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Can someone direct me to an article..


MichaelP
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Hi-

 

Can someone direct me to a semi- non -technical article on differential gear ratios and why one set of gears may be more desirable depending on the type of driving you are doing?

 

Wackypedia had an ok article..

 

But, I see the 2011 have 3.7?:1 differential VS my 3.55:1 on 2010.. Racers seem to like this but I dont know why other than MPH may be greater for a given gear...so that may be good for 1/4 mile runs?!?!?

 

Thanks, everyone

 

Mike

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As for 3.73s vs 3.55s if everything else is the same 3.73s is a lower gear ratio which means you will get there quicker or revs the engine faster. With 3.55s it is the higher gear ratio so you will have a higher top speed. These number don't mean anything I am just making them up to show you what i mean.For example if you are driving on the highway going 65 mph with 3.55s are revving the engine to 3000 rpm's well with 3.73s you are revving that same engine 3500 rpm's. If you are drag racing with perfect traction with no rpm limit you would get from A to B faster with the lower gear. The tricky part about the whole thing is there are many things that factor into it like transmission gearing, tire size, rear end gearing, mph and how high you plan to rev your engine. One thing to remember that alot of people get mixed up the higher the number is the lower the gear is and the smaller the number the higher the gear is. I am no expert on the subject but I have spent quite a bit of time playing around with the different calculators trying to decide which gears and tire size i wanted to go with. Which have helped me understand it alot more.

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As for 3.73s vs 3.55s if everything else is the same 3.73s is a lower gear ratio which means you will get there quicker or revs the engine faster. With 3.55s it is the higher gear ratio so you will have a higher top speed. These number don't mean anything I am just making them up to show you what i mean.For example if you are driving on the highway going 65 mph with 3.55s are revving the engine to 3000 rpm's well with 3.73s you are revving that same engine 3500 rpm's. If you are drag racing with perfect traction with no rpm limit you would get from A to B faster with the lower gear. The tricky part about the whole thing is there are many things that factor into it like transmission gearing, tire size, rear end gearing, mph and how high you plan to rev your engine. One thing to remember that alot of people get mixed up the higher the number is the lower the gear is and the smaller the number the higher the gear is. I am no expert on the subject but I have spent quite a bit of time playing around with the different calculators trying to decide which gears and tire size i wanted to go with. Which have helped me understand it alot more.

 

 

very good explanation.Anoter way of looking at it is that youd like to cross the 1/4 mile at tope end of 4th gear to max out hp during the run.With 3:73s youd almost be there,with 3:55s you wont,because the gearing is lower,so your ET will be lower with the 3:73s.On the downside, youll be running higher rpms say on highway at 70mph with the 3:73--the car will be louder and mpg will drop. But if you put it in 6th may be no big deal.

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very good explanation.Anoter way of looking at it is that youd like to cross the 1/4 mile at tope end of 4th gear to max out hp during the run.With 3:73s youd almost be there,with 3:55s you wont,because the gearing is lower,so your ET will be lower with the 3:73s.On the downside, youll be running higher rpms say on highway at 70mph with the 3:73--the car will be louder and mpg will drop. But if you put it in 6th may be no big deal.

 

RELATED QUESTION TO THE 3.73.: dO THE FRPP GEARS WHINE AS some aftermarker do; how much for them and the install and how much will it affect the 1/4 mile time. I am guessing .2 quicker.

 

Will my 2010 with a stage 0 tune / svt mufflers and 3.73 turn a 12. 4???? Responses??

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I have the stock 3.55 and a friend of mine has the 4.10's. At 70 mph my rpm's are at 2000 in 5th and his is 2400 in 5th. I am no mech, but with the lower gears your take off will be quicker and your shifting will happen faster.

 

I am still wanting to change my gears to 4.10, but at the same time I have been told to change my differential. The cost with the parts and labor will run about $1200.

 

Far as the wine... It is the mech skill that will make the difference. I was told that the 3.90 are not the gears they recommend and will not install. No idea why?

 

Tom

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I have the stock 3.55 and a friend of mine has the 4.10's. At 70 mph my rpm's are at 2000 in 5th and his is 2400 in 5th. I am no mech, but with the lower gears your take off will be quicker and your shifting will happen faster.

 

I am still wanting to change my gears to 4.10, but at the same time I have been told to change my differential. The cost with the parts and labor will run about $1200.

 

Far as the wine... It is the mech skill that will make the difference. I was told that the 3.90 are not the gears they recommend and will not install. No idea why?

 

Tom

 

 

So, 4.10's would even be better for drag racing?

 

M.

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Far as the wine... It is the mech skill that will make the difference.

 

 

AMEN! That's pretty much what I said in another thread.

 

I'm glad someone's listening.

 

 

Phill Pollard

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So, 4.10's would even be better for drag racing?

 

 

No, not necessarily.

 

What is your RPM going through the trap right now (in 4th gear)?

 

'Cause *that's* what determines what gear you need.

