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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > Rear Negative Camber



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      06-16-2008, 12:59 PM   #1
fast_lap28
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Rear Negative Camber

so what are your thoughts on negative camber (-2.1 or so) in the rear from factory specs? just wondering if any advantages or disadvantages when tracking with negative camber just in the rear. its not alot of adjustment but enough that I could probably tell once on the track?

coilovers w/ camber plates for the front will be done next year. right now I am just playing with what came from factory.

thoughts, experiences?
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      06-17-2008, 03:36 PM   #2
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interestd also, I want to get a new alignment w/ my coilovers.
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      06-17-2008, 04:32 PM   #3
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The more important thing is negative camber in the front...it helps with turn in.
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      06-17-2008, 04:38 PM   #4
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I'm running about -1.8 in the rear and -3.3 in the front with camber plates.

The rears, even with slightly less pressure than the fronts, are showing less shoulder wear. I think I can get away with -1.5 or so, which will help dial down some of the little remaining understeer. I would caveat that by saying that if you're not experienced, you should keep the stock rear camber specs as it'll save your ass.

A 335i slammed into the wall not too long ago when he came into the corner too hot and made the common mistake of suddenly getting off the gas. The trailing throttle oversteer threw his car into the wall. There is a reason why the factory dials in a bit of understeer.

FWIW, I also went with 3/16 total rear toe. That seems to plant the rear end just perfectly. I can really get on throttle on corner exit without too much drama and the car responds so well to throttle steering. With most changing-radius corners, I just set the steering once and steer mid-corner with my foot. Keeps the car nice and happy. Too little negative in the rear might make the car *too* responsive when I try to throttle steer.
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      06-17-2008, 05:02 PM   #5
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What's the right amount of front and rear camber for good, even tire wear? Say... 400 miles a week commuting and 50 miles a week having fun in the hills?
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Last edited by satakal; 08-16-2011 at 05:23 PM..
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      06-18-2008, 01:05 PM   #6
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Quote:
Originally Posted by S4to335 View Post
The more important thing is negative camber in the front...it helps with turn in.

noted. the reason why I asked is because I still haven't purchased my coils, yet I needed to do an alignment and in talking to the BMW tech he had some experience with setting up race cars and asked if I wanted a little more negative camber adjustment in the rear since there was some to be had....

I said heck, why not and lets try it. he said I would be happy with the small adjustment on the track...he knew I was headed to Road Atlanta in a month. the front is aligned to specs so I really won't feel the better turn in until I can get new coilovers. I don't mind a better bite in the rear when coming out of corners....
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      06-18-2008, 02:35 PM   #7
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Quote:
Originally Posted by fast_lap28 View Post
noted. the reason why I asked is because I still haven't purchased my coils, yet I needed to do an alignment and in talking to the BMW tech he had some experience with setting up race cars and asked if I wanted a little more negative camber adjustment in the rear since there was some to be had....

I said heck, why not and lets try it. he said I would be happy with the small adjustment on the track...he knew I was headed to Road Atlanta in a month. the front is aligned to specs so I really won't feel the better turn in until I can get new coilovers. I don't mind a better bite in the rear when coming out of corners....
Hmmm, that sounds like massive understeer to me. INCREASING grip in the back end while not changing the front? push-city.
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      06-18-2008, 02:51 PM   #8
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Quote:
Originally Posted by leftcoastman View Post
Hmmm, that sounds like massive understeer to me. INCREASING grip in the back end while not changing the front? push-city.
I didn't even consider this point, you are right. but since I planned to changing the alignment specs at end of summer I only have one more event to go to and then I can change back to spec. if anything, I will learn to drive pushing out of a corner, heck I need to learn a lot as it is....

what can you recommend to counter the understeer as it is in this case? tire pressures? I'm such a noob.....
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      06-18-2008, 03:45 PM   #9
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Quote:
Originally Posted by fast_lap28 View Post
I didn't even consider this point, you are right. but since I planned to changing the alignment specs at end of summer I only have one more event to go to and then I can change back to spec. if anything, I will learn to drive pushing out of a corner, heck I need to learn a lot as it is....

what can you recommend to counter the understeer as it is in this case? tire pressures? I'm such a noob.....
Best you can do stock is tire pressures (more in back, less in front) and maybe punch out those guide pins holding the strut in front. That'll give you another 1/2 degree or so.

