Another Alignment Story

[Fleethammer]

After the OME lift, I experienced the typical wandering, nervous feeling in the steering from loss of caster, so I installed the Light Racing UCA's and set the caster to the recommended "D" position, which is where most everyone else is starting off with their LR UCA's. I take it in for an alignment with the instructions to zero out toe and camber and max out caster to around +4.

I get the truck back and tow and camber are both zero, but they said max caster they can get is 2.8 on the passenger side and 3.1 on the driver's side. This seems a little low with LR UCA's, no? I thought the"default" setting on the LR UCA's gives you +2 MORE than stock to start with, hence the reason most set it there and get very good results.

Incidentally, the truck pulls to the right and the wheel is not centered anymore. I also never got back the "centering" action you get with positive caster. Also, with 265/70/17's the fronts were rubbing hard on the mud flaps, so I trimmed them and it went away, but after the alignment the left front rubs like hell with the slightest turn of the wheel to the left. I guess they have to come off completely

I am thinking of setting it to the next setting which gives +3 more caster and bringing it back. Or should I go even further and set it to +3.75?

 

[superman3043]

I started with mine in the "D" postition and it was all over the place pre-alignment so I adjusted it to "B" (+3.75) and it made a huge difference, but after I had them get everything else into spec and max out caster during the alignment, I was WAY over spec (like +6). I pulled it back to "C" (+3) and had it realigned and I'm still at the top of the spec (+4). Next time I get under it, I'll be returning it to the "D" position.

So that's just my experience, so to answer your question, if your guy has it maxed out and it's still under or low on the spec, then yes, you can use it to dial up more caster and should be happy with the results. I don't know anybody that runs plus size tires and can keep the front mud flaps successfully, and adding caster with the UCA defenitely won't help that problem.

Hope that helps, good luck!

 

[Fleethammer]

I started with mine in the "D" postition and it was all over the place pre-alignment so I adjusted it to "B" (+3.75) and it made a huge difference, but after I had them get everything else into spec and max out caster during the alignment, I was WAY over spec (like +6). I pulled it back to "C" (+3) and had it realigned and I'm still at the top of the spec (+4). Next time I get under it, I'll be returning it to the "D" position.

So that's just my experience, so to answer your question, if your guy has it maxed out and it's still under or low on the spec, then yes, you can use it to dial up more caster and should be happy with the results. I don't know anybody that runs plus size tires and can keep the front mud flaps successfully, and adding caster with the UCA defenitely won't help that problem.

Hope that helps, good luck!

Thanks, I appreciate the help. Losing the mud flaps tonight.

I'll try one more setting positive and see what the results are. Good thing I paid for a three year alignment or this would get expensive! Interesting your shop can't just back off the caster settings on the lower control arms to compensate for your high positive caster induced by the +3.75 setting. In my case, the shop said that my bottom caster adjustments are totally maxed out, so if I go to +3 as opposed to the +2 setting, They should be able to back off a bit if caster gets too high.

I don't know why I thought there would be less rubbing with more caster induced by the LR UCA's. Coming from the sports car world, caster is usually adjusted by pushing the wheel forward from the bottom control arm, not pulling it back from the top, so I thought there would be less rubbing :rofl: I guess in the end either method accomplishes the same thing- greater steering angle.

 

[4RunnerSeth]

Thanks, I appreciate the help. Losing the mud flaps tonight.

I'll try one more setting positive and see what the results are. Good thing I paid for a three year alignment or this would get expensive! Interesting your shop can't just back off the caster settings on the lower control arms to compensate for your high positive caster induced by the +3.75 setting. In my case, the shop said that my bottom caster adjustments are totally maxed out, so if I go to +3 as opposed to the +2 setting, They should be able to back off a bit if caster gets too high.

I don't know why I thought there would be less rubbing with more caster induced by the LR UCA's. Coming from the sports car world, caster is usually adjusted by pushing the wheel forward from the bottom control arm, not pulling it back from the top, so I thought there would be less rubbing :rofl: I guess in the end either method accomplishes the same thing- greater steering angle.

Adding Caster at the top moves the wheel further back in the wheel well and will cause more rubbing at the back of the wheel well. The best thing to do is get the most caster you can out of the stock adjustment and then only add the minimal necessary to get the recommended amount of caster. I set mine a neutral with the camber pulled all the way out and they were able to get it into spec. Sounds like you need to find a new alignment shop. If you want more information I explained this in detail to a friend on TW and he put it into a very informative post.

Alignment, Caster, Clearance, and Driving Report with Light Racing UCAs - Tacoma World Forums

 

[superman3043]

Thanks, I appreciate the help. Losing the mud flaps tonight.

I'll try one more setting positive and see what the results are. Good thing I paid for a three year alignment or this would get expensive! Interesting your shop can't just back off the caster settings on the lower control arms to compensate for your high positive caster induced by the +3.75 setting. In my case, the shop said that my bottom caster adjustments are totally maxed out, so if I go to +3 as opposed to the +2 setting, They should be able to back off a bit if caster gets too high.

