oddball question

KiltedBanshees93GT · 08-07-2003, 10:09 AM

I wasnt sure which forum this would be best asked in, but here goes:
Is there a way to figure out the rear gearing on a car using the other available data? i.e. wheel size, gear your in,gear ratio, RPM etc? I know it can be figured out, but what is the easiest formula? Sorry, dumb question, but I dont know where to start really

Thanks,
J

bigwhitecobra · 08-07-2003, 11:02 AM

Can you be a bit clearer in your question? I think I have the answer you are looking for, I just want to make sure that you are asking the question I think you are. Man, that was one long sentence. Sorry.

Later.

VeNuM · 08-07-2003, 12:30 PM

See how many times the driveshaft rotates to 1 tire rotation. I.E. Driveshaft rotates 3.73 times when tire makes 1 rotation: 3.73:1 rear gear. ~Brian

Rev · 08-07-2003, 08:57 PM

Acxtually, It depoends on whether you have a limited slip differential or not. Raise up one side lifting one rear wheel off the ground. With the car in neutral, try to rotate that off the ground wheel. If it turns easilly, you have an open rear differential.

If it won't turn, then you have a limited slip differential. With the limited slip differential, you must raise both rear wheels off the ground. Then each rotation of the (both) rear wheels will turn the drive shaft a certain number of rotations. That number (eg. 3.25) is your rear axle ratio.

Now, if you have an open axle, put one side firmly on the ground with the other side off the ground. Turn the wheel exactly 2 turns and note the number of turns of the drive shaft. That will tell you more or less the rear end ratio.

Rev

KiltedBanshees93GT · 08-08-2003, 07:00 AM

Thanks everyone, I'll try those suggestions this weekend,

J

08-07-2003, 10:09 AM	#1
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	oddball question I wasnt sure which forum this would be best asked in, but here goes: Is there a way to figure out the rear gearing on a car using the other available data? i.e. wheel size, gear your in,gear ratio, RPM etc? I know it can be figured out, but what is the easiest formula? Sorry, dumb question, but I dont know where to start really Thanks, J __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

08-07-2003, 11:02 AM	#2
bigwhitecobra Huh? Whatcha said? Join Date: Oct 2000 Location: Fayetteville, NC Posts: 1,073	Can you be a bit clearer in your question? I think I have the answer you are looking for, I just want to make sure that you are asking the question I think you are. Man, that was one long sentence. Sorry. Later. __________________ 2003 GT White---STOLEN May you burn in hell whoever took it. Dumbazz didn't even get the good engine that was in the garage.

08-07-2003, 12:30 PM	#3
VeNuM Registered Member Join Date: Apr 2002 Location: Downers Grove, IL Posts: 464	See how many times the driveshaft rotates to 1 tire rotation. I.E. Driveshaft rotates 3.73 times when tire makes 1 rotation: 3.73:1 rear gear. ~Brian __________________ 1989 Black Mustang GT Hatchback, Underdrive Pulles, Electric Fan, Cold Air Intake, Headers, Offroad H-Pipe, Magnaflow catback, Steeda Tri-Ax, Fluidyne Aluminum Radiator, Timing at 14*, 3.73's Coming not so soon: 408w Ricer Hater's Club Member #59

08-07-2003, 08:57 PM	#4
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Acxtually, It depoends on whether you have a limited slip differential or not. Raise up one side lifting one rear wheel off the ground. With the car in neutral, try to rotate that off the ground wheel. If it turns easilly, you have an open rear differential. If it won't turn, then you have a limited slip differential. With the limited slip differential, you must raise both rear wheels off the ground. Then each rotation of the (both) rear wheels will turn the drive shaft a certain number of rotations. That number (eg. 3.25) is your rear axle ratio. Now, if you have an open axle, put one side firmly on the ground with the other side off the ground. Turn the wheel exactly 2 turns and note the number of turns of the drive shaft. That will tell you more or less the rear end ratio. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe Last edited by Rev; 08-07-2003 at 09:57 PM..

08-08-2003, 07:00 AM	#5
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	Thanks everyone, I'll try those suggestions this weekend, J __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Another tire question	96Saleen	Modular Madness	6	02-10-2004 05:27 PM
A stupid question I hate asking about exhaust sound	jwboner	Windsor Power	4	08-05-2003 05:55 PM
simple question	Lonzo	Classic Mustangs	3	09-10-2002 09:37 AM
Newby here, I have a question on Odometers	mustangmama	Blue Oval Lounge	3	03-03-2001 06:43 AM
HP question	84Stang	Modular Madness	0	06-11-2000 10:17 PM