Be careful with too little pressure in front, you don't want to scrub off the tire logo - been there, done that.

Driving an understeering pig is quite a learning experience. I know you're a noob, but read up on trail braking, you can get the car to rotate nicely using it. Corner exit, with all that understeer, will simply be an exercise in patience...before you can get on gas.
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      06-18-2008, 09:30 PM   #10
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Quote:
Originally Posted by leftcoastman View Post
Best you can do stock is tire pressures (more in back, less in front) and maybe punch out those guide pins holding the strut in front. That'll give you another 1/2 degree or so.

Be careful with too little pressure in front, you don't want to scrub off the tire logo - been there, done that.

Driving an understeering pig is quite a learning experience. I know you're a noob, but read up on trail braking, you can get the car to rotate nicely using it. Corner exit, with all that understeer, will simply be an exercise in patience...before you can get on gas.
thanks leftcoastman for all your comments...well taken into consideration, actually I will be reading up on more techniques in coming days including trail braking....

I know what you mean about scrubbing off the tire logo. I ran autox last Thurs. on new RE01R's with pressures at 36F/39R and found that I didn't scrub down to the logo but was getting close....basically I am getting the practice on the new rubber before I head out on the track with this setup.

what tire pressures would you recommend to try out given I have more negative camber in the rear than in the front?

I def want to try different pressures this Sunday for another autox and see how the tires do...so far they look great! good rubber after switching from Falkens Rt615's - they gave me bunch of problems but now I am
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      06-18-2008, 10:24 PM   #11
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Quote:
Originally Posted by fast_lap28 View Post
thanks leftcoastman for all your comments...well taken into consideration, actually I will be reading up on more techniques in coming days including trail braking....

I know what you mean about scrubbing off the tire logo. I ran autox last Thurs. on new RE01R's with pressures at 36F/39R and found that I didn't scrub down to the logo but was getting close....basically I am getting the practice on the new rubber before I head out on the track with this setup.

what tire pressures would you recommend to try out given I have more negative camber in the rear than in the front?

I def want to try different pressures this Sunday for another autox and see
how the tires do...so far they look great! good rubber after switching from Falkens Rt615's - they gave me bunch of problems but now I am
Glad to be of at least minimal help, lol.

Try to shoot for 43front HOT and 40rear HOT. Then play around depending on how the car feels. Do not change things more than a psi or two at a time.

Ideally you want the tires to wear to the "triangle" on the sidewall and no further. If the car still pushes, decrease rear pressure and try again.

Making 5PSI adjustments between sessions is the stuff that wall-visits are made of!


HOWEVER, have an instructor ride with you. A lot of understeer, I've found, is due to a loose nut behind the wheel.

Last edited by leftcoastman; 06-19-2008 at 12:41 PM.. Reason: got my increase/decrease backwards
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      06-18-2008, 11:16 PM   #12
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Just got an allignment today. Never did it after changing back to stock. Toe was way out especially in front. .28 and .45! After alignment here are my specs:

Caster: 7.12/7.04
Front Camber: -1.09/-1.18 (with Dinan camber plates)
Front Toe: .04/.04
Rear Camber: -1.69/-1.65 (this is max I could get with toe setting)
Rear Toe: .09/.10

Interesting to note that factory min/max settings for toe are .03-.20 in front and .10-.20 in rear. The minimum is approximately 1/16" in front and 3/16" in rear which is a good track set up and what I shot for.
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      06-19-2008, 07:01 AM   #13
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Quote:
Originally Posted by fast_lap28 View Post
thanks leftcoastman for all your comments...well taken into consideration, actually I will be reading up on more techniques in coming days including trail braking....

