Firestone can’t align with JBA UCAs

Dude, your numbers were better before than after! They just needed to adjust toe pretty much.

 

They went by the specs. Its within spec now so it works for me..

 

Those are indeed the specs for a non-lifted truck. They have basically used your adjustment cams to remove all of the caster that you bought the UCAs to achieve. The truck will drive much better if you get back to that 3.5 degrees or higher. Take a picture of your alignment cams and you’ll see what I mean.

This is my alignment with stock UCAs. It drives a LOT better after than before.

 

I don’t see it on there now, I thought it used to be in the pictures.

 

Is it this one? I saw it on one of my emails.

 

That’s it!! I looked last night but couldn’t find it either. Just located the link. Check this out @Drunken Chewbacca. This link explains things pretty well.

My advice would be to print this out and take it to the alignment shop. If they take the time to understand what they did, they should be able to get you fixed up. I promise you’ll be happier with your caster back. It makes a big difference. It’ll drive like a Cadillac on the highway.

https://jbaoffroad.com/trails/difference-between-jba-std-ucas-vs-jba-hd-toyota-ucas/

 

My truck drives great. Idk what else to say... Smooth. Isnt Caster the Forward and back the wheels are? Wouldnt I want mine in the middle instead of it being to foward or back?

 

Most on here suggest higher caster numbers because it can help you clear larger tires that would otherwise rub the pinch weld with stock spec caster numbers.

3 degrees is usually the sweet spot but if you aren't looking to clear bigger tires then it's not something to worry about.

 

Remember that your steering angle changes as the tire cycles from full compression to full droop. By lifting, you’ve changed the point of the suspension cycle that your truck sits in at rest. If you wish the truck to handle as it did before lifting, you must increase the amount of caster that the truck has in its new neutral position.


Take a look at my before/ after numbers. Just adding that small amount of caster made the truck handle much better. If I could get 3.5, I would definitely do it. It’ll drive OK where you are, but steering is much twitchier, does not return to center after a turn in the same way, and you’ll experience bump steer when going through corners.

This video does a better job of explaining than my thumb typing. I know you think you like it now, but you’ll like it mo betta once you’re at the caster numbers that you bought the UCAs to achieve.

https://youtu.be/UUrDhtHCORE

 

Thanks for the explanation. I may get it done. We will see. I got a lot mor stuff to do to the Tacoma. Before I leave Kodiak, I'll try to get it done.

 

That’s it

 

What was your lift height when you got these numbers with stock UCA’s? If I could get those numbers with stock USA’s and 2-2.5” lift I would be happy with stock but my impression was that anything over 2” yields 1.4 and less of caster. The minimum requirement to stay in spec.

I have the JBA’s now but haven’t installed them because I am undecided if I should go with SPC’s for the benefit of controlling camber independent of caster and having the potential for fitting larger tires even though thats not on the plan as of yet, nice to know I have options. Never heard of anyone fitting 285 with JBA’s. For now sticking with 265/70-17’s to keep some on road performance and avoid problems.

From what I have gathered here though I’d like to get something between 2.5-3.5 caster and as close to 0 or slightly toed in and slightly negative camber for cornering.

Toyota obviously thinks that caster should be between 1.4 and 2.9 where 2.15 splits the difference between having twitchy and heavy steering. Everyone is on the high caster train though with 3.0+. As someone coming form competitive mountain bike racing, caster is similar to head tube angle. Over the years mountain bikes have gotten increasingly more head tube angle to improve trail handling. Its not a direct translation but it makes sense that this geometry shift would apply to trucks as well. Getting the lower ball joint out further in front of the upper ball joint is similar to getting the front hub further out in front of the handle bars on a bike. It allows the contact patch to stay behind the rake for good tracking over rough terrain and allows for a more direct distribution of bump force into the suspension. Although in a tacoma the shock itself is fixed vertical so adding more caster would to some degree require more translation of the impact through the ball joints and bushings potentially leading to premature wear. The other thing to consider here is that as bikes have gotten slacker the handle bars have gotten wider to account for the extra force to steer. Undoubtedly adding more caster is going to add more stress to the power steering system. I'm no engineer but I just have to think that maybe this is why Toyota wants the ball joint angles / caster so steep.