Best caster spec when aligning with lift

I'm trying to understand the best caster spec for an alignment after lifting. I've had alignments twice, with both resulting in the same spec of 3.5 and 3.9 caster. Is it typical to have higher caster after a lift, or is it worth trying to bring into factory spec?

The higher caster definitely makes for heavier steering.

 

Depends on tire size more than anything.
https://www.tacomaworld.com/threads/ucas-and-alignment.40470/

 

That is a mega thread @splitbolt , just what I was looking for. Seems like the tech was being a bit lazy and didn't even try to bring caster into spec, and given that it takes a bit of work to bring the truck straight after a turn, I can bring it down to 2.5-3 to get better driving.

Much thanks as usual

 

Thanks for the info, both of you! The 2.1° stock, 2.4° 33”, and 3.0° 35” in that superthread is really helpful, and really good to know that going too high on the caster will actually affect steering. Definitely wouldn’t want to be unable to turn hard on a cliff-edged switchback!

For the record: After I got my OME suspension my alignment caster was set at 3.0° with 285/75/16 tires (33”) and rode pretty well, so I think next time around i’ll aim for somewhere between 2.4 and 3.0 to find that perfectly ideal ride quality on and off-road.

 

Another key is to ask them to make the numbers as equal side to side as possible.

 

I don't think a lift automatically results in higher caster numbers unless you installed aftermarket upper control arms - most of them will give you more caster after install.

 

Yeah i bought JBA UCAs to complement the OME set (also the red looks amazing with my red Taco) and I think it definitely helped allow the increased caster.

@Clearwater Bill I’ve heard that a lower left-side caster is good to counter the roadway crown. Personally mine were equal and it felt fine, but i was considering trying the differential setup because I definitely noticed some right-side drift on roads with noticeable crowns. Tough choice though, because all crowns are different and some offroad trails are super’d pretty hard to the left.

 

Understand about the delta to allow for crowns. If you are primarily street driven and somewhat in one area (state? region?) where all the crowns are similar by DOT design. In fact, my Tacoma is done this way for that reason. But I have a 5 lug with Florida roads.

My equal side to side came from my years in autox, and HPDE road course tracks which are typically flat (or sometimes lightly banked in turns), and you need to turn equally crisp in either direction.

IMHO, unless you are running some known trail in a competitive situation, it seems that either equal side to side or a slight tweak for crown compensation would be just fine off road too......

 

3-4 is ideal, for big tires. 2.5-3.0 for stock.

0-0.5 camber

and 1-2 for total toe.

 

I was always told Camber and Toe should be near zero but a bit of negative is allowable (even desirable for handling). Never positive on either... was I misinformed?

 

Toe is ideally 0 same with caster, but every vehicle has different geometry that needs to compensate for road forces and load.

If you set the toe on a Tacoma to zero, it would push outwards to a negative toe.

Zero and negative camber is more reserved for cars with struts.

 

@Bishop84 can you dive a little deeper into this statement? Sounds like you're saying the toe will change while driving?

 

Yes. It's a dynamic item, just like camber, based on suspension movement.

 

I would never want to drive one of these trucks with zero caster it would be a handful on the highway. The variance about what works on one truck and not on the other is because you can get to x degrees of caster multiple ways. With a fixed upper control arm your tire placement in the fender is limited by your alignment specs and what you can get out of the lower control arm. With adjustable upper control arms such as spc’s you can max the cams to move the lower ball joint forward and then use the upper adjustment to bring your camber and caster back to the spec you want. I have ran my truck with 2-5 degrees of caster and can clear the cab mount on 285’s at full stuff with 3.3 degrees. I like the way it drives on the highway with more caster but adjusted it down to give me a little more clearance. I personally wouldn’t start with zero toe unless you are running mono balls on all the control arms, as soon as you start rolling the toe is going to go negative.

 

So it sounds like optimal setup for someone who drives on-road and off-road often would be:

1. zero Camber unless you're track racing on paved windy roads
2. at least 2 degrees Caster for handling, more to clear cab mount with oversized tires/non-stock offset wheels
3. positive toe (slightly) to counter natural negative drift in motion, and for self-centering

I think I'm gonna shoot for 0 Camber, +3.5ish Caster, and +0.5 Toe when I get my alignment done. I was still getting some rubbing during hard and fast switchback turns with 3.0 Caster

 

Suggestions? On stock uCA eibach stage 2R 265/75r16

 

find a better alignment tech. There is no reason to have a truck leave the rack with negative caster unless it has bent parts.

 

Positive caster is what keeps your truck going straight and also what helps immensely in the steering wheel returning to center when coming out of a turn. The reason this happens is that when you have positive caster you are, in effect, lifting the front end of the vehicle very slightly when you turn and the natural tendency is to return to equilibrium. Having three or even four degrees of positive caster will not make your truck more difficult to turn. You have power steering. It ain't going to jerk the wheel out of your hands.

For comparison, my 35 year old 911 specs six degrees on positive camber and I think we could get just under that. That's what keeps those cars tracking dead straight and it's also what helps give is such great road feel with manual (zero power assist) steering, and it's also what requires muscle when you're parking, as you're physically lifting the front end at full lock. At least the engine is in the back.

If you don't have crowned roads then set the caster the same on both sides. Since most of the roads I encounter here in California have some degree of crown I have my Tacoma (stock) set to half a degree less on the driver's side and unless you get that rare freeway which is crowned to the center median, it drives almost as well as the Porsche. And don't sweat it if it's a .3 or .4 or .5 differential left to right. It really won't matter. It's just that if you're going to compensate for road crown that you run slightly less positive caster on the driver's side. And don't drive your alignment tech crazy with that shit as sometimes when you're making the final adjustments those numbers will shift a tick just from tightening everything down. Once you start to get a handle on what all the numbers mean you also get a feel for what numbers matter and which ones don't.