Please help figure my gear ratio
Thread Starter
Racer
Joined: Aug 2006
Posts: 301
Likes: 0
From: GA
Please help figure my gear ratio
Just bought a 99 Vette. Codes G90 & G92 are present in the glove box. From reading the earlier post, this translates to a 3.15 gear ratio. I read on another post that at 75 mph in 3rd, rpm should be in 2100 range. I did this quick test, but my rpm is drastically different, At 75 mph in 3rd, my rpm was around 3100. Crusing at 80 mph, my rpm is around 2100 ish. So I'm thinking a 3.42 or 3.73 gear. Short of jacking it up and counting drive shaft revolution to wheel revolutions, I figured someone would be able to help.
THANKS in advance,
M.
THANKS in advance,
M.
Burning Brakes
Joined: Feb 2002
Posts: 1,137
Likes: 2
From: Texas
Use this:
http://www.f-body.org/gears/
If you don't know, the stock MN6 gear ratios are:
1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.74
6th 0.50
--Sean
Edit...well I checked and if you have a six speed (MN6) then you most likely have 2.73 gears. 2,100 RPM = 82 MPH 5th gear, 3200 RPM = 72 MPH 3rd gear. Do you have an automatic?
Auto Ratios:
1st 3.06
2nd 1.63
3rd 1.00
4th 0.70
G92 = M30 automatic with optional 3.15 gears.
3rd at 2,800 RPM = 71 MPH, 4th at 2,200 RPM = 79 MPH (3.15 rear gears, M30 auto, 275 40 18 rear tires <-- if your rear tires are a different size, the calculated numbers will be different)
http://www.f-body.org/gears/
If you don't know, the stock MN6 gear ratios are:
1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.74
6th 0.50
--Sean
Edit...well I checked and if you have a six speed (MN6) then you most likely have 2.73 gears. 2,100 RPM = 82 MPH 5th gear, 3200 RPM = 72 MPH 3rd gear. Do you have an automatic?
Auto Ratios:
1st 3.06
2nd 1.63
3rd 1.00
4th 0.70
G92 = M30 automatic with optional 3.15 gears.
3rd at 2,800 RPM = 71 MPH, 4th at 2,200 RPM = 79 MPH (3.15 rear gears, M30 auto, 275 40 18 rear tires <-- if your rear tires are a different size, the calculated numbers will be different)
Last edited by R6_C5_CLS55; Aug 30, 2006 at 09:55 PM.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by DBLX
I read on another post that at 75 mph in 3rd, rpm should be in 2100 range.
wrong.
at 75 mph in 3rd, divide RPM by 1000. For the 3.15 it should show 3150rpm (plus/minus 100rpm)
http://mikemercury.home.att.net/ratio.htm
Pro
Joined: Oct 2004
Posts: 538
Likes: 0
From: Edmond Ok
Originally Posted by Mike Mercury
wrong.
at 75 mph in 3rd, divide RPM by 1000. For the 3.15 it should show 3150rpm (plus/minus 100rpm)
http://mikemercury.home.att.net/ratio.htm
at 75 mph in 3rd, divide RPM by 1000. For the 3.15 it should show 3150rpm (plus/minus 100rpm)
http://mikemercury.home.att.net/ratio.htm
I have a 2001 auto with 3:15. At 75 it is right around the 3100 RPM
