Gear Question!

mystang0673 · December 2nd, 2007, 03:54 AM

ok... when i bought my car, i was told it had gears... it had a programmer on it and the guy that i bought it from took the tune off... im not sure but im thinking that my speedo went wack.. not for sure... well. i got a hypertech the other day and i set the speedo for 3.73 gears and now its 10mph slow... is this right? if its 10mph slow that would mean its stock gears right? did i tune it wrong? I dont think i could have gone wrong cuz it just asks a simple question, gear ratio. also... is it stamped on the pinion anywhere where i can take my rear diff cover off and check without having to count and what not?

outlawedstang · December 2nd, 2007, 04:35 AM

idk about with cars but when i use to mess around with truck we would take the rear tires off turn the pinion until the axle shaft make one complete rotation and see how many rotation you had to turn the pinion and it should get you in the genarl ball park of what gears are in it, like say if you turn the pinion 4 times to rotate the axle once it should be around 4.11's

cliffyk · December 2nd, 2007, 09:57 AM

Is the speedometer reading 10 mph slower than the actual speed, or is the actual speed 10 mph slower than the speedometer reading?

With the tune set to 3.73s, if the speedometer is 10 mph less than the actual speed you probably have 4.10s; however if the actual speed is less than the speedometer you probably have the stock 3.27 gears.

Here's a link to my "speed in gear" calculator that might help you out...

gsjohnson · December 2nd, 2007, 11:08 AM

Maybe 3.55s? I want one of those shift boots Cliff.

cliffyk · December 2nd, 2007, 01:12 PM

Originally Posted by gsjohnson

Maybe 3.55s? I want one of those shift boots Cliff.

Made it,

Here's how...

mystang0673 · December 2nd, 2007, 01:13 PM

Originally Posted by cliffyk

Is the speedometer reading 10 mph slower than the actual speed, or is the actual speed 10 mph slower than the speedometer reading?

With the tune set to 3.73s, if the speedometer is 10 mph less than the actual speed you probably have 4.10s; however if the actual speed is less than the speedometer you probably have the stock 3.27 gears.

Here's a link to my "speed in gear" calculator that might help you out...

Actually... it would be opposite of that... if the speedo is faster than actual speed it means you have gears... so.... consequently... if speedo is slower than actual speed it would mean that when i tuned it for 3.73's... it has stock gears because it is undercalculating to match the extra rotations in the rear end which would make it read less than the actual speed if the ratio is stock!

cliffyk · December 2nd, 2007, 01:52 PM

You are correct, got 'em back-end to...

If you are tuned for 3.73s and the speedometer is 10 mph faster than actual speed then you probably have 4.10s;

If you are tuned for 3.73s and the speedometer is 10 mph less than actual speed then you probably have 3.27s.

But, which is it--is the actual speed lower than the speedometer or vice-versa?

mystang0673 · December 2nd, 2007, 01:58 PM

ok... when my speedo says im doin 60.. im actually doin 70. with the tune to 3.73s

mystang0673 · December 2nd, 2007, 01:58 PM

which would mean i have stock gears

Drick · December 2nd, 2007, 02:03 PM

Nice shifter setup and fab man

gsjohnson · December 2nd, 2007, 09:35 PM

Originally Posted by cliffyk

Made it,

Here's how...

Holy crap, that looks like a lot of work and you've got to have sewing talent to boot. Hell, I can barely get dinner out of my wife. I love that MGW shifter & boot.

neverfastenough1 · December 2nd, 2007, 10:39 PM

If you have the diff opened up just count the teeth on the pinion gear and the ring gear. Divide the ring by the pinion.

