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[Turbo V6 Camaro]

Originally posted by andrew.brandon:
</font><blockquote>quote:</font><hr />Originally posted by viper04af:
i'm goint to upgrade next year..... maybe even a locker like James has.....

but i can't figure out 3.73 or 4.10's..... not sure what the turbo will like :mad:

this is a good write up about choosing gears but you need good track and dyno times first

http://firebirdnation.com/forums/ind...?showtopic=618 </font>[/QUOTE]Sorry, an error occurred. If you are unsure on how to use a feature, or don't know why you got this error message, try looking through the help files for more information.

[andrew.brandon]

The old addage about gearing(60's and 70's) was that the more gearing a car had,the faster it was.That was true,unless the car spun the tires,or the motor was overreving at the end of the quarter.Most of those cars of the era had big blocks and narrow hard compound tires,so they burnt the tires for blocks and ran slow times at high mph.
Today's cars use smaller,more efficient motors that make more hp/ci than previous models.To make a car run to its potential it needs the proper gearing,and I will tell you how to do that.


Most important item:
You want to cross the 1/4 mile mark at either peak power(rpm)in your 1:1 gear,or slightly below it.Why?Your car will pull only until the peak,then it dies regardless. Unfortunately the gear selection for 10 and 9 bolt rears that came from the factory is limited,so choose carefully.


An Example:

A car that has 500hp on the bottle at 5500rpm, 25.5" tires,and runs about 121mph in the quarter. I looked up the stock gear ratios in a Firebird manual.It gave the mph/1000rpm for every gear available.I proceded as follows:5500rpm with 3.42 gears gave 120mph,based on 21.82mph/1000rpm.You just multiply 5.5 times 21.82,and you get 120mph,right on the money.I didn't mention that off the bottle that the car runs 108mph,at the same rpm.If I had done the gearing just based on the motor,I would have picked 3.73 gears.Why?Because the 3.73 gears are 20mph/1000rpm,making 110mph(just slightly under).
The following list comprises gear ratio and mph/1000rpm with 25.5" tires(stock height).


2.73 gears: 27.35mph/1000rpm
3.08 gears: 24.24mph/1000rpm
3.23 gears: 23.10mph/1000rpm
3.42 gears: 21.82mph/1000rpm
3.73 gears: 20 mph/1000rpm
4.10 gears: 18.20mph/1000rpm
4.56 gears: 16.36mph/1000rpm

Of course.not all tires are 25.5" tall,all slicks and street slicks measure 26" and up. Tires taller than 29" don't fit,so I will give ratios for 26,27,28,29" tires.I also will show how to calculate based on different tire sizes and gearing for any application.

26" tires


2.73 gears: 27.89mph/1000rpm
3.08 gears: 24.71mph/1000rpm
3.23 gears: 23.55mph/1000rpm
3.42 gears: 22.24mph/1000rpm
3.73 gears: 20.39mph/1000rpm
4.10 gears: 18.55mph/1000rpm
4.56 gears: 16.68mph/1000rpm

27" tires


2.73 gears: 28.96mph/1000rpm
3.08 gears: 25.66mph/1000rpm
3.23 gears: 24.45mph/1000rpm
3.42 gears: 23.09mph/1000rpm
3.73 gears: 21.17mph/1000rpm
4.10 gears: 19.26mph/1000rpm
4.56 gears: 17.32mph/1000rpm

28" tires


2.73 gears: 30.03mph/1000rpm
3.08 gears: 26.61mph/1000rpm
3.23 gears: 25.45mph/1000rpm
3.42 gears: 23.94mph/1000rpm
3.73 gears: 21.95mph/1000rpm
4.10 gears: 19.97mph/1000rpm
4.56 gears: 17.96mph/1000rpm

29" tires


2.73 gears: 31.10mph/1000rpm
3.08 gears: 27.56mph/1000rpm
3.23 gears: 26.36mph/1000rpm
3.42 gears: 24.80mph/1000rpm
3.73 gears: 22.73mph/1000rpm
4.10 gears: 20.68mph/1000rpm
4.56 gears: 18.60mph/1000rpm

If you have gears that are imbetween,smaller,or larger than the numbers,or if your tires are a different height,use this formula:


rpm(at power peak) * tire height (inches)
------------------------------------------ = optimum gear ratio
mph(at end of quarter mile) * 341.73 (constant)

I'll do an example:

5500rpm * 25.5"
----------------- = 3.39 gears, a close match for what I picked
121mph * 341.73

Most street cars do not need over 3.73 gears for stock height tires,usually 3.23 to 3.73 works best.Do not overlook the fact that the higher the gear,the more wheelspin you will get,don't expect a car with 4.56 gears to hook up on street tires as well as a car with 3.73's.

