rear-end ratio... steeper than i thought

otislee · August 17th, 2010, 09:25 PM

Bought this car sight unseen. been really happy with it. I knew going into it that the previous owner was clueless about the diff. ratio. I just kind of gambled on that point. took it out on the highway for the first time today... I was amazed... 3000rpm at 60mph in 5th gear. What are these gears, 3.56? Higher? I might switch these out. a little steep for me.
What gears do you think i have?

qwkpny9150 · August 17th, 2010, 10:59 PM

this website will answer most of your questions PaladinMicro

Mach Boy · August 18th, 2010, 01:03 AM

Originally Posted by qwkpny9150

this website will answer most of your questions PaladinMicro

+1 we need more info than just your speed and RPM.

otislee · August 18th, 2010, 01:21 AM

wow. what a helpful site. Thanks.
So I plugged in the rear tire specs (285/35/17),
entered the 5 speed transmission I have,
and played with the rear gear ratios until i replicated the speeds I was traveling at in the respective gears (1-5)

All that to say, It seemed steep while driving 60 at 3000rpm...
turns out i was right, the table has me at a 5.71 ratio.

scary.
anyone in the market for 5.71 gears?

otislee · August 18th, 2010, 01:31 AM

Yep. The calculation is correct. I checked a second calculator and searched Summit's catalog. Turns out 5.71 gears are not too uncommon. What a mess. I'm switching them as soon as I have the chance.

walt1120 · August 18th, 2010, 01:35 AM

Originally Posted by otislee

Yep. The calculation is correct. I checked a second calculator and searched Summit's catalog. Turns out 5.71 gears are not too uncommon. What a mess. I'm switching them as soon as I have the chance.

dude what do you top out at thats crazy, the car probably reaches redline in 5th the very second after it finishes the 1/4 mile lol

Hourofpain · August 18th, 2010, 05:59 AM

Thats probably all it was even meant for.
i mean damn. Is first gear even usable?

question though.
Has your speed been calibrated with a speed cal or a different gear?
Because if not chances are your only doing around 50 or so

3000 rpm's sound alot like 4.10's or 4.30's

my gt would hit about that doing around 55 with the speed corrected.

92Notch · August 18th, 2010, 06:03 AM

5.71? Damn! Great if you got some gumballs and power behind um'...And you better bang them gears! Haha.

Smoothgrandmama · August 18th, 2010, 06:25 AM

Id be happy to pace ya and check your speed for you man.

majorownage · August 18th, 2010, 06:45 AM

571's are for 1/8 miles lol too steep for the 1/4

Hourofpain · August 18th, 2010, 06:46 AM

GPS ftw

rst1523 · August 18th, 2010, 12:08 PM

damn...i just put 4.10's in mine and i spin 3k at 50 in 4th on stock tires. Your top end must suck, 120's-130's?

ReverendDexter · August 18th, 2010, 12:11 PM

How do 5.71s even fit? I thought the steepest gears that worked in a stock housing were 4.56s, maybe 4.88s.

Have you checked your speedo against anything?

otislee · August 18th, 2010, 04:06 PM

All good points. You may be right. At least I hope you're right. The speedo may not be corrected... however, the speed limit was 60 in the area I was driving in and it's a pretty big speed-trap spot. I was just going with flow of traffic.
It is interesting, though... When the calculator told me 5.71 gears, I had never heard of that ratio before. I thought a mistake had been made until I searched 8.8 rear gears at summit.com and found them sitting right there at the end of the list... "5.71".
Regardless, I was revving way to high at whatever highway speed I was traveling.

otislee · August 18th, 2010, 04:11 PM

... and yes, you quickly blow through whatever impressive power band the boosted 4.6 has to offer.
I like the feeling of the gradual boost increase of a centrifugal supercharged/shallow geared car anyway... something that won't break the tires loose so easily.

Hourofpain · August 18th, 2010, 04:59 PM

have a buddy lend you the gps and check your speeds. most accurate way

Mach Boy · August 18th, 2010, 05:46 PM

If the speedo isn't corrected your car has fewer miles on it than you think.

Hourofpain · August 18th, 2010, 08:00 PM

^issue i had with the gt.
Rather frustrating

cliffyk · August 26th, 2010, 03:29 PM

OP, did you ever verify the speedometer accuracy--just curious?

Chris951 · August 29th, 2010, 03:21 PM

you could just jack the ass of your car up and spin one wheel one revolution and count how many times the driveshaft turns. That will tell you what gears you have more accurately than some online calculator.

