CA's What do they do?

What do they do? UCA's + LCA's I've read a Bunch why you need to upgrade them when you lift but. But WTF do they do?

 

The basics on an aftermarket UCA:
Stronger.
Allows for better range of motion.
Set at a different position from stock to allow for proper alignment geometry.

Basics on LCA:
Stronger.
Allows for better range of motion.
Optional lower tab for a secondary bypass shock.

UCAs and LCAs are different for stock length and long travel, but same basic benefits.

Does this answer your question, or what exactly would you like to know?

 

What is their function in suspension?

 

The control arms are what attach the spindle to the frame, the shock/strut assembly is connected to the lower control arm on the bottom side and the top side is mounted into a coil bucket on the frame.

 

http://www.fabtechmotorsports.com/suspension-101.php

https://www.tacomaworld.com/threads/tacoma-lift-faq-guide-read-this.11282/

 

Thank you

 

You're welcome. It is complex, dynamic geometry to begin with. Modifying suspension has many potential effects, depending on the specific modification...and of course this is complicated by the fact that the wheels turn left and right. Add to that aftermarket wheels with specs different from OEM parts (diameters, backspacing, offset, etc.), and around those wrap any number of different tires.

All that said, usually the most common issue after lifting is poor alignment results regarding caster. Too little caster makes the truck twitchy at speed. Stock UCAs are limited in the amount of caster they can provide. Aftermarket UCAs typically provide adjustability or built-in amounts if increased caster to accommodate this shortcoming and keep the truck more stable and tracking better. They can also provide a little more downward articulation (droop).