Adjustable control arm lengths for a 2.5" OME lift?

[Chris]

My complete set of Savvy control arms will be here on Wednesday. I'm going to put them on at the same time as my 2.5" OME lift, the Rokmen skids (gas tank skid and transfer case skid), the MML, and the 1/2" body lift.

Anyways, I don't expect anyone to give me a length for the rear upper control arms, since those will need to be adjusted to get the pinion angle lined up correctly, which can vary from vehicle to vehicle.

I'm mostly curious if anyone can give me a good idea of what the front and rear bottom control arms should be set to length wise for a 2.5" suspension lift, as well as the front upper control arms.

Currie says that lower control arms should be set to 15 3/4" (center to center), and their front upper control arms should be set to 15" (center to center), but that's with a 4" suspension lift, whereas I'm only running 2.5".

I'm hoping someone like @David Kishpaugh or @mrblaine might be able to give me an idea.

I'm guessing they're going to be close to the stock control arm lengths, but I'm hoping someone may have more input.

 

[tomtaylz]

You’re going to be busy!

 

[jjvw]

When I set mine up, I was sneaking up on two things at once. The pinion angle at ride height and centering the axle on the bump stops at full bump. I had to go back and forth between ride height and full bump several times to get there. You will be adjusting both the uppers and lowers together at the same time. Both are used to set the pinion and the wheel base.

2003 Rubicon

 

[ac_]

My complete set of Savvy control arms will be here on Wednesday. I'm going to put them on at the same time as my 2.5" OME lift, the Rokmen skids (gas tank skid and transfer case skid), the MML, and the 1/2" body lift.

Anyways, I don't expect anyone to give me a length for the rear upper control arms, since those will need to be adjusted to get the pinion angle lined up correctly, which can vary from vehicle to vehicle.

I'm mostly curious if anyone can give me a good idea of what the front and rear bottom control arms should be set to length wise for a 2.5" suspension lift, as well as the front upper control arms.

Currie says that lower control arms should be set to 15 3/4" (center to center), and their front upper control arms should be set to 15" (center to center), but that's with a 4" suspension lift, whereas I'm only running 2.5".

I'm hoping someone like @David Kishpaugh or @mrblaine might be able to give me an idea.

I'm guessing they're going to be close to the stock control arm lengths, but I'm hoping someone may have more input.

This may be bad news for you? When I was having so much problem with my OME, when I talked to the OME tech he told me that the lift is different every time. (I am still battling issues with it and contemplating going to BDS) But he said don't plan on doing the suspension once. He said that the A B springs are a guide line and sometimes you put them in and then might have to swap them from side to side. And you may need to remove or add spacers. I believe you will be changing your C/A's adjustment a couple of times. I wouldn't even put the CA's in till you get the lift where you want it because I think you will be messing with it for a while.

That said for the first time if it were me I would drop the bottom front and adjust the pinion angle to 6-7 degrees and adjust the the lower CA to where it slips in relatively easy then put the other one in then tighten them down and put the uppers in the stock spot to start out with. I am no guru, but that is how i would do it. But only after I was finished with the lift and driven on it first.


On mine I have had the lift on for a couple of months and it is now pretty level with the soft rears and the heavy fronts with the OME spacers only in the front, but after wheeling this weekend and maybe before I just noticed my passenger side is an inch lower in the front than the driver side. I have the A on the driver side and the B on the passenger side, so I think I may need to swap my springs from side to side because I believe there is a 1/2 inch difference, and that may finally square it up.

I am just saying you don't know what lift you are going to get till you put it on. Then once you are happy you should put your CA's on after in my opinion based on what i have been fighting.

 

[mrblaine]

My complete set of Savvy control arms will be here on Wednesday. I'm going to put them on at the same time as my 2.5" OME lift, the Rokmen skids (gas tank skid and transfer case skid), the MML, and the 1/2" body lift.

Anyways, I don't expect anyone to give me a length for the rear upper control arms, since those will need to be adjusted to get the pinion angle lined up correctly, which can vary from vehicle to vehicle.