August 17th, 2010, 09:25 PM	#1
otislee Newbie 1997 Mustang Cobra Join Date: Jul 2010 Location: Conroe, TX Posts: 30 iTrader: 0 reviews	rear-end ratio... steeper than i thought Bought this car sight unseen. been really happy with it. I knew going into it that the previous owner was clueless about the diff. ratio. I just kind of gambled on that point. took it out on the highway for the first time today... I was amazed... 3000rpm at 60mph in 5th gear. What are these gears, 3.56? Higher? I might switch these out. a little steep for me. What gears do you think i have? __________________ "The greatest trick the devil ever pulled was convincing the world he didn't exist"

August 18th, 2010, 01:21 AM	#4
otislee Newbie 1997 Mustang Cobra Join Date: Jul 2010 Location: Conroe, TX Posts: 30 iTrader: 0 reviews	wow. what a helpful site. Thanks. So I plugged in the rear tire specs (285/35/17), entered the 5 speed transmission I have, and played with the rear gear ratios until i replicated the speeds I was traveling at in the respective gears (1-5) All that to say, It seemed steep while driving 60 at 3000rpm... turns out i was right, the table has me at a 5.71 ratio. scary. anyone in the market for 5.71 gears? __________________ "The greatest trick the devil ever pulled was convincing the world he didn't exist"

August 18th, 2010, 01:31 AM	#5
otislee Newbie 1997 Mustang Cobra Join Date: Jul 2010 Location: Conroe, TX Posts: 30 iTrader: 0 reviews	Yep. The calculation is correct. I checked a second calculator and searched Summit's catalog. Turns out 5.71 gears are not too uncommon. What a mess. I'm switching them as soon as I have the chance. __________________ "The greatest trick the devil ever pulled was convincing the world he didn't exist"

August 18th, 2010, 05:59 AM	#7
Hourofpain Hardcore Enthusiast 2005 Torrid Red GTO m6 Join Date: Mar 2007 Location: Virginia Beach Posts: 1,524 iTrader: 0 reviews	Thats probably all it was even meant for. i mean damn. Is first gear even usable? question though. Has your speed been calibrated with a speed cal or a different gear? Because if not chances are your only doing around 50 or so 3000 rpm's sound alot like 4.10's or 4.30's my gt would hit about that doing around 55 with the speed corrected. __________________ 1996 Cobra To be sold... 2005 M6 Twin Turbo GTO Torrid Red Fully Forged LS2 Block Built to handle 1000RWHP. Fully ported Dart Heads. Edelbrock Jr Intake. Custom cut upper intake plenum. APS twin Turbo System with APS twin Fuel pumps. Last edited by Hourofpain; August 18th, 2010 at 06:02 AM.

August 18th, 2010, 06:03 AM	#8
92Notch Enthusiast 1996 Cobra Not fast enough. Join Date: Feb 2010 Location: San Jose..408! Posts: 787 iTrader: 0 reviews	5.71? Damn! Great if you got some gumballs and power behind um'...And you better bang them gears! Haha. __________________ Mods: Full 01 Cobra drivetrain (Teksid block ) T56, 3.73s, Pro 5.0, Aluminum driveshaft, JLT CAI, BBK O/R X, SLP LM1s, Full welded in sub frame connectors

August 17th, 2010, 10:59 PM	#2
qwkpny9150 Regular 04 Cobra Join Date: Jul 2010 Location: Newport News, VA Posts: 52 iTrader: 0 reviews	this website will answer most of your questions PaladinMicro

August 18th, 2010, 06:25 AM	#9
Smoothgrandmama Assistant to the Manager 12 GT 8.46@88 1/8 Join Date: Apr 2007 Location: Willis,Texas Posts: 7,136 iTrader: 6 reviews	Id be happy to pace ya and check your speed for you man. __________________ Join The MM Facebook: Modded Mustangs Facebook Vote For Modded Mustangs Ride of the Month Eskimo Brothers To Smooth: Safi, Blitz34, Graystang01, WillTheThrill, Bwal, 101Fng

August 18th, 2010, 06:45 AM	#10
majorownage Regular Join Date: Jun 2010 Posts: 424 iTrader: 0 reviews	571's are for 1/8 miles lol too steep for the 1/4

August 18th, 2010, 06:46 AM	#11
Hourofpain Hardcore Enthusiast 2005 Torrid Red GTO m6 Join Date: Mar 2007 Location: Virginia Beach Posts: 1,524 iTrader: 0 reviews	GPS ftw __________________ 1996 Cobra To be sold... 2005 M6 Twin Turbo GTO Torrid Red Fully Forged LS2 Block Built to handle 1000RWHP. Fully ported Dart Heads. Edelbrock Jr Intake. Custom cut upper intake plenum. APS twin Turbo System with APS twin Fuel pumps.

