Alignment questions

[demick]

Demick, did they mention how much rear camber was possible? Thanks

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I did my own alignment. I was only trying to increase front camber. I measured rear, but didn't want to increase it for tire wear reasons (I forget off the top of my head what the measurement was, but I'd guess around -1.5deg). So I don't know what the max is. I'd be hesitant to go more than -2 to -2.5 deg on a street car.

Was was really interesting, is after setting the front camber to max (-0.8deg), the toe changed drastically (gave me about 1.2" of toe out!!). I expected the toe change, just not nearly that much. Needless to say, I reset the toe to zero, but not after driving 40 freeway miles and competeting in an autox. Craziest thing is that the handling on the freeway wasn't half bad with that huge amount of toe out. Go figure.

[Adam]

Originally Posted by demick

Demick, did they mention how much rear camber was possible? Thanks

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I did my own alignment. I was only trying to increase front camber. I measured rear, but didn't want to increase it for tire wear reasons (I forget off the top of my head what the measurement was, but I'd guess around -1.5deg). So I don't know what the max is. I'd be hesitant to go more than -2 to -2.5 deg on a street car.

Was was really interesting, is after setting the front camber to max (-0.8deg), the toe changed drastically (gave me about 1.2" of toe out!!). I expected the toe change, just not nearly that much. Needless to say, I reset the toe to zero, but not after driving 40 freeway miles and competeting in an autox. Craziest thing is that the handling on the freeway wasn't half bad with that huge amount of toe out. Go figure.

Interesting, with that much toe it should've been all over the place. Do you have any ideas why Porsche would dial in - camber in the rear, but not the front from the factory?

[demick]

Originally Posted by Adam

Interesting, with that much toe it should've been all over the place. Do you have any ideas why Porsche would dial in - camber in the rear, but not the front from the factory?

Front wheels generally don't need as much neg camber as rears, because they have caster. With caster, when you turn the front wheel, the wheels lean into the direction you are turning - essentially giving you neg camber on the outside wheel and pos camber on the inside wheel. Exactly what you want when you turn. The rear doesn't have this, so it has to be built-in.

[Adam]

Originally Posted by demick

Front wheels generally don't need as much neg camber as rears, because they have caster. With caster, when you turn the front wheel, the wheels lean into the direction you are turning - essentially giving you neg camber on the outside wheel and pos camber on the inside wheel. Exactly what you want when you turn. The rear doesn't have this, so it has to be built-in.

Cool, thanks for the explantion. Caster is the hardest thing for me to wrap my head around. I've been researching it online trying to get a better understanding.

[demick]

Caster not only gives you added camber in whatever direction you turn like I mentioned, it is also responsible for giving stability to the steering system. When you go around a turn and let go of the steering wheel, it has a tendency to self-center. Or just going down the highway, it's why you can let go of the steering wheel and the car will continue to go straight. Both of these can be directly (although not entirely) attributed to caster.

[Topless]

Originally Posted by renzop

Boy, topless sure has a great alignment machine. He can get rear castor - 4 wheel steering anyone?

Very high tech indeed, or... he is kinda old and sometimes suffers from brain fade. Post has been edited for accuracy. Thanks Ren, I can always count on you.

[Kirk]

Originally Posted by demick

Max camber I was able to get with a stock '04S suspension was -0.8deg. Doesn't seem that -1.5deg is in the realm of possibility unless the suspension is modified, or unless lowering the car adds neg camber (I'm not sure if it does or not).

Yes, lowering the car adds more negative camber. Just look at the Porsche specs for stock, RoW, and RoW sport. As the car gets lower the camber specification goes more negative.

I'm going to assume then that I'm wrong here about being able to get -1.5 degrees of camber stock in the front. My recollection must be a bit fuzzy because, again, my car's been lowered for a few years. I'm 99% sure that -1.5 is the max you can go with lowering alone. The Boxster Spec guys are trying to get max camber and I think this is the most they can get with just PSS9 coilovers. To get more they either use camber plates or GT3 control arms.

I've driven with slight positive toe in the front and I don't like it one bit. The car gets real darty on the highway. It may be ideal for a dedicated autocross car, but I don't think it's probably ideal for a street driven car or for a higher speed track setup.

Kirk

[brp987]

Does anybody know? Do gt3 arms start at 0 camber and go further negative with each shim, or start positive and go negative? My eibach'd car is at -2.8 (rear) and I'd like to get it to -1.5.

Is there any way to get stock camber on a lowered car if your adjusters are max'd out?

[castors wheels]

Very informative discussion and never seen before. Thanks for sharing with us.

[Adam]

Originally Posted by brp987

Does anybody know? Do gt3 arms start at 0 camber and go further negative with each shim, or start positive and go negative? My eibach'd car is at -2.8 (rear) and I'd like to get it to -1.5.

Is there any way to get stock camber on a lowered car if your adjusters are max'd out?

I believe you can dial out camber or dial more in with camber plates. Also I think to get everything lined back up from the drop many people install aftermarket drop links.

Just to update the thread I took my car in for an alignment a couple months back and the most negative camber they could get up front was -.5. However, it had about .5 degree of positive camber on each front wheel when I took it in so there was about 1 full degree difference and it did handle better. Rear camber was -1.5 so I just left it there.