Need Experts Opinion on Why should someone change rearend gears
08-28-2007, 03:13 PM
#21
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Join Date: Apr 2007
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RE: Need Experts Opinion on Why should someone change rearend gears
ORIGINAL: howarmat
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
08-28-2007, 04:44 PM
#22
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RE: Need Experts Opinion on Why should someone change rearend gears
https://mustangforums.com/m_1754735/tm.htm
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
ORIGINAL: GidyupGo
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
ORIGINAL: howarmat
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
08-28-2007, 07:39 PM
#23
1st Gear Member
Join Date: Jul 2007
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RE: Need Experts Opinion on Why should someone change rearend gears
ORIGINAL: Barbarino
Gears are a waste of time, for what you get and the possibility you just ruined your brand new rear for marginal gain and lets not forget if you have loud exhaust good luck driving on the high way and get a second job for all the gas you will use and oh yea, it puts more wear on your engine for no reason. As you own your car longer and add more power adders, you will reach a point where the gears hurt you becasue you won't be able to hook up.
Gears are a waste of time, for what you get and the possibility you just ruined your brand new rear for marginal gain and lets not forget if you have loud exhaust good luck driving on the high way and get a second job for all the gas you will use and oh yea, it puts more wear on your engine for no reason. As you own your car longer and add more power adders, you will reach a point where the gears hurt you becasue you won't be able to hook up.
08-28-2007, 07:40 PM
#24
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Join Date: Jul 2007
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RE: Need Experts Opinion on Why should someone change rearend gears
ORIGINAL: Feng Houzi
so a guy with a V6 should go up to what? Not looking to win races or take it to the strip, just looking for a little more punch. Im not really sure what ratio i have now in the V6, is it 3.55 or 3.2something? Also what would the cost be to go to 3.73 or something, would it be worth it?
so a guy with a V6 should go up to what? Not looking to win races or take it to the strip, just looking for a little more punch. Im not really sure what ratio i have now in the V6, is it 3.55 or 3.2something? Also what would the cost be to go to 3.73 or something, would it be worth it?
08-28-2007, 07:40 PM
#25
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Join Date: Apr 2007
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RE: Need Experts Opinion on Why should someone change rearend gears
ORIGINAL: lldsandsll
https://mustangforums.com/m_1754735/tm.htm
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
https://mustangforums.com/m_1754735/tm.htm
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
ORIGINAL: GidyupGo
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
ORIGINAL: howarmat
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
I don't see the 4.10 gears going much over 135. The engine will be screaming like a raped ape at those rpms. Some say the front is as aerodynamic as a brick and that air will be the ultimate culprit. It is a little better than a brick but at 135, the hood does a mean hula dance. I don't see my gears falling so flat as to limit the top speed. The way I look at it, the 4.10 has the grunt to get you through the barrier, but runs out of steam. The 3.31 will eventually, but further down the road.
08-28-2007, 08:00 PM
#26
2nd Gear Member
Join Date: Apr 2007
Location: NH
Posts: 223
RE: Need Experts Opinion on Why should someone change rearend gears
i just put 3.73 in my car last week had the 3.31.the gas mileage is about the same. the motor seems to respond a lot better. driving at highway speeds the motor revs around 2500 to 2800 depending on speeds 70 to 90. i think if i went to the 4.10 the motor would have been reving to much for me.
08-28-2007, 08:04 PM
#27
RE: Need Experts Opinion on Why should someone change rearend gears
Ok by going here: http://www.cherod.com/mustang/HowTo/...lculations.xls
I came up with 135
using 331 @ 3800
using 355 @ 4100
using 410 @ 4600
I wouldnt say the engine is screaming quite yet and again i think the drag will play more of a role then the gears will and i agree that you actually have more power and torq at that RPM anyway to take you up to 150ish
I came up with 135
using 331 @ 3800
using 355 @ 4100
using 410 @ 4600
I wouldnt say the engine is screaming quite yet and again i think the drag will play more of a role then the gears will and i agree that you actually have more power and torq at that RPM anyway to take you up to 150ish
08-29-2007, 12:48 AM
#28
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Join Date: Apr 2007
Location: S.Florida
Posts: 1,612
RE: Need Experts Opinion on Why should someone change rearend gears
ORIGINAL: GidyupGo
I don't see the 4.10 gears going much over 135. The engine will be screaming like a raped ape at those rpms. Some say the front is as aerodynamic as a brick and that air will be the ultimate culprit. It is a little better than a brick but at 135, the hood does a mean hula dance. I don't see my gears falling so flat as to limit the top speed. The way I look at it, the 4.10 has the grunt to get you through the barrier, but runs out of steam. The 3.31 will eventually, but further down the road.
ORIGINAL: lldsandsll
https://mustangforums.com/m_1754735/tm.htm
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
https://mustangforums.com/m_1754735/tm.htm
stock setup (3.55) will theoretically take you 200+, but drag won't let you go much over 150.
4.10's will take you to 170+, and you are more likely going to reach that speed since you have more torque to overcome drag...
ORIGINAL: GidyupGo
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
ORIGINAL: howarmat
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
the drag of the car will slow you down before the gears will become a factor.....4.10 will get to 135 just as easy as 3.31, from there, the powers of nature are going to play about the same role reguardless of gear.
I hear what you are saying, but the 4.10's will be spent at 135 mph, while the 3.31's will continue to climb to 145+ mph.
