Alignment: go with what 949 says or back off a bit?

[MoonieGT]

Finally going to take my car in for an alignment tomorrow morning. According to 949's page, I should be using these settings as my front ride height is ~4":

Front camber: -2.8* (or as close as you can get to it)
Caster: +2.75 to +3.5*
Front total toe: 0

Rear camber : -2.5*
Rear total toe: 0

My car is my daily driver and only hits the track 2-3 times a year. I'm thinking I need to back off from -2.8* in the front? Or do I say the hell with it and go with the "race" alignment? I was considering backing it off to -2.2* front and -2.0* rear. Thoughts?

[johnwag]

That is the RACE ALIGNMENT specs.

Raise the car up. somewhere between 4.25-4.5" front and put it .25" higher in the rear. You shouldn't have any problem getting 2.2/2.0* degrees camber at that height. Each miata is different, but when I was running my miata ride height higher, I didn't have a problem.

Jeff and I are running his car a little higher than the recommended specs because of rubbing the inner fender, yet, we are able to get the "race alignment" specs.

[MoonieGT]

IMPOSSIBLE to raise the car up any more in the rear. It's been a big challenge to even get it up to ~4.2" in the rear. Emilio sent me an extra set of bushings to raise it up to where it is now and that's with the collars maxed all the way up. The only way to get more height would be to add something like an FM spacer. I've been kind of disappointed with that aspect of the coilovers... but they perform nicely.

[sean]

IIRC those have 5-inch springs on the back. You could easily get it up to 1.5 inches higher by swappping in some 6inch springs. You might monitor SCCA forums and other similar places. 350lb 2.25 inch 6-7inch springs are pretty common, you should be able to pick them up used for <100 a pair.

[MoonieGT]

Yes, I've got 5" springs in back. I think 6" may be the way to go... maybe I should hold off on the alignment...

[CarCar]

For a daily driver you may want to reconsider the 0 toe. I used the 949 alignment on my lowered daily Miata and I experienced significant uneven wear on my tires.

copied from another forum;
"with zero toe they will scrub more...the force of going forward "pushes" the
tires "out" if you can visualize that. It rotates better because of this, but
when the tires are pointing slightly inward, the force of going forward causes
them to straighten out, and this reduces wear on them

perhaps http://www.tirerack.com/tires/tirete...e.jsp?techid=4 says it better "A rear-wheel drive vehicle "pushes"
the front axle's tires as they roll along the road. Tire rolling resistance
causes a little drag resulting in rearward movement of the suspension arms
against their bushings. Because of this, most rear-wheel drive vehicles use some
positive toe-in to compensate for the movement, enabling the tires to run
parallel to each other at speed.

Additionally the vehicle's toe is one of
the most critical alignment settings relative to tire wear. A toe setting that
is just a little off its appropriate setting can make a huge difference in their
wear. Consider that if the toe setting is just 1/16-inch off of its appropriate
setting, each tire on that axle will scrub almost seven feet sideways every
mile! Extend it out and you'll discover that rather than running parallel to
each other, the front tires will scrub over 1/4-mile sideways during every 100
miles of driving! Incorrect toe will rob you of tire life."

I'm just putting it out there that you may want to reconsider doing a "track" alignment on a daily driver and may rather find a compromise somewhere in the middle. I wasn't happy to spend the extra money on sets of sticky street tires that were worn out prematurely from commuting just as I was able to score a day off for track.
Leaving 949 camber and castor alone and having a little front and rear toe in no more than 1/16" total, (don't ask me to convert that to degrees)
q= arcsin (t/d) * (180/pi)
t: toe setting in inches, e.g. 0.125 for 1/8 inch
d: diameter of the tire, usually 24" - 26"
pi: roughly 3.14
q= measurement in degrees)
and compensated with a grippier tire I felt I had the best of both worlds eg, longer tire life and a car that handled better than the stock alignment. I am not an expert and please don't bring up raccoons and my driving style. ymmv

[MoonieGT]

Exactly the kind of insight and experience I was after. Thanks CarCar.

On a related note, I'm putting the alignment on hold again. 949 is sending me longer springs to address some setup concerns I've been having. It doesn't seem right that I'm at a maximum ride heigh of 4" front and 4.2" rear pinch weld heights with the spring perches maxed out. This is about the height I want to be at, but I'm hearing that you don't want to have the spring perches all the way maxed out like I have them right now...