Those with 3.27's

FearThis SC

Registered User
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!

[edit]I have the correct speedo gear, 21 tooth![/edit]

Thanks,
Calvin
 
Last edited:
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
 
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
 
FearThis SC said:
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
 
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
 
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.
 
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
 
Something else to remember is that tire diameter does not have an effect on DISPLAYED MPH only actual MPH is effected.

Jeff
 
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?
 
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