SPC Upper control arms settings.

Hello, I'm getting ready to install these UCA's and was wondering what people that have these set them to before sending it to get aligned? I have 33'' tires with 3" inches of lift. So I'm mostly interested in the castor, I want to get as much clearance in the rear of the wheel well as possible. Thanks, Mark.

 

You want the positive castor settings if you want more clearance to the rear.

 

Use your factory adjustments to pull the wheels forward, then add caster and camber back with spc arms. I fit 33x10.5 on 17x8.5 -10 with mud flaps and no rubbing

 

Mine are in the C position according to the install sheet. I have 33" 285s and needed a cab mount chop. You could try position A or B if you don't want to do that and see if they can work with it.

 

Set it at "F" or "G" if you don't want to do the CMC.
Go to the 2 min. mark of this video:
https://youtu.be/f2YhnldfI50

 

F and G are negative caster and move the wheel towards the cab mount (back).

 

No F and G move the wheel forward

 

Here’s the spec sheet

 

F + G settings move the balljoint back. -1.75 and 2 degrees respectively from the built in caster of the control arm which technically may actually move the tire asy back towards the rear wheel well a little. Could actually create a rubbing situation depending on wheel size and offset and, of course the LCA eccentrics positioning.

 

As far as I know you would use F or G to correct caster and camber after pushing the lower control arm forward away from the wheel well. The lower control arm castor is what you have to adjust to try and prevent rubbing the cab mount

 

This is sort of correct. The A to G setting only adjust caster. You use the camber adjustment at the balljoint to adjust camber The arms come with 2 degrees + caster. which moves the top of the wheel asy forward then set the rear LCA eccentric all the way out to push out the rear of the LCA and turn the front eccentric all the way in then make your final adjustments with the SPC caster and camber adjustment to obtain the proper specs.

The nice think about the SPC is they have the ability to correct both caster and camber separately since both angles are affected by lifting an IFS suspension. This is evidenced by the fact that, on a stock vehicle, you cant adjust camber without adjusting caster and vice versa.

 

F or G I see the issue! (Read the numbers on the bottom. The larger numbers)
(G) is actually stock with 0* of caster added. This will get you into OEM settings but you need to use the adjustable sliding nut to achieve proper CAMBER.
(F) adds .25* of caster if you are too low.

Edit: The goal is NOT to add any Caster, but to correct the Camber. only add Caster if you are unable to get it high enough.

Stock UCAs can set the correct Caster. But it can't set the correct Camber. Use the SPC's to correct the Camber. and that should eliminate rubbing on the cab mounts. But you still need to trim the plastic on the lower bumper.

 

As I said you lose both caster and camber when you lift an IFS suspension. It's just the nature of the beast. As the top of the knuckle is raised it changes both angles as they are both tied to the same pivot points and the same adjustments. Also, changes toe too.

UCAs increase caster opposite the way LCAs do buy moving the upper balljoint more behind the lower balljoint thus increasing the angle. However, depending on the wheel assembly setup this really doesn't help if your trying to clear larger tires. The LCA adjustment is much more beneficial for this purpose. as they move the lower balljoint forward thus moving the knuckle forward and away from the cab mount. But you still need the caster for drivability. Low caster creates fidgety steering and bump steer and high caster creates a very heavy wheel. That's where you use the SPCs to dial it all in AND clear larger tires. I think the sweet spot, as mentioned in this thread is right around what the spec is, about 2.5 to 3 degrees with maybe +.2 to +.5 degrees camber.

 

start with position D. I had mine on that when i was on 33 with 2.25 lift and never rubbed even off road. I do have a cab chop though.

 

I'm not sure why you're trying to explain alignment? I have links in my sig that do just that.

 

Because some of the things are incorrect.

 

In my alignment link?

 

Well, I haven't read all that because I don't have to. Only in this thread but I have read some of the things and I'm not going to discect it. But, for instance, saying that a lift doesn't change caster only camber, is incorrect. Also, saying that having high caster creates bumpsteer which actually the opposite is true.

 

I’m trying to maximize clearance at the firewall and mitigate some minor rubbing on the cab mount/ rear fender well at full lock. Since I’ve also experienced plenty of frustration with my local alignment shops, I’m doing this in my garage and trying to get it as close as possible before I take it back to them for fine tuning.

I rotated my lower cam bolts for max clearance (fronts inboard, rears outboard). I changed my star plate position from D to F. Settled my suspension and checked everything a few times, making small adjustment to the UCA for Camber each time to get it a few tenths of a degree off from 0. By doing this my tire is now a 1/2 inch closer to the firewall, so I’ve actually decreased clearance by doing this. I’m sure my toe is out of whack but I’ll tackle that after I get my caster/camber set.

Everywhere I look, I see disagreements on the star plate settings. I called SPC, the tech suggested I move all the cam bolts outboard and go back to setting D. Before I try that, I think I’m gonna go to setting B or C on the UCAs first and see what that does.

I’ll do the CMC if I have to, but based on the majority consensus across several forums in regards to the star plate setting, I should have gained clearance, not decreased. Any suggestions are welcome.

 

Just to clarify, you lengthened the rear of the LCA arm and shortened the length of the front LCA arm? If you are toed out now clearance may be corrected once toe is aligned.