I don't know why I thought there would be less rubbing with more caster induced by the LR UCA's. Coming from the sports car world, caster is usually adjusted by pushing the wheel forward from the bottom control arm, not pulling it back from the top, so I thought there would be less rubbing :rofl: I guess in the end either method accomplishes the same thing- greater steering angle.

I've got a 3 year alignment plan as well. It's already paid for itself. If they offered a lifetime (which some places do), I would have bought that. It's a no-brainer.

I find it strange that they couldn't get it in spec with just the LCA adjustment as well, but I think it has to do with doing what was nessary to wrangle in the camber. They probably use up all of the adjustment they have to get the camber in, because I needed to run the UCA camber adjustment all the way out to clear my tires.

I'd prefer to have the UCA in the neutral position anyway. As was mentioned, additional caster with the LCA pulls the tire away from the body mount/mud flap, caster added with the UCA adjustment does the opposite which is no good in my case. Already get a lot of scrubbing back there off road with these tires.

 

[TRDCal]

Bare with me because I'm a bit of an alignment noob but since I'm installing a set of LR UCAs soon i'm curious, whats the advantage of having a positive caster? Why wouldn't you just want it back to factory specs?

 

[superman3043]

Bare with me because I'm a bit of an alignment noob but since I'm installing a set of LR UCAs soon i'm curious, whats the advantage of having a positive caster? Why wouldn't you just want it back to factory specs?

Here is a link to TireRack.com's alignment tech information page to help you better understand alignment.

And here is their basic jist to help you understand the benifits of positive caster:

"Caster angle settings allow the vehicle manufacturer to balance steering effort, high speed stability and front end cornering effectiveness.

Increasing the amount of positive caster will increase steering effort and straight line tracking, as well as improve high speed stability and cornering effectiveness. Positive caster also increases tire lean when cornering (almost like having more negative camber) as the steering angle is increased.

What's the downside to positive caster? If thevehicle doesn't have power steering, a noticeable increase in steering effort will be felt as positive caster is increased. Other than that, the effects of positive caster are pretty much "positive," especially increasing the lean of the tire when the vehicle is cornering while returning it to a more upright position when driving straight ahead."

The factory spec is already positive +2 to +4 degrees. As your caster angle decreases you car will begin to wander at high speeds. It just keeps the vehicle tracking straight, in a nutshell.

 

[sonerick]

A lift tends to exacerbate the issue of wandering on the highway (high-speed stability). It seems that the lower end of the factory spec does not compensate well enough for the changes in suspension geometry after a lift is installed. Setting caster to +3* or higher improves high-speed stability and gets handling back to a more stock-like feel.

Edit: Superman beat me to it, right on.

 

[Fleethammer]

More caster equals greater straight line stability (less wandering and steering "vagueness"). It also gives you that centering effect on your steering wheel when you complete a turn. When you lift, you loose caster and even if you can get it near factory spec, it isn't enough due to the effect of the lift. Whereas on the factory ride height 2.8 degrees would be fine, with a lift, you need more, or just deal with the side effects mentioned above. The LR UCAs will allow you to add caster, even well beyond factory specifications if you like/need. There pretty much isn't any negative to having more positive caster, except that at some point you might rub a lot (it brings the wheel back towards the passenger compartment). General consensus here is that anywhere between 3-4 degrees is ideal for our trucks.

Bare with me because I'm a bit of an alignment noob but since I'm installing a set of LR UCAs soon i'm curious, whats the advantage of having a positive caster? Why wouldn't you just want it back to factory specs?

 

[TRDCal]

Thanks for the info guys. Its like the whole crazy wheel on a shopping cart scenario, grade 10 autoshop is all coming back to me.

a noticeable increase in steering effort will be felt as positive caster is increased.

One final thought here, would that in turn put more wear on your power steering system or is it negligible?

 

[superman3043]

Thanks for the info guys. Its like the whole crazy wheel on a shopping cart scenario, grade 10 autoshop is all coming back to me.



One final thought here, would that in turn put more wear on your power steering system or is it negligible?

Shopping cart wheel... Exactly! Perfect example. The front spindle on a Dragster is also a good one.

To answer your question... I guess you could say so. The system is designed to function within the caster spec range, so as long as you're in tolerance, the vehicle should behave like you expect and the components should be fine. So I guess it's more of a matter of "working a little harder" rather than "wearing more"... To some that could be six of one, half dozen of the other. I'll say that additional caster, couldn't possibly stress the steering components more than turning wheels and tires like mine along with the weight of the vehicleagainst rock faces, when the vehicle has a natural tendancy to turnwith them. Hope that helps man.

 

[TRDCal]

I'll say that additional caster, couldn't possibly stress the steering components more than turning wheels and tires like mine along with the weight of the vehicleagainst rock faces, when the vehicle has a natural tendancy to turnwith them. Hope that helps man.

Actually this is a good point, it can't possible be worst than that. Thanks again for the info, I'm alot more comfortable about getting my LR UCA's.