UCAs and alignments

Well said and a very fair reason. I'm just trying to help with what I know and have seen.

I will be helping a buddy install a lift soon. I'll grab some measurements of the hub in fender (front to back) before and after UCAs are installed. I know it can change a little bit should provide a bit more additional data for anyone who is curious.

 

The reason the tire moves forward and back is because of the caster/camber cam adjusters on the LCA. The stock UCA limits this movement at a certain point, especially when lifted. This is why good aftermarket UCA's have a different geometry that allows for higher caster adjustment.

This video illustrates how camber, caster, and toe all interact. You can see the caster adjustment physically pushing the tire forward at 2:39.

https://youtu.be/cVtW41c0q3w

 

Good video/videos, very informative.

 

One major thing they are missing is that you can’t adjust caster off those values. Camber and toe is a live reading, the caster displayed is a calculated estimation of the value. You have to do a caster sweep after each adjustment attempt to confirm it’s correct. The calculated values get further and further off the more you adjust. Caster sweep is absolutely mandatory in confirming the caster is adjusted correctly.

 

Bumping this thread to the top, maybe kill multiple birds with one stone. Lots of interesting info on this thread.

I’ve been mulling around the thought of getting UCAs, and got lost in the weeds with the differences and possible limitations of each.

Specifically, I want to get a UCA that will permit:

-max caster should I need it for clearance if I get bigger tires/different offset.

-have maximum clearance to clear the spring/lower spring mount of my Dobinsons IMS coilovers at full droop

-allow maximum safe droop

@Crikeymike already told me that JBC UCAs will contact the strut on full extension, so those are out. He can verify the Dobinsons and Dirt Kings UCAs will clear. But Im still wondering what will be the limiting factor on extension for my setup. Will these coilovers tolerate being fully extended to their internal stops?

Im kind of intrigued by the SPC UCAs with their adjustable ball joint mount, but not sure if that is adding an unnecessary complication (although it makes changing the ball joint easier).

@koukimonster had some good questions and observations in this thread, and others posted some good videos and visuals worth looking over.

edit: looks like koukimonster hasnt been around in a while, thats too bad, I like his thought process

 

1 of 3 things usually happens on down travel.......you shocks max out, your ball joints max out, or your UCA maxes out by hitting the coil.

Ideally you should really be running limit straps to prevent any of these thing from happening if you want to preserve your suspension components as long as possible. Not many seem to run them unless they have high-end expensive set-ups.

 

I watched that video somebody recently posted on IFS suspensions, very good.

I have a question, regarding a completely stock suspension.

What component bottoms out at full droop on a stock IFS?

Balljoint? Strut?

Thanks

 

I wanna say it might be the shock? Thought I read it here actually. It makes sense because I havent noticed the uca touch the coils when Ive jacked it up.

 

Thanks, your probably right.

I should post my question on that guys YouTube channel.

 

I went through the comments and he stated that in a proper setup, full droop will be limited by the coilover length.

If I would have had this knowledge prior to buying my 18’, I would have NOT lifted it.

 

Just an uneducated but reasoned guess, but I would think that a coil limited system would be for a race trucks that spends a lot of time in the air. Not sure if any coilovers for the weekend warriors are designed in a way where the coil and strut are physically connected so that the coil could limit the travel. Maybe thats an option on Kings?? But as far as I know most of the good coilovers are still loose until captured and compeessed by the tophat. Like I said, totally spitballing here, but willing to learn!

 

On our stock set-ups, it's the shock that limits the travel.

When we lift our trucks, the shocks typically have longer shafts. From this, the ball joint or the UCA hitting the coil typically becomes the limiting factor.

 

I got a response from “Tinkerer’s Adventure” regarding too much lift, in my case a 1” top spacer. It increases the strut length and now it has too much down travel.

As a result, the ball joints now bottom out at full droop instead of the strut. This adds additional stress to the ball joints.

The strut is supposed to be the limiting factor regarding droop.

My guess is, that this would also be a problem with aftermarket struts with lift kits.

