Best alignment with SPC UCA and 33” tires

Hey guys, I recently bought this truck and it came with the SPC upper control arms already installed.

The truck had badly cupping cooper MTs when I bought it and I just bought some 285/70r17 Falken wildpeak instead (loved them on my old truck).

The truck rides smooth now but I have an obvious alignment issue, a slight pull and off center wheel.

I’m curious for those that have experience with the SPC, which position have you found best with bigger tires and are there any specific caster/camber specs that you have done and are happy with.

 

I have stock LCA’s and SPC uppers, but I’m on 325/75r16 tires. My uppers are set to the middle position D (+2.0°) because I wanted a higher caster angle but still fit big tires.



I’d say your best bet is to find a reputable alignment guy near you and don’t settle till the numbers and steering wheel look right. Just be aware a lot of shops will charge extra and look at you stupid when you ask them to adjust the uppers, even if you give them the SPC alignment sheet. http://www.spcalignment.com/instructions/25480-INS_WEB.pdf

 

Thank you for your input. Was there a reason you wanted higher caster?

im hoping to set the uppers myself before I take it to the shop so I don’t have to have them mess with it.

 

Personally I’ve found that a higher caster number tracks better; doesn’t wander, doesn’t follow road crown, doesn’t turn on potholes. The good news with the SPC’s is that D is the recommended setting to start and they have the added bonus of being designed with 2° more caster than stock uppers. You could also go higher for more caster but doing that to the upper will cause the tire to move closer to the cab mount and risks rubbing.

Yep, I did as well, it was too much of a headache getting shops to do anything right when I first installed them.

 

Do you have any rubbing with this setup?

I’m assuming you have a massive lift with those tires. I’m only running about 3” myself.

when you took it to the shop, did you say to just set your camber and toe? Or did you even have to say anything

 

I do have a slightly noticeable rub in reverse full turn as well as stuffed, mostly due to the 1.25” wheel spacers causing a wider scrub radius.

Nope, just 2.5” lift but a heavy cab mount chop and fiberglass fenders.

Yes, I didn’t say anything about the uppers, but I did ask them for 0° Toe, 0° Camber, and as much caster as they could get. Alignments are a balance of the 3 so the tech has to bounce between them to get it right but a good tech can do it without question, might just take them longer

 

Nice, taking a look at your alignment sheet again, it looks like everything is almost exactly in spec. Do you know if those scales are based off of what a stock Tacoma should be?

 

Yep, they will always bring up your vehicle in their system and then in my case it was also modified for the caster

 

I have a 6" lift with SPC UCA and caster was set at 3.4deg + (setting E on spc spec sheet)passenger side and 3.5deg + drivers side(also setting E). The truck was pulling to the right. Vehicles will tend to pull to the side with the least amount of positive caster so I set my driver's side to setting F. After a slight toe adjustment the truck drives straight as arrow. Good alignment shops will set less caster on driver's side than the passenger side to compensate for road crown.

 

It's a tricky thing, you want the most caster you can get from the lower arms, without adding more with the upper arm.

Lower caster pushes the wheel forward. Upper caster, creates more caster, but pulls the top of the wheel rearwards.

The idea behind SPC is to lower the camber thats created by maxing out the lower arms.

TLDR. Follow the manual, set it to the lift height you have. Max out lowers.

 

That's another thing I forgot to mention. I installed DK LCA and maxed them out (rears all the way out and front all the way in) since I'm running 35's and used the SPC UCA to adjust the camber and caster. I don't mess with the LCA for anything. I even told the alignment shop to don't touch them.

 

When you adjusted the uppers yourself before bringing it in, where in the slot did you have the setting for the camber?

 

Oh, good catch. I set mine almost all the way out toward the edges of the vehicle, maybe a half inch in.