warrensmanche Posted February 5, 2011 Share Posted February 5, 2011 how do u know what gear ratio you have.i thought you timed the last two numbers on the diff tag. Link to comment Share on other sites More sharing options...
Incommando Posted February 5, 2011 Share Posted February 5, 2011 Only sure way is to pull the cover and count the teeth. A good approximation: mark a point on the frame/floor/whatever and one inline on the wheel. rotate wheel until the two spots come back inline. about 3 turns-3.07. 3.5 turns-3.55. a little more than 4-4.10. Factory 4.0/AW4 ratio was 3.55 Link to comment Share on other sites More sharing options...
Pete M Posted February 5, 2011 Share Posted February 5, 2011 jack up one rear wheel, put the truck in neutral so the tire spins, rotate the tire around exactly twice while counting the number of times the driveshaft rotates. 3 and a half times around is 3.55, 4 times is 4.10 etc. If you have a posi rear, you'll need to jack up both tires and then spin them around only once. Link to comment Share on other sites More sharing options...
wannabeMJ Posted February 5, 2011 Share Posted February 5, 2011 check the tag on your diff here is mine last 4 digits 41 10 = 4.11 Image Not Found Link to comment Share on other sites More sharing options...
Eagle Posted February 5, 2011 Share Posted February 5, 2011 It's VERY rare to find a ratio tag on a rear axle. It's more usual to find it on the front, but with the newest MJ now being 19 years old, most of those that once had tags probably don't have 'em today. Unless there's reason to think your truck has been changed, with the 4.0L engine the 5-speeds were 3.07 and the automatics were 3.55. 4-cylinders had more variations. Link to comment Share on other sites More sharing options...
wannabeMJ Posted February 5, 2011 Share Posted February 5, 2011 It's VERY rare to find a ratio tag on a rear axle. It's more usual to find it on the front, but with the newest MJ now being 19 years old, most of those that once had tags probably don't have 'em today. Unless there's reason to think your truck has been changed, with the 4.0L engine the 5-speeds were 3.07 and the automatics were 3.55. 4-cylinders had more variations. mine was an 86 and the tag was in pretty good condition only surface rust Link to comment Share on other sites More sharing options...
Automan2164 Posted February 5, 2011 Share Posted February 5, 2011 It's VERY rare to find a ratio tag on a rear axle. It's more usual to find it on the front, but with the newest MJ now being 19 years old, most of those that once had tags probably don't have 'em today. Unless there's reason to think your truck has been changed, with the 4.0L engine the 5-speeds were 3.07 and the automatics were 3.55. 4-cylinders had more variations. mine was an 86 and the tag was in pretty good condition only surface rust I believe you would be in the minority. Not only the condition of them makes it hard to deal with, but previous owners too. Not many people doing a differential service are detailed enough to put back on what seems like an old rusty tag that means nothing to them. Rob L. Link to comment Share on other sites More sharing options...
warrensmanche Posted February 6, 2011 Author Share Posted February 6, 2011 i don't have a rear tag but i do have a front.i will check that tomoro to be sure.now i swore these were the stock gear ratio that came with this truck(4:11) but someone said you could not get that with a aw4 tranny and 4.0.the tranny is now a aw4 (ausin) but not sure what it use to be.guy before me put 4x4 in.and he didnt change the rear axle. Link to comment Share on other sites More sharing options...
Incommando Posted February 6, 2011 Share Posted February 6, 2011 Apparently a rare option with the 4.0/AW4/D44 rear w/towing package was 3.73 gears, but I'd say 99% were 3.55's. A factory 4.0/AW4 with 4.10's would be very very rare. Link to comment Share on other sites More sharing options...
Automan2164 Posted February 6, 2011 Share Posted February 6, 2011 The absolute sure way is to pull the cover, and look on the ring gear. It will have 2 numbers towards the end of the part number stamping. Those will be the tooth count of the ring and pinion. Example would be 41 11, or 3.73's once you divide it up. Rob L. Link to comment Share on other sites More sharing options...
Pete M Posted February 6, 2011 Share Posted February 6, 2011 Apparently a rare option with the 4.0/AW4/D44 rear w/towing package was 3.73 gears, but I'd say 99% were 3.55's. A factory 4.0/AW4 with 4.10's would be very very rare. I believe that was a cherokee thing. Link to comment Share on other sites More sharing options...
johnj92131 Posted February 6, 2011 Share Posted February 6, 2011 jack up one rear wheel, put the truck in neutral so the tire spins, rotate the tire around exactly twice while counting the number of times the driveshaft rotates. 3 and a half times around is 3.55, 4 times is 4.10 etc. If you have a posi rear, you'll need to jack up both tires and then spin them around only once. Pete: Drive shaft twice??? Thought it was ONE turn of the drive shaft and 3.5 wheel turns equals a 3.55 final drive? Not 2 drive shaft turns and 3.5 wheel turns equals 3.55? 3.55 to 1? Right??? Link to comment Share on other sites More sharing options...