December 2nd, 2007, 03:54 AM	#1
mystang0673 MM Fanatic 6.82@100mph 1.45 60' Join Date: Jan 2007 Posts: 3,260 iTrader: 0 reviews	Gear Question! ok... when i bought my car, i was told it had gears... it had a programmer on it and the guy that i bought it from took the tune off... im not sure but im thinking that my speedo went wack.. not for sure... well. i got a hypertech the other day and i set the speedo for 3.73 gears and now its 10mph slow... is this right? if its 10mph slow that would mean its stock gears right? did i tune it wrong? I dont think i could have gone wrong cuz it just asks a simple question, gear ratio. also... is it stamped on the pinion anywhere where i can take my rear diff cover off and check without having to count and what not?

December 2nd, 2007, 04:35 AM	#2
outlawedstang Regular 02 mustang gt Join Date: Oct 2007 Location: dixie Posts: 71 iTrader: 0 reviews	idk about with cars but when i use to mess around with truck we would take the rear tires off turn the pinion until the axle shaft make one complete rotation and see how many rotation you had to turn the pinion and it should get you in the genarl ball park of what gears are in it, like say if you turn the pinion 4 times to rotate the axle once it should be around 4.11's __________________

December 2nd, 2007, 09:57 AM	#3
cliffyk Hardcore Enthusiast Join Date: Feb 2007 Location: Saint Augustine, FL Posts: 1,807 iTrader: 1 reviews	Is the speedometer reading 10 mph slower than the actual speed, or is the actual speed 10 mph slower than the speedometer reading? With the tune set to 3.73s, if the speedometer is 10 mph less than the actual speed you probably have 4.10s; however if the actual speed is less than the speedometer you probably have the stock 3.27 gears. Here's a link to my "speed in gear" calculator that might help you out... __________________ -cliff knight- My Mustang 2003 GT, UPR X, 24lb/h injectors, Magnaflow, 180° stat, PP 70mm TB & plenum, DF Commando, Steeda UDPs, Ralco RZ_flywheel, RAM HDX clutch, WX EFX COPs 3.73s, 262 rwHP/305 lb-ft. Flex-fuel: burns gas and rubber...

December 2nd, 2007, 11:08 AM	#4
gsjohnson Enthusiast Join Date: Sep 2007 Location: Woodland Hills, CA Posts: 682 iTrader: 0 reviews	Maybe 3.55s? I want one of those shift boots Cliff. __________________ 2004 Mustang GT The difference between a girlfriend and wife is about 50 pounds.

December 2nd, 2007, 01:52 PM	#7
cliffyk Hardcore Enthusiast Join Date: Feb 2007 Location: Saint Augustine, FL Posts: 1,807 iTrader: 1 reviews	You are correct, got 'em back-end to... If you are tuned for 3.73s and the speedometer is 10 mph *faster* than actual speed then you probably have 4.10s; If you are tuned for 3.73s and the speedometer is 10 mph less than actual speed then you probably have 3.27s. But, which is it--is the actual speed lower than the speedometer or vice-versa? __________________ -cliff knight- My Mustang 2003 GT, UPR X, 24lb/h injectors, Magnaflow, 180° stat, PP 70mm TB & plenum, DF Commando, Steeda UDPs, Ralco RZ_flywheel, RAM HDX clutch, WX EFX COPs 3.73s, 262 rwHP/305 lb-ft. Flex-fuel: burns gas and rubber...

December 2nd, 2007, 01:58 PM	#8
mystang0673 MM Fanatic 6.82@100mph 1.45 60' Join Date: Jan 2007 Posts: 3,260 iTrader: 0 reviews	ok... when my speedo says im doin 60.. im actually doin 70. with the tune to 3.73s

December 2nd, 2007, 02:03 PM	#10
Drick Big timin' in a small town 2004 FX4 F150, 86 GT Join Date: Apr 2007 Location: Gods country. Nordern Michigan eh Posts: 14,336 iTrader: 1 reviews	Nice shifter setup and fab man __________________ FX4 Crew Crew member #1 Don't take anything I say to heart, I don't try to come off as an asshole. It just happens

December 2nd, 2007, 10:39 PM	#12
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,789 iTrader: 3 reviews	If you have the diff opened up just count the teeth on the pinion gear and the ring gear. Divide the ring by the pinion. __________________

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