DIY budget 3" lift

[Evan03]

Toe in should be 1/8"ish for oem style steering. In my exsperince with proper castor i havent found toe to make any difference in straight line or return to center tracking..

With to little or negative castor straight and return to center becomes troublesome. I am unsure if extra toe in this situation can help mask the lack of castor.

I have not had lack of castor cause death wobble. Badly worn parts can all contribute to death wobble but i would necessarily blame castor.

Everything has to work together perfectly to get a good death wobble tune.

 

[Bent]

@Gumbo, up front the offset is slight, but not eye-catching. I really don't notice it but it is there. I tend to dwell on such things and yet don't really notice it. It might be noticeable with bigger tires but I'm only running 235s.

I do have a new bracket and track bar slated for installation. It is not to correct the centering issue, it is the desire for heavier duty components. The reasoning behind that is the truck gets used for trail clean up. So I'm putting more strain on components with the weight and the difficult Terrain. If it wasn't for that I would leave it alone.

 

[75SV1]

Just curious, Manual or auto trans?

 

[Gumbo]

Tubular adjustable lower control arms for 0 to 4" lift, with poly bushings, are 100 bucks shipped.
The shims of course don't cost nothing but replacing the 30+ years old LCA's would be a good idea in any case.
There's even a bundle UCA + trackbar at 120, not bad considering the trackbar alone sells for 60.
If the seller will replace the bundled UCAs with LCAs, I guess I'll bight the bullet and buy the bundle.
Otherwise I'll do the trackbar later on, since the offset is barely noticeable according to Bent, and the tie rod angle is not too severe with a 3" lift
The question is how to set up the adjustable LCA's to restore original caster without taking the truck to an alignment shop (which would probably exceed the cost of the components).
I assume caster angle should be the in the 7° range, but measuring caster accurately is not easy.
Probably easier and more accurate taking measurements of the stock setup, do the math, and see at what lenght the new LCA have to be asjusted.

As for the rear I'll check what they have at the local junkyards, but I doubt spring packs will come cheap as those guys sell parts for slightly less than new...

@75SV1 , it's a 5 speed manual

 

[RCP Phx]

Measuring the caster with a angle finder is easy!

 

[Gumbo]

If you mean placing the angle finder on top of the spindle (video linked below) that is a rather approximate method.
Infact in the video the guy is puzzled by the fact that the two spindles are at different angles, which of course is not possible, unless they were welded at different angles on the axle tubes.
The reason for that is that the top of the spindle nut (where he placed the angle finder) is not square with the actual spindle "line".
This is more evident in other trucks, but jeeps are off a very few degrees and will trick you into believing they are square.
One should at least check that both spindles measure the same angle before doing anything, and even then I would not consider that a precision method.
It's in the +/- 3-4° range, which is not little IMHO.

https://m.youtube.com/watch?v=FU9OW8_HBEc

 

[RCP Phx]

No you measure off the diff cover surface. The knuckles are rarely the same from the factory but the numbers are not critical. I run about 3* of caster on my daily driver!

 

[Evan03]

You dont need to be acurate

But you need to be able to repeat your own recordings.

Say your angle finder first readings are 5 deg. Document this.

Now repeat after new arms installed. You know you gained 2deg if new reading is 7.

You can be on a incline or perfectly flat surface. Doesnt matter as long as you repeat what your first reading was.

I would also measure arms before install to verify tgat they are longer. Would suck to go backwords with castor when all it takes is tape measure check before installing.

 

[Evan03]

Its you easy a caveman can do it.

Castor and toe is it to the xj alignment numbers mean little.

Rcp is correct side to side varies. Just what it is.

Keep it stupid simple. Ounce this clicks the jeep becomes user tunable with nothing more than a tape measure and angle finder.

You can throw fancy numbers and math at it but isnt needed.

Just gota know where you came from and where your going make adjustments to move in the desired direction.

