MississippiComanche Posted Monday at 09:36 PM Share Posted Monday at 09:36 PM I currently have a 2.5L 4cyl with AX4. I recently upgraded my wheels to 31's, but I still have stock 3.55 gearing. Since getting larger wheels, I've noticed the sluggishness. What gear ratio should I upgrade to for 31's on my setup? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted Monday at 10:19 PM Share Posted Monday at 10:19 PM Going to leave this link here for this tool that @derf created a long time ago: http://www.grimmjeeper.com/gears.html Link to comment Share on other sites More sharing options...
MississippiComanche Posted Monday at 10:33 PM Author Share Posted Monday at 10:33 PM Yea I got a little confused by the form. I'm looking for suggestions rather than raw rpm data. Link to comment Share on other sites More sharing options...
Big_Mark Posted Monday at 11:18 PM Share Posted Monday at 11:18 PM 3:73 will do ya well. If you plan to go larger than 31's, ever.... go 4:10 but honestly 3:73 is a great ratio all around. Link to comment Share on other sites More sharing options...
89 MJ Posted Monday at 11:32 PM Share Posted Monday at 11:32 PM I’d run 4.10s. That will be slightly shorter gearing than stock. Cruiser always said that these AMC inline engines were designed to run 24 mph per every 1000 rpms in drive (1:1 ratio). You don’t need to be afraid of turning it some higher rpms. Link to comment Share on other sites More sharing options...
Dzimm Posted Tuesday at 12:30 AM Share Posted Tuesday at 12:30 AM 2 hours ago, ghetdjc320 said: Going to leave this link here for this tool that @Dzimm created a long time ago: http://www.grimmjeeper.com/gears.html Just wanted to clarify, I am not the one who created this tool nor do I know who did. Looks like a great tool though! Link to comment Share on other sites More sharing options...
ghetdjc320 Posted Tuesday at 12:33 AM Share Posted Tuesday at 12:33 AM 3 minutes ago, Dzimm said: Just wanted to clarify, I am not the one who created this tool nor do I know who did. Looks like a great tool though! My bad I quoted the wrong user. Now I'm trying to remember who it is. The creator of it has the link to that page in his sig. Edit: found it. Its @derf Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted Tuesday at 12:48 AM Share Posted Tuesday at 12:48 AM List of factory gear ratios. Using the grimmjeeper calculator 4.10 will be closest to stock gearing for you. Link to comment Share on other sites More sharing options...
watchamakalit Posted Tuesday at 01:42 AM Share Posted Tuesday at 01:42 AM Dunno if it helps any but I feel like my 4.10's are a great match to 31's Link to comment Share on other sites More sharing options...
MississippiComanche Posted Tuesday at 01:44 AM Author Share Posted Tuesday at 01:44 AM Yea I'm looking around at parts to do 4 10 and figure out how much this endeavor is going to cost Link to comment Share on other sites More sharing options...
89 MJ Posted Tuesday at 01:59 AM Share Posted Tuesday at 01:59 AM It might be cheaper and easier to just swap axles. Any 4cyl, 5 speed XJ or MJ will have 4.10s (most likely). If you could find a D44 or 29 spline Chrysler 8.25, that would be a stronger axle too. Link to comment Share on other sites More sharing options...
derf Posted Tuesday at 09:53 PM Share Posted Tuesday at 09:53 PM Yeah, that's my calculator. Glad y'all find it useful. I don't have a "this is optimal" shortcut. Trouble is, there's so many variables to what is optimal. A high revving motor for mud bogging is completely different than a diesel for rock crawling. So the ratio you want can vary. Even in the same truck, the answer depends on too many things to factor in. The RPM data is good if you know where you want to end up. You can do side by side comparison to match a gear ratio to a tire size change and keep the performance close to stock. Or if you're always downshifting you can try shorter gears (higher number) to get it where you want it. If you really scream down the highway in top gear you can see what it takes to make that more reasonable. Link to comment Share on other sites More sharing options...
Smokeyyank Posted yesterday at 12:35 AM Share Posted yesterday at 12:35 AM 4.10s, if you're going to pay to put gears in do it once. Link to comment Share on other sites More sharing options...
coheed Posted yesterday at 12:36 AM Share Posted yesterday at 12:36 AM 2.8 with an AX5 and 31s on mine and the switch from 3.55 to 4.10s was great. Without the 5 gear anything over 60 would be real buzzy, but I use 4th up until 60 95% of the time. If you decide that swapping axles will be easier then I'd also upgrade to a beefier axle while you're at it. Unless you can find an MJ or XJ that already has both to swap over. Link to comment Share on other sites More sharing options...
Pete M Posted yesterday at 03:32 AM Share Posted yesterday at 03:32 AM 2.5L + manual + 31s = I'd do 4.56 Link to comment Share on other sites More sharing options...
ghetdjc320 Posted yesterday at 06:18 AM Share Posted yesterday at 06:18 AM I’d also go 4.56. Link to comment Share on other sites More sharing options...
derf Posted 18 hours ago Share Posted 18 hours ago The AX4 doesn't have overdrive so I'm not sure I'd go to 4.56 with 31s. That puts you up near 4K on the tach on the freeway. Maybe with an AX5. Link to comment Share on other sites More sharing options...
MississippiComanche Posted 14 hours ago Author Share Posted 14 hours ago Yea I'm prob doing 4.56. Currently hunting for some axles. Link to comment Share on other sites More sharing options...
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