slimdawson

Hey guys. I need some help. I am not sure what gear to get for my car. It is an M6. The car should weigh around 3600lbs race ready. It will have a Procharger on it soon and should make over 450 lb/ft of torque. I haven't bought a rear yet but am looking for a 12 bolt. I don't think I need a 4.10 but a 3.42 seems kind of tall. I was thinking 3.73s would be perfect but it is just a guess.

I don't want to have to use 5th gear to make it through the 1/4. I plan on my mph being between 120 and 125 and will probably use a 28" tall slick. Anyone know the max speed I can get out of that with a 3.73 and a redline of 5800?

I just don't know. I love how my car pulls up top with the 3.42s but it puts a little more strain on the clutch than a bigger gear would.

Any info would be greatly appreciated.

Thanks, Mike

Redbird

... One of the best things about a 12 bolt is, there are so many gear ratios available. Things in between the 3.42-3.73-4.10-4.56.
Example, In my garage I have a 3.55 ratio ring and pinion. I
would consider a 3.90 gear option in your case. Plenty of gear to use the 4 speeds at the track, yet enough gear to pull your overdrives on the highway.

Remember you are taking advice from a guy who ran 4.56 gears in my '94 A4!!

mongse_1

I think you'll be fine with a 4.10. Just make sure you've got a good tire under it.

slimdawson

I thought about a 4.10 but I didn't think I could make it to 125 in fourth. Does anyone know? I probably won't be turning more than 5800.

STAR

I vote for 3.73!

zupmanZ28

With a 28" tire, and 4.10's 5800 rpm= 117.8mph in 4th

With a 28" tire, and 3.90's 5800 rpm=123.9 mph in 4th

With a 28" tire, and 3.73's 5800 rpm=129.5 mph in 4th

With a 28" tire, and 3.55's 5800 rpm=136.1 mph in 4th

Ideally, you want to be crossing the traps just a little past your redline, so assuming your not planning on making the car any faster the 3.90's would be a pretty good bet for ya. At least thats my .02...

those numbers were found using www.thirdgen.org's mph calculator btw...http://www.thirdgen.org/newdesign/te...ulations.shtml

sideways_Into_3rd

just rev higher dude !

i'll be running 4.10s with a 27" tire (28x9 ET drag .. 27.3 exact diameter) ... but i rev to 7k on my NA motor .. will probably rev to 6500 on the nitrous ... i think a 28" tire with 4.10s will go upto 132 mph at 7k

there is a good calculator (well .. was free to use) at www.smokenup.com .. not u gotta register and sh*t .. its still probably free .. but i havent bothered registering

OBE1 95Z28

If you're planning on using ET Streets or ET Drags your tires will grow approximately an inch at 120+ mph. I suggest you factor that in to your gear selection.

slimdawson

Thanks alot. That is exactly what I was looking for. I do plan on running quicker than 123 mph but I should be around there for a while, or at least until my motor disassembles itself.

I would turn harder but according to ATI, the boost rating is taken at around 5800(can't remember exactly) and turning it over that will create more boost. I have a stock motor so that won't work.

Thanks again, Mike.

EDS Z28

I am looking at getting a Moser 12-bolt soon. Why do they not offer other gear ratios like 3.55 and 3.90? A 3.90 sounds good.
Looking in the summit catalog, Richmond has those gears.