Jason Saini

I've only driven an '02 on the street in bone-stock format, but I drove it quite aggressively and it felt more settled than our '01 when it was stock. I don't think the changes make much of a difference for Autocross, although the smaller rear swaybar seems like it would help with getting the power down and keeping the rear settled.

I would imagine that the shocks are only very slightly different, only enough to compensate for the change in spring rate. I'll probably get a chance to compare our autocross car and a well prepped '02 in two weeks at a test/tune, and I'll report my findings in the racing/competition forum.

jerrypeterson

My guess is that alignment would have more of an effect than the suspesnsion changes at an autocross. In my experience a lot of rear toe (3/8"-1/2" in the rear) with 2degree negative camber will keep the rear end planted even on powered exits if the tires have the stock ~25% bias. (this is a great forumla for understeer) But then again, what do I know.

Pierre S2K

Has anyone tried running MY00-01 rear springs front and rear (291 lbs/in all around)?

Consider this: with the front's lower mechanical advantage, given the motion ratio, combined with the higher spring rate (291 vs 219) and considering the unloaded spring lengths (11.280" F & 10.689" R), if one were to install the OEM rears in the front on the lower spring perch position of Koni Yellows, which are about 1/2" lower than stock, the ride height should be very close to stock, shouldn't it? Anyone try this?


Pierre

Race Miata

Sorry to bring back this old thread but this is the most detailed thread I can find about different spring rates from different years.

I got some '03 springs on hand to play around with. I measured spring wire thickness and am astonished by the discrepancy with what OP found:
[CODE]

Race Miata

Also, can anyone point me to any calculated or measured motion ratios on our suspension? The closest I can find is this thread:

https://www.s2ki.com/forums/index.php?showtopic=169926

However, I highly doubt the accuracy of Windscreen's numbers. The shock absorber lower mount point is about 75% the length of the lower arm (both front and rear). That means motion ratio cannot be higher than 0.75 with the slanted shocks. It seems to me that the front shocks are slanted more than the rear so I would assume front motion ratio is lower than the rear.

From SpitfireS' thread with front suspension drawing:

https://www.s2ki.com/forums/index.php?showt...0&#entry7439630

I got 0.70 for front motion ratio. Without drawing but from pure estimate considering the front/rear geometry difference, I tend to think rear motion ratio is about 0.72.

If my motion ratio numbers are in the ballpark, I don't understand how Honda came up with such rear-bias spring rates on a 50/50 car. Depending on the exact motion ratio numbers, I would tend to start with equal spring rates first and work on anti-roll bars instead.

Again, if anybody can point me to any threads about measured/calculated motion ratios for the S, that would be much appreciated. If not, I'll probably have to find some time and do it myself.

SpitfireS

Maybe this will get you started?
With a "Photoshop" kinda program you'll be able to print it up to 250% on a A4 piece of paper to see if the scale is any good to "calculate" the rear upper and lower arms lenghts.
Then all you need is shock lenght ......There are enough pics to be found with programs like "Google" of front and rear shocks.
.....and mounting points on the chassis.
I guess there is no other way then to put the car on stands and.........

Let us know what you find and how it helps making better choices for offsets, shocks and springs

Wildncrazy

What are those spring rates in KG?

Since the aftermarket Japanese coilovers seem to all come calibrated as KG not N/mm or pounds.

Race Miata

Thanks for the help, but I think it's easier for me to just go down to the garage and measure them. I'm on sick leave today because of a sore-throat and a pretty bad headache this morning but am getting better now. I guess there's no conflict between that and the garage?

Will let you all know when I get the numbers (that's if I really do it today).

Race Miata

From lb/in to kg/mm, divide by 56.

For example,

219 / 56 = 3.9 kg/mm
291 / 56 = 5.2 kg/mm

EDIT: Ooops, I meant divide by

Race Miata

I did it! Measured the motion ratios on my MY00. See this thread for more details...

https://www.s2ki.com/forums/index.php?showt...0&#entry7471379