OEM control arm lengths

[cmitcham]

dirk's recommended starting point for the ome lift arm lengths is the stock lengths, except for +5/16" on front lowers. i'm ready to carefully go through mine again with all I've learned here. my oem arms are gone, so can anyone confirm these numbers for oem lengths?

rears - 15.75"
front uppers - 15"
rear uppers - 13.25"

mine is lj rubicon. are lj and tj lengths the same?

thanks.

 

[bobthetj03]

TJ an LJ are same lengths. I can confirm you lengths except for the rear uppers as I don't have any stock ones to measure.

 

[fuse]

I just put a tape measure on a rear upper that's currently installed. It's not a precise measurement, but it looks like it's 13.25".

 

[cmitcham]

thanks!!!

edit - thread ends here. useless chatter follows...

 

[Chris]

My personal opinion is that anyone who is giving you control arm lengths should probably be avoided. Lengths don't matter at all. What matters is getting the bump stops aligned properly, angles set, and making sure there is no bind.

The control arm length thing is something I fell into once upon a time when I was new to Jeeps. I've since then learned that it's stupid advice to go by, as it's literally useless and not needed one bit.

I am assuming we are talking about adjustable control arms here.

 

[jjvw]

Agreed. Factory control arm lengths are irrelevant on a non stock TJ. Make the arms what they need to be.

 

[mots]

To be fair, OP did say “as a starting point”, meaning it was understood that further dialing in would need to be done. Must be Dirk from DPG Off-road (never done business, but have browsed his site).

 

[fuse]

To be fair, OP did say “as a starting point”, meaning it was understood that further dialing in would need to be done. Must be Dirk from DPG Off-road (never done business, but have browsed his site).

That's what I understood the point of the thread to be. Sure you're going to adjust the control arms to whatever length they need to be, but what length do you start them at?

Blaine said it well here — which looks to me like you're starting with two lowers at the same length, probably close to stock length. And then you have one upper installed at something close to stock length. From there, you're adjusting both uppers and lowers to align the axle pads to the bump stops, maintain thrust angle, and set pinion angle.

Then the remaining upper gets set to whatever length lines up with the mounts and keeps the joints from binding.

 

[jjvw]

You can start with the control arms at any length and still always end up where there need to be. Any length is just as good of a starting point as another.

 

[fuse]

You can start with the control arms at any length and still always end up where there need to be. Any length is just as good of a starting point as another.

Of course you can. What length would you start them at?

 

[jjvw]

Of course you can. What length would you start them at?

Whatever length they came to me at. First thing I might do is make sure the pairs are close to even. But then I will stop caring once I start to see what is needed to square the axles to the frame and also make the axles parallel to each other.

 

[fuse]

Whatever length they came to me at. First thing I might do is make sure the pairs are close to even. But then I will stop caring once I start to see what is needed to square the axles to the frame and also make the axles parallel to each other.

I guess that would make sense if your control arms were already assembled.

Anyway, we agree that once they're installed, they get adjusted to whatever length they need to be given the other constraints.

 

[jjvw]

I guess that would make sense if your control arms were already assembled.

Anyway, we agree that once they're installed, they get adjusted to whatever length they need to be given the other constraints.

We do. If I were to assemble these arms, I would pick a length that seemed like a good starting point at that moment.

 

[fuse]

We do. If I were to assemble these arms, I would pick a length that seemed like a good starting point at that moment.

Since I'll eventually be replacing stock control arms, starting the adjustable control arms at stock length seems to make sense. At least I know the geometry in that configuration, and I know what my goals are for the adjustment and which directions I'd like to start moving things.