Do I need adjustable control arms with a 3" lift?

8524 Views 15 Replies 8 Participants Last post by bob1340, Nov 6, 2010

johncanfield

Discussion Starter · Oct 29, 2010

Apologies in advance for asking what must appear to be basic suspension questions :?

The mechanic installing my new gears told me with the Rubi on the lift, the drive shaft was fully compressed. He said he didn't want to alarm me, but in the right set of circumstances he thought there was a possibility the shaft could be forced into the transfer case breaking something.

So as I understand the situation, replacing the upper and lower stock control arms for adjustable ones will keep the axle a little further forward and avoids the drive shaft compression issue. If this is the scenario, it appears I should go to after-market control arms.

What recommendations for control arms do you guys have? Also, I don't understand short arm vs. long arm. Are most after-market control arms bolt on or do the lower arm frame attachments need to be welded on?

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jeepsyco

· #2 · Oct 29, 2010

Every Jeep is slightly different, but with only 3 inches of lift on an unlimited, you should be fine. I ran a 3.5 Rubicon Express super flex and netted close to 4 inches. Never even touched the drive shaft.

As far as control arms, I think the consensus is that Rokmen, Currie, and JKS probably are some of the best. I personally plan on running rokmen, no real rhyme or reason, just wanna try 'em.

As far as long arm (LA) or short arm (SA). LA's should be welded and the arms are longer therefore are farther towards down the frame. Most say if you run 4 or more inches, a LA is the ticket, but honestly, SA's are so much better than they were 10 years ago and the days of 6-8 inch lifts are gone, so a SA is really more than adequate for most applications and those are bolt are "replacements" of the stock CA's.

Mechanic's/tire guys/shops are all gonna have an opinion on your Jeep...most aren't Jeep enthusiasts/experts. Take everything, including what I just said with a grain of salt.

3rivers

· #3 · Oct 29, 2010

Yep, the arms you'll want will bolt right on.

In your other thread I commented on the drive shaft deal - I've never heard of it being a problem.

In a trail situation, when one side drops down that far, it's usually because the other side is stuffed
up into the wheel well, which won't over-compress the drive shaft.

As for which arms, I recommend arms with Johnny Joints over ones with the stock-like rubber bushings.

I have them, and the ride quality is better than the stock bushings by a very noticeable amount.

The suspension cycles smoothly instead of twisting all that rubber.

I chose Rokmen arms because those guys are talented craftsmen and I wanted to support their small business.
It wasn't a case of charity though - I believe the arms they make are the best of their kind.

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johncanfield

Discussion Starter · #4 · Oct 29, 2010

3rivers said:
In your other thread I commented on the drive shaft deal - I've never heard of it being a problem.

In a trail situation, when one side drops down that far, it's usually because the other side is stuffed
up into the wheel well, which won't over-compress the drive shaft.

Picked up the Rubi an hour ago (regearing) and had a nice long chat with the mechanic about the raised driveshaft concern and the conclusion was exactly your comment about one wheel up, one wheel down won't over-compress. So, never mind :spin: . I won't have to mess with control arms and I can focus on other goodies.

As always, thanks for the guidance guys!!

bob1340

· #5 · Oct 30, 2010

2

As far as control arms go, get the adjustable. You can adjust them to stock length if you wish, or you can fine tune them if you wish for pinion angle. I also have a LJ and plan on adjustable soon to get the rear pinion up a little so it don't bang on rocks!

On a stock LJ you don't have dual cardan joints, and the angle is close to this with a little lift.

You can do this and have better angles on the shaft for longer life and also get the pinion up a little with adjustable control arms.

Also, those stock rubber bushings in the stock control arms will really wear out faster than you think causing handling problems and death wobble. That is the stage I am at now. If you go with adjustable units I suggest you go with Johnny Joints all the way around. Currie and Rokmen make nice control arms which are well tested.
One issue with the stock stamped control arms is they can fail if bent. Their strength comes from their shape. Hit a rock good with them and the strength is compromised. If a front lower arm is compromised and you hit the brakes hard on the highway the dang control arm can fold up like a Taco causing death, destruction, Armageddon. Every time I go out wheeling I check mine good before I hit the road home.

Thanks to Doctor D for the pictures above.

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johncanfield

Discussion Starter · #6 · Oct 30, 2010

Bob - thanks, that's a great explanation and the proverbial picture is worth a thousand words! New control arms do sound like a good upgrade at some point, but not necessarily now. My upgrade list as it stands now is:

- Mile Marker hydraulic winch and PS steering pump upgrade
- Viair OBA
- Rear bumper w/swing away tire carrier
- Quick disconnect way bar links
- Install CB and ham radios
- Roadmaster tow bar base plates

bob1340

· #7 · Oct 30, 2010

3

johncanfield said:
Bob - thanks, My upgrade list as it stands now is:

- Viair OBA

That OBA really is a must have. I have used mine a lot and am glad I have it.
I used this:

I disassembled it and mounted it like this:

Pump under the hood, and tank under the Jeep.