August 18th, 2010, 12:08 PM	#12
rst1523 Regular 2003 Mach 1 Join Date: Jun 2010 Location: Suwanee, GA Posts: 179 iTrader: 0 reviews	damn...i just put 4.10's in mine and i spin 3k at 50 in 4th on stock tires. Your top end must suck, 120's-130's?

August 18th, 2010, 12:11 PM	#13
ReverendDexter Priest of the Car Gods Clapped-out '90 GT 'vert ~5.5 seconds off TTOD :( Join Date: Jan 2007 Location: Rohnert Park, CA Posts: 13,808 iTrader: 0 reviews	How do 5.71s even fit? I thought the steepest gears that worked in a stock housing were 4.56s, maybe 4.88s. Have you checked your speedo against anything? __________________ O o /¯/______________________ \|BLAAAAAAAAAAAAAAAAAAAAAAAAARGH!!! \_\

August 18th, 2010, 04:06 PM	#14
otislee Newbie 1997 Mustang Cobra Join Date: Jul 2010 Location: Conroe, TX Posts: 30 iTrader: 0 reviews	All good points. You may be right. At least I hope you're right. The speedo may not be corrected... however, the speed limit was 60 in the area I was driving in and it's a pretty big speed-trap spot. I was just going with flow of traffic. It is interesting, though... When the calculator told me 5.71 gears, I had never heard of that ratio before. I thought a mistake had been made until I searched 8.8 rear gears at summit.com and found them sitting right there at the end of the list... "5.71". Regardless, I was revving way to high at whatever highway speed I was traveling. __________________ "The greatest trick the devil ever pulled was convincing the world he didn't exist"

August 18th, 2010, 04:11 PM	#15
otislee Newbie 1997 Mustang Cobra Join Date: Jul 2010 Location: Conroe, TX Posts: 30 iTrader: 0 reviews	... and yes, you quickly blow through whatever impressive power band the boosted 4.6 has to offer. I like the feeling of the gradual boost increase of a centrifugal supercharged/shallow geared car anyway... something that won't break the tires loose so easily. __________________ "The greatest trick the devil ever pulled was convincing the world he didn't exist"

August 18th, 2010, 04:59 PM	#16
Hourofpain Hardcore Enthusiast 2005 Torrid Red GTO m6 Join Date: Mar 2007 Location: Virginia Beach Posts: 1,524 iTrader: 0 reviews	have a buddy lend you the gps and check your speeds. most accurate way __________________ 1996 Cobra To be sold... 2005 M6 Twin Turbo GTO Torrid Red Fully Forged LS2 Block Built to handle 1000RWHP. Fully ported Dart Heads. Edelbrock Jr Intake. Custom cut upper intake plenum. APS twin Turbo System with APS twin Fuel pumps.

August 18th, 2010, 05:46 PM	#17
Mach Boy MM's Orangest 2004 Mach 1 Mustang Join Date: Sep 2007 Location: Indy Posts: 2,846 Blog Entries: 1 iTrader: 1 reviews	If the speedo isn't corrected your car has fewer miles on it than you think. __________________ Looking for 03/04 4V ABS Wiring Harness Connector/Incomplete Wiring Harness (with ABS connector)

August 26th, 2010, 03:29 PM	#19
cliffyk Hardcore Enthusiast Join Date: Feb 2007 Location: Saint Augustine, FL Posts: 1,802 iTrader: 1 reviews	OP, did you ever verify the speedometer accuracy--just curious? __________________ -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...

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August 18th, 2010, 08:00 PM	#18
Hourofpain Hardcore Enthusiast 2005 Torrid Red GTO m6 Join Date: Mar 2007 Location: Virginia Beach Posts: 1,524 iTrader: 0 reviews	^issue i had with the gt. Rather frustrating __________________ 1996 Cobra To be sold... 2005 M6 Twin Turbo GTO Torrid Red Fully Forged LS2 Block Built to handle 1000RWHP. Fully ported Dart Heads. Edelbrock Jr Intake. Custom cut upper intake plenum. APS twin Turbo System with APS twin Fuel pumps.

August 29th, 2010, 03:21 PM	#20
Chris951 Hardcore Enthusiast 1991 mustang 5.0 Join Date: Aug 2007 Location: Mesa, AZ Posts: 1,938 iTrader: 0 reviews	you could just jack the ass of your car up and spin one wheel one revolution and count how many times the driveshaft turns. That will tell you what gears you have more accurately than some online calculator.

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