I'm mostly curious if anyone can give me a good idea of what the front and rear bottom control arms should be set to length wise for a 2.5" suspension lift, as well as the front upper control arms.

Currie says that lower control arms should be set to 15 3/4" (center to center), and their front upper control arms should be set to 15" (center to center), but that's with a 4" suspension lift, whereas I'm only running 2.5".

I'm hoping someone like @David Kishpaugh or @mrblaine might be able to give me an idea.

I'm guessing they're going to be close to the stock control arm lengths, but I'm hoping someone may have more input.

Dave will likely know. I don't know and don't care because they are irrelevant numbers to me. If I give you a number and you have vibes, what are you going to do? That's right, you will change the length until the vibes go away.

If I give you a length and there is interference at full bump, you're going to change the length.
If I give you a length and there is room up front to move the axle forward, you're going to change the length.

The rig and the small differences will tell you how long the arms should be, not a tape measure.

I do know if you want to set the uppers by a measured length, that is a really good way to put them in a bind and get them fighting each other which leads to exacerbated wear. I have yet to see a stock front axle that had both uppers in the same spot. There is enough give in the factory bushings that it doesn't matter. Not true for most aftermarket arms.

We set the lowers to the same length by laying them next to each other. We do all of our adjustments with a single upper installed with loose bolts. Get the pinion angle close, cycle it to check for clearances with the springs out. Once all that is done and the springs are in with the weight of the rig on them, we install the last arm. Typically it is the passenger side and we jack up under the tie to remove enough pressure off the bolts that they can be turned by hand. Install the last upper and float the length until you can install the bolts.

All adjustments are done on level ground side to side and not too much tilt front to back.

 

[tquig01]

Unfortunately there is no single number, as stated above. Differences in weldments on the axle / frame and spring rates mean everything is a little different. The upside is that there are only three important measurements that you need to be concerned with:

1- Axle centered on bumpstops at full compression. Centered is the goal, but on a 2.5" lift being off a fraction of an inch isn't going to hurt you unless you plan on doing heavy rock crawling where your suspension is maxed out all the time. I suspect that your lift might shift it off center by 1/4" or less.

2- Axle perpendicular to frame. This is pretty easy to maintain during the swap. Set the control arms to the same length, both sides, and remember to measure regularly between the axle and fixed points on the frame.

3- Pinion angle. This is the critical measurement and the one you will work hardest to set. Not sure if you have done this before or not, but it isn't that difficult if you go slow. I had to adjust the angle on mine because the previous owner lifted the Jeep and never put in new control arms. It shuddered like crazy under acceleration and engine load. I started out by setting the the lowers 1/2" longer than stock for a 3.25" lift. As the Jeep's suspension gets lifted, the nose of the differential rotates upwards. The goal is to rotate it back down so the pinion is parallel with the output shaft of the transfer case. That set my pinion angle pretty close to perfect. I then made a couple of turns from there to get to 0 degrees. The axles is off the center of the bumps a little bit, but not enough for the driving the Jeep will see to matter. To do it "right" I should have blocked the Jeep on its frame, pull the springs, measured and adjusted everything, but to be honest, it was too much work so I took the easy way out.

 

[Chris]

I understand what everyone is saying, but I will point out that on my Currie 4" lift, the control arm lengths they provide for the lower control arms and front uppers were dead on, literally. The only lengths that varied were the rear uppers, and that's because I had to adjust them specifically for my pinion angle. Nonetheless, they were very close on the rear uppers, I remember that.

I'm not asking for these numbers thinking that they might not change a bit, I'm asking for these numbers as a starting place. Currie gives a starting place with their numbers, I just thought it would be nice. Like I said, I'd follow the Currie numbers again, but that's fo a 4" lift.

Anyways, I'll ask @David Kishpaugh, if anyone knows it will be him.

 

[tquig01]

Got it Chris. For a 3.25 lift, the uppers on mine are the same length as factory and the lowers are about 1/2" longer. I don't remember what factory lengths are though. Maybe by comparing the 4" lengths, the 3" lengths and the stock lengths you can reverse-engineer something that gets you in the ball park, if you can't get the numbers elsewhere.

