Topic: Need help determining if my TJ gears & axles have been changed

[omnisi]

Bought a '99 TJ, 2.5/5spd a year ago with 54K on it.  It had 35s on it when I got it.  I removed the body lift and put 33s on it (left the susp lift on).  I have no idea what has been done, if anything, to the gears/axles.  Also, Im an old CJ guy and have no idea what susp lift is on it...?

Question is,  what is the easiest way to see if the rear axles have been upgraded?  Is jacking up the rear and rotating the tire the simplest way to check the gear ratio?

I seem to have more power with 33s than other 2.5s, so Im thinking its gears since it came with 35s on it.  I just havent had time to play with it much since I got it.

Any help is greatly appreciated

[Jeffy]

Well how did it drive with 35's on?  Were you ever able to get into 5th?  How about 4th?  And with 33's, how's 5th?  Diff tags won't really help you here.  You'll have to jack it up and then count to driveshaft rotations.  It will probably be 4.5 (ei. 4.56:1) or 4.9 (4.88:1) rotations for every one of the tire.  Stock is 4.11:1.

[rwing1]

You could make a mark on the tire at the ground, make a mark on the driveshaft and pinion housing as reference and you or a friend roll the truck one wheel rotation while the other is counting rotations of the driveshaft. unless you have a posi/locked rearend jacking it up and spinning a tire might not turn the axles/carrier in unison.  Another way to get an idea is watch your rpms in 4th gear(assuming a stick shift) at a given speed,  maybe have a friend with a known accurate speedo be your pace car.  Most gearing charts use 55mph in 4th gear 1:1 ratio to list the engine rpm with various tire/gearing options.  The last option I would use, is to actually pull the diff cover and count teeth.  Although on a new to you/used vehicle with questionable history it would be a good idea to change the gear oil anyways....... and know for sure what diff you may be running.

[rwing1]

Jeffy you beat me...... I got distracted while replying and you posted before I could..... didn't mean to repaet what you were saying about the driveshaft!

[Jeffy]

Jeffy you beat me...... I got distracted while replying and you posted before I could..... didn't mean to repaet what you were saying about the driveshaft!

Haha,  Just an FYI, I think when you're posting and someone else sends a new post, it will warn you and give you the option of seeing that new post while you're in the editor.

[omnisi]

Well how did it drive with 35's on?  Were you ever able to get into 5th?  How about 4th?  And with 33's, how's 5th?  Diff tags won't really help you here.  You'll have to jack it up and then count to driveshaft rotations.  It will probably be 4.5 (ei. 4.56:1) or 4.9 (4.88:1) rotations for every one of the tire.  Stock is 4.11:1.

With the 35s, I could get into 5th, but not unless cruising flat...4th was fine.  Didnt drive it much with the 35s, just to the tire shop.  Now with 33s (BFG A/Ts), I use 5th as normal....over 50 mph.  It will hold 5th on most hills/bridges.  It will accelerate up hills in 4th.  It just seems to wind out about 33-3500 rpms in gears 1-4, dont know about 5th.

How can I check to see if axles have been upgraded?

Thanks again for your replies...Im jacking it up now,

Mark

[omnisi]

On turning the drive shaft:

One exact revolution of the tire, the drive shaft turns exactly 2 1/4 (2.25)turns.  On 2 exact revolutions of the tire, the drive shaft turns slightly more than 4 1/2 (slightly more than 4.5) turns.

[Jeffy]

On turning the drive shaft:

One exact revolution of the tire, the drive shaft turns exactly 2 1/4 (2.25)turns.  On 2 exact revolutions of the tire, the drive shaft turns slightly more than 4 1/2 (slightly more than 4.5) turns.

Sounds like it's 4.56:1 then.

[omnisi]

Thanks for the quick replies.  thats what i thought...going to check the front now.

Any ideas on an easy way to see if the axles in the 35C have been upgraded?

Thanks again

[neale_rs]

Great test result.  Does this mean that as soon as a tire lifts it will spin twice as fast at it was while both were on the ground, assuming engine RPM stays the same?

[omnisi]

It just means that you have to have 2 full rotations of the tire to get your gear ratio...or one turn multiplied by 2...

[omnisi]

Anyone know how I can tell if my axles are stock without pulling the axle?

Looks like the tire end of the shaft has raised large letters "D1S" , and then a small number stamped on it read 581 1 310A .

[Jeffy]

Anyone know how I can tell if my axles are stock without pulling the axle?

Looks like the tire end of the shaft has raised large letters "D1S" , and then a small number stamped on it read 581 1 310A .

What does the flat area that sticks into the wheel look like?  If it looks perfectly smooth and milled, it's probably an aftermarket shaft.  Also, the paint used on aftermarket shafts looks darker then OEM's.  Take a picture of it if you can.

[omnisi]

Looks like OEM rusted crap, lol.  Kind of looks like it has a puller hole milled in the center of the protruding part.  No side-to-side play, and feels tight.  Seems like whoever did the gears did a decent job...no whining.  probably do fine in the sand and mud here in Florida...

Looks about like the second pic on this link"

http://72.14.209.104/search?q=cache:SC_BGreoxFsJ:www.offroaders.com/directory/axles/dana44.htm+35C+jeep+axle&hl=en&ct=clnk&cd=24&gl=us

Thanks for the help Jeffy,

[Jeffy]

Looks like OEM rusted crap, lol.  Kind of looks like it has a puller hole milled in the center of the protruding part.  No side-to-side play, and feels tight.  Seems like whoever did the gears did a decent job...no whining.  probably do fine in the sand and mud here in Florida...

Looks about like the second pic on this link"

http://72.14.209.104/search?q=cache:SC_BGreoxFsJ:www.offroaders.com/directory/axles/dana44.htm+35C+jeep+axle&hl=en&ct=clnk&cd=24&gl=us

Thanks for the help Jeffy,

Yeah, OEM's have those tabs in the center that allow for turning the axle shafts.  Aftermarkets don't have them.