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-   -   Question about Adjustable control arms (http://www.wranglerforum.com/f210/question-about-adjustable-control-arms-8327.html)

jherrin215 05-26-2007 02:38 PM

Question about Adjustable control arms
 
I understand the concept of adjustable control arms, and why you need them, but my question is how do you adjust them?? Is there a certain measurement that you have to take when adjusting them to get them the right length or what?? How do you know how long to make them when adjusting is more of what I am trying to ask. Thanks

1BLKJP 05-27-2007 01:44 AM

If you mess around with this stuff long enough then you just start to get the feel of what looks right. When you are sdjusting your rear pinion angle you want it 1 to 2 degree's beneath the rear output shaft of your TCase. In the front you want the appropriate amount of caster to make your suspension and your front dshaft happy.

Arms can be adustable in a couple ways. If they have right and left hand thread then you can adjust them in the vehicle. If not then you have to remove one or both ends and adjust them that way. Rule of thumb is just to adjust both sides the same length.

MR.CLIFFORD 05-27-2007 09:33 AM

While I agree that the visuals will usually get you there I believe that it is hard to get your vehicles thrust angle correct. This is usually only a factor if you are replacing all 8 control arms. You can get it close but a digital computer alignment is usually the only way you will find out how true you are. :)

jherrin215 05-27-2007 10:20 AM

So if I get a set of adjustable control arms what would I need to do? Take it somewhere and have them installed and adjusted, or install them myself and have them adjusted, or install them myself and try to figure out how to get them adjusted out right??

bluvikng 05-27-2007 10:25 AM

Are you replacing all 8 CA's, or just the four uppers?

mrblaine 05-27-2007 10:54 AM

Quote:

Originally Posted by 1BLKJP (Post 85846)
If you mess around with this stuff long enough then you just start to get the feel of what looks right. When you are adjusting your rear pinion angle you want it 1 to 2 degree's beneath the rear output shaft of your TCase.

I see that tossed about a lot as the rule and I often wonder why? Personally I'd never do it that way, but there is some reason for it, eh?

Quote:

Rule of thumb is just to adjust both sides the same length.
Typically, the lower mounts are much stronger and less likely to get moved around, the uppers on the other hand, are relatively easy to move around.

That said, I start with both lowers the same length, install them and roughly adjust the pinion angle with a floor jack.

Then center the axle. After the axle is centered, install 1 upper and fine tune the pinion angle.

The last upper gets floated between the bolt holes. If you jack the axle around and compress either of the joints in the arm trying to get the bolt lined up, it will wind up preloaded and stress the joint material.

Since cross caster isn't adjustable with the control arms, it doesn't make sense to try and do it.

jherrin215 05-27-2007 10:52 PM

Quote:

Originally Posted by mrblaine (Post 85892)
I see that tossed about a lot as the rule and I often wonder why? Personally I'd never do it that way, but there is some reason for it, eh?



Typically, the lower mounts are much stronger and less likely to get moved around, the uppers on the other hand, are relatively easy to move around.

That said, I start with both lowers the same length, install them and roughly adjust the pinion angle with a floor jack.

Then center the axle. After the axle is centered, install 1 upper and fine tune the pinion angle.

The last upper gets floated between the bolt holes. If you jack the axle around and compress either of the joints in the arm trying to get the bolt lined up, it will wind up preloaded and stress the joint material.

Since cross caster isn't adjustable with the control arms, it doesn't make sense to try and do it.

WOW!! I guess I need to get some one to do it for me cause that was way over my head!! I thought I had a pretty good grasp on things but that made me feel dumb reading that!!

mrblaine 05-28-2007 11:13 AM

Quote:

Originally Posted by jherrin215 (Post 86070)
WOW!! I guess I need to get some one to do it for me cause that was way over my head!! I thought I had a pretty good grasp on things but that made me feel dumb reading that!!

Take it one step at a time. It's not hard.

Jerry Bransford 05-28-2007 02:19 PM

Good thread that got me thinking. My TJ's thrust angle hasn't been checked since installing my last suspension so I will put that on my short list.

Blaine, can the thrust angle be measured accurately enough with just the careful use of a tape measure? I don't mean the actual angle but you know what I mean. It seems to drive fine but I just never gave much thought to the thrust angle due to having set the lower arms to the exact same lengths.

mrblaine 05-28-2007 03:21 PM

Quote:

Originally Posted by Jerry Bransford (Post 86185)
Good thread that got me thinking. My TJ's thrust angle hasn't been checked since installing my last suspension so I will put that on my short list.

Blaine, can the thrust angle be measured accurately enough with just the careful use of a tape measure? I don't mean the actual angle but you know what I mean. It seems to drive fine but I just never gave much thought to the thrust angle due to having set the lower arms to the exact same lengths.

Get someone to hold the end of a tape against the inside of your rear axle tube out near the tire. You read the dimensions at the front axle tube. Make sure your rig is on level ground and you don't have it loaded funny from side to side.

As you tilt the rig, the axles will move away from each other on one side and towards each other on the other making it hard to get an accurate reading.

If it's close and it's not handling funny, then it's likely close enough.

MR.CLIFFORD 05-28-2007 03:33 PM

I usually set my tape inside the axle tubes and lock the tape down. Have someone hold the dumb end of the tape equal distance in from the outer flange and butt the tape to the front axle tube. You can get a pretty good reading using that method. If your measurement is out of whack though how do you know which axle is not square to the frame(which isn't the best analogy).

A free computer alignment check up will tell you exactly how much each axle is out and better help you determine where to go. :)


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