Pre lift geometry assessment?

Have read through many 3rd gen lift related threads and seems to vary widely on wether or not uca’s are needed. Guessing the fit and tolerances of each individual truck affect this. Anyone come up with a way to use current setup, measurements, etc. to determine if uca’s will be required before purchasing components or to determine how much lift can be accomplished without getting out of spec ?

 

General rule of thumb is once you go up 2" you should get them.

 

General rule is that a 2.5 inches of lift you need new UCAs to keep it in spec and not destroy your upper ball joints. If you want more detail you are gonna need to tell us what kind of lift and tires you want to run.

 

I’m not certain yet, in more of a daydreaming and researching phase than planning at the moment. 3rd Gen dcsb sr 2wd. Wishing someone made 2 1/2” spindles. The available 3.5” and 4” are just too much. Not planning on larger than 265/75/16 tires.
I really like the look of a 2 1/2” lift. Have thought i might settle for 2” if it means I don’t have to buy Uca’s. Yet I have read about people that went up 2 inches and needed them and others that have done 2 1/2 and didn’t. Hence this thread.
Been looking at the bilstien and eibach setups. Should probably just be researching which uca’s to get and stop thinking like such a cheap ass.

 

every truck is different, what works for one may not work for others. You may be able to do a 2.5 lift without UCAs but that's the upper limit and might not work for your truck. Alignment is a different story an alignment tech who know what hes doing may be able to keep things in spec with stock UCAsa nd a 2.5 inch lift, one whos bad may need the extra degrees from aftermarket UCAs to help him out. With that tire size a 2 inch lift is more than enough, so erroring on the side of caution with that may be your best bet for a trouble free install and alignment.

 

Exactly, every truck is different. Had been wondering if anyone had come up with a way to gauge those differences to determine what alignment adjustment range would be available at a certain height. Some guys on here have scienced the shit out of cup holders.

 

Don't think anyone has gone that in depth with it, if you don't want UCAs stay at 2 inches for easy alignment, 2.5 MAY give you issues, but may be fine.

 

New UCA's are really only NEEDED if you are putting larger coils on. The stock UCA's will come in contact with larger coils when close to full droop.

Other than that, there is no lift at any reasonable height (<3") that absolutely requires new UCA's. The ball joints can handle the full range of motion that the rest of the IFS geometry can handle.

It's possible to still get good alignment numbers with stock UCA's. The LCA's have enough adjustment to keep decent caster angle. You just might have the wheel further back in the wheel well than you would like, causing rubbing. Most aftermarket UCA's will actually add caster angle (meaning they keep the top of the spindle further back in the wheel well). But this doesn't help clear larger wheels unless you can move the LCA's forward enough.

FWIW, I ran stock UCA's on 2.5" of lift for 9 years. No issues whatsoever with alignment or clearances. I just upgraded my suspension all around and went with SPC UCA's on the front. I don't notice any difference at all. Alignment numbers are basically the same, ride is same. Tire still fits in the wheel basically the same, rubbing only on the upper/inner portion of my mudflaps. I basically only got them to clear the 2.5 coils.

Now, all that being said... Every truck is different and sometimes things don't work in practice as well as they do in theory.

A good video on the subject > https://www.youtube.com/watch?v=huMztKaHsUE

 

Much appreciated info. I’m thinking I’ll plan on going up 2 - 2 1/2 inches with some coil overs and if for some reason I need to upgrade uca’s I will. I don’t have much personal knowledge of this stuff, but there seems to be some differences in opinion regarding caster to what is “technically in spec” and ideal for drivability

 

That's exactly what they are, difference in opinions. But the facts don't change. In spec is in spec. Some people like more caster, some like less. There are pros's and con's to both, but neither are wrong.

The concern with stock UCA's is not enough caster angle with higher lifts, because the angle changes as the wheels drop in relation to the frame. And the concern with too little caster angle is that you may find that you are getting too much bump steering over rough terrain. Pretty much all aftermarket UCA's have higher caster angles built in (or adjustability for it, like SPC has) to compensate for this. But as long as you still have some positive caster (you can't really get negative caster, so no worries there) you should be ok. It will just come down to personal preference on how "magnetic" towards center you like your steering wheel to feel.

Some people will also say that new UCA's give you more droop. That may be technically correct (in regards to the control arms themselves) but the CV joints are actually the limiting factor there so it doesn't really matter, unless you just have RWD.

There is nothing wrong with doing your lift while keeping stock UCA's and see how it goes. The only downside is you will need an additional alignment when/if you decide to change UCAs.