Fixed vs. adjustable UCA/LCA

Is there any "Rule of Thumb" when it comes to using fixed vs. adjustable UCA/LCA on a small lift. (4" or less).

Looking at stockpiling parts for the next MJ project. Either a buy a complete kit or buy good used parts here and there and try to save some $$$.

I figured I can't go wrong buying adjustable control arms and a trac bar. :dunno:

Your thoughts?

Thanks!!!

I went adjustable because I like being able to change my setup around.

I only ever use adjustable for both uppers and lowers. I love that option of dialing in what I want and where I want the axle, plus it lets you get the correct caster. When I built the 3-link long arm on the front of my Jeep, all three arms are adjustable on the frame end.

Is it possible to go with adjustable LCA and fixed UCA for phase 1 build and switch out to adjustable UPA at a later time or visa versa? :???:

You could but your not gonna save a lot by doing that,I paid $307 shipped for all four adj arms with rebuildable flex joints from Hell creek

Lift vs. Control Arm Lengths

LIFT......LCAs......UCAs

Stock...15.75"....15.00"

2"........15.92"....14.88"

3"........16.09"....14.92"

4"........16.33"....15.03"

4.5".....16.47"....15.11"

5"........16.62"....15.21"

6"........16.97"....15.44"

7"........17.36"....15.74"

8"........17.81"....16.09"

9"........18.30"....16.50"

10"......18.82"....16.96"

Lift vs. Control Arm Lengths

 

LIFT......LCAs......UCAs

 

Stock...15.75"....15.00"

2"........15.92"....14.88"

3"........16.09"....14.92"

4"........16.33"....15.03"

4.5".....16.47"....15.11"

5"........16.62"....15.21"

6"........16.97"....15.44"

7"........17.36"....15.74"

8"........17.81"....16.09"

9"........18.30"....16.50"

10"......18.82"....16.96"

Excellent post! This should be a sticky somewhere.

To me it looks like you can get away with stock uppers for at least 4.5" of lift, even if it is not "optimal." With fixed but longer lowers and stock uppers on my 4.5" lift I had no trouble getting the jeep aligned and back to where the wheel self-centered and tracked true.

Lift vs. Control Arm Lengths

 

LIFT......LCAs......UCAs

 

Stock...15.75"....15.00"

2"........15.92"....14.88"

3"........16.09"....14.92"

4"........16.33"....15.03"

4.5".....16.47"....15.11"

5"........16.62"....15.21"

6"........16.97"....15.44"

7"........17.36"....15.74"

8"........17.81"....16.09"

9"........18.30"....16.50"

10"......18.82"....16.96"

Thanks!!!

:bowdown: :clapping:

Excellent post! This should be a sticky somewhere.

Done. It's a sticky in the DIY section.

To me it looks like you can get away with stock uppers for at least 4.5" of lift, even if it is not "optimal." With fixed but longer lowers and stock uppers on my 4.5" lift I had no trouble getting the jeep aligned and back to where the wheel self-centered and tracked true.

You can actually get by with stock "fixed" control arms up up to 4" by shimming out the LCAs to correct caster. There's enough adjustment room there for a bit over 1/2 inch.

Hornbrod you are the man! I spent over 2 hours today putting in my control arms time after time trying to dial them in and I'm still not done! Looks like tomorrow will be my last time taking those frigging things out my my truck for a while

THANK YOU!!!! :cheers: :wavey:

Be advised this table was derived by triangulation, is for reference only, and does not compensate for other vagaries that may be present in your suspension/steering system. I didn't create the table, but did check the math, and it's correct and should get you in the correct caster ballpark. :cheers:

Great thread. My only comment to add would be that I would have the adjustable end of link at axle and the bushing end at frame (err, unibody) makes for a quiter setup and I personally find it easier for fine adjustments at axle end.

can't on the UCAs,the adj link has to go on the frame.

I have all four adj links at the frame end and bushings on the axle but I'm using rebuildable flex jounts so I don't get the noise and viberation of a hiem.

Great thread. My only comment to add would be that I would have the adjustable end of link at axle and the bushing end at frame (err, unibody) makes for a quiter setup and I personally find it easier for fine adjustments at axle end.

There's a few reasons I put all the adjustments on the frame end. The first was that the mounts protect the threads from all the rocks and debris in the mud. The second is that, with a 3-link, you are running all hard joints (Ballistic Fab joints in my case).

As mnkyboy pointed out, due to the UCA on the axle, the adjustable end has to be on the frame. That's unless you buy arms that adjust in the middle (forget who made them, think IronMan4x4?). If you're looking for a nice quiet ride, definitely go for rubber bushings on one side. If you're looking for the flex and plan on running M/T's all the time, hard joints are much stronger and flex better and you won't really notice the noise over the tire hum.

There are many link options, I still believe that bushing at frame and johnny joint (or like joint) at axle create best street ride. I've tried many lifts and styles over the years. Sand, dirt, and water will reach joints at both ends. Maintnance is key to anything surviving. Joints at one end create plenty of flex for any dd wheeler, anything beyond doesn't really help you in real world wheeling.. just my opinion, right or wrong

In personal experience, even with very small lift, some adjustable lowers at the very least would be wonderful. I went from 2wd 4cyl to 4x4 4 cylinder with springs form a 2.8 and an extra isolator for about 1 1/2-2" of lift. When I did my caster alignment, I had a VERY hard time getting enough adjustment at the frame side caster adjustment on the stock arms to give me correct caster. I still didnt get it where I wanted it to be, but since I was out of adjustment room, I had no choice. If I go any higher later, adjustable arms and control arm drop brackets will definitely be on my shopping list.