3.90 or 4.10 with mn6 anyone have this combo?

[TwistedFun]

I am wanting to put a 3.90 or 4.10 DTE gear in my car after this summer is over. I have heard good about both. Does anyone here know of someone that has done this mod in the central florida area? i would like to ride in a car that has had this done before i do it. If anyone can help please let me know.

[Rich Z]

Not sure it is relevant to this discussion but many moons ago I put a 4.10 rear in my GTO. I would think with the tranny gearing in the vette, you won't ever need to use first and second gear.

With the standard 3.42 gearing in the Z06 (I think that is what it is), I have started off from a dead stop in third gear accidentally and barely noticed the engine lagging......

[TwistedFun]

yea, i too have the 3.42 in my frc and have done the oops i am in 3rd gear when starting off at a light. with just a little more gas it will go. from the posts i have read about the 3.90 or 4.11 gear change in the MN6 cars, it seems to be the best bang for the buck. i read somewhere that it translates into the equivelant of adding 70hp to the car on the sotp dyno. also, from what i am reading most of the people that have done it say this is the gearing that the ls1 mn6 should have come with. i would just like to see one in person to see for myself before i drop the cash for it. i figured i would just ask around on this site since it is a florida based site, you never know who you might find. so far this looks like a good site and the members seem to be a good group of people. as for the 4.11 in the goat, i bet that was a fun ride, i always did like those cars.

[Rich Z]

Yeah, my goat was a '66, and I did about everything you could do to a car on that thing. Luckily my dad owned a service station so I had free access to a lift and help from the mechanics there tolerating the dumb bosses kid. I still remember sitting in one of the bays scrubbing out my engine compartment because my motor was all in pieces as I rebuilt it.

I learned a lot back in those days. Like NEVER trust a parts department. Ever. I got oversized crank bearings sent to me by mistake and didn't know about making sure the crank would turn BEFORE putting everything all together again. Or how just because you can SEE the bolts for the headers doesn't mean you can ever get a tool in there to turn them. At least not more then 1/8th turn at a time. Or how when people say that 400 heads SHOULD work on a 389 pontiac, doesn't mean that they 100 percent will.

Not everything I learned is what I WISHED I had learned.......

As for the gears, yeah, it made quite a difference. In first gear it was difficult to NOT burn rubber. But I also remember that back in those days when gasoline was maybe 40 cents per gallon, I was spending $5.00 per DAY just getting back and forth to work. And work was not more then 10 miles or so away. I would NOT want that car back today at all because it would take me broke just driving it!

I am still astonished to be driving my Z06 down the road and seeing it registering 33 miles to the gallon.

[TwistedFun]

From what i have been told with the 3.90 or 4.10 gears the car still gets 29 to 30 mpg in 6th at 75 to 80. i also have a 75 with a nasty 383 and you can see the gas guage move as fast as the speedo. it is hiding in the garage from the gas pump right now.

[4cefed]

I have 4:09 in my ZR-1. Unless you want to drag your car stay with the 3:42 gear. I would switch back in a heart beat. It is a great gear for the track. Top of third for the 1/8th mile (102mph) and top of 4th for the quarter (132mph). I would like to be able to hang 4th gear to over 150 instead of shifting at 132.

[TwistedFun]

i am not sure but i think the gearing is taller in the mn6 for the c-5. this is a chart from dte for rpms in 6th gear. i have to be running at least 80 before i can even use 6th gear with the 3.42.

3.90
60 MPH: 1475 RPM
65 MPH: 1598 RPM
70 MPH: 1721 RPM
80 MPH: 1966 RPM

4.10
60 MPH: 1550 RPM
65 MPH: 1680 RPM
70 MPH: 1809 RPM
80 MPH: 2067 RPM