Caster specific question...

OK, I'm considering doing an experiment and want to make sure I'm not doing something stupid.

I am thinking about having an alignment to try to help my larger wheels clear the pinch weld and cab mount and I'm thinking about trying to have my CASTER set to something around 1.3 degrees.

I've read Toku58's sticky thread, read the tirerack recommendations, searched my arse off and realize that when it comes to caster, more is better (especially if you have power steering). HOWEVER, the sticky talks about "bump steer" if you have too much caster but it does not speak of the negatives of having "too little" caster.

One advantage to less caster would be moving the tire further forward in the wheel well which is what I NEED! I have my truck sitting level right now and I have tons of room to move the wheel forward with the All Pro bumper, but don't know what the effect of having the CASTER set at the factory minimum would be.

Can anyone chime in and give some insight?

 

I pushed mine as far as it could go while keeping the other specs within range and it helped a ton rubbing.

I think you can go close to +3 deg for caster, I was originally at something like -0.5 and now I am at about +2.

 

Try to aim for 3 to 3.5. This will move your wheels forward away from the cab mount. Don't go too high or you'll suffer bump steer.

 

Cosign- I got a huge lesson in caster today....and what the tech boiled it down to:
Lots of positive caster (think motorcycle or European car-which tend to have 8-10* of caster) will tend to keep you going straight and will resist turning so your direction control is very good but too much and it gets to making steering hard.
Too little or negative caster (think a shopping cart or toolbox "caster" wheels) will follow every little bump and groove in the road- giving the poor directional control.

 

I'm confused. The measurements from my last alignment had the caster set at +2.1 degrees on the drivers side and +1.7 degrees on the passenger side. I'm pretty sure that I have worse rubbing on the drivers side than on the passengers side, so that made me think that LOWERING the caster would help me gain more clearance.

Another source of my confusion comes from this link... http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=4
It would appear as if positive camber moves the bottom of the wheel outward and the top of the wheel inward which doesn't appear to solve anything (I know I'm missing something).

The replies above talk about me wanting 3 and 3.5 degrees of caster which is MUCH greater than I have now. My factory alignment sheet says 2.8 degrees is the top end of the factory specs so do I want to INCREASE my caster to 2.8 degrees and if so, do those of you at that high of an angle experience bump steer?

Thanks for helping me get through this...

 

More Caster pushes the wheel forward in the wheel well. You want more Caster.

 

Thanks OakleyTRD... Yeah, I read that 2.4 is ideal in the sticky, then I saw Chris4X4 post just below Toku58's post and said that lower caster increased clearance (which is what I thought initially). Now, others are contradicting what I understood Chris to say and I'm confused.

I'm almost willing to risk bump steer to gain clearance. I know 1.7 degrees and 2.1 degrees rubs (which is what I have now) and I do not want to rub if I stuff the front end. I'm trying to find the right balance and am confused which direction I want to go... lower toward 1.3 degrees or higher toward 2.8 degrees.

 

That's what I was looking for! Thanks.

 

Because they adjust your caster from the LCA's your tire will move forward as your caster gets higher.

So raise your caster.
But ask them to do it from the LCA's NOT the LR UCA's!
Good Luck!

 

Now I'm confused!

 

Join the club!!!

I'll ask the tech to adjust the lower control arm (LCA) and try his best to nail 2.4 degrees of caster (or err on the high side if necessary). Should I have him/her chase the caster with the UCA to move the wheel further forward too? What I mean is that if they need to increase by 0.4 degrees, could they shift the UCA and LCA both an equivalent amount to get more clearance, then adjust the LCA a bit more to really create some clearance?

 

Son of a bitch.....Damn auto formatting the forums does....

Nope...looked great and made sense on my screen when I went to edit it and show up screwed up....


Trust me- It was a lame ass character drawing of positive and negative caster

::Jedi mind trick hand wave::

 

Rabbit, I don't think the UCA is adjustable. I have Total Chaos UCA and they are fixed, so all the adjustments are made on the LCA. If they dial in the Caster correctly, it will move the wheel to increase your clearance.

 

That's the beauty of the Light Racing UCA's. They have an adjustable ball joint with a lock plate that allows the front caster to be set at one of 7 positions: +2.0*, +1.75*, +1.0*, 0*, -1.0*, -1.75*, and -2.0* from the "default" setting when the UCA is installed. The instructions say for the instaler to measure caster on the stock UCA's, record measurement, install the LR UCA's and set the lock plate over the hex of the ball joint to the desired caster position (listed above)... That's why I was asking if I could "chase" the caster by moving BOTH the upper control arm AND the lower control arm. Hopfully Toku58 knows what I'm talking about and can chime in (or someone else for that matter).

I'm not sure where my arms are set right now, but I'm 100% sure the caster on the Light Racing UCA's is adjustable, in those increments at a minimum, because 1/3 of the installation instructions talks about it.