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My Next Mod--Gear Swap!!

C

caniroc

Member
I keep saying I'm going to stop the mods but....I couldnt pass up a new set of gears. Im going with a 3.91 rear (in place of the stock 3.46). I think this will be it for a while--its still my daily driver.
The car is a 2005 GTO with a small cam--exhaust and 3600 stall converter and has run 12.06 @ 113 mph.

http://www.youtube.com/watch?v=ZccF6Yp5Vyk
 
i went from a 2.73 to a 3.42 and now i'm planning on popping in a set of 4.10's..... Mileage schmileage.
 
T2urtle said:
does this small cam require any valvetrain upgrades? didnt think they could hit 12 flat pretty much with just a cam.
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When it was stock it ran 12.90 @ 110.

When the cam was done I upgraded the springs--but run the facotry lifters and rockers. The cam I put in is really small too 224/224 .580/.580.

The stall helped too but yes just that and the small cam its 12.0
 
Nice! I like what you are doing.

Can someone tell me the main difference of RPM? Will 4.0 ratio gear have less RPM at 60mph than 3.4 gear ratio?
 
ThatsABigOne said:
Nice! I like what you are doing.

Can someone tell me the main difference of RPM? Will 4.0 ratio gear have less RPM at 60mph than 3.4 gear ratio?
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With a shorter final drive, you'll be turning higher RPM at any given speed - so going from 3.4 to 4.0, you will be at higher RPM.
 
I have the stock 3.55's on my car.....4.10's are going on in the spring. Such an inexpensive upgrade, not sure why I didn't do it years ago. Under $200 for the ring and pinion gear.
 
ThatsABigOne said:
Nice! I like what you are doing.

Can someone tell me the main difference of RPM? Will 4.0 ratio gear have less RPM at 60mph than 3.4 gear ratio?
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if you do a lot of driving this isn't a good mod. Makes cruising harsher... more RPMs on the highway, more fuel consumption.
 
I knew it was a GTO when you said your stock gears were 3.46 :-D

I've got a cammed '06 but am leaving the gearing alone because I do a lot of highway driving.
 
I'm still debating on what I want to replace the Mustang's stock 2:80 gears with.

With the 4 speed, most people say 3:55 is the sweet spot for highway driving, but it isn't exactly going to be a daily driver. 4:10's would be loads of fun, but something about doing 3,500 RPMs at 60 MPH doesn't sound so hot. Maybe I'll go for 3:73's...

Now if I could just get it on the road so all of these decisions actually mattered. 😛
 
arcenite said:
I knew it was a GTO when you said your stock gears were 3.46 :-D

I've got a cammed '06 but am leaving the gearing alone because I do a lot of highway driving.
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Haha--my highway driving isnt even interstate--just 50 mph two lane roads. Right now it only turnsabout 2000 rpm at 60 though--and should only increase by aobut 200 rpm or so--nothing really to worry about.
 
exdeath said:
That's what 6 speeds with two overdrive gears are for 🙂
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these types of gear swaps are common in the Z/G community (with 6spds). I actually went the opposite way and went with taller gears. The car just became un drivable with the stock gears. I get 10% better mileage on top of a more enjoyable car to drive -
 
Zivic said:
these types of gear swaps are common in the Z/G community (with 6spds). I actually went the opposite way and went with taller gears. The car just became un drivable with the stock gears. I get 10% better mileage on top of a more enjoyable car to drive -
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Why is it more enjoyable with a taller gear??
 
caniroc said:
Why is it more enjoyable with a taller gear??
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With a shorter final drive, the car winds up very quickly. So, if you have a car with decent low-end torque that you aren't taking to the strip all the time, it can be nice to say within the mid-RPM ranges longer.

Edited - dumb moment.
 
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Your GTO has enough power and torque to be limited by traction even with the stock gears, right? So what exactly is it that you think gears are going to do for you other than force you to shift more often to get the same power?
 
thomsbrain said:
Your GTO has enough power and torque to be limited by traction even with the stock gears, right? So what exactly is it that you think gears are going to do for you other than force you to shift more often to get the same power?
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I wont be shifting more often--its an A4 trans. It will pull harder in all gears.
Accelerate quicker through each gear= lower ET's.
Im only crossing the line at about 5000 rpms now--car makes peak hp at just over 6000 so there is plenty of room for more rpms.
 
thomsbrain said:
Your GTO has enough power and torque to be limited by traction even with the stock gears, right? So what exactly is it that you think gears are going to do for you other than force you to shift more often to get the same power?
Click to expand...

I know my car is geared higher than a GTO and has wider tires with more power and I wish it was closer to 3.43. Even with drag radials in 315, the car is severely traction limited in 1st and 2nd.
 
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