Starting line ratio for manual transmission application

[Jim Caughlin]

Originally Posted by Nmbr1GMfan

[IMG][/IMG]

Oh man, I'm completely off the chart 21.4 with a 28" tall tire...

[Mike Pearson]

When I ran a stick in my super stock car the SLR was about 19 to 1 3.11 low gear and 6.17 in the rear. Had to yank the handle real quick low to second.

[Rory McNeil]

I am assuming the original poster must have a low gear ratio of 2.76, which is quite tall for a drag car, especially as it looks like he has a fairly big tire on there. Going to 5.57s should increase his trap RPM around 600 RPM, but I would also be looking for a lower first gear in the transmission. What the current 60 foot and 330 numbers, and what size tires on the car would be helpful.

[tavbfl]

Thank you all for your comments! The chart from Black Magic was exactly what I was looking for. To answer some of your questions, my 60 ft has been between 1.38 and 1.46, 330 ft between 4.10 and 4.15, and my first gear is 2.80. Finding gears for the Doug Nash is a challenge so this can be my callout to any racers that have them in a box on the shelf somewhere. I am looking to change to 5.57 gears as I am crossing at 6300 with the 5.14's and motor makes power to 7000. I am also dialing in a slipper clutch for the first time so it's a matter of optimizing my combo and then focusing on consistency.

[Glenn Briglio]

Originally Posted by tavbfl

Thank you all for your comments! The chart from Black Magic was exactly what I was looking for. To answer some of your questions, my 60 ft has been between 1.38 and 1.46, 330 ft between 4.10 and 4.15, and my first gear is 2.80. Finding gears for the Doug Nash is a challenge so this can be my callout to any racers that have them in a box on the shelf somewhere. I am looking to change to 5.57 gears as I am crossing at 6300 with the 5.14's and motor makes power to 7000. I am also dialing in a slipper clutch for the first time so it's a matter of optimizing my combo and then focusing on consistency.

You’ll need more rear gear to cross finish line at least 7500 rpm

[Robin Lawrence]

Lots of good information here. I just finished my stick shift Mustang and have made 2 runs before the track closed. Started out with a 3.32 first and a 5.43 rear gear.

I plan to test a few different first gear as well as rear gear ratio's this year.

[BRETV]

Originally Posted by Robin Lawrence

Lots of good information here. I just finished my stick shift Mustang and have made 2 runs before the track closed. Started out with a 3.32 first and a 5.43 rear gear.

I plan to test a few different first gear as well as rear gear ratio's this year.

What class Robin?




Bret Velde
2003 ??/SA

[Eddie Rezac]

Originally Posted by tavbfl

Thank you all for your comments! The chart from Black Magic was exactly what I was looking for. To answer some of your questions, my 60 ft has been between 1.38 and 1.46, 330 ft between 4.10 and 4.15, and my first gear is 2.80. Finding gears for the Doug Nash is a challenge so this can be my callout to any racers that have them in a box on the shelf somewhere. I am looking to change to 5.57 gears as I am crossing at 6300 with the 5.14's and motor makes power to 7000. I am also dialing in a slipper clutch for the first time so it's a matter of optimizing my combo and then focusing on consistency.

Check my ad in parts for sale section! Eddie Rezac

[bykr]

Originally Posted by Mike Pearson

When I ran a stick in my super stock car the SLR was about 19 to 1 3.11 low gear and 6.17 in the rear. Had to yank the handle real quick low to second.

Real close to my #'s 3.28 and 6.20's. 2nd gear has to be in about 1 second.

[Jim Caughlin]

Originally Posted by bykr

Real close to my #'s 3.28 and 6.20's. 2nd gear has to be in about 1 second.

The shift light is on in my car about as fast as I dump the clutch, I'm in 2nd well before the 60' timer. Looking at the data logger, the engine never drops below 6,000 and is at 8400 within 1 second. That's with a 3.29 1st gear, 6.50 rearend and 28" tall tire. I would guess that your car would be about the same. The ratio is so low that I usually drive around the pits in 2nd gear, I can outwalk the car in 1st!