JohnQ Posted June 22, 2008 Share Posted June 22, 2008 I am getting ready to swap my MJ dana 44 and my 97 TJ dana 30 onto my 88 comanche. Both axles have 3:55 gearing. I currently have 3:07 gearing and 5th gear is useless with the 31's. Will I see any difference with the 3:55 gears? Link to comment Share on other sites More sharing options...
jackel18 Posted June 22, 2008 Share Posted June 22, 2008 i run the same setup on my MJ and it's a world of difference going from the 3.07 to 3.55. Rich Link to comment Share on other sites More sharing options...
mvusse Posted June 22, 2008 Share Posted June 22, 2008 Assuming 4th has a 1:1 ratio and 5th has a .70 ratio (don't know what they are in Jeeps), the 3.55 gears will put 5th about halfway in between 4th and 5th with your current 3.07 setup. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted June 22, 2008 Share Posted June 22, 2008 I am getting ready to swap my MJ dana 44 and my 97 TJ dana 30 onto my 88 comanche. Both axles have 3:55 gearing. I currently have 3:07 gearing and 5th gear is useless with the 31's. Will I see any difference with the 3:55 gears? yep, you'll like it. my bro is going to 3.73's though from 3.07's with his 5 speed---we got the 3.73 axles cheap/free Link to comment Share on other sites More sharing options...
Geonovast Posted June 22, 2008 Share Posted June 22, 2008 3.07 x .79 = 2.43.1 3.07 x 1 = 3.07:1 3.55 x .79 = 2.80:1 Link to comment Share on other sites More sharing options...
Eagle Posted June 22, 2008 Share Posted June 22, 2008 It'll put you back close to "stock." I ran 31s with 3.73 gears. In terms of RPM-to-MPH, the final drive ratio in 5th gear was exactly the same as my wife's stock XJ with auto and 3.55 gears on stock tires. You'll see an improvement over 3.07s, but 3.73s or even 4.10s would be a far better choice IMHO. Link to comment Share on other sites More sharing options...
Car RamRod Posted June 24, 2008 Share Posted June 24, 2008 I run 3.55s and a ba10, it's perfect. I'm spinning 2k at 65 and pulling solid mileage. Link to comment Share on other sites More sharing options...
JohnQ Posted July 12, 2008 Author Share Posted July 12, 2008 I have the rear axel swapped, can I run my truck in 2WD until I have time to get the front axel swapped in? Should I pull the front drive shaft off? Link to comment Share on other sites More sharing options...
Motion Offroad Posted July 12, 2008 Share Posted July 12, 2008 I'd pull the front D-shaft just for added safety. It's only about a 10 min job and the piece of mind that your not gonna blow your TC is nice. Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 15, 2008 Share Posted July 15, 2008 Cool - I got the 3.07's and 5spd and am thinkin of going to 3.55's. Now I'm sure they will do the 31's right. Thanks! Link to comment Share on other sites More sharing options...
A-man930 Posted July 15, 2008 Share Posted July 15, 2008 I went from 3.07s to 3.55s and couldn't be happier! It's close to stock as far as the speedo is concerned and I can actually use 5th gear now. And yes, you can swap the rear and wait for the front, just don't engage the case and you'll be fine. Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 15, 2008 Share Posted July 15, 2008 I went from 3.07s to 3.55s and couldn't be happier! It's close to stock as far as the speedo is concerned and I can actually use 5th gear now. And yes, you can swap the rear and wait for the front, just don't engage the case and you'll be fine. Did u swap the whole axle or re-gear? If u swapped axles were they XJ or mJ? I really want to learn to re-gear but aint real hip with setting backlash Link to comment Share on other sites More sharing options...
