UCAs and alignments

Just curious , when you put UCA's on and get an alignment , what specs does the shop use to align the front end since the UCA's move the wheel forward ? Factory or new specs ?

 

If you’re lifted ask for 4-4.5 caster, camber and toe should be adjusted to stock specs.

 

I was thinking of going with the Eibach E80-82-071-01-22 pro truck lift kit . Not sure about UCA's .

 

When I put the UCA's on I followed the specs that JBA said worked well, so when you tell the shop to do an alignment, you tell them, stock camber adjustment, stock toe in adjustment, and to put the castor adjustment at 4-4.5 degrees. At this point when you get the print out there will be a vehicle description along with "Modified Specifications." The added castor is real noticeable going down the road at speed.

 

Would someone please tell me *how* the UCA "adds" caster?

I'm trying to picture the system in my head and I'm a little confused.

I always thought caster essentially referred to where the wheel sat, forward or backward, in relation to the vehicle. OK. Well, it's measured in degrees though. So what exactly is measured? Seems to me, while watching an alignment take place, that the angle of the spindle (clockwise rotation from 12 o'clock if you're looking at the tire straight on from the side) is what is being measured. Well, I suppose that would work if all else was constant. If the wheel moves forward while the UCA mounting point stays constant, the spindle's angle would indeed change, but because the bottom of the spindle is moving forward.

OK, so really what we want after lifting is to move the wheel forward, right? If the UCA stayed the same, and the caster reading increased, according to my imagined suspension system, that would indeed move the wheel forward.

However, if the UCA simply moves the upper mounting point rearward, that would increase the caster angle without actually moving the wheel forward any, no? So perhaps this could affect steering response, but how would that increase vehicle stability?

I'm probably imagining the system incorrectly, so thanks in advance for any clarification!

EDIT: Is it simply the ball joint where the knuckle and LCA connect that allows this play/change? If so, I still don't see how it could move the wheel forward any.

 

The aftermarket UCA's usually move the upper ball joint towards the rear of the truck a bit more, which then puts a larger angle on the spindle between the upper ball joint and lower ball joint. By doing this, the lower control arm can be adjusted to keep camber in spec and slightly push the LCA ball joint a bit more forward. Overall I wouldn't say the wheel moves forward, if anything it moves towards the back, which is one reason why BMC's exist and fender smashing can be an issue with larger tires.

If you really want to move the wheel forward you need to look at some options similar to the JD Fabrication LCA pivots. Those completely cut the LCA pivot off the truck have a custom system, allowing you to move the LCA up to 1" forward, which in turn will move the entire wheel forward and provide increased caster. They only make it for the Tacoma but a member on T4R had a shop make some tweaks and install on his 4Runner. I haven't heard how it is performing or how clearance is yet though.

 

Caster degrees work out in regards to the picture below. What's not shown in the picture is that negative caster will sit further back in the wheel well while positive caster will sit further forward.

 

I would say the only caveat to this is if you're only moving the top pivot point to get additional positive caster, it would still slightly move things towards the rear. the lower point of the caster axis is fixed by the LCA, and if you can't push this forward the only way you'll increase caster is by pulling the top point of the axis to the rear, effectively pulling the wheel slightly back.

 

If you drew a straight line between the upper and lower ball joints, that would the axis on which the tire pivots when it’s steered left and right. Caster directly affects stability. A shopping cart front wheel for example has extreme negative caster compared to a top fuel car that has extreme positive caster. One turns on a dime the other is stable at high speed. The 4Runners suspension is design with alot of anti dive, as a result lifting it brings the caster down quite a bit. To offset that you get control arms with a slightly relocated ball joint. The upper is a fixed point, you’re dropping it back slightly then using the lower control arm cams to push the lower ball joint and in turn the whole wheel and tire assembly forward.

 

Hmm. So it sounds like I'm right. Interesting...

All this seems to slightly diminish the argument for UCA's, in my book.

