2.73 vs. 3.23 vs. 3.42: Differences?
03-24-2003, 06:39 PM
#1
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2.73 vs. 3.23 vs. 3.42: Differences?
What are the differences between the 2.73, 3.23 and 3.42 ratios?
My car is an auto. with the 3.23s and my friend has the same car, but his is a 6 spd. with the 3.42s. I don't notice any difference when I drive his car.
My car is an auto. with the 3.23s and my friend has the same car, but his is a 6 spd. with the 3.42s. I don't notice any difference when I drive his car.
03-24-2003, 06:48 PM
#2
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You would not feel any difference. The gears you speak of are located in the rear differential. They change the speed of the input form the drive shaft and slow it down before it is sent to the wheels. The gears slow down the speed and give more torque, but lower the top speed.
The higher the number of gear, 3.23, 3.42, 4.10, the more the gears will slow down the speed coming into the differential. This will also give more torque to the rear wheels for quicker launches and low speed torque. One draw back is your car will run at higher RPM's while driving. In 6th, my car will be at about 1500 RPM at 65mph, with 4.10's, it might be at about 2000 RPM at the same speed (not accurate numbers). I don't have them for my car an will probably never get them because I do a lot of freeway driving and need the most fuel conservation possible. If you do mostly street and strip driving, go for them
The reason your car and your friends have different rear and gears is because you have different transmisisons. They change the engine speed slightly differently so the different rear gears accomodate for this difference.
The higher the number of gear, 3.23, 3.42, 4.10, the more the gears will slow down the speed coming into the differential. This will also give more torque to the rear wheels for quicker launches and low speed torque. One draw back is your car will run at higher RPM's while driving. In 6th, my car will be at about 1500 RPM at 65mph, with 4.10's, it might be at about 2000 RPM at the same speed (not accurate numbers). I don't have them for my car an will probably never get them because I do a lot of freeway driving and need the most fuel conservation possible. If you do mostly street and strip driving, go for them
The reason your car and your friends have different rear and gears is because you have different transmisisons. They change the engine speed slightly differently so the different rear gears accomodate for this difference.
03-24-2003, 08:44 PM
#3
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An A4 F-body with 3.23's is probably going perform more similar to an M6 F-body with 3.42's than if it had the 2.73's.
Cars with 2.73's (like mine
) are intended for the best "fuel economy", so the high gears keep the revs low, but they hurt your RWHP. Cars with lower gear ratios will make more RWHP with the same engine, because of a higher mechanical advantage. This helps the car's performance off the line especially, although your overall top speed will be limited as "Ferocity" stated. Depending on what your goals/expectations/uses for your car are, you may be fine sticking with the 3.23's that you've got, or if you want a better hole-shot, you can get lower gears such as 3.73's, or 4.10's, but once you get too low, the car's "streetability" and "fuel mileage" goes out the window.
Cars with 2.73's (like mine
) are intended for the best "fuel economy", so the high gears keep the revs low, but they hurt your RWHP. Cars with lower gear ratios will make more RWHP with the same engine, because of a higher mechanical advantage. This helps the car's performance off the line especially, although your overall top speed will be limited as "Ferocity" stated. Depending on what your goals/expectations/uses for your car are, you may be fine sticking with the 3.23's that you've got, or if you want a better hole-shot, you can get lower gears such as 3.73's, or 4.10's, but once you get too low, the car's "streetability" and "fuel mileage" goes out the window.
03-25-2003, 06:34 AM
#4
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Originally posted by Capn Pete
Cars with 2.73's (like mine ) are intended for the best "fuel economy", so the high gears keep the revs low, but they hurt your RWHP. Cars with lower gear ratios will make more RWHP with the same engine, because of a higher mechanical advantage.
Cars with 2.73's (like mine
) are intended for the best "fuel economy", so the high gears keep the revs low, but they hurt your RWHP. Cars with lower gear ratios will make more RWHP with the same engine, because of a higher mechanical advantage.
People constantly talk about losing 4-7rwhp going from 3.42 gears to 4.10 gears. This is not an anomaly. The same will hold true going from 2.73's to 3.23's or 2.73's to 3.42's.
While it is true that going from 3.42's to 4.10's will give you more mechanical advantage due to gear multiplication (so your acceleration will be better with equal traction), it will not result in higher horsepower output.
