How long should my lower control arms be?

[gorman]

I made these arms myself - large Johnny Joint on the one side, normal sleeve and OE bushing on the other. Friends of mine have the RE SF control arms and their flex joint sits on the axle end, hence why I installed mine that way too, but I think I'm going to be turning them around.

 

[TRAILREADYXJ]

The old style Rusty's arms adjust the same way with no lock nut! They sell them separate, but they actually suggested loosening them off-road to allow the arm to twist.

With that said... They have changed the design to use a forged flex joint and a lock nut.
I can see why they changed. I am running the old style and if I don't keep them very well greased, they clunk. They have been this way for over 4 years now though with no big problems. Once I installed DBs, the clunking pretty much went away since the arms are not at such a steep angle, so I will live with them for now. I inspected them when I transfered them to the MJ, and the threads looked fine.

IIRC RC adjustable arms also use a threaded stud with no lock nut to allow twisting.
You would not want to run them this way with fine threads though, they will easily strip.

On another note, above 4.5" you need to do something with your uppers as well. Of course DBs or Longarms would be best!

 

[muddeprived]

The old style Rusty's arms adjust the same way with no lock nut! They sell them separate, but they actually suggested loosening them off-road to allow the arm to twist.

With that said... They have changed the design to use a forged flex joint and a lock nut.
I can see why they changed. I am running the old style and if I don't keep them very well greased, they clunk. They have been this way for over 4 years now though with no big problems. Once I installed DBs, the clunking pretty much went away since the arms are not at such a steep angle, so I will live with them for now. I inspected them when I transfered them to the MJ, and the threads looked fine.

IIRC RC adjustable arms also use a threaded stud with no lock nut to allow twisting.
You would not want to run them this way with fine threads though, they will easily strip.

On another note, above 4.5" you need to do something with your uppers as well. Of course DBs or Longarms would be best!

RC's arms have been changed. This is what i got today:

They now use lock nuts and flex joints. :thumbup:

 

[xcm]

Critisism is somthing i have no problem with. Please tell me what problems you see with my lowers.

its a classic trolling technique, make a negative comment and make the OP guess what your talking shit about...

you just lost.
dont feed the trolls...

 

[Quinn1.8t]

I wondered about the zerk being in that spot - but I wanted to be able to reach it while installed. Maybe I should just turn the control arm around so that the JJ sits on the body end and the OE rubber bushing on the axle end?

What about just getting a zerk with a 90 degree bend and just flipping the JJ around?

 

[beakie]

You would not want to run them this way with fine threads though, they will easily strip.

Someone can chime in to correct me, but if by 'fine threads' you mean a higher TPI (thread per inch) say 18TPI opposed to 12TPI than I would say the opposite is true.
Fine threads (again, high TPI) are stronger than a large threads as more of them are engaged over the same area.
Compare a nut/bolt. Fine thread bolts are rated as approximately 1.15x stronger than course.

 

[TRAILREADYXJ]

Someone can chime in to correct me, but if by 'fine threads' you mean a higher TPI (thread per inch) say 18TPI opposed to 12TPI than I would say the opposite is true.
Fine threads (again, high TPI) are stronger than a large threads as more of them are engaged over the same area.
Compare a nut/bolt. Fine thread bolts are rated as approximately 1.15x stronger than course.

You are correct, if the bolts are tightened (ie. jam nuts). Sorry for the confusion, I didn't mean normal corse thread. Either of those would likely strip out in this application, simply due to the depth of the threads.

This is actually ACME thread, commonly used in farming applications (or bench vices ). It has deep, thick threads. It is NOT as strong as say a grade 8, fine thread bolt of the same size, it's just less likely to strip out when loosely fitted.
The problem is that the threads are still fairly loose fitting causing some play, thus the clunking many complain about.

I forgot RC changed as well! :clap: for them!

 

[D sanchez]

This is all very good info. Thanks for the help.

On the threads, if i dial mine in maby a tack weld or two might be in order.

I have not had a front end alignment done yet (due to the not quiet right yet lowers). But my jeep feels "light" in the frontend (guessing im lacking toe in).

So if i use conventional thinking on leaf spring axles, will the same thinking apply on spring axles? Meaning Can i use pinion angle to get me in the ballpark? Im Just trying to simplify my needs.

Agine thanks for the help and input.

 

[89xj]

This is all very good info. Thanks for the help.

On the threads, if i dial mine in maby a tack weld or two might be in order.

I have not had a front end alignment done yet (due to the not quiet right yet lowers). But my jeep feels "light" in the frontend (guessing im lacking toe in).