Higher powered cars need larger(taller) tires to hook well,this is because taller tires allow more tire patch on the pavement.You need to regear the car for the tall tires you need at the track,but live with higher rpm around town.

When you change gears and or tire height,you need to recalibrate the speedo gear so that the speedo is correct,and the computer functions correctly.I know for a fact that TH700R4 transmissions cars came with 2.73,3.08,3.23,and 3.42 gears from the factory,some might have come with 3.73's also(I am not definitely sure).To get the correct gears(2),go to a Chevy(or pontaic) dealer and ask them to look up replacement speedo gears for 3rd generation f-bodies,they have the numbers in the computer for the forementioned ratios.Those with T-5's can do the same thing,because GM stocks those gears also.Those with 4.10 or higher gears will have to ask questions and do research to find the correct speedo gears.


One last thing:
Changing the rearend gears to a ratio that suits quarter mile performance will sometime cut top speed(in OD).To figure out if this will happen,just leave the mph blank(at end of quarter mile) and multiply the gear ratio(you have) times the OD gear ratio.Working backward,you can find the mph(top end now,not quarter mile!).


Example:

5500rpm * 25.5"
------------------ = 3.42 * 0.70
Mph *341.73


You get 171mph,probably about 5mph faster than the actual top end.I was just lucky that the quarter mile gearing was the optimum top end gearing also,others may not be so lucky.

[Turbo V6 Camaro]

Originally posted by andrew.brandon:
The old addage about gearing(60's and 70's) was that the more gearing a car had,the faster it was.That was true,unless the car spun the tires,or the motor was overreving at the end of the quarter.Most of those cars of the era had big blocks and narrow hard compound tires,so they burnt the tires for blocks and ran slow times at high mph.
Today's cars use smaller,more efficient motors that make more hp/ci than previous models.To make a car run to its potential it needs the proper gearing,and I will tell you how to do that.


Most important item:
You want to cross the 1/4 mile mark at either peak power(rpm)in your 1:1 gear,or slightly below it.Why?Your car will pull only until the peak,then it dies regardless. Unfortunately the gear selection for 10 and 9 bolt rears that came from the factory is limited,so choose carefully.


An Example:

A car that has 500hp on the bottle at 5500rpm, 25.5" tires,and runs about 121mph in the quarter. I looked up the stock gear ratios in a Firebird manual.It gave the mph/1000rpm for every gear available.I proceded as follows:5500rpm with 3.42 gears gave 120mph,based on 21.82mph/1000rpm.You just multiply 5.5 times 21.82,and you get 120mph,right on the money.I didn't mention that off the bottle that the car runs 108mph,at the same rpm.If I had done the gearing just based on the motor,I would have picked 3.73 gears.Why?Because the 3.73 gears are 20mph/1000rpm,making 110mph(just slightly under).
The following list comprises gear ratio and mph/1000rpm with 25.5" tires(stock height).


2.73 gears: 27.35mph/1000rpm
3.08 gears: 24.24mph/1000rpm
3.23 gears: 23.10mph/1000rpm
3.42 gears: 21.82mph/1000rpm
3.73 gears: 20 mph/1000rpm
4.10 gears: 18.20mph/1000rpm
4.56 gears: 16.36mph/1000rpm

Of course.not all tires are 25.5" tall,all slicks and street slicks measure 26" and up. Tires taller than 29" don't fit,so I will give ratios for 26,27,28,29" tires.I also will show how to calculate based on different tire sizes and gearing for any application.