03-25-2003, 06:44 AM
#5
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Here is a thread talking about 4.10 dyno losses. (this guy put in a 12 bolt, so he will lose a bit of power there, but the general consensus is 4.10's dyno less hp to the wheels.)
http://web.camaross.com/forums/showt...ight=parasitic
http://web.camaross.com/forums/showt...ight=parasitic
03-25-2003, 06:46 AM
#6
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Originally posted by 96fbirdA4
This is untrue. Your rear end gears have nothing to do with the amount of horsepower your car puts to the ground, other than parasitic losses. With that, a 2.73 rear gear will have less parasitic loss than a 3.23 or 3.42 gear because there are less teeth on the ring gear, thus less frictional losses (heat) during one revolution of the ring gear.
People constantly talk about losing 4-7rwhp going from 3.42 gears to 4.10 gears. This is not an anomaly. The same will hold true going from 2.73's to 3.23's or 2.73's to 3.42's.
While it is true that going from 3.42's to 4.10's will give you more mechanical advantage due to gear multiplication (so your acceleration will be better with equal traction), it will not result in higher horsepower output.
This is untrue. Your rear end gears have nothing to do with the amount of horsepower your car puts to the ground, other than parasitic losses. With that, a 2.73 rear gear will have less parasitic loss than a 3.23 or 3.42 gear because there are less teeth on the ring gear, thus less frictional losses (heat) during one revolution of the ring gear.
People constantly talk about losing 4-7rwhp going from 3.42 gears to 4.10 gears. This is not an anomaly. The same will hold true going from 2.73's to 3.23's or 2.73's to 3.42's.
While it is true that going from 3.42's to 4.10's will give you more mechanical advantage due to gear multiplication (so your acceleration will be better with equal traction), it will not result in higher horsepower output.
FYI to the 4.10 haters/misinformed.
There is no streetability loss with the addition of 4.10s. Just a very little fuel mileage difference in the negative direction. Hardly worth justifying not buying them. IMO, behind nitrous, 4.10s are the BEST bang for the buck mod you can go with. Especially if you know someone, or know how to work on a rear end to do it yourself.
03-25-2003, 11:16 PM
#7
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Originally posted by 96fbirdA4
This is untrue. Your rear end gears have nothing to do with the amount of horsepower your car puts to the ground, other than parasitic losses. With that, a 2.73 rear gear will have less parasitic loss than a 3.23 or 3.42 gear because there are less teeth on the ring gear, thus less frictional losses (heat) during one revolution of the ring gear.
This is untrue. Your rear end gears have nothing to do with the amount of horsepower your car puts to the ground, other than parasitic losses. With that, a 2.73 rear gear will have less parasitic loss than a 3.23 or 3.42 gear because there are less teeth on the ring gear, thus less frictional losses (heat) during one revolution of the ring gear.
Ratio ---> Ring gear ---> Pinion
2.73 ---------> 41 ---------> 15
3.42 ---------> 41 ---------> 12
3.73 ---------> 41 ---------> 11
4.10 ---------> 41 ---------> 10
Sorry I can't remember the ring and pinion for 3.23's ---> they're the only set that's different from the norm, but for those ratios above, the ring gear always has 41 teeth, and the pinion is the one that changes. In regards to more heat build up though, I can sort of understand that, since the pinion is turning more times per revolution of the axles/tires, so it would theoretically generate more heat. The differences there would be negligible IMO though
.
While it is true that going from 3.42's to 4.10's will give you more mechanical advantage due to gear multiplication (so your acceleration will be better with equal traction), it will not result in higher horsepower output.
. I'm not going to argue it, but regardless of whether more HP is put to the rear wheels or not, there is no denying that it's easier for the engine to get the car moving (with more mechanical advantage --- like using a long lever --- more leverage) so that's why lower gears will net quicker acceleration / quicker E.T.'s.
03-26-2003, 02:27 AM
#8
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I agree with 96fbirdA4 on this subject as well... I don't see how by rear end gears is going to change your rwhp.. In order to actually change rwhp is to change HP @ fly wheel... Ofcourse a car w/ 2.73 (like my car) versus a similar car w/ 3.23 if they both are A4s, the car w/ 3.23 will have a faster launch but not by much..