 

[jjvw]

Is the Rockmen t-case skid raising the belly? If so, that is adding to the effective driveline lift some amount in addition to the spring lift. Currie, Savvy, Metalcloak, Core,... won't account for that variable in any recommended starting lengths they might provide for their arms. Really, you can pick any measurement you want as a starting point because you are only going to adjust from there.

2003 Rubicon

 

[bobthetj03]

I set my fronts to stock length and fine tuned from there to get my pinion angle close. My front lowers ended up 1/8" longer and uppers a tick shorter.

 

[Chris]

Is the Rockmen t-case skid raising the belly? If so, that is adding to the effective driveline lift some amount in addition to the spring lift. Currie, Savvy, Metalcloak, Core,... won't account for that variable in any recommended starting lengths they might provide for their arms. Really, you can pick any measurement you want as a starting point because you are only going to adjust from there.

2003 Rubicon

Yes, it is raising the belly. I didn't think that raising the belly would affect the lower control arm lengths, just the uppers... I'm obviously not thinking about this right though, so it's probably some confusion on my part.

I think I'm just going to have @David Kishpaugh do the install for me at his shop. I'd actually love to do it myself, but with the two little girls, finding time is nearly impossible. Not to mention that David is smart as hell, and he does this sort of stuff for a living, so he'll get it dialed in way better than I can, and in a much shorter amount of time.

 

[jjvw]

It is often bandied about the the upper arms are used to set the pinion and the lowers set the wheel base. It is not that simple.

The upper and lower arms are used to both position the axle and set the pinion. Both are used to roll the axle. Both are used to pull the axle front to back. The final position requires working towards both the wheelbase and the pinion at the same time, little by little.

2003 Rubicon

 

[Chris]

It is often bandied about the the upper arms are used to set the pinion and the lowers set the wheel base. It is not that simple.

The upper and lower arms are used to both position the axle and set the pinion. Both are used to roll the axle. Both are used to pull the axle front to back. The final position requires working towards both the wheelbase and the pinion at the same time, little by little.

2003 Rubicon

I think that's where my confusion lies. I still assume that the upper arms are for setting the pinion angle, and the lowers are for setting the position of the wheel base (and the wheels in relation to where they set within the wheel arches).

So in this situation, if I was to tackle this myself. How would you suggest installing the control arms? Lowers first, uppers first, one at a time, etc.?

 

[jjvw]

Do what Blaine says. He's got it down to a science.

 

[Chris]

Do what Blaine says. He's got it down to a science.

I missed that until you just pointed it out! Good advice.

 

[bobthetj03]

Blaine's suggestion seemed to make the most sense to me.

 

[Chris]

We set the lowers to the same length by laying them next to each other. We do all of our adjustments with a single upper installed with loose bolts. Get the pinion angle close, cycle it to check for clearances with the springs out. Once all that is done and the springs are in with the weight of the rig on them, we install the last arm. Typically it is the passenger side and we jack up under the tie to remove enough pressure off the bolts that they can be turned by hand. Install the last upper and float the length until you can install the bolts.

Yes, this makes perfect sense. It's similar to how I installed my Currie lift, I just used their suggested lengths as a starting point, though I did have to adjust the control arms to different lengths even then. The lowers were a pain on my Currie lift because since they aren't double adjustable, you had to remove one end of the control arm from the axle, each time you wanted to adjust it.

In the case that I end up doing this myself, I'll follow your procedure. I may end up having Dave do it though, only because it's so hard to find the time with two little girls running around, requiring constant attention.

 

[bobthetj03]

Time management can be tricky with the critters.

 

[StG58]

Time management can be tricky with the critters.

...and / or when you have a life outside of TJ's.

 

[Chris]

Whoa there, hold up...

Are my Savvy control arms ALL double adjustable?!

The Curries only had double adjustable rear uppers... These Savvy arms appear to all be double adjustable.

If so, then I'm f**king stoked! That will make things even easier not having to remove one end of the lower arms if I need to adjust them.