26" tires


2.73 gears: 27.89mph/1000rpm
3.08 gears: 24.71mph/1000rpm
3.23 gears: 23.55mph/1000rpm
3.42 gears: 22.24mph/1000rpm
3.73 gears: 20.39mph/1000rpm
4.10 gears: 18.55mph/1000rpm
4.56 gears: 16.68mph/1000rpm

27" tires


2.73 gears: 28.96mph/1000rpm
3.08 gears: 25.66mph/1000rpm
3.23 gears: 24.45mph/1000rpm
3.42 gears: 23.09mph/1000rpm
3.73 gears: 21.17mph/1000rpm
4.10 gears: 19.26mph/1000rpm
4.56 gears: 17.32mph/1000rpm

28" tires


2.73 gears: 30.03mph/1000rpm
3.08 gears: 26.61mph/1000rpm
3.23 gears: 25.45mph/1000rpm
3.42 gears: 23.94mph/1000rpm
3.73 gears: 21.95mph/1000rpm
4.10 gears: 19.97mph/1000rpm
4.56 gears: 17.96mph/1000rpm

29" tires


2.73 gears: 31.10mph/1000rpm
3.08 gears: 27.56mph/1000rpm
3.23 gears: 26.36mph/1000rpm
3.42 gears: 24.80mph/1000rpm
3.73 gears: 22.73mph/1000rpm
4.10 gears: 20.68mph/1000rpm
4.56 gears: 18.60mph/1000rpm

If you have gears that are imbetween,smaller,or larger than the numbers,or if your tires are a different height,use this formula:


rpm(at power peak) * tire height (inches)
------------------------------------------ = optimum gear ratio
mph(at end of quarter mile) * 341.73 (constant)

I'll do an example:

5500rpm * 25.5"
----------------- = 3.39 gears, a close match for what I picked
121mph * 341.73

Most street cars do not need over 3.73 gears for stock height tires,usually 3.23 to 3.73 works best.Do not overlook the fact that the higher the gear,the more wheelspin you will get,don't expect a car with 4.56 gears to hook up on street tires as well as a car with 3.73's.

Higher powered cars need larger(taller) tires to hook well,this is because taller tires allow more tire patch on the pavement.You need to regear the car for the tall tires you need at the track,but live with higher rpm around town.

When you change gears and or tire height,you need to recalibrate the speedo gear so that the speedo is correct,and the computer functions correctly.I know for a fact that TH700R4 transmissions cars came with 2.73,3.08,3.23,and 3.42 gears from the factory,some might have come with 3.73's also(I am not definitely sure).To get the correct gears(2),go to a Chevy(or pontaic) dealer and ask them to look up replacement speedo gears for 3rd generation f-bodies,they have the numbers in the computer for the forementioned ratios.Those with T-5's can do the same thing,because GM stocks those gears also.Those with 4.10 or higher gears will have to ask questions and do research to find the correct speedo gears.


One last thing:
Changing the rearend gears to a ratio that suits quarter mile performance will sometime cut top speed(in OD).To figure out if this will happen,just leave the mph blank(at end of quarter mile) and multiply the gear ratio(you have) times the OD gear ratio.Working backward,you can find the mph(top end now,not quarter mile!).


Example:

5500rpm * 25.5"
------------------ = 3.42 * 0.70
Mph *341.73


You get 171mph,probably about 5mph faster than the actual top end.I was just lucky that the quarter mile gearing was the optimum top end gearing also,others may not be so lucky.

[BLLDOGG]

its alright viper, its only math [img]tongue.gif[/img]

[Fbody3400]

Originally posted by viper04af:
</font><blockquote>quote:</font><hr />Originally posted by andrew.brandon:
The old addage about gearing(60's and 70's) was that the more gearing a car had,the faster it was.That was true,unless the car spun the tires,or the motor was overreving at the end of the quarter.Most of those cars of the era had big blocks and narrow hard compound tires,so they burnt the tires for blocks and ran slow times at high mph.
Today's cars use smaller,more efficient motors that make more hp/ci than previous models.To make a car run to its potential it needs the proper gearing,and I will tell you how to do that.


Most important item:
You want to cross the 1/4 mile mark at either peak power(rpm)in your 1:1 gear,or slightly below it.Why?Your car will pull only until the peak,then it dies regardless. Unfortunately the gear selection for 10 and 9 bolt rears that came from the factory is limited,so choose carefully.


An Example:

A car that has 500hp on the bottle at 5500rpm, 25.5" tires,and runs about 121mph in the quarter. I looked up the stock gear ratios in a Firebird manual.It gave the mph/1000rpm for every gear available.I proceded as follows:5500rpm with 3.42 gears gave 120mph,based on 21.82mph/1000rpm.You just multiply 5.5 times 21.82,and you get 120mph,right on the money.I didn't mention that off the bottle that the car runs 108mph,at the same rpm.If I had done the gearing just based on the motor,I would have picked 3.73 gears.Why?Because the 3.73 gears are 20mph/1000rpm,making 110mph(just slightly under).
The following list comprises gear ratio and mph/1000rpm with 25.5" tires(stock height).


