I need to adjust the caster on my Z1 adjustable front UCAs. The only thread in which these UCAs are mentioned is in the vendor classifieds, and neither that thread nor the instructions give specifics on making adjustments. The instructions say “measure and set Z1 FUCA to OEM FUCA specification.” I believe there are only two possible adjustments on these: 1) the chassis-side mounts can be adjusted by one-half rotations (and must be threaded equal in length), and 2) the steering knuckle-side can be adjusted one full rotation at a time.

My question is how can caster be adjusted on these things? I believe the SPL brand UCAs adjust caster at the chassis-side mounts. My Z1 brand chassis side mounts are set the same for both sides of the car and caster is off by .6 degrees. JasonZ-YA said somewhere that a .5 degree difference is too much even though factory specs allow for .75, and I’m pretty sure I can feel it on the freeway. If I add length to the chassis-side mounts, will this increase or decrease caster? How will decreasing caster affect toe and camber?

Background: I have had 2 recent alignments. When I first installed these UCAs, I set the chassis-side mounts and the steering knuckle mounts to the same lengths for both sides of the car. Because my passenger side had more negative camber at alignment #1, I lengthened my passenger side steering knuckle mount by 3 rotations (to increase camber) and the driver’s side steering knuckle mount by only 2 rotations (increase camber, but not as much). I should have kept them equal, because now my driver’s side has more negative camber. Also between alignment #1 and #2, I changed the compression rod bushings from Energy suspension to SPL. My car is running factory springs, shocks, and sway bars.

Alignment #1:



Alignment #2:

 

I would thread in the right side forward body mount one full turn. This will decrease caster and increase camber on the right side.

 

Awesome, thank you! And just to clarify, when you say this will increase camber, you mean increase negative camber (to bring closer to the left side)? And I'm guessing I need to get another alignment after doing this?

The instructions have a note, "assure chassis-side mounts are threaded equal in length. Failure to do so may result in catastrophic damage to FUCA and/or vehicle." I have a lot of faith in terrasmak's Z knowledge, I just wanted to throw this out there. I suppose if the chassis-side mounts are always equal in length, the caster would not actually be adjustable.

 

If you have the arm on the left in the pic it will be fine. If you have the arm on the right in the pic I could see it causing extra wear on the bushings from having the bolt crooked in them.

 

Correct, your toe will be off when your done.

With a good alignment tech, you can pay them to make the proper adjustmets to square it up. Most places do not want to make adjustments if it was not adjustable from the factory, they also just care about getting it in the green and off the rack.

Alignments prices have seriously gone up in the last years, while quality work has seriously gone down.

 

I did what terrasmak recommended (thread in passenger side front chassis-side mount one full turn) and I am much happier with the alignment:




Camber is now perfect all around. Maybe toward the end of the summer I will try to narrow in the caster difference, but I've spent enough money on alignments for now and the Z feels great, especially with my new squared tire set up, also recommended by terrasmak. Thank you, you've been a great help! I can't wait to feel the difference on the track.