Autocross Alignment Specs?
04-30-2006, 09:42 PM
#1
1935 lbs. FTW!
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Autocross Alignment Specs?
Just got my 05 RX8 5 days ago and plan on autocrossing it as soon as it's broken in. I was wondering what is the popular B stock alignment, I don't anything crazy like -3 degrees of camber since it's also a daily driver. I also don't want to add camber plates or anything, just whatever stock will allow.
Let me know what you guys have tried and if you like it or not.
Let me know what you guys have tried and if you like it or not.
05-01-2006, 12:58 AM
#2
Originally Posted by CosmosMpower
Just got my 05 RX8 5 days ago and plan on autocrossing it as soon as it's broken in. I was wondering what is the popular B stock alignment, I don't anything crazy like -3 degrees of camber since it's also a daily driver. I also don't want to add camber plates or anything, just whatever stock will allow.
Let me know what you guys have tried and if you like it or not.
Let me know what you guys have tried and if you like it or not.
05-02-2006, 12:37 AM
#4
1935 lbs. FTW!
Thread Starter
Ok, regardless I don't plan on going that far with the suspension yet since the car is 5 days old and not even broken in. I just want to get an alignment so I can start autocrossing it in about a month.
Anyone have good specs attainable with factory adjustment?
Anyone have good specs attainable with factory adjustment?
05-02-2006, 08:46 AM
#9
it's a very reasonable spec though some more front camber will be OK with that toe setting if you can get it. At least he has enough sense not to jack the rear camber up 
. Unless you run on extremely high grip surfaces I would run a bit more rear toe-in though; 0.12 deg in per side ( approx. 0.05" per side)
. Unless you run on extremely high grip surfaces I would run a bit more rear toe-in though; 0.12 deg in per side ( approx. 0.05" per side)
05-02-2006, 10:26 AM
#10
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Originally Posted by TeamRX8
At least he has enough sense not to jack the rear camber up
On track, the rear end does seem to be more glued on corner exit with less propensity to oversteer.
05-02-2006, 11:58 AM
#11
A proper autox alignment will be loosey-goosey at the track. The severe transitions and sharp turns of an autox, as opposed to the long, continuous turns at a track, require more rotation to maneuver through
However, you can deduce from your statement that he is only guessing. It really depends what the suspension geometry is doing and few cars are rarely identical in this regard. Just because you do X on Car A does not mean that it is the right thing to do on Car B. Rear camber will stabilize the RX-8 rear end, but too much so for autox. Then people crank up the rear shock rebound trying to compensate by destabilizing all the grip they just added in. This in turn creates some negative consequences on some of the finer handling details. It's a bassackwards treating-the-symptom approach to suspension tuning instead of analyzing the cause-effect relationship of the actual application ... more/bigger/stiffer is not always a good thing.
That's not to say running high rear camber doesn't have a place on an RX-8. My approach above is all relative to an OE/Stock Class application. Once you have fully tunable suspension then IMO you can run high rear camber in a proper way that doesn't create other issues. You don't have that option in Stock. So what your guy is saying is not necessarily wrong, it just depends on the situation.
However, you can deduce from your statement that he is only guessing. It really depends what the suspension geometry is doing and few cars are rarely identical in this regard. Just because you do X on Car A does not mean that it is the right thing to do on Car B. Rear camber will stabilize the RX-8 rear end, but too much so for autox. Then people crank up the rear shock rebound trying to compensate by destabilizing all the grip they just added in. This in turn creates some negative consequences on some of the finer handling details. It's a bassackwards treating-the-symptom approach to suspension tuning instead of analyzing the cause-effect relationship of the actual application ... more/bigger/stiffer is not always a good thing.
That's not to say running high rear camber doesn't have a place on an RX-8. My approach above is all relative to an OE/Stock Class application. Once you have fully tunable suspension then IMO you can run high rear camber in a proper way that doesn't create other issues. You don't have that option in Stock. So what your guy is saying is not necessarily wrong, it just depends on the situation.
05-02-2006, 05:03 PM
#12
1935 lbs. FTW!
Thread Starter
I never plan on taking my car to a road course, i've done it a few times and it's murder on the brakes and tires etc.
Sounds like the max front camber you can get is -1.3 then you just need to max out the caster and zero out the toe. Equal camber front and rear and a bit toe in in the rear. Actually it sounds a lot like the standard S2000 autocross alignment except the S needs a lot more rear camber and toe in for the rear.
Autocross S2000 alignment specs
-1.3 front camber both sides
Max caster around 6
0 the toe in the front
-2.0 camber rear both sides
.20 per side toe in .40 total
Sounds like the max front camber you can get is -1.3 then you just need to max out the caster and zero out the toe. Equal camber front and rear and a bit toe in in the rear. Actually it sounds a lot like the standard S2000 autocross alignment except the S needs a lot more rear camber and toe in for the rear.
Autocross S2000 alignment specs
-1.3 front camber both sides
Max caster around 6
0 the toe in the front
-2.0 camber rear both sides
.20 per side toe in .40 total
05-02-2006, 05:05 PM
#13
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Originally Posted by TrackAddict
Could you please elaborate. My last alignment, the tech dialed in -1.6 up front and -2.0 in back. He said he likes to keep the rear a few tenths higher than the front. I thought that -2.0 sounded a bit high but trusted his judgement since he has been aligning race cars for over 20 years.
On track, the rear end does seem to be more glued on corner exit with less propensity to oversteer.
On track, the rear end does seem to be more glued on corner exit with less propensity to oversteer.
