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Author Topic: Miata setup at 4 3/4" static ride height
Reggie Verified Driver
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Region: Delta
Car #: 77
Year : 1990
Posts: 74
Status: Offline
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If my car were 52% cross weight at that height, with front wheels weighing 609 each, LR at 602 and RR at 509, total weight of car with driver at 2329 lbs. I don't have scales, so I am trying to figure out a closer setting to 50% CW. I am wondering what 1/2 turn up for the LF and RR, and 1/2 turn down for the RF and LR would do, CW-wise? I'm thinking that would help the CW without going too far-but maybe not far enough.

Anyone have an educated answer? I'm trying to get to 50%, or as close as possible to that CW. I could fine-tune at the track if my buddy can bring his scales to the track. Am I better off not to adjust anything without the scales? Thanks.

Eric Barbaric Verified Driver
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Region: Kansas City
Car #: 95
Year : 1991
Posts: 311
Status: Offline
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You need to put more weight on the RR. So you will turn the spring perches up. That will also put more weight on the LF.

Already you can see that this is going to create a "chase the weight" game. And the game really can't be played very well without scales.

Maybe someone here knows a scientific way to do it. But I sure don't.

Reggie Verified Driver
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Region: Delta
Car #: 77
Year : 1990
Posts: 74
Status: Offline
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What I'm looking for is a better starting point for my first lap at the track. By the way, my '90 SM has the '99 shock hats.I'm thinking 1/2 turn down on RF and LR, with 1/2 turn UP on LF and RR would give it a better balance from my initial ride height (prior to alignment) of 4 3/4" with me in it. I have not remeasured the car with and without me in it; I'll do that later today.

Does anyone have a SWAG of how much difference the four 1/2 turns would make? Surely that would not over-correct, would it?

Dusty Bottoms Verified Driver Made Donation to Website
99 all the way!

Region: Lone Star
Year : 1990
Posts: 4253
Status: Offline
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Jack the car up from the diff and see which tire lifts first and adjust appropriate corners from there. Old RC trick for when you don't have a tweak board.

--------------------
"Your victory is tainted! Asterisk! Asterisk!!!"--Lisa Simpson

Jeremy Pike
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Region: SFR
Car #: 89
Year : 90
Posts: 163
Status: Offline
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If you are “wedged” (cross more than 50%) you need to do the following.
Up on the RR & LF (equal amounts, ¼ to full turns)
Down on the LR & RF (equal amounts, ¼ to full turns) JD setup guide..

I think 1/2 a turn would probably do it. But in all honesty if the car is alligned where it's at now and this is a track day, just drive it.

Reggie Verified Driver
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Region: Delta
Car #: 77
Year : 1990
Posts: 74
Status: Offline
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Jeremy, I have borrowed some scales and have 2 days before track day, so I think I'll try to improve on the setting. BUT, the question comes to me: How close to 50% is close enough. Someone else has suggested the numbers are "close enough" to just drive as is, but then I thought J.D. had suggested we get within .5% of 50%. Would you adjust it if you had 2 days to get it done? Just interested in how to control this animal.....

Cajun Miata Man Verified Driver
Overdog Driver

Region: Houston; SWDIV
Car #: 15
Year : 99
Posts: 680
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Reggie- PM Sent; I can get you a rough set in less than an hour.

--------------------
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Jay Lutz
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Region: Indy
Car #: 33
Year : 1994
Posts: 422
Status: Offline
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Reggie,

I had the same question for my 94 SM so some time ago I found out by running a little experiment on the scales: 1 full turn on all 4 corners (ie RF and LR down 1 turn each and LF and RR up 1 turn each) yielded 2.45% change in cross weight %. As JD correctly points out you must do all 4 perches simultaneously otherwise ride heights change and we all know where that gets you. Your results may vary. ;^)

PS- I'm sure many others have done this experiment as well so I'd like to see what numbers they got.

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"In our sport if you go out of bounds you're most likely not coming back" Michael Waltrip

Gibscreen Verified Driver Series Champ
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Region: NASA-SoCal
Car #: 23
Year : 1995
Posts: 912
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We got a little over 3%.

--------------------
Rob Gibson
RJ Racing
2010 NASA Nationals TTE Champion
2008/2009 WERC Champion
2007 NASA SoCal SM Champion
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Reggie Verified Driver
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Region: Delta
Car #: 77
Year : 1990
Posts: 74
Status: Offline
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I got 3.1% change in crossweight, going from 52.3% to 49.2%. I made one other adjustment, approx. 1/6 turn upward to LR and ended up with 49.871% CW. This isn't 50%, but is about as close as I expect to get to it. I calculate that to be within 3 lbs. of optimum. Thanks to all you guys for your help and suggestions.

d mathias Verified Driver Made Donation to Website
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Region: OVR
Car #: 88
Year : 1991
Posts: 2401
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Sometimes a little wedge/de-wedge is good, depending on the track.

Reggie Verified Driver
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Region: Delta
Car #: 77
Year : 1990
Posts: 74
Status: Offline
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Update: As of the second week in November I have now finished leveling and scaling the car, resulting in a 50.0% cross weight at 4 5/8". Thanks to a generous friend who loaned me his computerized scales I am now good to go. I realize I might need to make some additional adjustments, but this is much better than when I first started this process of Ride Height and Cross Weight adjustments. Thanks to everyone who chimed in!

   

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