|11-26-2010 09:29 PM|
|rbloodhound||I have a 05 LJ with 4.88 and 35's. it seems great. If I had a Dana 44 in the front I would go with 5.13.|
|11-26-2010 09:21 PM|
It's all good. Just trying to provide information and experience. Maybe you could find someone local that would allow you to drive their rig before you shell out the cash. At least you would know where you want to be.
Let me know if you want help with a purchase.
|11-26-2010 09:12 PM|
|badrubi03||well. with the 35s and the factory 4.10 now. anything under 65 and wind not blowin 100 i can keep it in OD with no prob. just i think gettin on the interstate will start to jump out some, and just wanna stop the motor from straining quite so much from tryin to turn them tires ya know?|
|11-26-2010 08:12 PM|
Courtesy of Car Craft. You can figure out your final RPM by multiplying the results from the math below times your overdrive gear reduction percentage.
70 X 4.88 X 336 ÷ 35 = 3279 X .8 (OD ratio)= 2,623 RPM roughly.
MPH = (RPM X Tire Diameter) ÷ (Gear Ratio X 336)
MPH = (3,000 X 26) ÷ (4.10 X 336)
MPH = 78,000 ÷ 1,377.6
MPH = 56.6
RPM = MPH X Gear Ratio X 336 ÷ Tire Diameter
RPM = 70 X 4.10 X 336 ÷ 26
RPM = 3,709
Gear Ratio = (RPM X Tire Diameter) ÷ (MPH X 336)
Gear Ratio = (3,000 X 26) ÷ (70 X 336)
Gear Ratio = 78,000 ÷ 23,520
Gear Ratio = 3.31:1
Tire Diameter =MPH X Gear Ratio X 336 ÷ RPM
Tire Diameter = 65 X 3.31 X 336 ÷ 2,700
Tire Diameter = 26.8 inches
Effective Gear Ratio = (Old Tire Diameter ÷ New Tire Diameter) X Gear Ratio
Effective Gear Ratio = (26 ÷ 28) X 3.55
Effective Gear Ratio = 3.29:1
|11-26-2010 07:20 PM|
I should have thought about that though, there must be some formula associated with the chart then?
|11-26-2010 06:58 PM|
|AOR||Don't forget they are assuming a 1:1 final drive ratio with these types of charts.|
|11-26-2010 06:33 PM|
Heres a chart for ref
|11-26-2010 06:24 PM|
Go with 4.88s. I had 37s and 4.88 in my '06 LJ and I was constantly shifting up and down with the auto. Had I been on 35s the 4.88s would have been perfect. When you
re ready to purchase, shoot me a PM or check out my current promotions in the vendors section.
Have fun with the build.
|11-26-2010 05:38 PM|
im gonna get gears coome first of the year. u know the rubi comes with 4.10s from the factory. i got 35s now and plan on stayin 35s for street driving, but will run 36 to 37s when offrading. so mainly for highway, decent mileage(i know its a jeep) and to get my overdrive back after 70 or 65 n a windy day, should i go with 4.88 or 4.56? just dont want my rpms up around 3 grand at cruisin speeds ya know? just tryin to get my stuff straight for when i order them.