Eagle Posted February 6, 2011 Share Posted February 6, 2011 jack up one rear wheel, put the truck in neutral so the tire spins, rotate the tire around exactly twice while counting the number of times the driveshaft rotates. 3 and a half times around is 3.55, 4 times is 4.10 etc. If you have a posi rear, you'll need to jack up both tires and then spin them around only once. Pete: Drive shaft twice??? Thought it was ONE turn of the drive shaft and 3.5 wheel turns equals a 3.55 final drive? Not 2 drive shaft turns and 3.5 wheel turns equals 3.55? 3.55 to 1? Right??? Twice if you DON'T have a limited slip, 1:1 if you do have limited slip. If you DON'T have limited slip and you jack up both wheels, they'll just turn in opposite directions when you try to rotate one and you can't count anything because the driveshaft won't move. For open rears, do as Pete said: jack up ONE wheel and rotate that exactly two revolutions, counting revolutions of the driveshaft. If you have limited slip, when both rear wheels are up they both rotate in the same direction when you turn one by hand. In that case, rotate the tire one turn and count driveshaft revolutions. And you have it reversed. It's 3.xx revolutions of the driveshaft for one revolution (or two) of the tire(s). Link to comment Share on other sites More sharing options...
Pete M Posted February 6, 2011 Share Posted February 6, 2011 yup. you turn the tires around with your hands. and count the times the driveshafts rotates during the same period. all will become obvious when you try it. :D Link to comment Share on other sites More sharing options...
warrensmanche Posted February 7, 2011 Author Share Posted February 7, 2011 yep.wire wheeled tag in front and it says 4:11 and to be sure i jacked up the rear end and marked the drive shaft and tire.i turned the tire one rveolution and a tad bit more to get the drive shaft in the same spot.(got limited slip).so either i have a very rare find with factory 4:11 gearing or the rear axle was swapped at one time which i doubt.now you said this gear ratio is super rare for this truck how ever this gear ratio came when it was 2wd and may of had a different brand automatic tranny.i had the old tranny come with the truck since the guy beforme swapped in the tranny but it was sold while i was at work one day so i wish i would have looked to see what tranny it was.what do you guys think it was.it was for a 88 2wd 4.0 comanche. Link to comment Share on other sites More sharing options...
Automan2164 Posted February 7, 2011 Share Posted February 7, 2011 What is your VIN? Also, if you give me ALL the numbers on that tag, I should be able to tell you what it came out of. If the tag doesn't jive with the gears, they've been swapped. I would still pull the cover to be sure. Rob L. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 7, 2011 Share Posted February 7, 2011 I don't believe in diff tags or the BOM number stamped on the axle tube. Been fooled too many times. You don't know what you have until you look inside, especially with a suspected Trac-Loc axle. Link to comment Share on other sites More sharing options...
Automan2164 Posted February 7, 2011 Share Posted February 7, 2011 I don't believe in diff tags or the BOM number stamped on the axle tube. Been fooled too many times. You don't know what you have until you look inside, especially with a suspected Trac-Loc axle. Ding! As I said. Don't be sure until you read the numbers on the gears themselves. Rob L. Link to comment Share on other sites More sharing options...
Pete M Posted February 7, 2011 Share Posted February 7, 2011 still pretty sure my (quick and clean) method works. :D also, I've seen gear sets without stampings on them. :fs2: counting teeth sucks. Link to comment Share on other sites More sharing options...
Automan2164 Posted February 7, 2011 Share Posted February 7, 2011 Pete, your not helping the situation. Rob L. Link to comment Share on other sites More sharing options...
Pete M Posted February 7, 2011 Share Posted February 7, 2011 :D uh, it's always a good time to change your gear oil and inspect the innards? Link to comment Share on other sites More sharing options...
Automan2164 Posted February 7, 2011 Share Posted February 7, 2011 :D uh, it's always a good time to change your gear oil and inspect the innards? Maintenance first. Rob L. :cheers: Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 7, 2011 Share Posted February 7, 2011 :thumbsup: Link to comment Share on other sites More sharing options...
warrensmanche Posted February 8, 2011 Author Share Posted February 8, 2011 well i am for sure its 4:11.i gota picture of the tag.how can you tell by the tag that this axle is original to this truck? Link to comment Share on other sites More sharing options...
warrensmanche Posted February 8, 2011 Author Share Posted February 8, 2011 o just about forgot.this is off the front axle cause the rears missing.so this was off of an xj cause the 4x4 was swapped in.this is not original to truck.how can i tell if the rear axle is original to the truck.this is a random pic of it.doubt if it helps Link to comment Share on other sites More sharing options...
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