Lesson learned, believe me.

I'm just glad my highly-accurate butt-dyno was able to discern that the car had too much rear toe... never thought it would have almost 1/2" total toe-in at the back... I get what I deserve for listening to clyde.

 

I just told you what it had been set to the last time. Lots of things can happen in a long period of time.

 

if it's any consolation, I learned the same way ...

 

If I hadn't driven like complete a$$ on the second day at Nats we wouldn't be having this conversation, not that I'm still beating myself up over it or anything.

 

yeah, you and about a dozen other people ...

 

I know we've just about talked this topic to death but I'm going to run this by anyway. I'm thinking about this for autocross (all numbers in degrees).

FRONT
CAMBER: -1.75 R/L (no cross camber)
CASTER: Max available after camber set (no cross caster)
TOE: 0.0 R/L

REAR
CAMBER: -1.75 R/L (no cross camber)
TOE: -0.10 IN (-0.20 total toe)

I'm trying to solve my understeer "problem" and at the same time give the rear tires a good hold through the turns while stabilizing the rear with a touch of toe in. Does this sound reasonable?

I want neutral and balanced and an ability to turn quick but not at the cost of sacrificing too much stability. I think this might be a good starting point.

Or should I zero the rear toe? Opinions? Too unstable?

One last thing - I'm using Tein S.Techs so I have a stiffer setup and dropped a little over an inch over the tires and have Koni sports on set to 50 front 80 rear. I think I can get the camber I want because of the drop but we shall see.

Does anyone see anything wrong with this? I'll admit - I barely know what I'm doing (but I'm having fun anyway.)

Thanks.

 

Doesn't negative toe mean you will have toe out in the rear?

 

I think you should take some toe out, try setting it to 0.05 each side and see if it's fix the problem.

 

I honestly do not know if negative toe is "in" or "out". I'll be sure the tech knows I mean "in" and get the difinitive answer on that.

According to this chart on TireRack:
http://www.tirerack.com/tires/tirete....jsp?techid=58

It shows you should increase rear toe-in to decrease understeer.

If this chart is correct, it looks like it could be pretty useful.

I guess I'll just try this setup it and see what happens. Thanks.

 

 

must be a typo, more rear toe in = more understeer. more rear toe out = more oversteer.

 

You are right - it was a typo. How frustrating to find the right info! But I'm glad you said something before I took their word for it and screwed something up. Thanks.

I found a pretty decent article that says, "toe-out encourages the initiation of a turn, while toe-in discourages it. The toe setting on a particular car becomes a tradeoff between the straight-line stability afforded by toe-in and the quick steering response promoted by toe-out. Toe settings at the rear have essentially the same effect on wear, directional stability and turn-in as they do on the front. However, it is rare to set up a rear-drive race car toed out in the rear, since doing so causes excessive oversteer, particularly when power is applied"

Since understeer has been my enemy, I definately don't want to toe the rear wheels in. But I think that rear toe out might take it too far the other way. So, maybe I should set toes to ZERO front and back because:

1) when torque is applied to the rear drive wheels, they pull themselves forward and try to create toe-in. So setting these to zero would be a good place to start and a trade off between turn ability and stability under acceleration (in theory) without too much likelihood for oversteer.

2) when then non-driven front wheels are pushed, they tend to toe out. Setting these to zero will probably drastically reduce understeer especially while turning under acceleration (in theory again).

 

So that's toe IN a little in the rear on each side for the rear correct?

-1.75 camber
0 toe
max caster

-1.75 camber
0 toe
.05 toe in each side, .10 total (basically almost 0 toe but slightly toe in)

Does that sound right? Also shouldn't the front camber be more than the rear usually?

 

you could go a littlr less rear camber too
may be 1.5 with 0.05 toe on each side.

 

Hey Mark,

Care to share some of the tips and tricks for getting -2.5 degrees out of the front of a B Stock car? I'm sure some of it involves the typical suspects (loosen everything and give it a solid yank in the right direction, degassed shocks, etc.), but Jon and I were only able to get roughly -1.2 out of the front of his car. The car still felt pretty good in the tight stuff at the Mineral Wells Pro, but I've yet to meet a Stock car that didn't respond well to a little more front camber. If you don't want to publicize it, you can PM me.

 

Yes, I have since reconsidered my numbers. I think 1.5 on the rear would be much better. Otherwise I may end up with oversteer on exit..

 

i'd really like to know myself. =) my 8's at the shop right now (bone stock save for wheels/tires) and they're telling me they can only get -1.1 front camber after minimizing caster first. how is -2.5 achieved mechanically or does one have to degas the shocks? there's some time urgency to this request. ;-)

teamrx8, dannobre, i've pm'd you about this topic earlier today. thanks!

 

I could only get -.9 out of mine in the front. Maybe if we give to the Mark STU fund to aid in his transmission rehabilitation program we can get this valuable information.

 

I got aligned yesterday. Got -2.0 camber on both fronts easy. This is the same front camber that Mark is using. I believe (but can't say for 100% sure) it has something to do with being lowered.

Mark's front fender is lowered down to (pretty close to) the same height as what I ended up with when I installed my S.Tech springs. (I think)

 

should i merge this with the sticky?

 

this one?

 

The car will only get that kind of camber if it is lower than stock..........I got -2.6deg front...but I'm dropped to a bit below 26" ride height. I could get -1.6 deg out of the car stock with the caster adjusted for max camber

 

hmm. there's just so much conflicting info on max negative front camber. some say -2.5 bone stock is possible. others say they can only get ~-1.0 and some up to ~-2.0 and others anywhere in between. what accounts for this variability (apart from your normal wildly inaccurate internet claims... )? i think everyone interested in hitting specific front negative camber settings would like to get to the bottom of this issue. we know that lowering (via springs or degassing stock shocks) will yield higher negative camber due the rx-8's impressive camber curve. however, if someone can share a repeatable means to hit -2.0 to -2.5 apart from lowering everyone would be in your debt.

 

As far as I understand you have to lower your RX8.

Thats what my alignment shop says. Max neg is 1.3 to 1.6 from factory

 

The car mentioned is SCCA Stock Class legal, which means it has the OE springs and OE spring perch height ....

my STU racer is lowered, but I am only running 2.0 deg camber in the front, the 500# front springs limit body roll particularly since we're only allowed to run a minimum 140 treadwear-rating street tire