Do I need UCA?

So, hopefully someone with the same set-up can comment from experience, but I am all ears on this one. The question is this: I have Bilstein 5100 adjustable height shocks. If I put the clip on the highest setting, I think it lifts the truck 2.4 inches. With this height, do I need UCA's? If I need, but don't change the UCA, what could happen? I know I will prob have to drop the front diff, but not sure on the UCA. Any input will be appreciated!

 

UCA's usually aren't necessary for lifts below 2.5-3“. you'll find out for sure when you get an alignment. The most likely issue would be that they are unable to get your caster in spec. This will affect how the vehicle tracks down the road.

I would not install a diff drop. I seem to read about them causing more problems than they solve.

 

I’ve got approximately 3” lift with stock UCA’s and diff drop. After 3 years and 25k miles, no issues yet, knock on wood.

 

Really? Wondering what kind of issues a diff drop causes? Do you have a link where you read this?

 

It had something to do with the way the gears are oiled and the differential sitting on an angle due to the diff drop in front. I think it came up in one of the needle bearing threads.

Besides, a diff drop really isn't necessary for a smaller lift. My CV's angled slightly upward stock, and now angle slightly downward after lifting ~2.5“. The actual angle is pretty close to stock.

 

The diff drop causes problems if you get a mild lift & don’t need it. It creates more change then needed. OP if you get UCAs then get SPC UCAs for the best alignment possible. If your alignment is fine now - you’re good to go. The factory pro lift uses oem UCAs

 

What are SPC UCA's?

 

A brand of UCAs. Most preferred brand for tacos & 4runners

 

https://www.4runners.com/threads/ucas-and-alignments.17733/

 

https://www.4runners.com/threads/uca-recommendations.9261/

 

According to the 4x4 shop I went some shocks need after market UCA.
Eg - shop was ok to use stock UCA with Bilstien5100 / TRD Pro Fox when lifting. But said no for stock UCA to be used with Toytec 2.0 / 2.5 or Fox 2 / 2.5, etc.. I guess talking to Toyota specialist 4x4 shop you can get advice.

 

That seems odd to me. It is dependent on the actual lift height, not brand of suspension. Different shocks or coilovers don't change anything in the geometry. Only the height does.

Maybe what they are saying is that some setups are not capable of achieving enough height to require upper control arms. It usually seems that somewhere around 3" is where they become a necessity.

In the case of the OP lifting 2.4 in, I would not be concerned about upper control arms.

 

They were saying about shock travel not how much lift I wanted. I wanted to keep under 2.5 since my Limited is non off-roading one. Since they didn't tell me in exact numbers like Fox has X amount of travel vs Bilstien only has Y amount of travel so I can use stock uca, something like that. So I didn't want to post any wrong info here.

 

Oh, gotcha.

So, for extended or long travel, you might need them regardless of lift height.

I hadn't thought of that.

But, they can be required just to get alignment in spec above a certain lift height as well.

 

I doubt you'll add enough travel to need a diff drop. Maybe with the dobinson extended travel struts. But I could be wrong. All I know is I have 2.5" or lift, jba uca and no diff drop. I do want to replace the needle bearing, but it hasn't been an issue yet.

 

Not required but they can allow you to achieve perfect alignment. In my case I went with SPC's for the greater caster adjustability in the future for larger tires.

 

The best info I have seen on UCA'S:

https://www.youtube.com/watch?v=huMztKaHsUE

 

^^^^

Kai is the shit. I love the dude, and have spoke to him a few times. (my shop tells me i NEED after market uca's, id be weary of that shop, if they dont tell you why, but, just want you to dig into your pocket) ....

What i also find beyond funny, is those that get a "lift" and think they have actually added any real added "droop" or any more articulation. Man, there is a dick ton of internet, out there on the internet. Ive been told by more than many, in my local area, that uca's are needed for strength, ... and when i ask where? where do you need added strength? One person will tell me in the arms themselves, while the other(s) tell me the ball joint itself. When i ask for a single picture of ANY oem broken arm,... they never find one (from anything off roading did,..... but accidents) then, when i tell them "hey, you know that after market uca you showed, uses OEM ball joints??" and get the ole "well, you do whatever then" reply.

EDIT- a bit over 2 inches of lift here (vated adjustables up front, OME rear) ... OEM uca's. 90k miles. Tires wear like a boss, and zero issues. And not worried about any. 285-70-17, all alignment #'s, well beyond inside the green.
Also, ive seen, and like the iron man set up, more than others ive seen.

 

I think I know why companies like Wescott or Eibach have a 2.75" front with 1" rear lift. As Kai explained Caster changes depending on the front to rear height difference. Must be the magic number for Caster, but you end up with 1.75" of negative rake.

 

Hi, for a bilstein 5100 front lift of under 2", do you think there will be alignment issues? (if I keep the stock UCA)

 

No, I wouldn't expect to have any trouble getting it aligned. It's usually higher lift that makes them necessary.

 

I read to utilize the longer travel of the shock you need UCAs. You can drive fine without them though.

 

I have 5100’s set at 1.75”, but actually measured 2” of lift even after letting it settle. I wasn’t able to get more than 2.3° of caster with the stock UCA and found tracking less than desirable. After a year I installed aftermarket UCA’s which now have me at 4.1° of caster and I find it much better to drive.

Do you need higher caster UCA’s? No, but you may end up wanting them.