my uppers (since I don’t have adjustable lowers... ) to get the axle centered forward and backward on the jounce pad as best I can.

As for left and right alignment thought I got things pretty close during install but at full bump it’s still not centered

Should I/can I adjust the track bar in order to center the axle and the bump stops?

I’ve read how to jump on the bumper or use ratchet straps and measure points on the tread and the spring perch, which is what I did the first and second time.

Also read that when adjusting the track bar the front suspension should be under the full weight of the vehicle.

So what’s the consensus? Seems logical that I could use the bump stops at full bump for all three.

 

[Chris]

This really helped me realize what to focus on and what not to focus on.

So when I have my shocks and springs out at full bump all I’m trying to do is center my bump stops. From what I can tell there are three things that effect my bumps stops and their position on the jounce pad. 1st my upper control arms, 2nd my lower control arms, and 3rd my track bar.

I am lengthening/shortening my uppers (since I don’t have adjustable lowers... ) to get the axle centered forward and backward on the jounce pad as best I can.

As for left and right alignment thought I got things pretty close during install but at full bump it’s still not centered

Should I/can I adjust the track bar in order to center the axle and the bump stops?

I’ve read how to jump on the bumper or use ratchet straps and measure points on the tread and the spring perch, which is what I did the first and second time.

Also read that when adjusting the track bar the front suspension should be under the full weight of the vehicle.

So what’s the consensus? Seems logical that I could use the bump stops at full bump for all three.

View attachment 107043

View attachment 107044

Yes, install the track bar while you do this, that's fine.

I always centered my axles literally by getting a ratchet strap and putting one end around the tire and the other end around the huge metal post in my garage that sits in front of the furnace (so you don't ram the furnace with the car). Worked every time for me!