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FearThis SC
07-30-2003, 02:25 PM
Here's the deal: I have a 1992 SC 5sp

I just swapped out those useless 2.73 for 3.27's out of a 90SC.

At around 75 mph, I'm pulling about 27-2800 rpms in fifth gear. Does that sound normal with 3.27's?

I'm thinking that the rear end gearing is higher than 3.27's, but that is purely speculation on my part. Thus the reason I posted this question! Appreciate any input!

I have the correct speedo gear, 21 tooth!

Thanks,
Calvin

racecougar
07-30-2003, 03:53 PM
Yes you have 3.27's with a T-Loc unit. On the second line of code you see "3L27" (the "3" is partially covered by the diff cover bolt). The "3 27" stands for "3.27:1 gears, and the "L" stands for "Trac-Loc".

-Rod

FearThis SC
07-30-2003, 03:58 PM
Thanks Rod, but really my question was about how many RPM's should I be at/or around 80mph. Just curious, because it seems that the RPM's are a little high at 27-2800 for that speed. Just looking for peace of mind from someone that is running 3.27's in an early M5R2 tranny.

Calvin

Aaron Pedroza
07-30-2003, 04:02 PM
It's right, I think the 5 speeds have the same .85 OD gear.

racecougar
07-30-2003, 04:03 PM
Originally posted by FearThis SC
I'm thinking that the rear end gearing is higher than 3.27's, but that is purely speculation on my part. Thus the reason I posted this question! Appreciate any input!


That's why I thought you were asking if you had 3.27's or not. I don't have a 5-speed with 3.27's, so I really can't help.

-Rod

FearThis SC
07-30-2003, 04:07 PM
Thanks. I believe that what I'm experiencing is normal for 3.27's at highway speeds. Just wanted confirmation.

Calvin

http://www.sccoa.com/forums/showthread.php?s=&threadid=7864&highlight=3.27s

FearThis SC
07-30-2003, 04:24 PM
Originally posted by Aaron Pedroza
It's right, I think the 5 speeds have the same .85 OD gear.
Thanks Aaron.

Calcin

fast Ed
07-30-2003, 06:13 PM
The OD ratio is actually 0.75:1 in all of the SC 5-speed transmissions. Your rpms sound about right, I have 3.27s in my 5-speed with slightly taller than stock tires, and it's very close to that.


cheers
Ed Nicholson
SCCoO

DLF
07-30-2003, 09:52 PM
What size are your tires? Hard to calculate the gears unless we know that, and if your speedo is accurate.

The 21 tooth gear is correct for say 255/45-17's, but for near to stock size tires you need a 20 tooth speedo gear.

FearThis SC
07-31-2003, 08:38 AM
The OD ratio is actually 0.75:1 in all of the SC 5-speed transmissions. Your rpms sound about right, I have 3.27s in my 5-speed with slightly taller than stock tires, and it's very close to that.
Thanks Ed, basically what I needed to know.


What size are your tires? Hard to calculate the gears unless we know that, and if your speedo is accurate.
DLF- I have 235/55/16 and have done the speedo calculator. I may have the wrong gear as you suggested with those tires and rear axle. I have a speed controlled bridge that has a radar speed display, so at 60 on my speedo, the radar display shows 56mph. So it looks to be about 4mph off.

Calvin

JJanney
07-31-2003, 09:17 AM
3.27s
245/45/17s
Red 21-tooth speedo

Mine is 4mph off.

J57ltr
07-31-2003, 10:25 AM
Something else to remember is that tire diameter does not have an effect on DISPLAYED MPH only actual MPH is effected.

Jeff

fastsc92
07-31-2003, 07:08 PM
i've been racing my 5 speed with the new gears lately (3.27)....and i hold 4th gear through the lights.....at 5000rpms. It doesn't seem right because 4th is a 1:1 ratio. BUt i also pull through the lights at 101mph. Still...it seems likes its reving kinda high. Anyone else have this problem.....at the track?