I am getting a 12 bolt rear end soon and I had a question about gears. I am probably going with either 4.10 gears or 4.30 gears I ran a 12.4 going through the traps right after shifting to 4th I need some gears bad.... I don't want to have to use 5th gear though since 4th is our 1:1 ratio.... What size tires are you guys using and do you guys have to shift to 5th??? I am probably looking at geting either 4.10 or 4.30 with a 28 inch tall tire... Will that be too big??? Any input is greatly appreciated!

 

4.30 with a 28" tire will be fine depending on RPM limit.

 

I cross at 6500 rpm. That is 123mph with 4.11's and a 15x11.5x15 MT ET Street. My setup is maxed out. I will be swapping to a 28" tire and spooled 4.30's.

 

Well im gonna be si but I am getting hp turners soon so If I have to bump the rev limiter I will be able to. But I don't see the point in that since im not going to have a cam in the car...

 

I'm about like cainsw, crossing the traps at the top of 4th with my 26s. And I think 4000ish with the 28"s. I have not really got a good feel of what the 28s will do yet. I had clutch problems.

 

I'm also SI.

26 ET Street, 4.30 gears, crossing at 6300-6400 in 4th, 3200 lb raceweight.

12.1@110 on a 1.60 60 Albuquerque 7000 ft DA
11.88@112 on a 1.60 60 Roswell 5000 ft DA

 

Keep me informed on your set up. I'll be swapping over after the good racing weather is over. I want to get everything I can out of my setup before I swap.

 

For a M6, 4.56 with 28" Stiff side wall is the Ticket!

 

4.11's,m6 26x11.5x15 i cross in 4th at 6,300rpm's. you really don't need a 28'' tire. if you do a 4.11 gear w/28'' tire,it will make the rear gear like a 3.73 and that is not a big jump from stock. the 26'' tire and 4.11's will give you what you want. hell....i ran 10.2's on 26'' tires and 4.11's. i'm doing 1.42 60's on motor w/that tire gear combo. goodluck to ya.

 

that's why you step up to 4.88's

I don't know how much longer I want to stay SI. I have 100lbs left to lose on the car as far as weight is concerned. My goal was to hit 11.9X or less at this ungodly altitude SI I'm pretty damn close and the weight will get me there but I'm still curious how much more I can go with a 28" tire and 4.88 gears. Although mathmatically 26" tire and 4.56 gears will be the same I think a 28" will be more consistant and the 4.88's will definitely hit the tire harder.

Anyone?

 

430 and 27'' hoosier qtp 11.5 wide works or me.M&H 275x60x15 28.4 high for the street, knocks a little gear out and helps bite on the street.