 

[Bent]

K.I.S.S. FTW!

 

[Gumbo]

Well I still believe that measuring stock geometry and feeding the numbers into a simple smartphone app such as "triangle calculator" is the easiest and more precise way to do it and all you need is a tape measure.

Before the lift:
1. Measure distance of LCA front eye (bolt axis) from ground.
2. Measure distance of LCA rear eye from ground
3. Measure LCA lenght eye to eye.
Feed the three numbers into the triangle calculator app and you get the stock caster angle.
Now add amount of lift to point 2 and adjust point 3 until you get same angle (or obtain desired angle).
That will be the PRECISE length of the arm (or the difference between the two figures will be the thickness of the shim) required to restore stock caster angle.
Write down those numbers and next time you install same lift on same vehicle you dont have to measure anything.
I don't see why one should not be precise when it is stupid simple, and may even save you (or someone else) time in the future.

And that's the reason why I asked if there's anybody here who has done a 3" lift and has the figures...

 

[RCP Phx]

What is your plan if you need to compensate for the pinion angle? A angle finder takes the math out and only costs a few bucks and tells you instantly what's going on!

 

[Evan03]

I think the app is cool. Another usefull tool to use.

I have a 100 dollar construction calculator app on my phone that i use daily at work. Id be lost without it.

 

[Tim_MN]

I detect some OCD.

I just install longer lower control arms on a 2-3 inch lift. I have done this with three different XJ Cherokees I have owned over the last 22+ years. After several hundred thousand miles traveled on the three different lifted XJ's, the handling, return to center, and tire wear are all acceptable. At about 3 or more inches of lift, a reduction in caster may be necessary to achieve a usable front drive-line pinion angle that has no vibrations. With larger tires, I add a small amount of additional toe-in.


This control arm chart is an excellent starting point.
.

 

[Bent]

I detect some OCD.

NOW what did I do?

 

[Gumbo]

I detect some OCD.

I just install longer lower control arms on a 2-3 inch lift. I have done this with three different XJ Cherokees I have owned over the last 22+ years. After several hundred thousand miles traveled on the three different lifted XJ's, the handling, return to center, and tire wear are all acceptable. At about 3 or more inches of lift, a reduction in caster may be necessary to achieve a usable front drive-line pinion angle that has no vibrations. With larger tires, I add a small amount of additional toe-in.


This control arm chart is an excellent starting point.
.

According to this chart, a 3" lift would require 1/4" longer LCAs to restore stock caster.
Now the question is if a 1/4" additional shim will fit.
Buying new LCA's just for 1/4" adjustment seems a waste of money to me.

Re: Pinion angle
I wonder why one should be concerned about front pinion angle, when
1) the front driveshaft has a CV (double cardan) joint, that is extremely forgiving about angles, and do not require matching operating angles at the two ends of the driveshaft.
2) the front driveshaft is normally engaged only in off-road, or conditions where the vehicle is not operated at highway speed, or at speed at which driveline vibrations could become an issue.

In this regard, a T-Case drop actually mess up the front driveshaft geometry on top of the lift (increased T-Case to driveshaft angle and decreased pinion to driveshaft angle), still it never caused any front driveline problems/vibrations to me, on any vehicle, while it significantly improves rear driveline operation (especially with tall lifts and short wheelbase vehicles).
Reason why a T-Case drop (with matching tapered rear block) IMHO is the best bang for the bucks and a very effective approach to address potential driveline issues.

 

[Evan03]

I havent had any driveline issues at 4"ish of lift. Im running 7degish of castor to.
Ive never had my jeep on a aligment rack so my actual castor # is unknown

You could make a 1/4" lower control arm shim

 

[Gumbo]

Is there room enough for a 1/4 shim in the stock location ? And is the bolt long enough ?

 

[RCP Phx]

Should be more than long enough.

 

[Evan03]

Ive never used the shim to make adjustments so i dunno.