Why does no one attack the real issue, moving the LCA forward more? Why no redesigned LCA's? I understand that the LCA takes more abuse, but so?

Odd that everyone always says "get UCA's and move your wheel forward more." I suppose if camber was of paramount concern, this could be considered true. However, if the LCA's are going to be the limiting factor, regardless, I would stand behind a statement that UCA's do nothing for moving the wheel forward or increasing wheel-base / decreasing chance of BMC.

 

See my post above, JD fabrication has moved the LCA but it's a bit feat/requires welding. You might get caster with dirt king LCAs but I believe they also cost around $2k, so cost is a big factor.

Freedom Off-road just dropped a sneak peak of new LCAs, no info if these have caster built in.

For UCAs, you can get the caster back to numbers around 4 degrees with a lift. This is huge so the 4Runner isn't as squirrelly at high speeds. Also upgraded UCAs have better clearance, usually, allowing full droop without contacting the front coils. I can post some overlay pictures of my UCA vs OEM when I get home to show the additional clearance.

 

So it sounds like the confusion might come from this:

If you lift the truck on stock UCA's, you essentially will want to move the wheel forward at the bottom, by adjusting the LCA, in order to regain some of the lost caster. This also gives the added benefit of moving the wheel forward which further helps stability, and decreases the chance for hitting the tire on the rear of the wheel well. The downside to this is that when you adjust the LCA to move the wheel forward and add caster, you are simultaneously taking away camber. Might not be an issue. That said, it also seems like "twisting" the LCA like this could add additional stress to the suspension.. at the very least, I imagine those bushings to be under a lot of stress when the rear cam bolt is all the way "out" and front cam bolt all the way "in."

However, if this can not give you enough caster, you can replace the UCA's which will move the UCA ball joint rearward, increasing caster further. Then, you could alleviate the stress on the LCA, and get back some camber, by moving the LCA cam bolts back near their original positions. That said, this would actually move your wheel backward (and lower caster a little).

So UCA's help with stability by adding caster, and also give more adjust-ability head-room with respect to the LCA bushing cam bolts, however in no way do they actually increase wheel base, or move the wheel forward in the wheel well. Correct?

FWIW, I catch some pretty high speeds coasting on that shopping cart from the store to my 4Runner in the slightly sloped grocery store parking lot.

 

Thanks for the info!

Yeah, good point.. the droop clearance is another benefit! That said, I recently saw where a couple of aftermarket UCA's (JBA and Dobinsons, I beleive) still hit the spring/strut under full droop. So I wonder how much of a difference that typically makes? Your pics would be awesome!

I am probably going to 6112's which are a larger shock and larger spring... should I be very concerned about my OE UCA's hitting my spring/strut under full droop? I'm going with the 6112's because they are the best option I can find for a 2" front lift, and 2" is what I personally want to keep OE UCA's but raise the truck an appreciable amount. I'm considering going with a 2.5" front lift but that absolutely means UCA's in my book, which makes the package cost more while having lower performing shocks. I wanted to go with a 1.75" front lift, but after many hours of looking at pics, I just don't think that's enough for my 275's (my preference).

 

This is overall exactly what aftermarket UCA's are doing, the bolded info above. You've got it! And the droop which you got in your other post.

edit - no idea why my photos loaded up all crazy

 

My JBA's do not hit anything at full droop.

I'm at 2.5" front lift.

 

Info here regarding contact: I'm thrown off though because JBA says that Kings uses a thinner spring.. but I thought Kings/6112/TRD Pro all had a wider spring than the regular 4Runner? I think JBA is simply wrong and confused there.

 

As many others have said before when it comes to wheel, tire, and suspension modifications..."results may vary" lol.

 

It can make small differences to your wheel base. This shows caster movement more accurately.

 

With you on that...!

P.S. Sorry for the thread hi-jack lol...

