3.90 Gears
Dig
Joined: Jan 2006
Posts: 5,460
Likes: 1,125
From: Port Saint Lucie FLORIDA & HONDURAS
3:90's are the best !!
my a4 couldnt spin the tires befor the 3:90's
after install... first gear and into second !!
my rear was $1,600.00 from dte
install was $300.00 in miami
my a4 couldnt spin the tires befor the 3:90's
after install... first gear and into second !!
my rear was $1,600.00 from dte
install was $300.00 in miami
Drifting
Joined: Mar 2006
Posts: 1,665
Likes: 4
From: FL
I went to 4.10 hardened gears and I love it. Also got hardened driver side output shaft and DTE brace. East Coast Supercharging rebuilt and installed. I think charges are around $1,100. I also had an RPS stage 3 clutch and headers installed at the same time. My actual rear charges were less than $1,100 (for the differential re-build alone) as the other parts had to be removed at the same time.
ECS said I would feel like I had 85+ more HP (as a direct result of the rear gears) and I totally agree with them. The car should have come like this from the factory. Interestingly, my first and second gears have about the same range but with more power/torque. Third and fourth gears have considerably more power/torque, and fifth and sixth gears give you a lot more power throughout (much more useable). I used to get 32 MPG in sixth gear at 75 MPH. I now get 29.5 MPG at the same speed. But, I can also get rubber up through 3rd gear without really pushing it, and without losing around-town driveability.
ECS said I would feel like I had 85+ more HP (as a direct result of the rear gears) and I totally agree with them. The car should have come like this from the factory. Interestingly, my first and second gears have about the same range but with more power/torque. Third and fourth gears have considerably more power/torque, and fifth and sixth gears give you a lot more power throughout (much more useable). I used to get 32 MPG in sixth gear at 75 MPH. I now get 29.5 MPG at the same speed. But, I can also get rubber up through 3rd gear without really pushing it, and without losing around-town driveability.
Team Owner
Joined: Jul 2004
Posts: 24,652
Likes: 298
From: NJ
St. Jude Donor '05-'08
Just as an FYI - Before you make your gear decision make sure you plan out your long term goals for your car and figure out what type of driving you like to do. In the long run you will save money.
I currently have 3.73 gears in my car. I did start with 3.42s and decided that I wanted 4.10s as a replacement because I was doing more 1/4 mile stuff and my car only had a cat-back and air intake. As my power increased, g5x3 cam and afr heads, the 4.10s were still good for 1/4 mile stuff, but on the open road I had to watch my shifts. I did love them though.
My interest then changed to road racing and it only took me a few days at the track to realize the 4.10s were not good. I then had to go back and change to 3.73s to give me more range on the track.
I am not stating that you shouldn't change your gears because as you can see I changed mine twice, but if you think about the type of driving you plan on doing and your future rwhp/rwtq you will make a better decision.
Bob
I currently have 3.73 gears in my car. I did start with 3.42s and decided that I wanted 4.10s as a replacement because I was doing more 1/4 mile stuff and my car only had a cat-back and air intake. As my power increased, g5x3 cam and afr heads, the 4.10s were still good for 1/4 mile stuff, but on the open road I had to watch my shifts. I did love them though.
My interest then changed to road racing and it only took me a few days at the track to realize the 4.10s were not good. I then had to go back and change to 3.73s to give me more range on the track.
I am not stating that you shouldn't change your gears because as you can see I changed mine twice, but if you think about the type of driving you plan on doing and your future rwhp/rwtq you will make a better decision.
Bob
Thread Starter
Drifting
Joined: Oct 1999
Posts: 1,669
Likes: 98
From: Jacksonville FL
Thanks to all.
I was contemplating the 3.73's, but my installer said that he'd recommend at least 3.90's.
I've done about all of the power mods that I will, but would like some more "quickness" now that I've been spoiled with the new Z.
----
Mike
I was contemplating the 3.73's, but my installer said that he'd recommend at least 3.90's.
I've done about all of the power mods that I will, but would like some more "quickness" now that I've been spoiled with the new Z.