Now comparing a M6 w/ 3.42 to an A4 w/ 2.73, the M6 will have a better launch (especially if the driver actually knows how to drive the car properly) because of the lower rear end gearing.. The reason why a car w/ A4 and 3.23 gears versus a car w/ M6 and 3.42 gears, does not feel any different is because of the lower 1st gear in the A4 compared to the M6's 1st gear.. What actually helps make more rwhp is the fact that our cars has Posi... Take an older camaro w/ non-posi (not all of the older cars had posi though) w/ similar gear ratios like 2.73 for A4's and the car w/ posi will get a better transfer of power compared to the car w/ an open rear end.. Hell eventhough my 68 C10 project has 3.73 gear ratio w/ TH400, seems a little faster off the line compared to my Z, but since my 68 C10 does not have posi, my bets are on the Camaro Z out getting a better roll.. If you actually know how a posi (Limited Slip is a form of Posi) works where power is sent to the wheel w/ the most traction when one tire is spinnng, where as the open rear end when one wheel is spinning the wheel that has the least traction gets all the power...
So if adding a lower gear actually makes more rwhp, then GM would have put in lower gear ratios then what the cars came stock w/... Yeah 4.10 gear would be great since 5th gear can actually be used... and 3.73 would be the lowest for an A4 then I would go because any lower, will make the car great for track use rather then being used as a daily driver.. In my opinion though, for daily use I would not go lower then 3.42 since gas mileage on an A4 would be down to low 20's to High Teens while driving down the freeway.. With my 2.73 gears, the highest I have ever gotten on the freeway was 28 MPG @ 80 mph.. So I will not be changing my gears unless I was going out for Track use...
L@tez,
Charlie
Now comparing a M6 w/ 3.42 to an A4 w/ 2.73, the M6 will have a better launch (especially if the driver actually knows how to drive the car properly) because of the lower rear end gearing.. The reason why a car w/ A4 and 3.23 gears versus a car w/ M6 and 3.42 gears, does not feel any different is because of the lower 1st gear in the A4 compared to the M6's 1st gear.. What actually helps make more rwhp is the fact that our cars has Posi... Take an older camaro w/ non-posi (not all of the older cars had posi though) w/ similar gear ratios like 2.73 for A4's and the car w/ posi will get a better transfer of power compared to the car w/ an open rear end.. Hell eventhough my 68 C10 project has 3.73 gear ratio w/ TH400, seems a little faster off the line compared to my Z, but since my 68 C10 does not have posi, my bets are on the Camaro Z out getting a better roll.. If you actually know how a posi (Limited Slip is a form of Posi) works where power is sent to the wheel w/ the most traction when one tire is spinnng, where as the open rear end when one wheel is spinning the wheel that has the least traction gets all the power...
So if adding a lower gear actually makes more rwhp, then GM would have put in lower gear ratios then what the cars came stock w/... Yeah 4.10 gear would be great since 5th gear can actually be used... and 3.73 would be the lowest for an A4 then I would go because any lower, will make the car great for track use rather then being used as a daily driver.. In my opinion though, for daily use I would not go lower then 3.42 since gas mileage on an A4 would be down to low 20's to High Teens while driving down the freeway.. With my 2.73 gears, the highest I have ever gotten on the freeway was 28 MPG @ 80 mph.. So I will not be changing my gears unless I was going out for Track use...
L@tez,
Charlie
03-26-2003, 06:34 AM
#9
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Originally posted by Capn Pete
Ratio ---> Ring gear ---> Pinion
2.73 ---------> 41 ---------> 15
3.42 ---------> 41 ---------> 12
3.73 ---------> 41 ---------> 11
4.10 ---------> 41 ---------> 10
Sorry I can't remember the ring and pinion for 3.23's ---> they're the only set that's different from the norm, but for those ratios above, the ring gear always has 41 teeth, and the pinion is the one that changes. In regards to more heat build up though, I can sort of understand that, since the pinion is turning more times per revolution of the axles/tires, so it would theoretically generate more heat. The differences there would be negligible IMO though.
That just doesn't make sense. I'm not going to argue it, but regardless of whether more HP is put to the rear wheels or not, there is no denying that it's easier for the engine to get the car moving (with more mechanical advantage --- like using a long lever --- more leverage) so that's why lower gears will net quicker acceleration / quicker E.T.'s.