I know what you mean about scrubbing off the tire logo. I ran autox last Thurs. on new RE01R's with pressures at 36F/39R and found that I didn't scrub down to the logo but was getting close....basically I am getting the practice on the new rubber before I head out on the track with this setup.

what tire pressures would you recommend to try out given I have more negative camber in the rear than in the front?

I def want to try different pressures this Sunday for another autox and see how the tires do...so far they look great! good rubber after switching from Falkens Rt615's - they gave me bunch of problems but now I am

RE01R ftw!
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      06-19-2008, 11:54 AM   #14
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Quote:
Originally Posted by longodj View Post
RE01R ftw!
do your RE's make a noise at all during sharp turn in's btw? they are pretty quiet compared to the Rt615's overall....and what tire pressures have you experimented with on track? just gathering various parameters to test with myself.
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      06-21-2008, 08:23 AM   #15
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My RE's make shit tons of noise...always...I love it

I haven't really dialed in my pressures...at all... Last time I was at the track I was using 42F/38R cold to induce some oversteer (xi == understeer city). However, now I have a rear sway so I shouldn't need to do that anymore. During autocross I usually use 39F/36R with pretty good results. If you have a better set of parameters please let me know
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      06-22-2008, 01:37 PM   #16
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Originally Posted by westwest888 View Post
Does "total rear toe" mean L + R = 3/16 = 0.18? So like 0.09 toe on each side, ideally?

Yes, toe-in.
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      06-22-2008, 05:40 PM   #17
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dinan plates are only good for about a half degree. Look at previous camber spec of mine above.
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      06-22-2008, 06:55 PM   #18
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Yeah, Dinan gives you a whopping half a degree. I have the TCKline plates and am able to get -3.5 in front.

You don't have to disconnect the reinforcing bar to adjust. I drilled a small hole in the rebound adjustment tab and just use a "pick" to adjust it. Works like a charm.
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      06-22-2008, 09:08 PM   #19
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Quote:
Originally Posted by fast_lap28 View Post
so what are your thoughts on negative camber (-2.1 or so) in the rear from factory specs? just wondering if any advantages or disadvantages when tracking with negative camber just in the rear. its not alot of adjustment but enough that I could probably tell once on the track?

coilovers w/ camber plates for the front will be done next year. right now I am just playing with what came from factory.

thoughts, experiences?
negative camber is fine. it is for driver tend to over steer the wheel. With the negative camber, it help to ajust the degree of over steering on a track.
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      06-30-2008, 10:10 PM   #20
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I just got my KMAC Stage 2 in the mail...apparently they allow for 2.5 degrees in either direction.

leftcoastman, I'm getting my KW V3 and KMAC camber plates installed next week. You mention experience in this thread and in my thread about brakes. I have an xi so I have a fair bit of understeer (less so with a rear sway but I'm also adding a front sway). Would you recommend even touching rear camber? Should I just stick to say -2 degrees in front (and play from there) and leave the rear stock? I'm learning quickly and have been autocrossing every other weekend....(not that that means anything)

Thanks
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      07-01-2008, 12:06 AM   #21
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Quote:
Originally Posted by longodj View Post
I just got my KMAC Stage 2 in the mail...apparently they allow for 2.5 degrees in either direction.

leftcoastman, I'm getting my KW V3 and KMAC camber plates installed next week. You mention experience in this thread and in my thread about brakes. I have an xi so I have a fair bit of understeer (less so with a rear sway but I'm also adding a front sway). Would you recommend even touching rear camber? Should I just stick to say -2 degrees in front (and play from there) and leave the rear stock? I'm learning quickly and have been autocrossing every other weekend....(not that that means anything)

Thanks
Do the KMAC camber plates work with KW coilovers?
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      07-01-2008, 12:24 AM   #22
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Quote:
Originally Posted by sambonator View Post
Do the KMAC camber plates work with KW coilovers?
I sure as hell hope so... They apparently work with or without coilovers, I don't see why KW would be special.
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