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contol arm lengths?

rsprman

rsprman

NAXJA Forum User
Location
Silverdale, WA
OK, I contacted Tomken and they say that my LCA's should be 16.75" and my UCA's should be 16". I got their 6" lift does anyone have any experience with these lifts? Should I change my UCA's to 15" and LCA's to 17" or keep em this way? Would this affect my ride (smoothness)? What do I need to check and how?
Thanks,
 
You need to adjust your arms until they locate your front axle correctly. Ideally your springs should be straight without any S bend when setting at normal ride height. I did this way back in the Dark Ages and it got my steering angles pretty close to factory. One clue to having your arms too short will be a crushed exhaust where it crosses under the oil pan when the suspension compresses
 
MistWolf said:
You need to adjust your arms until they locate your front axle correctly. Ideally your springs should be straight without any S bend when setting at normal ride height. I did this way back in the Dark Ages and it got my steering angles pretty close to factory. One clue to having your arms too short will be a crushed exhaust where it crosses under the oil pan when the suspension compresses
Click to expand...
?? There's an expression called SPOBI. Much more important than concerning yourself with an "S bend" is your caster. Adjustable upper and lowers allow more flexibility in the caster adjustment. Keep your Tomken arms the way they recommend them, they are manufactured to fit. aside from that, keep in mind that any lift above around 5" or so that uses the stock control arm unibody mounts is not going to ride super smoothly. You'll need long arms or drop brackets to get a smooth ride.
 
rsprman said:
Yeah, but my exhaust is crushed and it doesn't make any sense till he said it.
Click to expand...
There is a factory-installed dent in the down tube that lots of people mistake for being 'crushed' by some suspension or driveline component. Fact is, it isn't crushed, its tuned from the factory. My post still stands. If you lengthen your control arms beyond their calculated length, you will mess with your caster. Adjustable contol arms will allow you to account for this, fixed won't. What is the main concern in the first place that leads you to think they are too short?
 
Well, I put in a post about long arms. Some are for them some against. The real deal is, I have had this lift on for about 2 years. A few months ago, I get to go out on the trail and try it out. I couldn't even make it down the access road without my teeth feeling like they were going to fall out. So, I started checking and everybody recommends drop brackets. Well, If I had that money I wouldn't try and fix this, but I can't imagine that me ride should be this bad. I have to dodge the reflectors in the road. So I saw a post about control arm lengths through a guy out here. I call Tomken and they give me another length. And lets just say that I would trust a junkie over Tomken. So not to keep going, but if this could be my problem it is alot cheaper to adjust a bolt than buy RE's $300's worth of metal. But It also might be my shock's. But this thing has ALWAYS rode like this. They are skyjacker nitro's.
 
It will always ride that way without long arms or drop brackets. The problem is that the steep angles introduced to the control arms with the 6" lift, deflect more NVH to the unibody, making it ride rough. Brackets and long arms each have pros and cons. Long arms are ideal for prerunners and street goers with taller lifts, like 6+ inches. Their main drawback is their tendency to allow the front suspension to unload when approaching vertical angles. You can get around this by using a limiting strap. Drop brackets allow stock-like control arm angles, but hang down low and theoretically can hang you up on the rocks. I say theoretically, because I have only actually met one person who had this difficulty. Both methods (DB's and Long arms) achieve the same goal, bringing the control arm angle as close to parallel with the ground as possible. Frankly, the easiest way to fix your problem is the drop brackets. If you don't want to pay for RE's, then see if you can get a local guy to fab some up for you. Shouldn't be too much to have them done, and its definitely worth the money to drive smoothly and safely.
 
So my next question is with the drop brackets, am I going to have to readjust my control arms? If so, will I have to get new UCA's. They are either 15" or 16" long depending on where you put the bolt.
 
Yeah, I don't doubt that the drop brackets would help, but I live in Hawaii and shipping it a bear. I'm trying to find some used, but if I have to get a new UCA anyway, that's over $500 bucks for something that a LA kit could do. And that's a grand. I just don't want to spend that money on this when it could go to other things.
 
Thanks for the chart. But I still have a problem with the length on my UCA's. They are not adjustable. They just have 2 bolt holes. One at 15" and one at 16".
 
The lower one can be adjusted a bit on the body side... Loosen the big bolt going through it and there should be an adjuster on the back. You may have to put a shim back there. You can't get a whole lot of adjustment out of it, but might be enough depending on how much you need. I'd say maybe 1/2" tops. If that's not enough you'll have to get some adjustable control arms.

-Mike
 
Oh, after re-reading your post...

6" is way too much for stock length control arms. You'll have to get some new ones or lower the lift height a bit. I'm very surprised you don't have death wobble or other drastic problems already.

-Mike
 
BIG-G said:
The chart DOESNT apply to XJ's with R.E. drop brackets which is what i have so do ya know that info cause i still have stock LCA and UCA..?
Click to expand...

They cover that at the top of the chart... subtract ~ 4" from the lift height.

Like it says at the top, though, the chart is just to get you in the ballpark. You may have to play with the final lengths.

-Mike
 
rsprman said:
So my next question is with the drop brackets, am I going to have to readjust my control arms? If so, will I have to get new UCA's. They are either 15" or 16" long depending on where you put the bolt.
Click to expand...
Yes you will need new lowers, or have them shortened to fit. Go by Jim's (Yucca-man) chart. The other one (below) is useless as tits on a boar:
mgolden said:
Jebus! Will somebody give the poor guy the darn chart! Here ya go, man:
Control arm chart link
Click to expand...
mgolden said:
The lower one can be adjusted a bit on the body side... Loosen the big bolt going through it and there should be an adjuster on the back. You may have to put a shim back there. You can't get a whole lot of adjustment out of it, but might be enough depending on how much you need.
Click to expand...
Don't count on this working. Those are not meant to adjust for this problem.
mgolden said:
Oh, after re-reading your post...6" is way too much for stock length control arms. You'll have to get some new ones or lower the lift height a bit. I'm very surprised you don't have death wobble or other drastic problems already.
Click to expand...
They aren't stock, they're tomken. Read it again.
 
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