2.73 gears: 27.35mph/1000rpm
3.08 gears: 24.24mph/1000rpm
3.23 gears: 23.10mph/1000rpm
3.42 gears: 21.82mph/1000rpm
3.73 gears: 20 mph/1000rpm
4.10 gears: 18.20mph/1000rpm
4.56 gears: 16.36mph/1000rpm

Of course.not all tires are 25.5" tall,all slicks and street slicks measure 26" and up. Tires taller than 29" don't fit,so I will give ratios for 26,27,28,29" tires.I also will show how to calculate based on different tire sizes and gearing for any application.

26" tires


2.73 gears: 27.89mph/1000rpm
3.08 gears: 24.71mph/1000rpm
3.23 gears: 23.55mph/1000rpm
3.42 gears: 22.24mph/1000rpm
3.73 gears: 20.39mph/1000rpm
4.10 gears: 18.55mph/1000rpm
4.56 gears: 16.68mph/1000rpm

27" tires


2.73 gears: 28.96mph/1000rpm
3.08 gears: 25.66mph/1000rpm
3.23 gears: 24.45mph/1000rpm
3.42 gears: 23.09mph/1000rpm
3.73 gears: 21.17mph/1000rpm
4.10 gears: 19.26mph/1000rpm
4.56 gears: 17.32mph/1000rpm

28" tires


2.73 gears: 30.03mph/1000rpm
3.08 gears: 26.61mph/1000rpm
3.23 gears: 25.45mph/1000rpm
3.42 gears: 23.94mph/1000rpm
3.73 gears: 21.95mph/1000rpm
4.10 gears: 19.97mph/1000rpm
4.56 gears: 17.96mph/1000rpm

29" tires


2.73 gears: 31.10mph/1000rpm
3.08 gears: 27.56mph/1000rpm
3.23 gears: 26.36mph/1000rpm
3.42 gears: 24.80mph/1000rpm
3.73 gears: 22.73mph/1000rpm
4.10 gears: 20.68mph/1000rpm
4.56 gears: 18.60mph/1000rpm

If you have gears that are imbetween,smaller,or larger than the numbers,or if your tires are a different height,use this formula:


rpm(at power peak) * tire height (inches)
------------------------------------------ = optimum gear ratio
mph(at end of quarter mile) * 341.73 (constant)

I'll do an example:

5500rpm * 25.5"
----------------- = 3.39 gears, a close match for what I picked
121mph * 341.73

Most street cars do not need over 3.73 gears for stock height tires,usually 3.23 to 3.73 works best.Do not overlook the fact that the higher the gear,the more wheelspin you will get,don't expect a car with 4.56 gears to hook up on street tires as well as a car with 3.73's.

Higher powered cars need larger(taller) tires to hook well,this is because taller tires allow more tire patch on the pavement.You need to regear the car for the tall tires you need at the track,but live with higher rpm around town.

When you change gears and or tire height,you need to recalibrate the speedo gear so that the speedo is correct,and the computer functions correctly.I know for a fact that TH700R4 transmissions cars came with 2.73,3.08,3.23,and 3.42 gears from the factory,some might have come with 3.73's also(I am not definitely sure).To get the correct gears(2),go to a Chevy(or pontaic) dealer and ask them to look up replacement speedo gears for 3rd generation f-bodies,they have the numbers in the computer for the forementioned ratios.Those with T-5's can do the same thing,because GM stocks those gears also.Those with 4.10 or higher gears will have to ask questions and do research to find the correct speedo gears.


One last thing:
Changing the rearend gears to a ratio that suits quarter mile performance will sometime cut top speed(in OD).To figure out if this will happen,just leave the mph blank(at end of quarter mile) and multiply the gear ratio(you have) times the OD gear ratio.Working backward,you can find the mph(top end now,not quarter mile!).


Example:

5500rpm * 25.5"
------------------ = 3.42 * 0.70
Mph *341.73


You get 171mph,probably about 5mph faster than the actual top end.I was just lucky that the quarter mile gearing was the optimum top end gearing also,others may not be so lucky.

