Front end setup Caster/ Camber thoughts/ theories ?

Been reading a fair bit of theory on the subject, as having consulted the setup guides for rocket and lazer. Lazer doesn't call for a lot of caster or much of a split, where as rocket calls for a pretty substantial amount of RF caster with a great deal of split between. Going over the settings on my front end for my car which is originally a black front rocket with raise cross member/strut mount and raised rail, have talked to a few local who are pretty in the know but none seem to have any thoughts on were i should start. Camber given the style track we run everyone pretty much maxes out whatever they can get without getting into the shock around here an i guess that is what we are gonna start with here. Also any big thoughts on bump steer ?

caster and camber run rocket standard numbers bump.050-.075 out per inch of compression travel from ride height min .150 at 3". 0-.015 out per inch. never in. From 1"compressed to 2"droop. Some are more aggressive on the rf but these numbers won't steer you wrong. (Pun intended)

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Originally Posted by Jking24

caster and camber run rocket standard numbers bump.050-.075 out per inch of compression travel from ride height min .150 at 3". 0-.015 out per inch. never in. From 1"compressed to 2"droop. Some are more aggressive on the rf but these numbers won't steer you wrong. (Pun intended)

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I like it, just trying to better understand the numbers, everything information wise is so geared toward asphalt, I follow the raceknowhow guys and they cover some good stuff, but everyone seems to neglect front end geometry like its some voodoo science. I know that there is alot of gains to be made there if you understand the changes and why your changing them.

you are correct but your not really changing geometry by changing your base settings you just moving the start and stop point. So unless your planning on cutting on the car the best results are generally found from running the manufacturers recommended settings. Also back in the day we would chase camber settings based on tire wear. But just because your tire is wearing evenly doesent necessarily mean your settings/ geometry are promoting the best handling. And this isn't directed at anyone but the average guy needs to worry more about maintaining his suspension ie.... bent ball joints bad heims binding upper control arms straight spindals!!!! Etc. And keeping up with the changing racetrack through the night then trying to find speed in altering front end settings. Also don't try to mix or compare settings from one manufacturer to another because its not apples to apples for a whole slew of reasons

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Originally Posted by Jking24

you are correct but your not really changing geometry by changing your base settings you just moving the start and stop point. So unless your planning on cutting on the car the best results are generally found from running the manufacturers recommended settings. Also back in the day we would chase camber settings based on tire wear. But just because your tire is wearing evenly doesent necessarily mean your settings/ geometry are promoting the best handling. And this isn't directed at anyone but the average guy needs to worry more about maintaining his suspension ie.... bent ball joints bad heims binding upper control arms straight spindals!!!! Etc. And keeping up with the changing racetrack through the night then trying to find speed in altering front end settings. Also don't try to mix or compare settings from one manufacturer to another because its not apples to apples for a whole slew of reasons

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I agree, I'm pretty savvy with the regular maintenance aspect of racing been working on late models, street stocks and mods for a very long time for a young guy, and been apart of some pretty successful campaigns in all these divisions. That said its my car now and trying to really understand these things better. I know what worked for other guys whos cars i helped setup, but never really understood why some cars/drivers took better to high caster numbers so liked the feel for one reason or another of very low split, while others seemed to like more radical settings. Part of the problem is ive never meet a driver that could tell me why they liked any change out side of it felt better. I want to know why it felt better, did it make it easier to turn in, did it hold the turn better ect, maybe i ask to many questions and should just fall in line and do as the book says lol. I thank your in put i really am here just to learn and absorb whatever knowledge is out there.

The more total (both sides)caster a car has the more force/ feed back their is in the steering wheel. The bigger the left to right split is the more the front end pulls into the corner. Ex. When you load the car in the trailer or let go of the steering wheel while driving and the wheel pulls left the caster split is the main contributor to that. Caster also plays a big roll in jacking weight while counter steering this is realy big in street stock and stock suspension classes. If a driver likes a loose race car he may prefer alot of caster and a larger split. This will promote the turn in and then when the car is bent more caster in the rf will create more dynamic loading when steering to the right. This tightens the car back up or in a different way of saying it helps the driver catch the car with the wheel. A real type a or straight driver may prefer less caster because he wants to point the car with the steering wheel. Late models have so many other dynamics effecting overall handling that i feel these effects while still very present aren't as dramatic but in the stock suspension and carting stuff it's huge especially for driver feel\preference. Hope this made sense and helps

Bumpsteer: This isn’t quite as important as it was before, since usually the RF doesn’t travel much like the old days where it compressed more during cornering. Before we used to use more bump out on RF to help with Ackerman while cornering, now it doesn’t really need to bump out as much as long as you know your dynamic toe’s and Ackerman. It can be a much simpler bump pattern now as the RF is working in a smaller travel range then years past. Not saying it doesn’t matter, but as long as the dynamic toe out is somewhat correct that’s what you’re after.

Camber: Ok, I’m going to play devils advocate here. Why does the RF need 11 to 16 degrees of camber but the RR doesn’t? Meaning if that max camber is beneficial to the RF to make the car steer better, then why wouldn’t the RR gain a butt load of lateral traction if it had some camber also????

There has to be a reason? Either the RF has way too much or the tire isn’t actually seeing what we think it does? I mean if that RF really needs that much then surely the RR would benefit from least a few degrees.

Caster: This sort of relates to the camber in a way, if guy’s figure out where I’m going to on the camber post above. Caster is also gonna vary car to car just out of design, because some cars have caster loss and some have caster gain. One car may have higher static numbers then another but end up dynamically similar or could be still vastly different.

Won't let me edit:

Bumpsteer: This isn’t quite as important as it was before, since usually the RF doesn’t travel much like the old days where it compressed more during cornering and come back up more late exit and straights.

I would add kingpin inclination and scrub radius to factors not usually discussed, but relevant to why different settings are used by different manufacturers.

Billet's post about camber, as I see it, relates to actual dynamic camber at the RF at dynamic ride height, for given lateral load while cornering.
FYi, stagger gives a smal degree of camber to rear tires. Too much rear camber can become a compromise between lateral grip and forward drive.

Good info here guys thank you all for getting into the details of why and how in this stuff Works cause and effect. Love all the technical stuff that helps me understand how this stuff works together. Never was one to just accept the this is what your supposed to do and that’s why we do it answer.

4.75" of rear stagger is only .658 degrees of negative camber on the RR. SIDE note: this is not taking account that the LR has less air pressure and bags more then the RR would thus making the static camber more then that .658 degree's.

HMMM

Now think about dynamic camber in the rear axle.

What do wheel weights look like mid corner?

How much difference is there really in dynamic camber?