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Unread 11-07-2019, 03:39 PM   #1
m@xim
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Default Daystar lift. Factory UCA manipulation to get more Caster?

***I am cross posting this one since my original thread got zero replies on the T4R forum. Which is weird since the question can't be that dumb in my opinion. Here we go...***

My vehicle: 2006 Limited + XREAS + Daystar Kit 2.5"/1.5"

Fact 1: any lift has a negative impact on alignment settings, specifically camber and caster.

Fact 2: to achieve maximum caster, the rear leg of the LCA must be fully extended and the front leg must be fully retracted using respective camber adjustment bolts. This setting displaces the lower ball joint to the front, but then the "short" leg will impact your camber setting. If you extend both LCA legs, you'll get a better camber, but then the ball joint moves back, and caster suffers.

Fact 3: to find the sweet spot of camber/caster, you fully extend the rear leg of the LCA, and then start playing with the setting of the front leg/cam bolt to find the best compromise.

Fact 4: aftermarket UCA (upper control arms) offer extended camber/caster ranges.
Now this part needs confirmation, but I am assuming it's because they displace upper ball joints towards the rear, so that the steering axis is more inclined, which gives you more caster range.

Fact 5: We can't manipulate factory UCA... OR CAN WE?

==========================================

I bought a bushing kit for the front end from Energy Suspension. The UCA bushings have 2 parts - the poly bushing itself and a metal sleeve (inner).

Installation is pretty simple - you slide the metal sleeve inside the bushing and then the bushing inside the UCA housing. Then mount the UCA to the car.

UCA-bushings.jpg

Installed, front bushing:

UCA-front.jpg

Installed, rear bushing:

UCA-rear.jpg

First thing I notice, is that the Energy Suspension bushings are shorter. The metal sleeves are longer and compensate for the that difference in length.
So after all is tightened, the metal sleeves stick out by approximately 10 mm:

UCA-both2.jpg

==========================================

And this, gentlemen, got me thinking.

If I shorten the sleeve in the front my 10 mm, and find a longer sleeve for the rear (+10 mm), I will effectively displace the UCA to the rear by 10 mm! As a result, this will incline the steering axis by 10 mm, giving me extra caster!

Based on the distance between upper and lower ball joints, this would translate to 1 degree gain of caster!

So this is my RFC (request for comments). Any input will be appreciated. Calling out to knowledgeable members, who know/work with alignment and suspension geometry.
Can this "hack" have a negative effect? How does this compare to aftermarket UCA's that also supposedly displace the upper ball joint? Am I missing something?
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Unread 11-11-2019, 04:13 PM   #2
bulldog
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Interesting idea, however you will want to check the UCA clearance with the coils on full extension. Especially with a Daystar top spacer lift.

IIRC the stock arms have little clearance to the coils on full extension, and sometimes can even bind with the coils using the Daystar lift kit. Moving the UCA back by 10mm will likely cause even more issues.

Fully droop the both sides of the front and measure how much clearance you have first.

Aftermarket UCAs tend have a different bend pattern to create more space for coilers, etc.
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Unread 11-11-2019, 04:46 PM   #3
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Quote:
Originally Posted by bulldog View Post
Interesting idea, however you will want to check the UCA clearance with the coils on full extension. Especially with a Daystar top spacer lift.

IIRC the stock arms have little clearance to the coils on full extension, and sometimes can even bind with the coils using the Daystar lift kit. Moving the UCA back by 10mm will likely cause even more issues.

Fully droop the both sides of the front and measure how much clearance you have first.

Aftermarket UCAs tend have a different bend pattern to create more space for coilers, etc.
Thanks a lot for the comment! Very good to know, I will do that and report back!
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Unread 11-14-2019, 03:19 PM   #4
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Quote:
Originally Posted by bulldog View Post
Interesting idea, however you will want to check the UCA clearance with the coils on full extension. Especially with a Daystar top spacer lift.

IIRC the stock arms have little clearance to the coils on full extension, and sometimes can even bind with the coils using the Daystar lift kit. Moving the UCA back by 10mm will likely cause even more issues.

Fully droop the both sides of the front and measure how much clearance you have first.

Aftermarket UCAs tend have a different bend pattern to create more space for coilers, etc.
Promised update, and I believe it's good news.

Full droop, wheels are in the air, both sides:

IMG_20191113_174657.jpg

Front view. Indeed, there is a point of contact. Upper ball joint is touching the spring.
No modifications have been made yet, just the Daystar 2.5/1.5 kit, that I've been running for 5 years now, but I never ended up in a situation where both wheels were in the air, except for maintenance.

IMG_20191113_174937.jpg

Upon closer investigation and analysis of the contact surface, it appears that displacing the ball joint further back, will actually ELIMINATE the bind with the spring, since it's moving away from it!
And there is plenty of room between the front leg of the UCA and the spring, no way it'll bind there.

IMG_20191113_174716.jpg

Any comments gentlemen?
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