Not sure if true, but I just read someone (who, honestly, I dare trust) say that Toyota engineers designed the UCA ball joint to be the limiting factor of droop. That makes sense to me because that would be the cheapest and easiest component to swap out if it was constantly being "banged up" while fully drooping. I want to keep it that way.. I don't want my CV axles, spring on UCA contact, or shock topping out to be the limiting factor (and don't want to deal with limiting straps).

I'm not over here jumping train-tracks, but I also don't want to make contact with the spring when lifting a tire off the ground, which does happen some on the trails I travel.

The general consensus seems to be that most setups will be OK, but some people have contact for various reasons. Looks like most UCA's definitely add some room for droop/extension without spring contact. However, if the UCA's joint allows for more articulation, that means the UCA can move lower thus increasing chance of contact with the spring. It looks like the JBA's (and maybe Dobinsons) don't give as much spring/droop clearance as others.. this may be a result of the fact that the ball joints used in the JBA's are rather large, so the housing much be larger to accommodate. That also means the JBA UCA extends closer to the wheel/tire, hence the details on their page referring to such.

Maybe there is also some resistance against droop from the LCA bushings? That would mean that older trucks on worn bushings would have a higher chance of making UCA to spring contact.

 

I'm not saying that this illustration is incorrect for the 4Runner, because honestly I don't know for sure. But, I bet that the vehicle's particular spindle design directly affects how much changing caster via UCA moves the wheel forward.

 

The reason this is incorrect is it is also moving the LCA connection point to the spindle forward. When you install aftermarket UCA's you're only moving the top connection back, the lower connection is staying in the same location. So the axis of rotation isn't the center of the wheel but the connection point to the LCA.

This image I've attached is very rough and exaggerated, but shows how the UCA will affect and increase caster. The LCA mounting point overall stays in relatively the same location.

 

FWIW, I catch some pretty high speeds coasting on that shopping cart from the store to my 4Runner in the slightly sloped grocery store parking lot. [/QUOTE]

Not enough caster is why those damn front wheels rattle back n forth like crazy!....LOL

 

Your droop has a maximum value controlled by the shock being extended. There is no way to extend past the maximum droop shown with the truck fully jacked up. If your UCA's don't contact then, you should be good to go.

 

I'm not saying it's a lot of movement fore and aft, but there is some movement.

How is it possible to clear tire rub with increased/decreased caster if there is no fore or aft movement?

 

To the topic of the post... everyone seems to agree on getting the toe and camber to stock range.

Caster is where you will see the opinions vary.

Many say to set it above 4...which will decrease the likelihood of larger tires rubbing on the cab mount.

JBA recommends setting the caster at 3.1-3.2.

I've read some people prefer it at 2.5.

I've even read of some people buying SPC UCA's and still choosing to do a CMC on their 4Runner in order to fit 285's as opposed to maxing out the caster to make the 285's not rub. Reason being that they feel too much caster negatively affects the driveability.

I have JBA UCA's and my alignment guy set my caster to 3.0L and 2.6R. Some people will say this caster variance is wrong. My alignment guy said he recommends this to counter road crown.

Others will say that these numbers are backwards and that the front left should have lower caster than the right to battle road crown.

Many insist that the caster should be perfectly even side to side.

The guy that did mine is the owner of a small independent shop that has been in business forever and works on stock, lowered, and lifted vehicles. He aligned my 4Runner himself and road tested it himself. I believe he knows what he is doing.

All I can say for sure is that my 4Runner drives great with these numbers and I have no rubbing on anything. I am running 265/70R17 tires on 17 X 8.5 wheels with 4.30" backspace and -10mm offset.

 

I think you’re getting to caught up on the whole pushing the wheel forward thing. That is not the purpose of the upper control arm, it’s a just a very slight side effect. You’re not moving the wheel an inch forward, it’s just enough that if you your barely rubbing on the mud flap area with the shoulder of the tire while turning, you might clear it after doing control arms and getting 4.5 degrees.