I don't see the 4.10 gears going much over 135. The engine will be screaming like a raped ape at those rpms. Some say the front is as aerodynamic as a brick and that air will be the ultimate culprit. It is a little better than a brick but at 135, the hood does a mean hula dance. I don't see my gears falling so flat as to limit the top speed. The way I look at it, the 4.10 has the grunt to get you through the barrier, but runs out of steam. The 3.31 will eventually, but further down the road.
08-29-2007, 01:36 AM
#29
3rd Gear Member
Join Date: Feb 2006
Location:
Posts: 523
RE: Need Experts Opinion on Why should someone change rearend gears
Why are some people so concerned about top speed? I mean seriously, how often do you drive 150+ ? But how often do you get involved in a little stop light skirmish where the shorter (higher ratio) gear will shine?
Anyway it's true, while the stock gear mathematically has a higher top speed, you just won't make enough torque at the wheels to overcome drag and you'll top out around 3-4k rpm. A 3.73 will allow you to use just about all of your fifth gear which will result in a higher actual top speed (assuming you defeat the speed limiter).
But, if you want top speed, get a vette.
Anyway it's true, while the stock gear mathematically has a higher top speed, you just won't make enough torque at the wheels to overcome drag and you'll top out around 3-4k rpm. A 3.73 will allow you to use just about all of your fifth gear which will result in a higher actual top speed (assuming you defeat the speed limiter).
But, if you want top speed, get a vette.
08-29-2007, 01:57 AM
#30
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Join Date: Feb 2006
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RE: Need Experts Opinion on Why should someone change rearend gears
Below isan excerpt of an explanation that I was using to justify cams, but it relates to gears as well. As that ignorant guy mods his car, he'll never fully realize it's potential if he stays with the stock gear. Part of selecting the right gear is to match it to the torque curve of your particular configuration of mods. For example, my torque curve is very strong in the upper range so it makes sense to go with a higher gear ratio so that as I'm shifting (while racing), my engine will stay in the upper rpm range where I'm making more power/tq. IfI had stock gears, I'd be spending too much time in the lower rpm range and not get the full benefit of my mods.
Anyway, here's the excerpt (I hope it's not too confusing):
In stock configuration pk TQ arrives at just over 4000 rpm (around 285 lb-ft). For simplicity, lets look at what happens in 3rd gear with a 3.55 axle: upon shifting to 3rd, rpm drops to 4000 rpm with tq around 282. At this point, tq is just below pk, then headed down towards 230 @ 6000. This means that for the virtually all of 3rd gear, a stock Mustang's rate of acceleration is decreasing.
Without regard to the axle ratio, at 4000 rpm, my engine still has not reached its peak tq - 329 lb-ft at around 5300 rpm, thus my rate of acceleration is still increasing after the shift to 4th. From 5300 rpm, tq drops to 304 at 6000. So between 4000 rpm and 6000 rpm, in stock form there is net change in tq of -52 lb-ft (282@4000 vs 230@6000), while my car experiences a net change of +5 lb-ft (299 @ 4000vs 304 @ 6000). This is an absolute difference in change of tq of 57 lb-ft bewteen the two configurations. This is huge and is why you can't just focus on pk values. The shape of the curve is what ultimately determines your overall performance in acceleration. Peak values are great for bragging on Saturday nights, but the proof will be in how the cars accelerate and by how much one beats the other.
Now, in the real world with my actual configuration (4.10 axle), I'll actually shift out of 3rd at 6250 rpm which will land me at 4700 rpm in 4th. I'll then finish the 1/4 mile at about 5500 rpm in 4th (roughly 110 mph). Between 4700 and 5500, my net change in tq is +8 lb-ft (320@4700 vs 328@5500).
Anyway, here's the excerpt (I hope it's not too confusing):
In stock configuration pk TQ arrives at just over 4000 rpm (around 285 lb-ft). For simplicity, lets look at what happens in 3rd gear with a 3.55 axle: upon shifting to 3rd, rpm drops to 4000 rpm with tq around 282. At this point, tq is just below pk, then headed down towards 230 @ 6000. This means that for the virtually all of 3rd gear, a stock Mustang's rate of acceleration is decreasing.
Without regard to the axle ratio, at 4000 rpm, my engine still has not reached its peak tq - 329 lb-ft at around 5300 rpm, thus my rate of acceleration is still increasing after the shift to 4th. From 5300 rpm, tq drops to 304 at 6000. So between 4000 rpm and 6000 rpm, in stock form there is net change in tq of -52 lb-ft (282@4000 vs 230@6000), while my car experiences a net change of +5 lb-ft (299 @ 4000vs 304 @ 6000). This is an absolute difference in change of tq of 57 lb-ft bewteen the two configurations. This is huge and is why you can't just focus on pk values. The shape of the curve is what ultimately determines your overall performance in acceleration. Peak values are great for bragging on Saturday nights, but the proof will be in how the cars accelerate and by how much one beats the other.
Now, in the real world with my actual configuration (4.10 axle), I'll actually shift out of 3rd at 6250 rpm which will land me at 4700 rpm in 4th. I'll then finish the 1/4 mile at about 5500 rpm in 4th (roughly 110 mph). Between 4700 and 5500, my net change in tq is +8 lb-ft (320@4700 vs 328@5500).