Alignment Issues, I dont think my mech know's what he is doing...

I have the SPC Light Racing Upper Control arms installed. A the "0" possition these have +2* caster over the stock UCA's and can be adjusted +/- 2* for overall +4* caster over stock or 0* caster over stock (basically in the stock location). Additionally they have 2* camber adjustment.

So my thought process is this: If the stock alignment is ~+2-2.5* caster, I should have at least 6* of caster adjustment with these UCA's. That should be plenty of room to move the tire fwd/out and still have enough adjustment for 3* of + caster.

I explained what I wanted: Move the bottom caster adjustment as far forward and camber as far out as he could (tire forward and out, about 50/50 camber caster if that makes sense). Then use the upper adjustments to make 3* caster and fix the camber.

He claimed to max out the bottom caster (didnt bother with camber) yet had to max out the top + caster (set the upper ball joint to the +4* setting, effectively shifting the tire back so it now rubs if turning to sharp over a bump). I don't understand, the math doesnt work. If the bottom was maxed AND the top, I should have +5-6* caster now...

Anyone help me here? Is he right or is he trying to get a quick 3* alignment?

 

Any ASE techs? How do I check to see if the Caster is maxed on the lower arms?

 

PM member "David Tarrantino". He sets up the majority of the trucks in our tri state area and has been doing alignments before I was born.

 

I'm trying to figure out something like this myself. Not really knowledgeable regarding alignment. I signed up for a 3 year plan at big o tires. They told me that something was maxed out. Can't remember what. But didn't really matter much at the time. Seemed like it was aligned pretty good. Until now. Since I just upgraded to 33" tires from 32", it rubs like crazy in reverse while turning. But not really in drive unless I hit a good bump turning. But I'm trying to figure out if I can get big o to adjust them to help minimize the rubbing. Cuz I remember in the instructions for the camburg uca's I installed said to do something like increase the caster or camber a couple degrees or some shit. Idk. But I'm not sure I want to trust big o techs to go messing around with it. I was thinking maybe take it to a 4wheel parts shop and see if they can figure it out better since they deal with the crazy alignment issues all the time whereas big o deals in mostly stock stuff. Idk I just don't want any headaches. And I want to stop turning heads and getting stared at when I back out of a parking spot every time. Lol.
Edit: And yes I have already done the pinch weld mod and all that stuff. Still rubs.

 

33's will generally require some pinch weld cutting/hammering. Look up "pinch weld mod." No tubing required. I had to cut mine to get it to stop rubbing, but after this abortion of an alignment, they are rubbing again.

Edit: Oh. Cut more? It tooke me three cuts to get it right. Also, ask them to increase/max your caster (this will make it a bit harder to turn but your wheels will track straighter). IIRC, stock UCA's max out at ~2.5* positive caster. For more caster I believe you will need new UCA's.

 

You can't add caster in the same sense as you are thinking. The upper control arm units adjust caster at the ball joint. The lower control arms adjust caster at the inner bushing area. When you adjust caster using two different locations like that, you can't just add the numbers together to get a max caster number. Maximum positive caster, which allows for better steering re-center, is achieved by adjusting the rear lower adjuster all the way in, and the front lower adjuster all the way out. This equated to a zero camber angle, assuming that the suspension system is 100% perfect. If you need to gain camber, then in this type of system you will have to sacrifice some caster. Now throw in the mix and adjustable caster/camber upper ball joint. This will help out by giving you a lot more adjustable angles, but again, you cant just add all the maximum numbers to get maximum caster. Because in order to gain camber, you will lose some caster. I have done many alignments with adjustable ball joints and control arms. There are a lot of things you can play with, but there are limits as well.

 

My question is this: If I was getting 2.5* caster with the OEM UCA then why do I have to set the LR to 4* of extra caster (vice the OEM ball joint location) to get 3* of caster? I understand how the Camber/Caster adjustment works; I was hoping that i could get 3* of caster with the LR in their "0" position (+2* of caster vice the OEM ball joint location) with enough adjustment left over for some extra camber (which can be matched with the LR camber adjustments).

 

Perhaps I am misunderstanding you on some of this. Your factory UCA was not adjustable, thus you could not have been getting 2.5* caster adjustment. Were you meaning that with the factory UCAs, your LCA adjustment points were capable of 2.5* caster?

 

Sorry, no, no adjustments from the factory UCA's but I was able to get 2.5* from the lower adjusments with the factory arms. It stands to reason that if the LR's can get 4* extra caster when compared to the stock position (moves the upper ball joint back towards the cab), that the 4* upper + the 2.5* lower should result in up to 6* total...

For anyone not following, this is how the LR adjust:

http://www.spcalignment.net/instructions/25470-INS_WEB.pdf

 

ok. Got it.

You would think logically that you could get a total of 6* of caster, but why would you want it? When you get above 4* you start to develop issues with steering effort, road crown issues, and power steering system load.

Looking at the PDF it shows that they recommend setting your lower control arm adjustments to neutral. Based on that suggestion by them, you would only be able to have the maximum caster available by the UCA ball joint. Also, by that design, as you modify caster, camber will be affected, so you would have to cancel out some of the camber with the LCA depending on what you have caster set at on the UCA. It is really hard to explain in print, and I don't have a way to really explain it any other way. Perhaps a phone call to them would be in order?

 

I dont want 6, just 3. But the tech seems to think (or says) I can only get 3 with the upper arms maxed at the +4* position. I think thats BS and he doesnt want to adjust the upper arms a second time (he maxed them the first time after I asked to max the lowers and adjust the uppers to get 3*). I think the second time he was just being lazy.

Im taking it to a new shop when I have a chance. I didn't get confrontational with the guy (I have lifetime alignments with them and don't want a pissed off mech working on my truck). I just need a second opinion before I drop $100 on an alignment somewhere else.

 

Yeah, I see no reason that you couldn't get a solid 3* of caster, and get the camber to around 2.4*