Miata Mailing List: April 1995, Message #62
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   From: Quentin Fennessy 
Subject: Miata tuning summary from autox list
   Date: Mon, 3 Apr 1995 11:06:35 -0400


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Dorothy Raymond published a good miata tuning summary to the autox list
yesterday.  She gave me permission to forward it to y'all.  

Quentin
94 R Novice CS

Date: 2 Apr 1995 21:49:25 -0600
From: "Dorothy Raymond" 
Subject: miata info summary

Maybe you can tell that we didn't go to Mineral Wells this weekend, and that
Peter has been sitting around bored.  Anyway, this is his April 2 posting:

This is a posting on what I've learned so far on parts and settings and so on
for the Miata.  First, thanks to all who helped bury me in info.  You will all
remain nameless because I'll probably forget someone and because this posting
is already too long.  All of you who answered will notice that the stuff here
is mostly stolen from you directly, and there was enough it won't all fit
here.  Everyone is welcome to send me corrections or additions.  Maybe there
will a 2'nd shorter update if I get enough significant new/corrected info.

Front alignment - Camber and caster are set with 2 eccentric cams which slide
the lower control arm inner mounting bolts in and out.  Because the bolts
slide in and out in slots in the subframe, the cams don't move the bolts up or
down, and so the adjustment doesn't mess up roll centers or anything.  The
maximum camber (good) is with both bolts full out.  Kyle Watkins and I played
with the front alignment of my '94R on Kyle's rack and saw several things. 
The camber with and without driver was about the same on the left but the
right went about .3 more negative with me in the car (170lbs).  We also turned
the wheel about how far we thought it would need to turn for a 50ft slalom
(7.5deg at the tire) and saw .4 to .5deg camber gain with 3.6 and 4.7deg
caster.  We also found that compromising camber to increase caster didn't
payoff at these steering angles.  For example, compromising camber by .5deg
will give you significantly less than .5deg additional camber gain with a
steering angle of 7.5deg at the tire.  Sorry I don't remember how much less. 
Maybe sometime I'll look at steering angle in one of our video tapes and redo
this measurement.

Rear alignment - Two cams on the inner end of the lower control arm again,
except this time they adjust camber and toe.  This time the left went .1deg
negative with the driver, which is within the noise of the measurement.  The
right camber went .5deg more negative with driver.  Obviously you better align
with the driver in the car, but what about co-drivers of different weight?  It
looks like you can get plenty of camber at the back, but the interaction
between adjusting camber and toe is very irritating.  The rear toe is seems to
me the most critical alignment to set accurately on the car.  On an early MR2
(now also in CS) the rear toe is set with a screw adjustment just like
adjusting toe in the front.  This is much nicer than the double cam system on
the Miata.  Of course the Miata is control arm, not strut, so the MR2 wins for
convenience, the Miata for function.

Front sway bars - The bar diameters that I know of are (in increasing order):
19 non-adjustable='93 stock; 
20 non-adjustable='94R(all?); 
21 non-adjustable='92; 
22=?; 
22.2(7/8") adjustable?=?; 
23 adjustable= Motorsports Auto; 
23.8(15/16") adjustable=Racing Beat; 
25.4(1") adjustable?=Millen.
This data came from the net.  As I recall, Motorsports Auto said their bar is
a 22, not 23.  They also said that '94 and later Miatas have a longer arm
length, so none of the after market bars fit.  Anyone know if this true?

The relative stiffnesses (assuming the same torque arm length, and calling the
stiffness of my current 20mm bar 100%) are:
19=81.5%
20=100%
21=121.6%
22=146.4%
22.2=151.8%
23=174.9%
23.8=200.5%
25.4=260.1%
What I don't know is how the various torque arm lengths compare.  I assume the
pre '94 stock bars all have the same arm length, but who knows? And I don't
know how much longer the '94 bars are, or how much the adjustable ones vary.

Rear sway bar - The stock diameters I've heard of are:
11='93
12=?
14=?
I forget what the '94R is.

Shocks - In no particular order.
- non-R Mazda, these are too soft and should be replaced for best
performance.
 - '94R Bilstiens, These ride terrible on the road.  Based on using them a few
times on course, they seem pretty good, but they aren't adjustable.
 - Koni, I drove Gary Baughman's car a couple times earlier this year and
thought they were too soft.  He's had them forever though, and I'm not sure
they are even what Koni is selling now.  Koni is the most successful with (for
example) Bob Klingler and Michael Butler running Koni.  So far I have never
driven the car twice with the same alignment, but my first impression of the
Konis is a tendency towards snap oversteer.  I'm still trying to figure this
car out though, so don't trust this impression.
 -GAB,  these have 8 settings and go from softer than stock to, perhaps,
stiffer than anything else.  They are also the most expensive.  Mixed signals
on Koni or GAB being better.  GAB may have a new model soon.
 - Tokico, they worked well enough to win DS on an '85 MR2, but I've heard
little about them on Miatas.  What I did hear was not positive, but not
extensive enough to draw any real conclusions from.

Exhaust - There were some postings on this.  Could someone supply a summary? 
I am leaning towards Flow Master.  Could someone give me order info for what
appeared to be the best choice?  Has anyone tried a straight pipe?  Sorry to
repeat this subject, maybe it would be best to post direct to me, not the
whole net.

Wheels - At least for '94 and '95, it would be hard to beat stock.  I got take
offs from Globe tire in San Diego for $135 plus shipping each.  They used to
do more of this than they do now.  I wish I had thought to try Dan Heydluff at
the N. Academy Blvd., Discount Tire store in Colo. Springs, CO.  I don't know
how much of this Dan does, but as anyone from around here knows, Dan is a good
person to do business with, and drives a Miata too.

Sources / phone numbers
Mazda Motorsports: 800 435-2508, 714 727-6940
   Register Mazda contingency
   Discount prices on Mazda and non-Mazda stuff incl. Koni, GAB...
   Special closeout prices eg:  green hardtops, white alloys...
   Help finding a particular car and stuff like that.  Very helpful.
Miata list: miata-request@jhunix.hcf.jhu.edu someone correct me if this is
wrong.
   Useful info. (just like team.net)
   Useless info. (just like team.net)
Wings / GAB: 510 490-7078
   GAB shocks
RD enterprises: 800 683-2890
   Maybe the best prices on performance parts
Performance buyers club 800 359-4093, 202 232-1136
   Maybe the best prices on performance parts
   President, Al Staats is an Internet kind of guy
Motorsports Auto: 714 639-2620
   23mm adjustable front bar for a reasonable price
Racing beat: ?
   23.8mm adjustable bar.  
   Mixed reviews, it maybe too stiff for some.
   Cool red paint.
Millen: ?
   25.4mm bar for those suffering from bar envy
Helm: 800 782-4356
   Service manual for apx 25$
Classic motor books: ?
   Miata enthusiasts manual for apx 45$

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