Quote:
Originally Posted by Pedro367
Curious if you'd actually see a difference between 4+ degrees or so with a JBA or 5.5 degrees with a Camburg in a normal application. I.e. your everyday 4R with a 2-3" lift and 285s.
|
There's probably a limited benefit between the two, but there's also a downside to high caster arms. Namely adding caster via the upper control arm results in potential for reward relocation of the spindle for two reasons. First is that it physically moves the upper ball joint back to increase caster. Adding 4 degrees of additional caster would require roughly 2cm of relocation of the upper ball joint and that translates to maybe 0.5cm of rearward adjustment of the spindle center with the lower arm unchanged.
Where it's a bigger issue is if you have something like say a 2" lift and you max out the cams on the LCA and you can get 2* of caster. So now if you add a 4* correction UCA - you would then have 6 degrees of caster. Probably too much. So the alignment back to 4* caster will move the LCA back about 1cm and the UCA is back about 2cm, net is probably 1.25cm movement of the spindle (and therefore the wheel location in the fender) toward the firewall and body mount. So, particularly on less than 3 or 3.5" lift heights, the extra high caster arms may give you good alignment geometry, but also cause significant rub where it cleared before.
And if you watch the videos testing travel, you'll see that the higher lift heights result in significant reduction in front articulation and travel. Probably 1.5-2" lift is the best bet and that puts you in a bit of no-man's land UCAs except for the adjustable ones like SPC that let you keep the full forward lower control arm and therefore wheel placement relative to body mount, but also dial in the proper caster and camber. I'm becoming more and more of a fan of the SPC design despite not having ever had them so I can't say from experience.
I think there's a real market for an OEM style stamped low cost arm that adds only 2* of caster, or an aftermarket LCA that adjust caster by 2* for folks who want to run a low height lift, have good geometry, but also run larger tires. I've set mine down to roughly 1" front lift for daily driver duty and I ended up swapping back to the OEM UCAs for this reason - I had too much caster with the JBA at that height and the correct adjustment on the LCA ended up causing rubbing with 34" tires. But with the OEM UCAs I can still get about 3.8* caster, great highway manners, and still fit 34" tires with plenty of fender clearance even with 1" wheel spacers.
Just some experience that might help someone. If you're going 2.5" plus - for sure go for UCAs to correct caster. If you're sticking below 1.5" - I think the OEM ones are better in most cases. If you're going between 1.5 and 2.5 - it's not obvious what the best choice. You're stuck in the middle without an adjustable UCA.
Final thought - I Fawking hate the LCA cam hardware. It's expensive. It seizes very quickly. And it's a huge PITA to get out once it has seized. I need to design a fix kit for it. I have a few ideas of a fix that wouldn't require cutting out the old bushings and sleeves. I'd also love to try building a mini hydraulic press to press out the seized cam sleeves in place, but I just don't have time right now to do it. I think a kit for a portable hydraulic press could be build to do it though and save a lot of alignment shops a lot of labor. Ideally - Toyota should put some better coatings on the hardware so we don't constantly have to fight with this shit. If I buy another new Toyota - I'm going to include that in the sales agreement that the dealer pull them apart when new and completely slather them in antiseize and then re-align it before I take delivery. It's annoying to me to have this issue at 50k miles.
Hybrid Mode