The ball joint is not the limiting factor in droop, the dampener is. Once you change the dampener the suspension can then move further and the upper ball joint can become the limiting factor. That’s a good way to cause a catastrophic ball joint failure, it’s a load it’s not meant to handle.

 

Regarding max droop and the limiting factor...

So you guys are saying, for sure, that the strut shaft is the limiting factor for droop with stock suspension? So that means the strut is "topping out" at full droop, which surely must be a bad thing, right? EDIT: Apparently not. Even though I see talk of topping out shocks blowing them, it seems that only happens under extreme circumstances when the shocks are already performing on the edge of their stroke, and are topping out hard and often?

I don't know a whole lot about shocks but I imagine the piston banging up against the top of the body couldn't be good. Then again, maybe with the pressure in the shock, it never really hits and hurts it? That said, I was under the impression that topping out shocks (for whatever reason) was bad for them and would lead to failure and leaks. So it seems odd that Toyota would design that to be the limiting factor. Granted, nothing wants to go to the limit.. EDIT: Supposedly there are built in rubber stoppers and yes, the shocks are meant to use them.

Hmm, I need to just go mess with the truck and see what I find out. I was thinking that the stock UCA ball joint was the limiting factor. But then I was wondering if the sway bar also would put up a fight toward max droop, which would help alleviate the impact in case the real limiting factor was utilized / hit.

 

OK just thinking over here.. I saw a guy who had 5100's and he was hitting his UCA on his spring. I suppose that means that the shock must be the limiting factor as that was his only changed variable from stock, and obviously his UCA must have been falling lower than on a stock vehicle in order to contact his spring. I guess it's possible his spring wasn't "turned" right but.. but I'm more inclined to think that the stock UCA will simply contact the spring most likely, under droop, when extended length shocks are used.

I'm not sure if all aftermarket shocks are extended or not. Looks like the 5100's are (I think), as well as probably the Eibachs. I wonder about the 6112's.. and Dobinsons twin tubes (other than the "extended length option" which obviously is longer than stock).

 

You're overthinking stuff here, 6112s at a 2" lift will be just fine with OEM arms.

He was likely hitting due to too much lift or having the coils incorrectly clocked, it does create an issue.

The droop comes into play for guys wanting to run 3-3.5" lifts, that's where contact is much more prevalent. The Extended travel shocks from Dobinsons too, as they allow the wheel to have a bit more down travel.

Worst case, when you install and have the truck jacked you'd see any contact issues. If coils are assembled correctly (tails towards the rear of the truck) you should be just fine, based on tons of others running the same setup.

 

Thank you for your help.

I think the issue was with his coils not being clocked correctly, maybe. He was also using a 2.5" top-hat spacer, so perhaps the spacer affected where the coils sat, which caused his problem. All of this advice is what gets me there.. gotta figure it out myself though lol!

Yes, I may be over thinking. Honestly, it's a personal problem ha. That said, I've learned to not trust everything I read on internet forums immediately. So often do people write in a manner as if they have authority on a subject when they are actually very wrong and ignorant. We all want to believe something easily so lots of people receive misinformation as gospel then regurgitate it accordingly. Once enough have gotten onboard, the misinformation practically becomes fact in the community... no bueno. I'm quite skeptical in my 30's as I learn what people are really like. When it comes to car mods, lots of guys say "buy once, cry once." I'm in the "research once, cry once" boat lol.. cause yeah, the research and stress is a pain in the ass lol, but I bet with my first 4X4 I'll learn enough about suspension that I'll know more than 90% of "professionals" around here. That might sound cocky, and maybe it is.. but it's also sadly true.

Perfect example is the UCA's. The general thought I've found in the 4Runner online-forum community is that they "push the wheels forward and add caster." After reading literally hundreds of posts, it wasn't until I used my own brain and looked at the dang part and thought "huh.. how could that move it forward??" All those posts and none of those people really dove into what the arm does. Most people just want it done and they don't care how it works. That's fine until we start trusting people that also don't know.