I have used it hundreds of times over the last 5 years with zero glitches.

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johncanfield

Discussion Starter · #8 · Oct 30, 2010

That's a really neat idea! I noticed that empty platform under the brake master cylinder and thought something needed to be mounted there :laugh: I'm not sure where I'm going to stick mine, maybe in the back on the wheel well - I need to buy it and then ponder I guess.

Edit: I like your yellow Rubi and I was hoping I would find one in that color. My dark blue is okay - it 'changes' color a little bit depending on the light. I always wanted a yellow 'vette - my old 1997 vette was aquamarine or turquoise (which dear wife loved and I wasn't crazy about, but the vette purchase was approved due to the color.)

bob1340

· #9 · Oct 30, 2010

3

johncanfield said:
Edit: I like your yellow Rubi and I was hoping I would find one in that color.

I've had a yellow Jeep since 4/18/77 except for a couple years after I sold the CJ below.

Pic taken in 1977

Pic taken in 2007

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johncanfield

Discussion Starter · #10 · Oct 31, 2010

What a great contrast in pictures - hippy-dippy days to the present :cheesy: I did own a yellow VW bus in the early 70s (strictly off the record - I'll deny it in a public forum.)

Steve578

· #11 · Oct 31, 2010

We have a member here with a VW Bus. I believe it is Shano.

Ryan Mauzy

· #12 · Nov 2, 2010

yes to adjust your rear pinion angel

JeepnBlake

· #13 · Nov 2, 2010

I would like to point out that in the second one of those driveline pictures, that driveshaft should be a double cardan or "CV" or it's going to have some fantastic bind issues.

In single cardan setup (2 ujoints) you use the top picture just like stock

When you start changing stuff like lifts, TT, etc is when you also have to consider you driveshaft angles changing.

This brings us to the Double Cardan setup (3 ujoints, 2 at the tcase, 1 at the axle) this is when you should point the rear pinion at the rear output yoke like pictured.

:lildevil:

bob1340

· #14 · Nov 2, 2010

JeepnBlake said:
I would like to point out that in the second one of those driveline pictures, that driveshaft should be a double cardan or "CV" or it's going to have some fantastic bind issues.

:

Where is it going to bind at?

The drive shaft does not care how it has the front and rear joints canceling themselves out, it just likes doing it. On an LJ, as the OP has, the shaft is long enough with a small lift to have the u-joints still cancel them selves out angle wise. If you turn the pinion up you can get the same angles that will cancel each other and also have the advantage of getting the pinion up.

Jough

· #15 · Nov 6, 2010

I think there is a problem or two with the lower picture.
1. That is not a double cardan, but a regular 2 u-joint shaft angled upward at the rear.
2. The pinion angle at the rear is higher than the angle of the driveshaft. Normally you want the pinion angle to be 1-2 deg below that on a double cardan (CV) shaft. When under power, the pinion will want to rise, bring it in line with the main body of the driveshaft.

bob1340

· #16 · Nov 6, 2010

Jough said:
I think there is a problem or two with the lower picture.
1. That is not a double cardan, but a regular 2 u-joint shaft angled upward at the rear.
2. The pinion angle at the rear is higher than the angle of the driveshaft. Normally you want the pinion angle to be 1-2 deg below that on a double cardan (CV) shaft. When under power, the pinion will want to rise, bring it in line with the main body of the driveshaft.

The 1-2 deg below is for double cardan (CV) shaft. The picture is an example Dr D gave on what you can do on an LJ to improve both ground clearance at the pinion and improve the u-joint angles if you have adjustable CA's. If you bring the angle of the rear joint/pinion in line with the shaft without a CV the drive shaft will be out of phase. When you say the pinion rising I assume you are saying the angle will go up due to torque? That will only happen on leaf springs or LJ's with worn out suspension components. I see no problem with the picture. If the drive shaft had a dual cardan on the front then yes, it would be incorrect. A drive shaft having one u-joint on each end needs to run in phase and have the u-joints close to similar angles. The drive shaft does not care how this is done, but it gets grumpy if it is not done. Put in a 2-3 inch lift and a belly up trans skid and you really make the drive shaft grumpy. On a short TJ shaft a CV is best, but on the much longer LJ shaft you can make the shaft happy with adjustable CA's.

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