[L.L.]

Do you like the change?

How much did it hurt traction coming out of the hole?

How bad did it hurt gas mileage?

Thanks, L.L.atriot:

 

[Black Devil]

I have been thinking of 3.91's. I need to get in the diff soon anyways. I would like to see the outcome here before I choose which gears though.

 

[FI05Goat]

Yeah I would be interested in what 3.91s would do in a Maggie car.

 

[Dbluegoat]

Yeah I would be interested in what 3.91s would do in a Maggie car.

you'd probably be sideways for the 1st 1/8 mile

 

[Smitty's05GTO]

you'd probably be sideways for the 1st 1/8 mile

WEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!! :gears:

 

[GoatChs]

I'm running 3.73s with a M6 and getting 21mpg combined with my 408. As to the move from 3.46 gearing, I was looking for a better rpm thru the traps...any further adjustment will be made with tire diameter. I'm currently running MT drag radials and traction is not an issue. I would think that Nitto drag radials would provide good street manners and traction as well.

Stickier tires would take care of the "sideways thru the 1/8th" issue, if it actually existed.

 

[Black Devil]

I'm running 3.73s with a M6 and getting 21mpg combined with my 408. As to the move from 3.46 gearing, I was looking for a better rpm thru the traps...any further adjustment will be made with tire diameter. I'm currently running MT drag radials and traction is not an issue. I would think that Nitto drag radials would provide good street manners and traction as well.

Stickier tires would take care of the "sideways thru the 1/8th" issue, if it actually existed.

What are your rpm's at 75mph in 6th?

 

[GoatChs]

About 2100.

 

[whatsaholden]

you'd probably be sideways for the 1st 1/8 mile

some of us do that on purpose.............

 

[smoop1]

mileage w/ 3.42's: ~17mpg with a heavy foot...
mileage w/ 3.91's: ~16mpg with aforementioned foot...

 

[Season'd]

I had the 373s put in our 06' M6 car as an overall improvement. I felt the car was not in a very efficent range while in high gear(6th) at the speeds we usually go..wife and i. In fact, the display showed better MPG in 5th so that was part of my selling point given to her . I also felt that being as this car will only accept so big of a rear tire and i didnt want to be short shifting in the intersection had i gone 391s, that they would be a decent middle of the road improvement. I was right. I also had the communist (skip shift)function removed.

 

[L.L.]

Good info. Thanks guys.:gears:

 

[kwiktsi]

Where are you getting the 3.73's from? I was told 3.91 was the next step.
Joe

 

[Jontall]

Where are you getting the 3.73's from? I was told 3.91 was the next step.
Joe

http://www.difftechnics.com.au/gto.html

 

[GMH GTO]

Had 3.91 Kaaz in my car when I was headers only, made it very fun driving, did 1.7x 60'

Driving to AMES gto meet it did 22mpg
Driving to Indy for us nationals with 402ci and 3.91 gear my GTO did 21 mpg (according to the cluster).

 

[berjet]

I got the 3.72 w/ kaaz. Like them for what I do (road racing and autox). I have no idea right now on economy since I haven't had my speedo fixed from the gear install yet.

 

[kwiktsi]

http://www.difftechnics.com.au/gto.html

Thanks for the link. I'll see where my car traps and then decide which gears will work best. Even the 3.46's pull like hell with 600 whp .
Joe

 

[Speedy0009]

Speaking from an M6 standpoint I love the 3.91s. Made the car a heck of a lot more fun to drive around town, they made 5th and 6th more useful on the highway and MPG doesn't change much, if at all!

Oh yeah and :gears:

 

[Muff Daddy]

i wonder how much difference it would make performance wise if i put 3.73's behind the 408...

 

[GoatChs]

i wonder how much difference it would make performance wise if i put 3.73's behind the 408...

I'm running 3.73s with a M6 and getting 21mpg combined with my 408. As to the move from 3.46 gearing, I was looking for a better rpm thru the traps...any further adjustment will be made with tire diameter. I'm currently running MT drag radials and traction is not an issue.

I wonder as well...