Hey guys, I am currently running 4.10's in my 4wd truck and most of the racing we do is 1/8th of mile..
I was running 32" tires but since it spun pretty bad off the line, I bought a set of 28" slicks for all 4 corners..
For a RACE ONLY setup.. which gear ratios should I go with? I have a 14 bolt 9.5" that I am putting together just for racing..
Thanks guys! Any advice or previous experience would be appreciated!

 

My truck

 

Man, you're gonna be the only one that can answer that.

In a race car, the idea is to gear the thing to be in the traps at a desired rpm. So for a race car the decision process looks something like this:

1. Pick a tire.
2. Pick a converter. (the idea here is to give yourself a slip number to factor in).
3. Pick a rear gear that puts the motor where you want it at the finish line.
4. Pick a first/second gear ratio for the trans that works with the tire/converter/gear and power/weight of the car.

 

Generally speaking you're going to want a pretty damn steep gear. A 4.56 will work well even with the 28" tall tire. You shouldn't run out of gear before the finish line.

 

Thanks guys! I think that should be my question, how steep in gears can I go with before I run out of gear in the 1/8th of mile with my 4L80..
People are running 4.56's with their 350's & 400's transmissions with 28-29" tires..
Another thing, whats the steepest gear my rear & front differential can fit?
Again, thanks guys!
Felix

 

How much power do you plan to out down? In general I would say a 4.10 - 3.73

 

I am at 740rwhp/770tq right now and just added a 75 shot of nos

 

Go to Wallace Racing - Automotive Calculators and play with infinite scenarios. I would go steep for 1/8 only.

 

With that much power you can still spin in 4wd so you may find it easier to go with a shallower gear and make the power you need with the turbo. That lets you keep your top end also.

 

I would go to a 3.73 gear to lessen the chance of wheel spin with the shorter tires even though they are slicks. With that much power and 4.10 gears you are likely gonna spin through first gear unless you baby the throttle.....and that will make the boost take longer.

Better to have less gear and be able to leave with more throttle and more boost.