Ranger

I've been reading old posts re. camber (here and in Racing & DE forum) and it seems to be a contradictory mess. Like a lot of folks, my car is a dual-use DE and street machine. But it lives for the track so if it's streetability suffers, that's ok.

But if you read all the camber posts here carefully, you will see some posts that say that the rear should generally have more neg camber and some that say that the front should generally have more neg camber. Usually with -0.3 to -0.5 separation. An example from last Apr:

JimB says he runs -3F and -2.5R on his 996 racecar.

02 Carrera recommends to Galun that he should try -1.2F and -1.6 to -1.8R.

My perception is that both these guys are very knowledgeable. So why does one seem to subscribe more neg camber in the rear (relative to the front) and the other says less?

The above was just one example among many. What am I missing here?

Bob Rouleau

A wide wheel needs less camber so it is normal to have less in back on a 911.

AudiOn19s

The front should require more camber in a track setting.

However there are no inexpensive camber solutions for the 996 at the front so many people often get the most they can in the front and run what's appropriate in the rear ending up with more rear camber than front just becuase it's easy to get camber in the rear and very hard / expensive to find a solution for the front.

a .5 degree to .75 degree more in the front (depending on what tire) is the ideal setup IF you've got GT3 control arms or camber plates or both to get those values in the front of the car.

Andy

Ranger

Ok, but let me be a devil's advocate for a moment. There are smart folks here (and RennTech and PCA) saying that you need more neg camber in the rear. Are we going to say that the reason they think that is because rear camber is cheaper?

You guys in the "more rear camber" school of thought....... what is your reasoning?

JimB

If you want to go fast and have the tires and suspension to support it, your car should have -3 to -3.5 degrees of camber in front with about .5 less in back. So -2.5 to -3. Your front toe should be set at .5 to 1 mm out with your back at about 2 mm in.

Having said that, it's not realistic in a street/track car. Especially, as Andy pointed out, with the limitations you have on camber. I would max out your front camber up to around -2.5. I'm guessing your max will be much less. Then subtrack .5 from your front camber. If it's more than -1.5 then use that number. If it's less than one -1.5 then use -1.5. So:

Front = -2.5 set rear at -2
Front = 1.8 set rear at -1.5
Front = -.75 set rear at -1.5

Just my 2 cents worth.
Jim

JimB

There is no 996 racer that will tell you that more rear camber is faster. If you find one I promise you they are not fast. (Oddly, 997 cup cars are running more camber in back but that's a different story) The only reason that you would run more camber in back of a 996 is that you can't get enough front camber to be above the minimum (-1.5) that you need in back.
Jim

STDFAST

Interesting enough... This weekend I went to get my 996 aligned and found that it was done totally wrong. I'm running 285 30 18's in the rear. and standard in the front. After they finished with my car, it was lose as a goose and still pulling to the left:-( I'm not driving it again until it fixed correctly.

I'm a street driver as well, yet am interested in tracking it maybe 2 or 3 times a year.

The problem is, I don't totally understand the whole camber & toe thing (negative in the front & back, etc) Can someone please help me out with that so that I can follow this conversation. thanks in advance.

STDFAST

Doug Donsbach

Alignment basics:

http://www.familycar.com/Alignment.htm

STDFAST

thanks...

JimB

To add to the article, on the street alignment is primarily about making your car stable while minimizing tire wear. On the track, it's all about maximizing your cornering ability without totally destroying your tires on the straights. You don't worry about the car being a little unstable (darty) or about tire wear. That's why it's so hard to come up with a good alignment for both.

Ray S

That is the real problem. For a dual use car, the original poster is probably best off using mildly aggressive street settings.

If he uses the values you used on your 996 race car he will destroy his street tires when he puts them back on.

JimB

I agree Ray although he does state he wants more of a track setup. I think if I were in Ranger's shoes I'd put as much camber in front as I could up to about -2 and set the rear at -1.5. I'd set the rear toe at around 2 mm in and leave the front pretty close to zero. The car would wander a bit on the street and wear tires but would do ok on the track. I hate compromises.

You missed a good time at the BRIC. What an event.

Ray S

Bummer, I just didn't have the time. I am going to Gingerman next weekend and then I'll probably look for you at TRAC (Road America).

You're making me cry when I think about my Boxster set-up.

I could make the car faster, but I don't want to sacrifice the tire wear on the street.

Kerry

With the stock suspension, even M030 ROW sport suspension, you might get -0.5 camber up front. So, you'll end up with -0.5 front and -1.5 rear.

Ranger

Good feedback guys, thx. My ROW M030 allowed -1deg F and I put about 20 track days on that. Based on my, apparently wrong, research I was running -1degF, -1.5R.

I've just dremeled out the front strut mounts and now can get -2F. But I wanted to keep 0.5deg separation and I couldn't get -2.5R. So I ended up with -1.6F -2.1R. Note that I was still under the impression that more rear camber was desireable.

Note Kerry's post above. He is advocating more REAR camber. See how much of a clusterF this issue has become?

Are we comfortable that the "school solution" is 0.5deg separation between front and rear? My understeer issues used to be significant, but now they've largely gone away. A little bit of oversteer is occuring tho. One of the things that I want to work on this weekend is to figure out if my oversteer is consistantly "power-on" oversteer or "not-enough power on" oversteer. I need to figure out which is really an issue and which one is just my crappy driving.

My point is that I'm in a small struggle with oversteer and the guidance for me seems to be to reduce rear neg camber. That sounds, a, problematic.

So given my adjustment range and what you've told me, I should set my camber to -2F, -1.5R. But since I'm working on reducing oversteer, what are your thoughts on -2F, -1.7R instead?

I haven't played with toe yet. I'm tempted to go ahead and do that, but I don't want to change too many variables at once.

Re. tire wear. I'm on the track 4-6 days/month. Street tires. The tires don't get much chance to wear on the street. 4 months is 20 trackdays and the tires are shot.

Re. compromises. Roger that. It kills me that there are so many compromises between track and street. Inevitably, I end up with something that is less-than-ideal for both. I'm thinking about getting into E30 spec. But my credit cards are counseling against it.