Calculations made easy
#1
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Year: 1996
Model: Grand Cherokee
Engine: 4.0
Calculations made easy
In my quest to identify my gear ratios for my 96 ZJ so I could match new tire size and gear ratio's correctly, I happened across these calculators. They may have been posted here before but searching the sight I never found one this simple. If I got this in the wrong spot I trust someone will correct it.
Looks like I'll be rolling on 33's with 4.30 gears, Dana 30 up front and Dane 35 rear with 30 spline chromoly axles and lockers. The calculator punched out a 4.11 ratio but I bumped it up to 4.30 to increase RPM 5% for a fraction more power at the wheels.
http://www.crawlpedia.com/calculators.htm
This is the calculator page but if you click on "full calculator" under the category it gives you a lot more pertinent info.
Hope this helps guys...
Looks like I'll be rolling on 33's with 4.30 gears, Dana 30 up front and Dane 35 rear with 30 spline chromoly axles and lockers. The calculator punched out a 4.11 ratio but I bumped it up to 4.30 to increase RPM 5% for a fraction more power at the wheels.
http://www.crawlpedia.com/calculators.htm
This is the calculator page but if you click on "full calculator" under the category it gives you a lot more pertinent info.
Hope this helps guys...
#2
CF Veteran
The problem with that is that they don't make 4.30 gears. They make 4.27s for D30s, but not Dana 35s. So you will have to choose between 4.11 and 4.56
#3
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Year: 1996
Model: Grand Cherokee
Engine: 4.0
I see that. So the plot still thickens...LOL 4.11 would keep RPM's the same, 4.56 would be 10% Hmmmmm. For me, even though I would like the extra RPM, I think the extra strength of the 4.11 may be the way to go but I'm open to other trains of thought...
#4
CF Veteran
4.11 is popular. Your biggest strength issue is with the axle shafts. The C clips on them can fail. Fortunately you have rear disc brakes so you won't spit the shaft out
#5
CF Veteran
Do you want to know the formula that that website uses to calculate everything?
RPM=speed × transmission gear ratio × axle gear ratio × 336 ÷ tire size. You can figure it all out yourself using that formula.
RPM=speed × transmission gear ratio × axle gear ratio × 336 ÷ tire size. You can figure it all out yourself using that formula.
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#8
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Year: 1996
Model: Grand Cherokee
Engine: 4.0
Here is a better one http://www.grimmjeeper.com/gears.html
#12
Old fart with a wrench
I used to like straight-line G force until I got addicted to lateral G force. Now it's that kick in your spine when the spinning stops and you grab something!
#13
Senior Member
4.56 gears are good. you also need to consider the higher ride hight with a lift (push more air), armor you may have installed, and any cargo you plan to carry. so even though 4.56 carries slightly higher RPMs those things mentioned above will work against you.
#14
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Year: 1996
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#15
Old fart with a wrench
IDK about your ZJ, but I've put 1500 lbs in my stock, cheap WJ Laredo and it still has spring action left! It only looks slightly low, my headlights are a little high, and braking is a little late, but it seems to handle the weight like it was designed for it. Although, this might be the reason my rear axle blew up!