2004 time trials M3 caster

[snaponbob]

How much caster is TOO much ??

Currently running 650/750 springs, bars, and 285/30x18 tw200 tires and static front camber -3.3°

[aeronaut]

Every time I've asked this question I always hear, as much as possible. It's even what the competition tire manufacturers say. Maximum castor. I'm sure physics shows something goes awry eventually, but does anyone get more than 8 deg on our cars?

[snaponbob]

Every time I've asked this question I always hear, as much as possible. It's even what the competition tire manufacturers say. Maximum castor. I'm sure physics shows something goes awry eventually, but does anyone get more than 8 deg on our cars?

Well, apparently none of them know much about BMWs !!!!! Mine (2004 M3) is lowered (for racing, not stance shit) and running Ground Control race suspension. In stock trim, specs show about +7 deg of castor. With my camber/caster plate slammed all the way back, I have +12 deg of castor. A friend has a viscous V8 power E46 M3 that is BUILT, owns a well respected prep shop in the KC suburbs, and KNOWS BMWs. I asked him, and his (initial) answer was "E46s love castor". I asked him what he thought about 12, and said "umm, that's sort of a lot". I goggled it and spent some time absorbing some info.

Given tire temps, wear patterns, and handling characteristics, I may be running too much. That is why I asked.

The car is parked for the winter, so I have time to learn more. I'm going to rest everything up front based on +9 deg of castor and see how it works in the spring.

[aeronaut]

12 is a lot. lol. With that much caster, you'll get a lot of added camber with steering angle.
But with your plates maxed out with caster at 12, can you still get -4 or so static camber? Do the wheels have enough space in the wheel wells to turn w/o rubbing?
So yea, I don't know about 12.

[snaponbob]

12 is a lot. lol. With that much caster, you'll get a lot of added camber with steering angle.
But with your plates maxed out with caster at 12, can you still get -4 or so static camber? Do the wheels have enough space in the wheel wells to turn w/o rubbing?
So yea, I don't know about 12.

I had to roll my front fenders short of distorting the wheel opening. Right now have 285/30x18 Falken RT660s on ARC8 10.5/18 wheels. When I had 285/30X18 RE71s, I was running -3.6 camber and +12 caster with no issues. BUT, the 660s are REALLY stiff, a tad wider tread. The 660s are stiff enough that I have been running 3-5 pounds less pressure but had to reduce camber. I was limited by tire run at the edge of the wheel arch so could not under -3.3 camber. NO issues with rubbing anywhere else except the inner/rear of the wheel well, but only when turning tight off track.

So, with -3.3 camber and +12 castor, I may be running too much caster -- at least for the 660. Since there are few 285s (that won't burn down a bank), I may have to go to 275/35s, give up a bit of tread width, but get more of the tread "working" on the ground.