Yeah, What the title said.

 

Its a preference thing. I myself like the 4.56's But ereone is diff. im sure you will hear plenty of 4.10 reponses and a few 3.73's.

 

after driving em with stock, 3.73's, and 4.10's i like the 3.73's the most. 1st gear with 4.10's goes by way to fast

 

It all honesty depends on your setup and where you plan on shifting the car.

 

Exactly. Depends on where your motor makes power. 3.42's were perfect for me with either the M6 or the TH400 because I have optimized my setup for drag racing. My trap speeds in the low 140's put the car just past peak power in 4th (M6) or 3rd (TH400), which is ideal for drag racing.

OTOH, if you have a high revving NA setup you may need 4.10's or an even higher gear. The nice thing with the M6 is that with the 0.50:1 top gear, you can get away with a really short rear gear and still maintain a reasonable cruise and top end capability.

Rich Krause

 

I got 4:10's when I had bolt on's only and now with the cam and they have worked great for me so far, feels like the perfect gearing to me. When you start making bigger power like with big heads/cam setups 3:73's often work better for some people. When you start making big power like Rich said 3:42's may be the better choice for you.

 

140 mph

Rich if you don't mind me asking. Where did you shift your car with the M6. Also how did you launch the car. Thanks in advance.

 

With ET streets (and a 12-bolt) I was launching at ~4,000rpm. Just a touch of clutch slip until the tires "bit" and then foot to the floor. 60' times were in the low 1.5's with a "road race" type suspension. So don't believe what you read about how hard it is to launch an M6. It takes some time to get it down to a science though! My setup was low rev, I shifted at 6,000rpm.

Rich

 

Thanks I appreciate the advice. My setup is pretty similar. My car's hp peaked around 6100 rpm. I am going to launch at 3500 rpm and go up from there. Do you think I should go with a 27 or 28 in slick? I have a 3.50 gear in my 9-in.

 

For the street, I don't see how you can beat the 3.73's. They make 6th gear more usable (and 5th a little less usable). I can even go up hills in 6th now, whereas before I could not. My car pulls harder than ever now, A great gear IMO.

As far as drag racing, most guys have the 4.10's or higher. It all has to do with your targeted trap speed and the size tires you have. A 28" diameter tire would be a good idea with taller gears.
A larger diameter tire will give you more traction, resulting in a quicker elapsed time. The problem is fitting the big tires on your car. There are formulas to determine your needs. You should study those formulas, they make a lot of sense.

 

The way to figure it is based on knowing the amount of hp you are making. This allows trap speed to be estimated, which in turn will allow you to determine what tire and gear combo puts you a couple of hundred rpm over peak hp through the traps.

Unless you are making huge hp, a 28" might be too big for your setup. 6,500rpm with a 28" tire and a 3.50 rear is over 150mph. And that isn't accounting for tire expansion which makes the speed even higher.

Rich Krause

 

My car should be making close to 750 rwhp. So how tall of a tire do you think I should go with?

 

At what rpm? And what gear do you currently have, and do you plan to change it? You should be trapping at 135mph+ with that much hp.

Rich Krause

 

I currently have a 3.50 gear. It hp is peaked at 6100 rpm. I currently have no plans in changing the gear out. My car should weigh 3600lbs with me in it. I appreciate the help.

 

If you plan to stick with 3.50:1 a 28" v. a 27" is a tossup. 27" has a bit less grip, but will put you in just the right rev range (6,200rpm = 142mph). A 28" is a little too tall (6,000rpm = 142mph) but will launc a bit harder. I'd go witht he 28". Also a better selection of tires in this size.

Rich Krause