Someone Who Knows LCA Cam Bolts... Take me to school!

[WEAK_E90]

I came upon this video this weekend - yes its a 3rd gen but it looks to be the same as a 5th gen (cam bolts rear/front).

In the video he states this is the proper way to have your cam bolts set in order to achieve maximum caster...

Currently right now I have aftermarket ucas set for maximum caster. yes looking for just 0.5deg more for clearance.

My curiosity comes in wondering if i could achieve another 0.5degree or even 1.0 degree by setting my cam bolts like the gentlemen states in his video:
see 0:21-1:23
https://www.youtube.com/watch?v=v1RXnk7b2Bs&t=79s

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTaMQBzh4I5htJejuH5vOWGHRirzjTnFuqnaw&usqp=CAU

reviewing my alignment sheet drivers and passenger sides are almost identical but yet it seems i rub much more on the passenger side than the drivers side (measure from center of hub i have 0.25" less clearance...) any chance what it could be because of?

 

[Jetboy]

That is the correct way to maximize caster. But there's more to alignment than caster. The same tabs also set the camber and you want some cross caster. So you rarely are able to set them fully forward on the caster adjustments and still get a decent alignment overall. And almost never can you set both sides all the way forward and have a vehicle that tracks well due to the need for some cross caster.

The exception to this is adjustable upper control arms like the SPC ones. With the SPC arms, you can set the cams full forward and then adjust the UCA to get the right caster and camber. The SPC arms are one of a few options for adjustable UCAs that allow you to setup the front suspension better for clearance.

Hope that helps.

 

[WEAK_E90]

That is the correct way to maximize caster. But there's more to alignment than caster. The same tabs also set the camber and you want some cross caster. So you rarely are able to set them fully forward on the caster adjustments and still get a decent alignment overall. And almost never can you set both sides all the way forward and have a vehicle that tracks well due to the need for some cross caster.

The exception to this is adjustable upper control arms like the SPC ones. With the SPC arms, you can set the cams full forward and then adjust the UCA to get the right caster and camber. The SPC arms are one of a few options for adjustable UCAs that allow you to setup the front suspension better for clearance.

Hope that helps.

very much does! i have spc upper control arms and if im understanding you correctly i could set the LCA cams all the way forward and use the UCAs (SPC) to bring the camber back in (or attempt to)

is that correct?

 

[Forgetful]

Maximizing caster with the LCAs is managed by setting the rear cam bolt so it's pushed out towards the tire and the front bolt pulled in away from the tire. Then I tweak the front bolt to get the camber needed. (This is for a 2in lift with OEM upper and lower arms).Then adjust the toe. Drive it a few feet to let the bushings settle.

Then go back and adjusted the camber and readjust the toe. Drive it again. repeat till good.


Adjusting the toe will affect your camber and vice versa. So until you get a feeling for how much each affects the other it's a iterative process.

This is why a good alignment shop is worth it.

 

[WEAK_E90]

can one have max caster from spc's (+4deg) then set LCA cam bolts for max caster to achieve more? I understand there are other factors (toe, camber)

But to truly achieve max caster 1) spc would need to be set to max. 2) LCA would need to be configured for max.

Is that a true statement?

 

[Jetboy]

very much does! i have spc upper control arms and if im understanding you correctly i could set the LCA cams all the way forward and use the UCAs (SPC) to bring the camber back in (or attempt to)

is that correct?

Yes. That's correct. You could set the LCA cams to move the lower ball joint forward as far as possible. That is what is shown in the video. You would do that on both sides. Then you would adjust the SPC upper arm to set caster and camber. It may not be the same SPC setting on both sides to achieve this. A good alignment shop who is familiar with SPC arms should be able to quickly align it for you.

I don't think you probably want the max possible caster with the SPC arms. Depends on your setup, but it may be too much caster for good driving. Also - increasing caster means changing the relationship between the lower and upper ball joints. So increased caster on the lower ball joint means moving the lower ball joint forward. Increasing caster via the upper control arm means moving the upper ball joint backward. More caster via the upper control arm moves the wheel back toward the firewall. What you should target is about 4 degrees of caster once the lower control arm is set to move the lower ball joint as far forward as possible. That will give you the best driving and the most firewall/body mount clearance.