So if i use conventional thinking on leaf spring axles, will the same thinking apply on spring axles? Meaning Can i use pinion angle to get me in the ballpark? Im Just trying to simplify my needs.

Agine thanks for the help and input.

set the lowers so you have the wheels centered in the wheel wells and use the uppers to adjust pinion/caster. at 6" of lift, you have to compromise between pinion angle and caster, with pinion being more important so you dont get front drive shaft vibs or ujoint binding. negative or not enough caster will effect steering.

 

[beakie]

On the threads, if i dial mine in maby a tack weld or two might be in order.

I would think a nut would be easier, and allow you to keep the adjust-ability of the arms you just made.
Any 'tack' you weld will either not be strong enough to hold through the constant stress it would come under. Or it will have to be so large a weld, you lose the option to adjust in the future.

 

[Blaine B.]

Do not follow YuccaMan's website regarding control arm lenghts when NOT using drop brackets. Although his RE and RC drop bracket CA lengths are good as they come from the companies themselves, the non-drop bracket CA lenghts are off.

I followed his upper and lower control arm lengths recommended for a 7" lift without drop brackets (prior to installing my drop brackets) and I ended up with 13* caster and a terrible pinion angle.

If you look at the pattern for the RC drop bracket measurements you'll see that the upper control arms need to be adjusted to .75" shorter than the lowers.

For instance you could adjust the lowers to 17" eye to eye and then the uppers should be 16.25" (remember that .75" difference with the lowers being shorter than the uppers I mentioned above)

That should be a pretty good estimate to start with for you for 6" without drop brackets.

I am running my lowers at 16.5" and uppers at 15.75" with 7" of lift (and drop brackets) and it has stretched my wheelbase a bit, but that is fine with me.

 

[2xtreme]

I read through quickly so if I didn't see this already mentioned I appologize.

The LCA should be used to set the wheel base (either stock or new).
Then use the UCA to adjust the (pinion angle/castor).

If you can't adjust all of them then you will be sacrificing one parameter for another.

Preferably, you want the rubber joint at the frame to isolate as much "noise" as possible, metal joint at the axle end. This is not always the correct way, but most beneficial.

Michael

 

[Blaine B.]

BTW all of the aftermarket control arms I've seen put the metal joint at the body end and the rubber at the axle. That makes most sense to me, especially since usually the adjusting threads and lock nut are on the end of the metal joint (so you keep it up further and out of harms way and debris)

My friend has a 96 ZJ with Rubicon Express adjustables. They may be an older style or something, I'm not sure...but they use a thicker thread and no loc nut.

 

[beakie]

Preferably, you want the rubber joint at the frame to isolate as much "noise" as possible, metal joint at the axle end. This is not always the correct way, but most beneficial.
Michael

ya know thats the first time I have heard that. I always thought you wanted rubber at the axle, hard joint (JJ, etc) at the frame.

My friend has a 96 ZJ with Rubicon Express adjustables. They may be an older style or something, I'm not sure...but they use a thicker thread and no loc nut.

my RE XJ adjustable arms have the locking nut, 2 years old. I have seen/heard of people removing the nuts to shorten the arms if required.

 

[Blaine B.]

What kind of thread are on your RE arms? Does it look like a standard thread or "bigger" threads?

 

[jeeperjohn]

Yes the nuts are welded. Without disconnecting one side of the lower arm you cannot disconnect or unthread the nut bolt combo.

Thank you for your input. Im not looking to argue, but good input is what im after. Cheers.

I think with a good coat of antiseize compound on those threads, you will have plenty of life out of those arms. Just reapply the antiseize when you do water crossings or drive in the rain.

 

[beakie]

seems like a standard thread to me. I actually sold them to a buddy (still in my garage tho) but last look seemed standard to me. They seem much like the threads on the TNT long arms I have in the basement.

 

[D sanchez]

Mine in the pics are standard thread. It is 1 1/2" allthread, it fit pretty well inside the skyjacker lowers, And I punched a 3/4" hole through the receiving tube for another aditional 1 1/2" of pluggweld. If anything it (could) bend, but i dont see it braking anytime soon.

 

[D sanchez]

Thanks allot for the help and input:cheers:.
I lengthend the uppers to 16", and left the lowers at 16 3/4", and my jeep drives more like a stocker than it ever has (post lift and mods).

 

[TRAILREADYXJ]

Good to hear you got it all figured out.
Now, if you really want a stock like ride, get some DBs for your newly adjustable arms . I'm at about 6", and can't believe I didn't do that mod sooner...wow!