Today I am replacing the front front control arm on my 82 rx7. I decided i should look into the caster/camber adjustment because they are set differently on both sides, and last week when i had an alignment done i had a ton of camber on one side and none on the other.

My problem is that the FSM seems to be wrong in the way it explains to adjust caster. It explains that in order to achieve maximum positive camber and maximum positive caster i should move the strut top forward and in. This is labeled position C in the diagram. Common sense tells me that moving the strut forward would either make caster zero or negative. Am i over thinking the situation, or is the FSM wrong?


This thread on nopistons has a post by j9fd3s that reads "if you look at the strut top the strut is off center, you want it to be rear and inwards, this gives you the most negative camber and the most caster." which contradicts the FSM and confuses me.

 

the strut top is on a square pattern, but the actual strut is not centered in the strut top, so you can rotate the strut top to change the camber and caster. i find it easier to just look at the position of the nut than the a,b,c,d positions, Mazdas way is too complex.

positive caster is when the strut is angled back, top of the strut is behind the center of the wheel. negative cater is when the top of the strut is forward of the center of the wheel

positive camber is when the top of the tire is leaning out, and negative camber is when the top of the wheel is leaning in.

the stock setting is 1 degree positive camber, and i think 4 degrees of caster. for a performance application, you actually want 1 degree of negative camber (or maybe more, in the race cars we generally run 2-5 degrees), so i like to rotate the strut top to get as much negative camber as possible (which isn't much).

i also put it in the spot where it gets the most positive caster.

this has the strut in and rearwards.

i do find that the strut tops are not usually in the same place side to side when i get a car, and Mazda's alignment doesn't have equal caster, plus there is 30 years for someone to have aligned it, or changed the struts without paying attention to where they orient, etc

and then of course, the adjustment range is so small, it doesn't matter a lot.

 

Not sure about a street car but on our chumpcar we have the camber plates as far back as possible to maximize caster, and run about 3 degrees of camber

 

Thanks
But I didnt mean to give the impression that i do not know what caster or camber are.
Thats the purpose of this thread.
I was confused why the FSM would tell me to use position C to gain the most positive caster and most negative camber.
Why does the FSM say that most caster and camber is gained when at position C not position D?

I now realize that the FSM is showing relative change when comparing between position A. Which seems like a stupid (and complex as you said) way to describe the change.

I think attached picture would of been far more helpful

 

i read as many FSM's as i can find, but keep in mind it is a book translated from japanese.

or maybe the best one is that there are pages that say "this page intentionally left blank". how can you have a blank page when there is writing on it?