dyi front camber mod

[baxster]

The box is mostly for street, then some auto-x, and hopefully some DE days. It has 17" S-02A's.

From what I've read, maxing the front camber will get you something like .5 to .7 of neg camber, and that's with about 1/2 inch of movement of the strut tower bolts. If I can get 1/4 inch more movement of the bolts, I might be able to get up to 1 degree negative camber.

Are you saying that -1 deg of front camber will make my braking noticeably worse?

[insite]

-1 up front is too much for street tires. -0.8 is about perfect. aim for -1.8 to -2.0 in back. the amount of neg up you can get up front will depend on whether your car is lowered or not. when you lower your car, neg camber increases.

and yes, more neg camber reduces braking distances. you are trading straight line traction for turning traction. always a trade off......nothing is free.

[Pat]

The nice thing is, with increased camber you don't have to slow down as much for corners, so loss of braking isn't such a big deal.

[j.fro]

Just some information, FWIW.
I use aftermarket struts with mounts that give me a lot of camber adjustment. Camber is set to -2.3 degrees up front with zero toe.
In a typical year, I'll put 12,000 miles on the car and do 12-14 auto crosses. The car eats two sets of tires: a set of r-comps for the AXes and a set of street tires for the rest of the driving. Every spring my tax return goes straight to a tire purchase.
Is it sensible? no way!
Is it fun? HELL YEAH!!!

[baxster]

Originally Posted by j.fro

Just some information, FWIW.
I use aftermarket struts with mounts that give me a lot of camber adjustment. Camber is set to -2.3 degrees up front with zero toe.
In a typical year, I'll put 12,000 miles on the car and do 12-14 auto crosses. The car eats two sets of tires: a set of r-comps for the AXes and a set of street tires for the rest of the driving. Every spring my tax return goes straight to a tire purchase.
Is it sensible? no way!
Is it fun? HELL YEAH!!!

I think 'insite' would say that your braking will suck at -2.3. What have you noticed with your braking with street tires at -2.3 camber?

[j.fro]

The brakes are unreal! I've got Hawk HP Plus pads, stainless brake lines, and use Ate Blue. I can brake very late and still get no understeer in a corner. But that's for AX on the R-comps. I don't push my street tires nearly hard enough, and as a result the inside edges wear fast. I'm lucky to get 10K on a set of front street tires, but that's the price of an aggressive AX set-up. There really is no such thing as a car that does everything well .

[insite]

the max camber a given tire can use is proportional to the tire's grip capability. if you use too much camber for the tire, you won't be using the entire contact patch & you'll lose total grip.

imagine zero camber: when you turn, the tire rolls over onto the sidewall. the result is that you're using the outside half of the tire too much & the inside half of the tire not at all.

imagine correct camber: when you turn, the tire rolls, but because of camber, the tire actually rolls ONTO the contact patch, giving you 100% of the tread contact with the road.

too much camber: while straight, the tire rides on the inside shoulder. when you turn, the tire rolls onto SOME contact patch, but the outside half of the tire is still not making good contact with the road.

the result of too much camber will be that the insides of the tires wear too fast. also, ultimate grip in corners will be reduced because you've actually reduced the size of the contact patch.

keep in mind that CASTER affects mid-corner CAMBER, so while you may only have -0.8 dialed in with the wheels straight ahead, when the wheels are turned & the suspension is compressed, you will have significantly more (-2.5 or more). it's easy to go too far w/ front camber on street tires w/ the boxster because the car has a LOT of caster designed into it.

to understand caster, it helps to illustrate extreme scenarios:

zero degrees caster: the rotational axis for the steering is completely vertical. turning the steering wheel ONLY turns the wheels right & left.

90 degrees caster: the rotational axis for the steering is completely HORIZONTAL (i.e. straight out in front of the car). turning the steering wheel tilts the tires left and right, but does not turn them at all.

SOME caster: turning the steering wheel BOTH turns the wheels AND tilts the tires.

as to braking, less camber generally means better braking distances. that's not to say that great braking doesn't exist w/ heavy camber, only that great braking gets even BETTER with less camber.

that having been said, the reason i say -1 may be too much for street tires has more to do with wear & grip than braking sacrifice. you will wear the insides of the tires down.

[baxster]

Originally Posted by insite

-1 up front is too much for street tires.

With the mod I'm talking about, I'll probably be lucky tp get up to -1. Why is -1 too much for street tires?