View Single Post
Old 10-05-2010, 10:50 AM
  #2  
TheRabbit
Senior Member
RACING JUNKIE
 
TheRabbit's Avatar
 
Join Date: Jan 2007
Location: Augusta, Ga.
Posts: 2,276
Default

You didn't say what size tires you run. I couldn't figure it out because 39's with 4.10 @ 6,500 = 66mph and 44's @ 6,500 = 75mph ( that's using 39"'s and 44"'s for the math. Tires are almost always 1.5" to 2"'s shorter than what they say they are, but don't get hung up on tire speed)

Two problems going with a gear lower than a 6.20.
1. You can't get a match for the front gear. Even with 38's on the front you'd need a 6.50 front gear to match.
2nd The pinion is getting way to small to handle the power / abuse

Also if you're hitting high gear with only 650hp with a 4600lb truck you aren't hooking up very well even if it's muddy as heck.

High side is the way to go, but need a little more info about your truck and tracks you run.
Just as a base idea I use to run (with a gutted 208 case) a 6.20 rear with 44's and a 5.13 front with 38's, but was over 1,180hp in a 3600lb truck. It ran a best time of high 3.2's in 200' on DOT's and constantly ran low 3.0's to high 2.9's on cuts.
TheRabbit is offline