 

 

Phill Pollard

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the 3.73 are the ideal set upin a 2010 gt500 from what I understand as they are the kr stock gears.At 6000 in 4th it gives about 126 mph which is about perfect. I used to drag for FOMOCO IN 69 -71 with up to 5.14's in a detroit locker witha 428 scj at 3090 lbs.The 3.73 will be my choice.ONLY NON FRPP GEARS HAVE BEEN MAKING NOISE DUE TO THE QUALITY OF MANUFACTURE.4.10'S are a little steep but for drag only would be fine.

 

REGARDING CHANGING THE WHOLE REAR END; yes go to a 9" or locker if you will heavily mod your car.I have seen many broken axles at the line basically due to good hook up and lots of torque with little wheel spin.the std 8.8 is a good set up unless you are going " over the top "".

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the 3.73 are the ideal set upin a 2010 gt500 from what I understand as they are the kr stock gears.At 6000 in 4th it gives about 126 mph which is about perfect. I used to drag for FOMOCO IN 69 -71 with up to 5.14's in a detroit locker witha 428 scj at 3090 lbs.The 3.73 will be my choice.ONLY NON FRPP GEARS HAVE BEEN MAKING NOISE DUE TO THE QUALITY OF MANUFACTURE.4.10'S are a little steep but for drag only would be fine.

 

REGARDING CHANGING THE WHOLE REAR END; yes go to a 9" or locker if you will heavily mod your car.I have seen many broken axles at the line basically due to good hook up and lots of torque with little wheel spin.the std 8.8 is a good set up unless you are going " over the top "".

 

 

 

This is all good info for me. I plan on starting drag racing with my stock car (except for some MT's) then move up the mod list little by little.

 

This forum has been really fantastic for me. I really appreciate everyone's input.

 

M.

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This is all good info for me. I plan on starting drag racing with my stock car (except for some MT's) then move up the mod list little by little.

 

This forum has been really fantastic for me. I really appreciate everyone's input.

 

M.

 

 

I havent drag raced for a while,but as everyone knows,with ET racing its all about consistency so you hit the dial-in numbers.Given each driver hits the dial in, the winner is determined by reaction time.So when you start practicing , work on your RT,-- when i raced ,a perfect tree was 0.5 secs--practice getting as low as possible, then worry about gearing etc.If you can run around .5-.6, and your compettiuon runs a .8, youll win by 3 car lengths, even though you both hit your dialin

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I havent drag raced for a while,but as everyone knows,with ET racing its all about consistency so you hit the dial-in numbers.Given each driver hits the dial in, the winner is determined by reaction time.So when you start practicing , work on your RT,-- when i raced ,a perfect tree was 0.5 secs--practice getting as low as possible, then worry about gearing etc.If you can run around .5-.6, and your compettiuon runs a .8, youll win by 3 car lengths, even though you both hit your dialin

 

 

 

ok. how do u practice RT without being at track all the time?

Does someone make a practice light for home?

 

I was just going to do Friday night grudge races. for now :)

 

M.

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ok. how do u practice RT without being at track all the time?

Does someone make a practice light for home?

 

I was just going to do Friday night grudge races. for now :)

 

M.

 

 

if itsa regular friday night drag,youd be lucky to get in 4 runs.here in Atl, Year One will have a car show drags at IHRA track here,and not many folks go,so you can get in 10-15 runs.Perfornace Yaers is in Pa, as well as Lethal--id watch and see if they sponsor a night/day at your local track.Even if you only get a few runs,id concentrate on RTs. The trick is to not spin the tires,and leave before the light turns green.I used to wait ill the last yellow,say cheese to myself,and leave.Its harder with a manual shift,but you should be able to get .6secs.

.

I do recall someone selling a pratctce light set using an acceloratometr in your car for RTs

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So, 4.10's would even be better for drag racing?

 

M.

 

 

It all really depends on how fast you are planning on going that's why i gave you the link to the calculators. Also it depends on how you plan on driving the car. For an example most people want to finish the 1/4 mile in forth gear 1:1 ratio. Well if you think your car can run 130 mph in the quarter mile you should gear it closes to how ever high you want to rev your engine in 4th gear that equal that mph. That kind of thinking is for a car that is mainly a race car and you are going to also want to think about what that will do for driving it around town and on the highway. Sometime gearing a car really low will actually help in town driving because you can shift into 5th or 6th for in town driving but that will kill your mileage on the highway. So people changing gears really need to think about how they drive the car and where they are going to drive it.

Edited by trolls56
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I think I am beginning to understand why a lot of people have a "track" car and a "daily driver". My gt will not be daily but it will also not

be another garage queen.

 

Would you say that adding HP like a different Supercharger would be a better first mod than changing differential gears? To get me down the track faster?

 

M.

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Would you say that adding HP like a different Supercharger would be a better first mod than changing differential gears? To get me down the track faster?

 

 

Absolutely, without question!

 

As a double benefit, you can take advantage of a higher gear with a increase in torque. More torque will pull a taller gear.

 

As a matter of practice when you supercharge a naturally aspirated car, you ADD gear (go to a higher gear ratio, lower numerically) to take advantage of the increased torque.

 

Been there done that (with a 1967 Camaro w/Shelby SpearCo turbo kit).

 

 

Phill Pollard

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