 

[WEAK_E90]

Yes. That's correct. You could set the LCA cams to move the lower ball joint forward as far as possible. That is what is shown in the video. You would do that on both sides. Then you would adjust the SPC upper arm to set caster and camber. It may not be the same SPC setting on both sides to achieve this. A good alignment shop who is familiar with SPC arms should be able to quickly align it for you.

I don't think you probably want the max possible caster with the SPC arms. Depends on your setup, but it may be too much caster for good driving. Also - increasing caster means changing the relationship between the lower and upper ball joints. So increased caster on the lower ball joint means moving the lower ball joint forward. Increasing caster via the upper control arm means moving the upper ball joint backward. More caster via the upper control arm moves the wheel back toward the firewall. What you should target is about 4 degrees of caster once the lower control arm is set to move the lower ball joint as far forward as possible. That will give you the best driving and the most firewall/body mount clearance.

Thank you again for the response! very helpful!

my spcs are maxed for caster (+4/5deg) and with my setup i need a little more room behind the wheel (only on one side yet my caster is dead even on both... confused) (so need more positive caster). If i cant do anything with my UPCs (because im maxed already) i was wondering where else i could get additional positive caster from (which is when i saw the video of LCA's). My LCA bolts are setup for MIN CAMBER (per the pic here) so i think i can adjust those slightly and hopefully gain just a little bit to stop rubbing
https://www.alldogsoffroad.com/images/uploaded/Lockout Plates Camber.jpg

 

[Jetboy]

Thank you again for the response! very helpful!

my spcs are maxed for caster (+4/5deg) and with my setup i need a little more room behind the wheel (only on one side yet my caster is dead even on both... confused) (so need more positive caster). If i cant do anything with my UPCs (because im maxed already) i was wondering where else i could get additional positive caster from (which is when i saw the video of LCA's). My LCA bolts are setup for MAX CAMBER (per the pic here) so i think i can adjust those slightly and hopefully gain just a little bit to stop rubbing
https://www.alldogsoffroad.com/images/uploaded/Lockout Plates Camber.jpg

Adding caster with the SPC arms reduces the clearance. So you would want less caster adjustment on the upper arm to get more body clearance. But the reverse is true on the bottom. So if the bottom is maxed out, you need to start reducing caster on the top UCA if you want to gain more clearance at the body mount/firewall area.

But keep in mind that the lower ball joint is closer to the spindle center. So an extra degree of caster from the LCA will have a lot more movement of the wheel center than the UCA. I think it's about 4:1 ratio or something like that.

The chassis will have variation between each one. That's why it's adjustable - to make up for variability in the manufacturing of the vehicle. So it's totally normal that both sides are not adjusted the same to get the correct matching caster. And you generally don't want the same caster on both sides. For vehicles that drive on the right side of the road, the right-side tires will have more negative camber and more positive caster.

 

[WEAK_E90]

guess this answered it too
https://www.youtube.com/watch?v=f2YhnldfI50&feature=youtu.be

my lca are not set for maximum caster

 

[j-dub]

The same tabs also set the camber and you want some cross caster. So you rarely are able to set them fully forward on the caster adjustments and still get a decent alignment overall. And almost never can you set both sides all the way forward and have a vehicle that tracks well due to the need for some cross caster.

Hope that helps.

Jet,
Can you please elaborate more on Cross Caster. I understand caster and camber but not super familiar with this idea. I think you are talking about the difference in caster from side to side to deal with the crown of the road, I believe it is accepted to have slightly more caster on the passenger side however I here to learn and not really sure.

If this is the correct thinking, what have you found to work well on this chassis? are we talking 0.1 degree or 0.5 degrees, a quick google says about 0.25 degrees is common however I don't remember seeing that on a alignment sheet.

Thanks,
Jeremy