first gear ratio's

L79racer · 11-18-2007, 09:15 PM

Just wondering what first gear ratios different weight cars have. Let me know rear gear, first gear and tire size plus weight of car. How much first gear needed for a light car compared to a heavy car? I have a 2.64 first 4.56 rear on 28" tires @2800lbs. 4.56x 2.64= 12.03 Is this way off? I would think a light car doesnt need as much first gear as a heavier car running 14x32 tires. Is there a formula that you guys go by when setting up a car? This would be for stick cars. I would think automatics is a whole different ball game with the converter.

Jeff Lee · 11-19-2007, 01:14 AM

The formula is:
$ x $ squared / busted knuckles = inverse of expectations

greg fulk · 11-20-2007, 03:56 AM

It goes more on what the engine needs then weight of the car. big blocks need less then small blocks.....what's the car weigh? what motor? & what the hell ya running? Brackets....S/ST Hot/Rod Super/Gas? It all makes a differance. My old car had a 6cyl 5.13 gear with 26" tall tires it crossed @ 5800 in the 1/4 new car has a 5.13 gear with 30" tall tires and crosses @ 6800....

L79racer · 11-20-2007, 08:21 PM

Greg, Car is just over 2800 lbs with me in it. 4.56 rear and 2.64 fist gear.28"slicks.383 small block in it. Its just a street strip car. Shift at 7200 and running through the traps at 7000-7400 depending on which slick I use. Best I went was 10.44 at 133 with 1.52 60 foot. I know the clutch is wrong for optimal ets.

Dave Goob Cook · 11-21-2007, 12:20 AM

I would say that you are about right, I would think 12.5 - 15: 1 starting line ratio would be right.
Yup, automatics are a whole different bag.

I've run starting line ratios from 15.77:1 down to 7.23:1 and everywhere in between, with automatics.

Your 60' time is a little soft for the ET and MPH, but you're close.

greg fulk · 11-21-2007, 03:00 AM

this is a street strip car? I don't think I want to come down that street! LOL Anyway for the most part I think stocker guys use somewhere between 2.90 & 3.10 low gear. what trans are you running? Like dave said before your 60' is a little off....I turn 1.61 60's but that with a 3600# car running 12.70's. I think a lower gear will make it a little more "street" frendly......now then can you "hook" the car after you do that?......I guess the question is are you happy with the car? If your not go for it....add some gear ! my 6 cyl picked up .15 going from a 1.82 to a 2.08 low gear in a powerglide.

L79racer · 11-21-2007, 03:16 PM

Greg, its a proshifted super T-10 with the nodular iron case and tail housing. I'm sure with an advanced clutch and a better first gear I will go right into the 9's with it. Unfortunatly money is to be considered at this time so they will have to wait. In due time I will have both.

greg fulk · 11-22-2007, 03:08 AM

Street Car???? sure.....Good Luck!

give us updates on that "street" car!

11-18-2007, 09:15 PM	#1
L79racer Member Join Date: Jan 2005 Location: North Massapequa, NY Posts: 218 Likes: 0 Liked 0 Times in 0 Posts	first gear ratio's Just wondering what first gear ratios different weight cars have. Let me know rear gear, first gear and tire size plus weight of car. How much first gear needed for a light car compared to a heavy car? I have a 2.64 first 4.56 rear on 28" tires @2800lbs. 4.56x 2.64= 12.03 Is this way off? I would think a light car doesnt need as much first gear as a heavier car running 14x32 tires. Is there a formula that you guys go by when setting up a car? This would be for stick cars. I would think automatics is a whole different ball game with the converter.

11-19-2007, 01:14 AM	#2
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: first gear ratio's The formula is: $ x $ squared / busted knuckles = inverse of expectations __________________ Jeff Lee 7494 D/S '70 AMX

11-20-2007, 03:56 AM	#3
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: first gear ratio's It goes more on what the engine needs then weight of the car. big blocks need less then small blocks.....what's the car weigh? what motor? & what the hell ya running? Brackets....S/ST Hot/Rod Super/Gas? It all makes a differance. My old car had a 6cyl 5.13 gear with 26" tall tires it crossed @ 5800 in the 1/4 new car has a 5.13 gear with 30" tall tires and crosses @ 6800.... __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

11-20-2007, 08:21 PM	#4
L79racer Member Join Date: Jan 2005 Location: North Massapequa, NY Posts: 218 Likes: 0 Liked 0 Times in 0 Posts	Re: first gear ratio's Greg, Car is just over 2800 lbs with me in it. 4.56 rear and 2.64 fist gear.28"slicks.383 small block in it. Its just a street strip car. Shift at 7200 and running through the traps at 7000-7400 depending on which slick I use. Best I went was 10.44 at 133 with 1.52 60 foot. I know the clutch is wrong for optimal ets. Last edited by L79racer; 11-20-2007 at 08:26 PM.

11-21-2007, 12:20 AM	#5
Dave Goob Cook Member Join Date: Dec 2006 Location: Indy Posts: 422 Likes: 0 Liked 0 Times in 0 Posts	Re: first gear ratio's I would say that you are about right, I would think 12.5 - 15: 1 starting line ratio would be right. Yup, automatics are a whole different bag. I've run starting line ratios from 15.77:1 down to 7.23:1 and everywhere in between, with automatics. Your 60' time is a little soft for the ET and MPH, but you're close.

11-21-2007, 03:00 AM	#6
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: first gear ratio's this is a street strip car? I don't think I want to come down that street! LOL Anyway for the most part I think stocker guys use somewhere between 2.90 & 3.10 low gear. what trans are you running? Like dave said before your 60' is a little off....I turn 1.61 60's but that with a 3600# car running 12.70's. I think a lower gear will make it a little more "street" frendly......now then can you "hook" the car after you do that?......I guess the question is are you happy with the car? If your not go for it....add some gear ! my 6 cyl picked up .15 going from a 1.82 to a 2.08 low gear in a powerglide. __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

11-21-2007, 03:16 PM	#7
L79racer Member Join Date: Jan 2005 Location: North Massapequa, NY Posts: 218 Likes: 0 Liked 0 Times in 0 Posts	Re: first gear ratio's Greg, its a proshifted super T-10 with the nodular iron case and tail housing. I'm sure with an advanced clutch and a better first gear I will go right into the 9's with it. Unfortunatly money is to be considered at this time so they will have to wait. In due time I will have both.

11-22-2007, 03:08 AM	#8
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: first gear ratio's Street Car???? sure.....Good Luck! give us updates on that "street" car! __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"