</font>[/QUOTE]I second the but not because of the math. But because the oddness of the incredibly lengthy answer that came out of nowhere.

But i did learn some from reading it.

[ezrollin]

better to have a modified car setup to support/aid/bring to life the 4.10s.
not just stock.
at least a tune

[foff667]

Originally posted by ezrollin:
better to have a modified car setup to support/aid/bring to life the 4.10s.
not just stock.
at least a tune

little g has stock heads/cam/intake/manifolds/ypipe so im not sure you have a point.

[Rowdy Burns]

don't forget rowdy burns running 13.64 with 3.73s. some of you might remember me, most probably won't.

having a healthy fear of gear is one of the most important factors in drag racing. [img]smile.gif[/img]

[shenanigans]

Originally posted by foff667:
amazing...so lets see here guys
Abbott-4.10's 12 bolt right
little g-4.10's 10 bolt
Magnus-4.10's 10 bolt I assume
James-4.10's 10 bolt

the 4 fastest na cars running gear...if thats not proof enough guys I dunno what is.

Not saying 4.10s are the wrong gear... but I just want to point out...

you lested 3 guys with race weights under 2900 lbs. Decent amount of money of aftermarket parts, And the son of probably the #1 3.8L engien builders for us.

Not trying to start a debate... just pointing it out that there is a bit more then "adding gear" to those cars.

[Rowdy Burns]

would you agree that adding gear has resulted in the fastest NA times?

[shenanigans]

Originally posted by Rowdy Burns:
would you agree that adding gear has resulted in the fastest NA times?

Increased gearing helps... I have never gone extreme my biggest jumps were 3.23s-3.42s usually to budget constraints.

Example, I just put 3.42 WS6 rear in my car for $120, I could probalby sell the Zexel Torsion out of my 3.23 rear on ebay for $150, or sell the complete rear for that much. Made $30 maybe more to upgrade from 3.23-3.42s.

But I see alot if not more people say 4.10s are NOT the way to go. Just saying research it before people start all jumping on 4.10s [img]smile.gif[/img]

And by listing some fast guys with 4.10s, people assume 4.10s are what got them there. These guys have a few other mods as well. Some of them more money then we spent on our cars and all our mods. That is a factor as for why they have good times as well.

I mean i coudl also say Camaros are faster then Firebirds. Shirl ran an 11.8. No firebirds are in the 11s yet.


Pick 4.10s if your right for your car but don't say its the only reason those cars are fast. [img]graemlins/burnout.gif[/img]

[foff667]

I mean i coudl also say Camaros are faster then Firebirds. Shirl ran an 11.8. No firebirds are in the 11s yet.
[/QB]

they are its a proven fact lol why do you think im getting another one :D as far as gears goes Im probably going to throw in a 9" with 4.3x+ gears in anticipation for an ls1/ls2 motor swap.

[foff667]

Originally posted by Rowdy Burns:
don't forget rowdy burns running 13.64 with 3.73s. some of you might remember me, most probably won't.

having a healthy fear of gear is one of the most important factors in drag racing. [img]smile.gif[/img]

what mods do you have? And whats your trap speed to run that time?

[foff667]

Originally posted by shenanigans:
</font><blockquote>quote:</font><hr />Originally posted by foff667:
amazing...so lets see here guys
Abbott-4.10's 12 bolt right
little g-4.10's 10 bolt
Magnus-4.10's 10 bolt I assume
James-4.10's 10 bolt

the 4 fastest na cars running gear...if thats not proof enough guys I dunno what is.

Not saying 4.10s are the wrong gear... but I just want to point out...

you lested 3 guys with race weights under 2900 lbs. Decent amount of money of aftermarket parts, And the son of probably the #1 3.8L engien builders for us.

Not trying to start a debate... just pointing it out that there is a bit more then "adding gear" to those cars. </font>[/QUOTE]I know exactly what your saying and until one of them swaps to 3.73's or 3.42's and runs a better et & mph I think it will be debated...so james when are you swapping to 3.73's? Maybe we'll start a collection so we can end this debate :D

[Rowdy Burns]

Originally posted by foff667:
what mods do you have? And whats your trap speed to run that time?

cam, bolt-ons, gear, stock tune. trap was 98.something. i think you know me. i know you.

details are here: http://www.fullthrottlev6.com/forums...ips.php?&do=na

# 3 [img]smile.gif[/img]