 

I just watched tinkerers IFS videos. Wow, talk about not wasting a single word! Incredible explanations and demonstration! I need to watch it several more times to let it all sink in.

@Slopemaster Regarding my self quote above, I take it back, as I misunderstood/misread your statement as referring the spring/coil, where you were referring to the entire coilover assembly

 

Does anyone know what the max amount of caster is that you can get out of factory control arms? I'm currently sitting at 2.9 with Bilstein 5100 set to 1.75 and I'm just not super happy with how it's driving can I get over three with factory?

 

I read somewhere on here you can get 3.5 degrees out of them. Also, to respond to some old comments on here: 1) I have Dobinson’s UCAs with 2.5” lift and they don’t hit. 2) I have Bilstein 5100s and Dobinson’s UCAs. I had it max flexed and stretched in every direction a couple weeks ago, no UCA-strut strikes.

 

Ok.
I've had three alignments done since putting a lift on this vehicle a year ago as stated before 1.75 in the front 1 in eibach in the rear the latest alignment is the best yet but still not great really feel like it could drive better... First two alignments were absolute garbage done by separate shops central Pennsylvania sucks

 

What specifically is it doing? Drifting, pulling, bump steer…how could it drive better?

 

Drifting and doesn't track super straight.. just doesn't feel tight.

 

I kept my stock UCAs after lifting 2.5/1.5. The most caster the shop was able to get was a bit over 2.5 degrees.

But I consider it well aligned. It doesnt pull either direction. But the low caster numbers do mean less stability in general. It has a greater tendency to drift. What I mean by that is that I need to add more frequent steering inpu compared to before. And maybe it has somewhat less “return to center” tendency after turns. Nothing huge though.

For my tastes, I dont think the tendency to drift as being excessive. However, it definitely feels more lively on the interstate of choppier roads. Im easily bored, so I enjoy that extra bit of liveliness.

Not sure if that’s what you’re experiencing. But if it is, and you dont like it, you might need aftermarket UCAs to get more caster.

 

I have a 1.6" lift on mine and get 3.6 degrees of caster with the stock UCA's. 2.9 is a little low for your lift height.

Have you gone in and specifically told the shop to max out the caster? That's what I do.

 

So tell them to Max the caster first and then get everything else within specs?

 

Yeah…they might not be able to squeeze much more caster out of stock UCAs, but they might be able to get it spec. Did you ever get a printout of previous alignments. My 2.5 degrees caster is out of specs, but I dont remember if 2.9 is within spec.

 

Yes, tell them you are interested in getting the maximum caster you can while having everything else remain in spec. Tell them it should be around 3.5 degrees.

 

This may be difficult. Trying to get more caster is going to impact camber, which will result in uneven tire wear obviously. UCA’s are going to be your best option. I have both Dobinsons and OME and no issues with either. Both are basically maintenance free with OEM type rubber bushings and OEM style ball joints.

 

The printout I have from my dealer says spec. range is 2.9 to 3.9. This matches up pretty much with fishbum’s pic above.

 

I have had little success in getting a proper alignment with aftermarket UCA's. Find a shop that listens or walk. Many of these shops will not listen to you even though you tell them what you want. First thing to ask is if they can give you before and after printouts of your alignment values. Second thing to make sure they understand is that if they cannot show that they have achieved the figures you are communicating to them that you will not be paying for said alignment. Twice now I have had shops hand it back to me exactly the same with only toe/camber adjusted and neither provided caster values at all (greyed out and untouched).

 

You could ask for maximum caster, but Im thinking you wont be able to get much, if any more as long as you have stock uca’s.

I took mine to a local off road shop and asked them for max. They were able to get slightly less than what you got (but mine is a bit higher lift than you at 2.5in).

 

You don't need aftermarket UCA's with 1.75" of lift. They should be able to achieve 3.5 degrees of caster and also have camber and toe perfectly in spec with stock UCA's and your lift height. Just explain what you want to the shop beforehand. If they don't want to listen or aren't able to meet your needs, go elsewhere.