outlaw star Posted January 25, 2016 Share Posted January 25, 2016 28÷31×4.88= 4.40:1 Outlaw Star can you explain what this means? Old Tire Diameter X New Tire Diameter ÷ Current Gear Ratio = Effective Gear Ratio. Effective Gear Ratio is what your truck "acts" and feels like it has. The trick is to plug different available gear ratios into the Current Gear Ratio slot until the final math is as close to stock as possible. Link to comment Share on other sites More sharing options...
pug Posted January 25, 2016 Author Share Posted January 25, 2016 Yes I replaced Dana 35 for a ford 8.8 and the front is out of a 1998 Cherokee hp. So it looks like 4:56 is what gears i am going to get. Just need to find out what brand get. Link to comment Share on other sites More sharing options...
Pete M Posted January 25, 2016 Share Posted January 25, 2016 28÷31×4.88= 4.40:1 Outlaw Star can you explain what this means? Old Tire Diameter X New Tire Diameter ÷ Current Gear Ratio = Effective Gear Ratio. Effective Gear Ratio is what your truck "acts" and feels like it has. The trick is to plug different available gear ratios into the Current Gear Ratio slot until the final math is as close to stock as possible. unless the stock ratio sucks. in which case I want more gear :D Link to comment Share on other sites More sharing options...
outlaw star Posted January 25, 2016 Share Posted January 25, 2016 28÷31×4.88= 4.40:1 Outlaw Star can you explain what this means?Old Tire Diameter X New Tire Diameter ÷ Current Gear Ratio = Effective Gear Ratio. Effective Gear Ratio is what your truck "acts" and feels like it has. The trick is to plug different available gear ratios into the Current Gear Ratio slot until the final math is as close to stock as possible. unless the stock ratio sucks. in which case I want more gear :D Can't argue with that. Link to comment Share on other sites More sharing options...
NorthWoods Posted January 26, 2016 Share Posted January 26, 2016 4.56 gears on a set of 31's is probably a safe bet behind your 2.5. Ive run gears from 4.56 behind a chevy 2.2 with 33's to 4.10's behind a cherokee with 33's to 5.38's behind a chevy 383 stroker with 44's to a full size jeep with 5.13's and 40's. Thats just vehicles I've changed the gears in, let alone ones I've bought with swapped gears like 3.73's with a chevy 4.3 and 35's. Been there done it. I'm a firm believer in power to tires without loosing top end within reason and not over working a motor to turn tires with a unrealistic gear ratio. For example 4.88's or lower behind a 2.5 jeep motor with who knows how many miles on it. Me personally, I don't want to turn 3000 rpm to go 70. What am I gonna turn to do 80 mph if I want to? Link to comment Share on other sites More sharing options...
dustyinthedirt Posted January 26, 2016 Share Posted January 26, 2016 Pete M, on 24 Jan 2016 - 11:05 PM, said: outlaw star, on 24 Jan 2016 - 10:13 PM, said: dustyinthedirt, on 24 Jan 2016 - 09:05 AM, said: Quote 28÷31×4.88= 4.40:1Outlaw Star can you explain what this means?Old Tire Diameter X New Tire Diameter ÷ Current Gear Ratio = Effective Gear Ratio. Effective Gear Ratio is what your truck "acts" and feels like it has. The trick is to plug different available gear ratios into the Current Gear Ratio slot until the final math is as close to stock as possible. unless the stock ratio sucks. in which case I want more gear :D Can't argue with that. thanks guys. now i gotta go do some math :doh: Link to comment Share on other sites More sharing options...
Eagle Posted January 26, 2016 Share Posted January 26, 2016 thanks guys. now i gotta go do some math :doh: No, you don't. The math is all done for you in the spreadsheet I posted a link to. Link to comment Share on other sites More sharing options...
mnkyboy Posted January 26, 2016 Share Posted January 26, 2016 Here is a handy tool. http://www.grimmjeeper.com/gears.html Link to comment Share on other sites More sharing options...
pug Posted January 27, 2016 Author Share Posted January 27, 2016 Any opinions on Ford performance gears 4:56 part# m-4209-88456. Will I need to buy the cross pin also part# 8002791. Thanks Link to comment Share on other sites More sharing options...
Pete M Posted January 27, 2016 Share Posted January 27, 2016 Dana and factory Ford gears would be my first picks. :thumbsup: did you read somewhere that the crosspin is needed? Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 27, 2016 Share Posted January 27, 2016 With the Ford 8.8 there's no carrier break to be concerned with. Yukon sells 4.88 gears for it - they are one of the best aftermarket gear sets IMO. The front D30 has a 3.73 carrier break, so what's in your D30 now? You need to know because you will either have to use "thick" gears or buy a new carrier if your existing ratio is 3.55 or below. Link to comment Share on other sites More sharing options...
pug Posted January 27, 2016 Author Share Posted January 27, 2016 Yes on the pin said it had to be notched. Yukon gear recommend the pin also. Will have to get a carrier for the front. Link to comment Share on other sites More sharing options...
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