Pete M Posted July 15, 2008 Share Posted July 15, 2008 3.55 geared XJ axles are everywhere and can be cheaper than regearing, even if you do it yourself. I'd go for a 29 spline 8.25 axle from a 97-01 XJ if I could find a cheap one and then match that off with a Dana 30 from any year that came with the 297 joints. "If you're going to build it, build it right." :D Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 15, 2008 Share Posted July 15, 2008 3.55 geared XJ axles are everywhere and can be cheaper than regearing, even if you do it yourself. I'd go for a 29 spline 8.25 axle from a 97-01 XJ if I could find a cheap one and then match that off with a Dana 30 from any year that came with the 297 joints. "If you're going to build it, build it right." :D The boneyards around here never have any Jeeps that new in them so I'll probly have to settle for what I can get. I'm going tomorrow to see what I can find. I also will be getting a clock and cig lighter socket - NEITHER OF WHICH THIS TRUCK HAS! Was a cig lighter actually an option??? :huh???: Link to comment Share on other sites More sharing options...
Eagle Posted July 16, 2008 Share Posted July 16, 2008 Was a cig lighter actually an option??? :huh???: Yes Link to comment Share on other sites More sharing options...
A-man930 Posted July 17, 2008 Share Posted July 17, 2008 I used an 8.25 out of an XJ (not sure what year) and a 30 out of an '86 to '89 MJ... I did the whole axle swap for the same reason. Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 17, 2008 Share Posted July 17, 2008 I used an 8.25 out of an XJ (not sure what year) and a 30 out of an '86 to '89 MJ... I did the whole axle swap for the same reason. I'd like to find a Ford 8.25 but like I've said a hundred times there just aint none in the boneyards here so I'll look for the ol reliable D35 with 3.55's. I did however score major parts today in a junkyard run but thats a bigass post yet to come I just gotta get pics after the works done. Link to comment Share on other sites More sharing options...
Pete M Posted July 17, 2008 Share Posted July 17, 2008 The 8.25 is a chrysler axle and you're almost as likely to find it under that random XJ as the Dana 35. The 8.8 is the ford one found under Explorers. Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 17, 2008 Share Posted July 17, 2008 The 8.25 is a chrysler axle and you're almost as likely to find it under that random XJ as the Dana 35. The 8.8 is the ford one found under Explorers. Is that the one with the disc brakes? There are a few ZJ's at the yard. I wonder, nah too much hassle to spring Link to comment Share on other sites More sharing options...
Eagle Posted July 17, 2008 Share Posted July 17, 2008 The 8.25 is a chrysler axle and you're almost as likely to find it under that random XJ as the Dana 35. The 8.8 is the ford one found under Explorers. Is that the one with the disc brakes? There are a few ZJ's at the yard. I wonder, nah too much hassle to spring The 8.25 as used in the XJ did not have disc brakes. Dunno if they ever used the 8.25 in the ZJ. I believe the ZJs all got either the Dana 35 or the crappy aluminum "Dana 44" Link to comment Share on other sites More sharing options...
XJs4Ever Posted July 18, 2008 Share Posted July 18, 2008 The 8.25 is a chrysler axle and you're almost as likely to find it under that random XJ as the Dana 35. The 8.8 is the ford one found under Explorers. Is that the one with the disc brakes? There are a few ZJ's at the yard. I wonder, nah too much hassle to spring The 8.25 as used in the XJ did not have disc brakes. Dunno if they ever used the 8.25 in the ZJ. I believe the ZJs all got either the Dana 35 or the crappy aluminum "Dana 44" Yea I know all that. I was just thinkin out loud. The ZJ's all had the quadralink which was eight control arms. Coils all four corners, and on most - 4whl disc. Trust me I know this stuff. I was just sayin I wouldnt want to convert ZJ to XJ rear springs. Coils in the rear would be cool but that would involve arms - one way or the other control or long but arms either way Link to comment Share on other sites More sharing options...
dragonrider477 Posted July 20, 2008 Share Posted July 20, 2008 the first thing i did to my 88 5 speed was rip out the 3.07's and put 3.55's in. even with the small stock 205-75-15's 5th gear was useless.gas mileage actually went up with road trip mpg at 22 or better.(4x2 all stock). Link to comment Share on other sites More sharing options...
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