abadss

iTrader: (4)

thinking about switching out the stock 3.42 for something bigger. i dont get to race very often and use the car mostly for just riding on the weekends. but i am afraid i wont see enough difference switching to 3.73, and 4.11 is too much. i heard someone mention 3.90's on another board, but havent seen anyone with them. anyone know anything about them?

JeffT

iTrader: (22)

if you have the stock 10 bolt then your are limited to 3.73 or 4.10 because no one that I know of offers 3.90's for that. If you have a 9" then yes you could split the difference and run 3.90's wich are available for that.

For your set up I wouldn't hesitate to put the 4.10's in-they wont be too much like you think.

MacADaYear

Arnt the rears in camaros the same as trucks? 8.5 10 bolt? If so they make them cause im puttin some in my truck

JeffT

iTrader: (22)

not the same, 7.5 in the car.

Blue Hawk

No it's not the same unit. The 10 bolts for the f-body are 7-1/2 or 7-5/8 with 26 or 28 spline axles (depending on year).

abadss

iTrader: (4)

i would like to go with 4,10's but i am kinda worried about traction, which is already an issue. i am planning on getting a LS6, crank pulley and tune, so that will only get worse. that and the gas mileage are the reasons i was leaning towards the 3.73

Blue Hawk

I had 4.10's with a stock engine (only bolt-on mods). I had exactly the same traction and mileage concerns when I was planning my 382 stroker. Ended up with a Moser 12 bolts with 3.73's, along with SFC's and adjustable torque arm, and I'm really happy with that setup. With 411rwtq, I cannot floor it in first on street tires, but no problem in 2nd.

I achieved 30.4mpg at 55mph during a 560 miles trip recently. At 75mph, I'm down to 26.8mpg, and city driving is around 14mpg.

abadss

iTrader: (4)

what mods do you have? what gear was your before the 3.73? if it was 3.42, which i think it should be in a firehawk, could you tell a noticeable difference with the swap? thanks

Blue Hawk

I went from 3.42's to 4.10's with only bolt-on mods: SLP lid, K&N filter, 160 thermo, HPP3, SLP y-pipe (299rwhp/312rwtq).

PROS: The 4.10's felt like having 50 more rwtq! I went from 13.49@105.4 to 13.33@107.3 at the track. Top speed jumped from 141mph to 152mph in 5th (limiter). Better mileage in city driving because I was able to use my 5th gear.

CONS: Traction issues in 1st. Worse mileage on the highway. Weaker rear end (never busted mine but was howling bad after several runs with D/R's).

Right now I have: Lunati 382 stroker (399rwhp/411rwtq), SFC's, adjustable torque arm, 12 bolts (3.73's), steel DS, dual-friction clutch. I went with 3.73's with the 12 bolts mainly because of my lack of traction with the 4.10's and to retain decent consumption numbers. I cannot do a fair comparison between the 4.10's and the 3.73's because now I have 100rwhp and 99rwtq more and there were a bunch of mods made to the car at the same time. Overall, I'm glad that I went back to 3.73's from 4.10's because IMO these would have been overkill for my street setup.

The way I see it for M6 cars:
For stock, bolt-on or H/C: 4.10's
For big cubes, nitrous, blowers or turbos: 3.73's for daily drivers. 3.90's for the track.

abadss

iTrader: (4)

very well said bluehawk, exactly what i was thinking. i might have made my decision to stick with the 3.73's i was leaning towards. although i wouldnt mind riding in a car with 3.90's. but i am not sure if anyone offers them for the stock 10 bolt.

OWENMUSTANG

iTrader: (2)

if im not mistaken you can get 3.90's for 12 bolts.

NOBR8KSS

iTrader: (12)

You can get 3.90's for the 12-bolt or the 9" rears. The disadvantage to them is that they are gauranteed by Moser and Strange to howl worse than ony other gearset. I don't know why, but that's what they say. Plus they cost about $50 more for some reason.

1fastWS6

iTrader: (3)

Cause they're made by Richmond. They're the ONLY ones that make a 3.90 gear for a 12 bolt. You can't get one for a 7.5" 10 bolt.

abadss

iTrader: (4)

oh well, guess i still have my decision to make, 3.73 or 4.10

2000 Tran Zam

iTrader: (2)

ya, i decided to get 3 90's in my strange 12 bolt. with my new 408 motor, this way i will be able to trap 130 at 7k rpm.

2000 Tran Zam

iTrader: (2)

at least thats what FMS is saying i should hopefully be able to trap. i guess it depends on weather and track conditions.