----
Mike
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Le Mans Master
Joined: Nov 2003
Posts: 8,003
Likes: 249
From: Tampa Fl
St. Jude Donor '12-'13-'14
Originally Posted by WKMCD
I've got an M6 with 460-470RWHP and 3.90's. This is a street only car and the 3.90's are the way the cars should have come from the factory.
Im this I I close to pulling the trigger on 3.90s while my car is at the shop.
PHIL97SVT doing the work
Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
Originally Posted by phils C5 vette
I drove his car, and it drives really good and fun.
Im this I I close to pulling the trigger on 3.90s while my car is at the shop.
PHIL97SVT doing the work
Im this I I close to pulling the trigger on 3.90s while my car is at the shop.
PHIL97SVT doing the work
Supporting Tuner
Joined: Sep 2004
Posts: 51,896
Likes: 39
From: ================== Houston, Texas www.englandgreen.com ================== Necessary Evil™ __________
CI 6-7-8-9-10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Have 'um, love 'um, in hindsight - wished this was my very first mod 
Le Mans Master
Joined: Nov 2003
Posts: 8,003
Likes: 249
From: Tampa Fl
St. Jude Donor '12-'13-'14
Originally Posted by EnglandGreen
Have 'um, love 'um, in hindsight - wished this was my very first mod
Does that strap around the tranny give you more boost ?
And yes kevin, I swaying towards the gears
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
There's a good reason why future plans should always be taken into consideration: Simply supercharging your C5 would make spinning the tires an all-too-common occurance. Yeah, it's be fun at first, but 390s or 410s with 500+ HP will earn you the nickname "Squirrel' very quickly. I do agree that if you choose to have only mild mods, the numerically-higher gears are the way to go.
Supporting Tuner
Joined: Sep 2004
Posts: 51,896
Likes: 39
From: ================== Houston, Texas www.englandgreen.com ================== Necessary Evil™ __________
CI 6-7-8-9-10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Originally Posted by Dave68
There's a good reason why future plans should always be taken into consideration: Simply supercharging your C5 would make spinning the tires an all-too-common occurance. Yeah, it's be fun at first, but 390s or 410s with 500+ HP will earn you the nickname "Squirrel' very quickly.
Burning Brakes
Joined: Jul 2005
Posts: 788
Likes: 33
From: Cedar Rapids IA
Looking to keep up with the LS2C6/Z06C5 with my 97C5 6spd daily driver. A 220 cam, Z06 intake, LG street headers, ported/milled stock heads, 295/35/18 tires. Will I need 3.90 gear or will I have traction problems already?
Melting Slicks
Joined: Mar 2001
Posts: 2,978
Likes: 280
From: Tulsa OK
I have a DTE stage II differential with 3.90s in my car. It is a great combination with the heads/cam/headers. I've been running the heads/cam for 2 years and the gears for over a year. The only reason I waited for the gears was mod money.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Just put 3.90s in my z06 and all I can say is WOW!! The car pulls alot better on top end, which was already good with 450+rwhp. Now I need to see what it does at the track. Traction is very limited when I get on it in first or second.
Pro
Joined: Dec 2005
Posts: 535
Likes: 2
From: Shorewood Illinois
yeah, but...
Interesting thread. I'm still in the planning stages, most likely looking for 400 rwhp/rwtq. My question is will the 3.90's be enough ('98 M6), or would the 4.10's be a better all around gear with that amount of power. Or isn't there enough difference between the two to notice? This car is a fun daily driver, very limited track and strip. Wondering what you guys think....
S
S
Pro
Joined: Feb 2002
Posts: 606
Likes: 0
From: Virginia Beach VA
I installed a set of 3.90s in my FRC and love'em. Now I'm MPH per RPM with a Z06 in 1st 2nd 3rd. The down side is I'm running out of RPM on road course. 3.90 Rocks at an AutoX and on the Street!
Bang For the Buck it's a Great Mod!
Bang For the Buck it's a Great Mod!
Last edited by Roadrace65; Jun 15, 2006 at 10:56 PM.