Soo happy!! 3.90's are on!

Bob Cosby

Active Member
Established Member
Joined
Nov 28, 2001
Messages
1,309
Location
Sherman, TX
jtfx6552 said:
I have already said that I agree 100% the n/a Cobras need a very steep gear...
LOL. The shape of the powerbands (in the useable rpm range) are nearly identical - just that the blown motor is significantly higher. I could have geared the car to go 2-3 mph faster, but would have likely lost at least a tenth in ET.

The gearing philosophy for getting best MPH is different than that for getting the best ET.

1-2 tenths is VERY worth it for me. I'd much rather run a 10.9 than an 11.0. Might not be worth it for someone else.

$400-$500 for 1-2 tenths is a VERY reasonable gain. No, its not near as good as bolting on a pulley and going half a second faster, but it is still a very reasonable $$$ amount to spend for the gains. And you WILL feel it on the street.

Beyond that....Uncle. Ya'll decide for yourselves...my 3.90s and live axle go in late next week. That's nowhere near optimum, but it will provide a nice increase in performance, ET, feel, etc over the stock 3.55s. :)
 

BL1SN8K

New Member
Established Member
Joined
May 22, 2004
Messages
8
Location
Richmond
For those of you with 3.90's, is there much change in driving response in part-throttle, off-boost conditions? I have a porky convertible that doesn't feel particularly eager in those situations and I was considering a gear change to liven that up. Any thoughts?
 

fastball19

South Florida King !
Established Member
Joined
Apr 19, 2004
Messages
2,247
Location
Miami Lakes
:banana:
BL1SN8K said:
For those of you with 3.90's, is there much change in driving response in part-throttle, off-boost conditions? I have a porky convertible that doesn't feel particularly eager in those situations and I was considering a gear change to liven that up. Any thoughts?


:banana:
 

SWEET03COBRA

Active Member
Established Member
Joined
Dec 24, 2003
Messages
3,022
Location
Wausau, Wi
See, this is what I'm think too, my vert could use the extra UMTH when I get on it. Anyone shed some like on the gear change in a vert vs. a coupe?
 

11secCobra

Way2Fast4These LS1 guys
Established Member
Joined
Apr 6, 2003
Messages
1,114
Location
carrollton TX
SWEET94COBRA said:
See, this is what I'm think too, my vert could use the extra UMTH when I get on it. Anyone shed some like on the gear change in a vert vs. a coupe?

verts are a little bit heavier than a coupe, but i doubt itll make any difference. in the city, youll get better gas mileage because the motor doesent have to work as hard to get up to speed. your motor is most efficient at its torque peak, so the closer you are to your torque peak, the better gas mileage youll get. (im not saying cruising around at 3800 is gonna save you gas, but that little bit of extra RPM while cruising may help ya out)
 
Last edited:

projekZERO

Werd
Established Member
Joined
Jun 27, 2004
Messages
260
Location
SoCal
i have a vert.

gears will help nomotter what.

the problem with our verts isnt just the weight itself but where the weight is.

alot fo the weight is in the doors and front a/pillars, this is not ideal for weight transfer and traction.

also our springs are softer, and again doesnt help us with traction.

our frames flexing also contributes to lesser traction, and im not sure but might change the pinion angle slightly when going down the track which will rob some power.

good subframes, suspension mods, and reducing the weight over the front end goes along way on verts to keep up with the coupes.

but yes the gears will help.
 

redstaf426

New Member
Established Member
Joined
Sep 6, 2004
Messages
177
Location
Dallas,TX
projekZERO said:
i have a vert.

gears will help nomotter what.

the problem with our verts isnt just the weight itself but where the weight is.

alot fo the weight is in the doors and front a/pillars, this is not ideal for weight transfer and traction.

also our springs are softer, and again doesnt help us with traction.

our frames flexing also contributes to lesser traction, and im not sure but might change the pinion angle slightly when going down the track which will rob some power.

good subframes, suspension mods, and reducing the weight over the front end goes along way on verts to keep up with the coupes.

but yes the gears will help.


You know what I'm hearing :rollseyes

Excuses

Excuses

and more Excuses

J/K Buddy :thumbsup:

Let us know how you and Marc do on Sunday :beer:
 

projekZERO

Werd
Established Member
Joined
Jun 27, 2004
Messages
260
Location
SoCal
redstaf426 said:
Dame,from 12.3-11.7??same tires??

3.90s for me :pepper: :pepper: :pepper:

no e.t. streets

but that 60ft is nothing you couldnt pull

your cars have about the same power ricky

that run was atleast a 7.3 @ 94mph at any other track
 
Last edited:

Power Trip

New Member
Established Member
Joined
Apr 24, 2004
Messages
443
Location
Saugus, MA
Ok i dunno how old this thread is as i was searching some gear related threads. But damn all this argueing is crazy. If anyone honestly thinks that steeper gears wont make your car faster, you are nuts!!

Bob cosby - alot of GREAT tech info.. Good to have you on these boards.
 

adamb258

New Member
Established Member
Joined
Feb 26, 2003
Messages
3,101
Location
Texas
i was todl with 4.10's the rpm at 70 in 6th gear is about 2,300 rpms. Is that acurate? I looked for a gear calc but couldnt find one and figures one of you guys would know
 

Snarf

Lacey Chabert FTW!
Established Member
Joined
Oct 31, 2004
Messages
1,153
Location
Lexington, KY
adamb258 said:
i was todl with 4.10's the rpm at 70 in 6th gear is about 2,300 rpms. Is that acurate? I looked for a gear calc but couldnt find one and figures one of you guys would know


Thats pretty spot-on. 75 in 6th with my 4.10s is almost exaclty 2500.
 

Users who are viewing this thread



Top