05-02-2006, 06:03 PM
#14
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Originally Posted by TrackAddict
Could you please elaborate. My last alignment, the tech dialed in -1.6 up front and -2.0 in back. He said he likes to keep the rear a few tenths higher than the front. I thought that -2.0 sounded a bit high but trusted his judgement since he has been aligning race cars for over 20 years.
On track, the rear end does seem to be more glued on corner exit with less propensity to oversteer.
On track, the rear end does seem to be more glued on corner exit with less propensity to oversteer.
05-02-2006, 06:20 PM
#15
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Team - thanks for your response. I do not consider myself an autocrosser although I do a few each year. I am more into open track.
My suspension is RB springs and sways with stock shocks. My latest alignment specs are as follows:
Front Camber -1.6
Cross Camber -0.1
Front Caster 6.9
Cross Caster -0.1
Front Toe In 0.03
Total Toe 0.06
Rear Camber -2.0
Rear Toe In 0.05
Total Toe 0.11
The alignment shop I used is well known in Georgia as the place to go. it is called Grand Tourismo East and any given day you will find trailered-in race cars and autocross competitors as well as other folks in the know. I can probably get a few more tenths of front negative camber if I want to but it may be at the expense of caster. I am not so knowledgablwe about suspension geometry... I do know that with my current settings, the car is predictable, has good grip on exit under full power, and excellent turn in. For example Blue (since you recently drove Road Atlanta) - Playing around during track touring at the Mitty last weekend, I was able to take turn 7 in 2nd (normally a 3rd gear turn with no traffic) and just pile on the power way before the apex. I was trying to break it loose and couldn't do it on my RE040s. Same in exiting 10B at about 8500 RPM in 2nd (also normally a 3rd gear corner).
My suspension is RB springs and sways with stock shocks. My latest alignment specs are as follows:
Front Camber -1.6
Cross Camber -0.1
Front Caster 6.9
Cross Caster -0.1
Front Toe In 0.03
Total Toe 0.06
Rear Camber -2.0
Rear Toe In 0.05
Total Toe 0.11
The alignment shop I used is well known in Georgia as the place to go. it is called Grand Tourismo East and any given day you will find trailered-in race cars and autocross competitors as well as other folks in the know. I can probably get a few more tenths of front negative camber if I want to but it may be at the expense of caster. I am not so knowledgablwe about suspension geometry... I do know that with my current settings, the car is predictable, has good grip on exit under full power, and excellent turn in. For example Blue (since you recently drove Road Atlanta) - Playing around during track touring at the Mitty last weekend, I was able to take turn 7 in 2nd (normally a 3rd gear turn with no traffic) and just pile on the power way before the apex. I was trying to break it loose and couldn't do it on my RE040s. Same in exiting 10B at about 8500 RPM in 2nd (also normally a 3rd gear corner).
05-02-2006, 06:37 PM
#17
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I read that RB developed the springs to work with the OEM shocks. They also developed them with the sway bars. Since I don't know enough to properly match spring rates to damping to roll stiffness, I figured that a respected company like RB had someone who knew what he was doing.
05-02-2006, 07:49 PM
#19
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Originally Posted by TeamRX8
we've seen as high as -2.5 degree front camber on OE springs, it depends on what else you do or know ...
Guess I don't know the secret... -1.2 in front was all we were able to get. 
05-02-2006, 08:07 PM
#20
Originally Posted by whiterex
Guess I don't know the secret... -1.2 in front was all we were able to get. Once I get ahold of a camber / caster gauge I'd like to run a couple trials to see how much static camber we can gain by sacrificing caster and see if it's worth it.
Then again knowing TeamRX8, he's already figured this out and I should just trust him.
Last edited by John V; 05-03-2006 at 12:25 PM.
05-09-2006, 04:24 PM
#21
Originally Posted by John V
Not sure I would sacrifice much caster to gain camber, now that I think about it. caster = 180/pi * (delta camber / delta turn angle). Depending on how much caster you sacrifice to gain static camber, you might actually lose dynamic camber at a given steering angle.
Once I get ahold of a camber / caster gauge I'd like to run a couple trials to see how much static camber we can gain by sacrificing caster and see if it's worth it.
Then again knowing TeamRX8, he's already figured this out and I should just trust him.
Once I get ahold of a camber / caster gauge I'd like to run a couple trials to see how much static camber we can gain by sacrificing caster and see if it's worth it.
Then again knowing TeamRX8, he's already figured this out and I should just trust him.
05-09-2006, 08:26 PM
#22
Originally Posted by ULLLOSE
For every 1 degree you give up in caster you will gain .1 -camber. It is worth it. Even if you take every bit of caster out you can it is still like 4-5 degrees which is more than enough.
More than that and the lost dynamic camber outweighs the small amount of static camber you're getting.
Obviously I'm missing something... :dunno
I was a big fan of rear toe-out on the BMW, not sure I would want it on the '8. Think I would rather run zero toe and play with the rear camber and shock settings to make the car rotate but still be planted enough in high speed stuff.
Anyway these minor setup changes are not even close to what's holding me back right now.
Last edited by John V; 05-09-2006 at 08:28 PM.
05-10-2006, 06:11 AM
#24
Originally Posted by TeamRX8
there once was a tech article on the Ground Control website that totally debunked the increased caster theory, it dropped off in a recent update though ...
If I'm missing something totally obvious please do fill me in, wouldn't be the first time...
Last edited by John V; 05-10-2006 at 06:38 AM.
