Whats this UCA business

Just picked up a 2015 access cab, and am looking to do a 3" coilover lift in the front and eventually run 285/75 r16s. Preferably without trimming anything on my new truck (can it even be done?)

I am aware the info is on here, I just can't seem to come up with the right choice of words in the search function.

So would one of you mind pointing me to the right link to explain when and why I would need new UCAs and what specifically about them is needed to solve this "UCA problem" ( and what problem is it in the first place ).

Also pros, cons, when's, why's, and contraindications for running wheels with various amounts of backspace.

Again I know I'm being lazy about finding the info, I just know there's got to be the be all end all thread for this setup since I see it is fairly common

Thanks in advance.

 

Right around 2.5" of lift is where you loose the ability to get the correct caster adjustment with factory ucas. Caster is the alignment of the suspension so as to angle it in a manner to make the tires trail in the direction you are driving. Think of a wheel caster on a shopping cart. Your handling is sacrificed when you can't get the correct caster adjustment.

 

I want to preface this by saying I am running a 3" lift on 285's.

There's many links, but a lot of people run stock UCAs on 3" of lift with out issues. Others run into problems with the tire rubbing on the UCA.

What I have read over and over is that if you put a lift kit on 2.5" or more, it is highly recommended you get new UCAs. You will not have rubbing of the tires on the UCAs and your alignment will be in spec. My thoughts are if you're spending the money, better get everything you need at once and have it installed all at once; buy once, cry once.

You will have to trim a little running 285's just for on road driving alone. If you take it off road there is a whole lot more trimming and modifications needed. Such as a cab mount chop, beating/flattening the pinch weld, and trimming more plastic. For on road, I trimmed so little that I could hold all the pieces in one hand; not much at all. I have yet to test and flex off road but I can surely tell you, I am not done trimming.

 

what specifically am I looking for when buying upper control arms? different length, bend, etc? I definitely will be doing off roading, not high speed race truck business, but lots of back road exploring.

 

Just an adjustable uca. It will state that it's adjustable. Be sure to get a good brand. They are pricey unfortunately.

 

Lifting the truck in that manner with stock UCAs results in low caster. This causes the truck to be twitchy and have a floaty feeling. Larger diameter tires and added rotational mass exaggerates this. UCAs move the top of the steering knuckle closer to the rear of the vehicle which adds caster.

 

Thanks a lot, that answers a lot of questions. With 3" of lift up front, does anybody run into any other issues with their steering components, CV boots, drivelines, etc. And what could be done to fix these problems?

 

For driveline vibes, OME/ARB FK29 kit.

 

on tacomahq's ultimate tacoma lift guide it said: All front-end lift kits over 1.5″ should also include a differential drop kit". What is the story with that?

 

Premature wear due to increased angles. I had to replace steering rack, lower ball joints, and tie rods. I did the CV boot mod and had no problems with boots. No issues with axles. Had driveline vibes, but not enough to concern me. Ran lift for about 50k.

 

Diff drop on and 05+ is useless. It rotates the diff in a way where the internals no longer are getting the proper lubrication those causing damage in the diff. Does more harm than good.