Ratio ---> Ring gear ---> Pinion
2.73 ---------> 41 ---------> 15
3.42 ---------> 41 ---------> 12
3.73 ---------> 41 ---------> 11
4.10 ---------> 41 ---------> 10
Sorry I can't remember the ring and pinion for 3.23's ---> they're the only set that's different from the norm, but for those ratios above, the ring gear always has 41 teeth, and the pinion is the one that changes. In regards to more heat build up though, I can sort of understand that, since the pinion is turning more times per revolution of the axles/tires, so it would theoretically generate more heat. The differences there would be negligible IMO though
.That just doesn't make sense
. I'm not going to argue it, but regardless of whether more HP is put to the rear wheels or not, there is no denying that it's easier for the engine to get the car moving (with more mechanical advantage --- like using a long lever --- more leverage) so that's why lower gears will net quicker acceleration / quicker E.T.'s.
I agree with pretty much everything else you said. It doesn't make much sense why there is that much more HP loss with 4.10's, but this result has been the consensus from pretty much every dyno comparison I've seen. And no doubt, a car with 4.10's will give you better acceleration and quicker E.T's as long as you can keep traction, which will far negate any RWHP loss.
03-27-2003, 06:18 AM
#11
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Re: I want higher gears like 3.23
Originally posted by samsonn2525
I want to change my 3.42 to 3.23 so i can run it up to 7k rpms and have more top-end.
I want to change my 3.42 to 3.23 so i can run it up to 7k rpms and have more top-end.
03-27-2003, 10:33 AM
#12
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Ooops i'm sorry, what i meant was "top-end" like top terminal speed ont eh highway not the 1/4. I was having problems with the engine running out of rpm before the power did. With a M6 and a 3.32 rear gear, at about 6700 rpm thats about 192ish so hopefully 7,000 should get to about 200 mph. 
in 5th gear.
Or maybe one can run it topping out in 6th at a lower rpm, but you'll need a much higher final ratio like 4.11 or 4.60
in 5th gear.Or maybe one can run it topping out in 6th at a lower rpm, but you'll need a much higher final ratio like 4.11 or 4.60
03-27-2003, 11:20 AM
#13
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Originally posted by samsonn2525
Ooops i'm sorry, what i meant was "top-end" like top terminal speed ont eh highway not the 1/4. I was having problems with the engine running out of rpm before the power did. With a M6 and a 3.32 rear gear, at about 6700 rpm thats about 192ish so hopefully 7,000 should get to about 200 mph. in 5th gear.
Or maybe one can run it topping out in 6th at a lower rpm, but you'll need a much higher final ratio like 4.11 or 4.60
Ooops i'm sorry, what i meant was "top-end" like top terminal speed ont eh highway not the 1/4. I was having problems with the engine running out of rpm before the power did. With a M6 and a 3.32 rear gear, at about 6700 rpm thats about 192ish so hopefully 7,000 should get to about 200 mph.
in 5th gear.Or maybe one can run it topping out in 6th at a lower rpm, but you'll need a much higher final ratio like 4.11 or 4.60
03-27-2003, 03:05 PM
#14
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RWHP is kind of related to rear gear.
I have 2.73's...When I shift to 3rd @ about 95mph, my car falls completely out of the power band. So, at 100MPH WOT in third Vs a 3.23 WOT in third I am putting out LESS RWHP due to me being out of the powerband.
Peak RWHP will be *roughly* the same though. Until you drive a 2.73 car WOT in third at 100mph, you may not know what it is like to be WAY out of the powerband.
I have 2.73's...When I shift to 3rd @ about 95mph, my car falls completely out of the power band. So, at 100MPH WOT in third Vs a 3.23 WOT in third I am putting out LESS RWHP due to me being out of the powerband.
Peak RWHP will be *roughly* the same though. Until you drive a 2.73 car WOT in third at 100mph, you may not know what it is like to be WAY out of the powerband.
03-27-2003, 03:07 PM
#15
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But then again, I have NOTHING to complain about. I have yet to see a 3.23 or even 3.73 car with the same mods that can keep up to 100MPH. I usually put the smack down on similar modded M6's (even my own)