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M3LAW
10-24-2003, 05:06 PM
A real thanks to Steve M., Jay M., Shep and others for all of their experience and advice on suspension set up, etc... Roadfly is truly a "marketplace of ideas" where the cream in accurate information generally rises to the top.

Did have the opportunity to salivate over the coming air box conversion with Jay. I mean 35% increased air flow!?! at a given rpm. Wow! Not sure what this translates as far as HP, but it can only be good!.

Anyway, I do have one question on the GC spring SIZES. I have decided to stick with the 500# front and 550# rear settings. My M3 is "fully loaded" (i.e. fully weighted) including the regretted moonroof. Still have stock muffler and battery in the rear (although no CD changer, removed the mobility kit and tools, and have not added any after market amps/speakers, etc...).

My question to those who run a similar set up with GC, will the 7" springs in the rear with the 550# rating allow a drop down to 13.00"? Steve M. suggests going with the 6" spring to ensure the full 13 inch drop while Jay generally reccomends 7". Frankly, both of these gentlemen know mountains more on the subject than I. I was wondering if any others with the stock exhaust, Moonroof, power seats, Nav, (other weight adding stock options) have had any difficulty getting down to 13" with the 7" spring. Any insights would be welcomed.

Thanks as always.<br>M3Law

SmurfM3
10-24-2003, 05:36 PM

StMedina
10-24-2003, 05:40 PM
550 is right at the magic number.....where the 550 doesn't quite make it....

see if you can call em up...and do the 6 in 550...<br>














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meem
10-24-2003, 05:48 PM
i'm at 12 7/8" right now and there's still another 1/3" of travel or so.

if you want to run 13" in the <i>front</i>, you will need 6" springs. personally, i'd get the 6" front springs just to give yourself some options.
<br><table cellspacing=5 nowrap align="center" frame="hsides"><tr><td align="right">
<font size=1>
2003.5<br>
35% tint<br>
brembo gt kit<br>
euro equipment<br>
folding mirrors<br>
clear bra<br>
uuc ssk<br>
</font>
</td>
<td><img src="http://m3.mayzurk.com/meem/m3-sig12.jpg"></td>
<td>
<font size=1>
hre 545r<br>
toyo t1-s<br>
eisie race<br>
gc 450#/450#<br>
phatbox<br>
5400k<br>
etc ...<br>
</font>
</td>
</tr>
</table>

StMedina
10-24-2003, 05:50 PM
<br>














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meem
10-24-2003, 05:50 PM
but would the 550# really cause one to ride 3/4" higher for a given perch setting? 'cause i can probably get down to 12 1/4" at 450#.
<br><table cellspacing=5 nowrap align="center" frame="hsides"><tr><td align="right">
<font size=1>
2003.5<br>
35% tint<br>
brembo gt kit<br>
euro equipment<br>
folding mirrors<br>
clear bra<br>
uuc ssk<br>
</font>
</td>
<td><img src="http://m3.mayzurk.com/meem/m3-sig12.jpg"></td>
<td>
<font size=1>
hre 545r<br>
toyo t1-s<br>
eisie race<br>
gc 450#/450#<br>
phatbox<br>
5400k<br>
etc ...<br>
</font>
</td>
</tr>
</table>

StMedina
10-24-2003, 06:08 PM
not remember how to do it again....and then I'll have to bug Jay with the same question.

lets assume the corner of the car weighs 800.....

the control arm is 21 inches long, and the spring sits 14 inches from the pivot point...

21/14 = 1.5

1.5 x 800 = 1200

so with a 450 7 inch,

1200/450= 2.66 inches is what the spring will compress....

7 inch - 2.66 equals 4.34 inches, is how tall the spring is when the car is sitting at rest....




So now lets convert to 550

1200/550 = 2.19 inches is what the spring will compress

7 - 2.19 = 4.81 inches is 550 sitting at rest...

so difference in compression between 4.81 - 4.34 is = .47 inches....

.47 inches/.125 (each turn of the collar) 3.76 turns down, to get the height the same with the 550....

with a 500 lb 7 inch spring, you're about 1.5/2 threads from the bottom, so a 550 7 in even at the bottom of the perch, won't quite make 13...have to go to a 6 in.<br>














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StMedina
10-24-2003, 06:10 PM
than, the numbers will change.<br>














<font color=#660000><font size=1><font>

sjsharks
10-24-2003, 06:21 PM
although my rears are 500. No sunroof. Do have Ti exhaust. With 7" I couldn't get to 13" even though I was at the bottom. Called dale and he sent to the 6" no prob..now just ~12 7/8.

<img src="http://members.roadfly.org/sharks/pic1.jpg">

sxxb
10-24-2003, 06:41 PM
order and should arrive sometime in December. That should get you to 13" no problem.<br>

SB

"If everything seems under control, you're just not going fast enough." - Mario Andretti

<img src="http://members.roadfly.org/sxxb/M3signature.jpg">

to the track again tomorrow. M3Law
10-25-2003, 03:49 AM


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