Originally Posted by neegdogdig
Alright guys, here is the Formula for regear :
RPM = MPH x Gear Ratio x 336
Tire Diameter (in)
Got this from Fearless Gear Inc.
n also i had 4.20 on my 02 Taco 4cylinder 4x4 running 33x12.50x15 Toyo Tire Open Country M/T n i still do 70, 75, or 80 with no problems. RPM is around 2700 +/- But i'm still not happy so I regear mine with 5.29, with this gear ratio i can almost zoom like a sport car
. Rpm is not much of a different just save more $$$ for gas
in another word the truck is now consume less gas better Mpg.
hope this clarify some confusions that you may have.
That formula is way off. I don't know where 336 came from but that will vary from transmission to transmission, hell even gear to gear if you are talking crawl speeds vs hwy speeds.
EDIT: I just did some math and that formula is actually right, sort of. For the gear ratio you need to factor in both the diff gear and the tranny gear. So in my case I just take 4.88x0.716 and plug that in for the gear ratio to get my 5th gear rpm at various speeds.
This calculator is much better: http://www.grimmjeeper.com/gears.html
The 5 speed auto is the A750F, the 6 speed man is the RA60F, the 5 speed man is the W56. Can't remember the 4 speed auto and I am not sure of the 1st gen trannies.
Also I have 33's and just went from 3.73's to 4.88's. My rpm went from about 2000 at 75 to 2650 and I lost about 2 mpg on the freeway. From what I can tell, I should be using less fuel on inclines and getting up to speed, but I believe it takes more throttle to maintain those extra 650 rpm plus I lost my ability to pretty much coast at all. Ultimately that lack of coasting is what I blame for my loss of mpg's. When I let off the throttle it slows down much faster than it used to which means I am back on the throttle sooner than I used to be on declines and such. I'm sure it also doesn't help that at 75 mph when it down shifts to 4th I am running over 4000 rpm. Takes some extra fuel to maintain that kind of momentum.