Rear End Ratio Opinions

Hello! We're running a 3100lb outlaw 10.5 car w/ a kb 526 fuel headed hemi, 1471 hi helix, 30 over. We're running 33x10.5x16w on 16x16 double beadlocks. This is our first year w/ the hemi and we're curious where we should start as far as rear end ratio. We're running a bruno/lenco three speed, 1.80 first gear. Obviously traction is our concern. Any direction would be appreciated!

Josh

 

your problem will be your first gear.

 

spin or shake

it is hard to shake the little tires but it can be done. the ultimate setup for your car will depend on how good the car hooks and how tight the converter acts. i would guess that any gear from 3.90 to 3.60 will work. good track and tight converter 3.90 (maybe 4.10).
lesser track and (or) looser converter try 3.70-3.60-3.50. i have some 3.70 & 3.50 big pinion sets for 9" ford. chuck

 

gear

Wheel speed is key. 4.11 will work. You can rattle the heck out of the 10.5 tire if you dont get your wheel speed where it needs to be. One important deal will be you will have to knock timing out of the motor and ramp it in. A 1.64 1st would be a good starting point.

Sean

 

What exactly is the definition of "wheel speed?" I'm assuming a 3.90 gear would give you more wheel speed than a 4.30 gear...correct? ...or is it more along the lines of leverage?

 

wheel speed

Exactly. It takes more time to recover with a 3.90 gear or lower been there done it. Much easier to work with the ratios in the trans. Alot of guys will just leave the ratios alone but it is the differnace between getting down the track and not. On a good track use more 1st gear on a crappy track use less lets say for example on the crappy track use a 1.64 and a good track you can go to a 1.81 or 1.92. TEST TEST TEST!!!!!!!!!!!!!

Sean

 

Sean is right. A 1.6X something low gear is a great starting point. As well as you need to have a way to knock timing out of it at the hit to assist with traction, and making the car repeatable. I dont know what ignition you use, but the MSD 8973 is a great ignition box to use.

 

Hey thanks for the info guys! I am going to run a Digital 7 7531 w/ a Promag 44. So we might be messing w/ the slew control later in the season. Definately will be pulling timing out on the launch.