Did all early 4-cyl's come with 4.10's?

[DeadEyeJ]

Found an '84 or '86 (?) at a junkyard with a 4 banger. No tags on the axles.

Did all these come with 4.10's or did some come with 3.73's?

Anybody?

Jared

[Kejtar]

I believe that it's been reported that early 4cylinder units came with anything from 3.07's to 4.11's.... and there was no real way to determine which without popping the cover off...

Kejtar

[DeadEyeJ]

Well, my lying-in-the-dirt analysis says that they might be 3.73's. I just wedged a screwdriver to stop one spindle from turning. Then it took me just less than four turns of the pinion to make the other spindle make 1/2 turn. According to my amazing math skills, this should be a 3.73. Does this sound right to anybody else?

Jared

[ChuckD]

Even the 2.8l models had 4.10 and some had 3.73. I can usually read it off the tag on the D30 if they have them. I know when DC took over the 4 bangers had 4.10's. Also the YJ's/TJ's had 4.10's also with thier 4 bangers.

[Ghost]

If you want to know for sure..... pop the cover and read the ring gear. Dana stamped the ratio on the ring gear. Both my axles have the tooth count on the ring gear. Also the 86 FSM list the different ratios as 3.54, 3.31 fuel economy package, 3.73, and 4.10's.

[MudDawg]

My 85 model had 3.73's...I looked at a ton of junkyard axles and yet to find a 4.10 equipped axle...a quirk of being in Florida????

[xjdaddy]

My 84 with the 4 banger came with 3.73's but I promptly went to 4.10's

[Static-XJ]

Most 4cyls that I have seen have 3.73's. I have personally seen one exception to this, going back to the yard later this week (when I'll have help pulling it) to buy the axle.

[Jeff in VA]

If it has an auto tranny, it may have 3.73 or 3.55's...I screwed up ASSUMING all 2.5's had 4.10's. I got an identical year to mine, 2.5L MJ D30 that was 3.55. The only difference was my MJ has an AX5 and the other MJ was an auto.
I'm having a h*ll of a time finding a 4.10 as well..must be a southern thing (???) Can't swing a dead cat without hitting a D30 w/ 3.55 or 3.73's here in VA. I may have to go north to find one.....
Jeff

[David - Atlanta]

The 4.10 equiped axles I picked up last week came from an '86 with the V6 engine, auto trans and factory tow package. Fortunately both axles had their tags on them and were clearly readable.

You mentioned only turning the axle 1/2 turn. My understanding was that one complete rotation of the axle (spindle) and count the number of rotations of the pinion. If the pinion rotates four times then it should be the 4.10's. If you've marked the starting point on your pinion then 3.73's would clearly come up short of the fourth rotation.

[DeadEyeJ]

Dave, you would be right on the money on the 1/2 turn thing if the front end were equipped with a spool. Because of the differential, the axles' speeds are the average of the speed of the pinion, divided by the gear ratio.

So, if one spindle (axleshaft) were stopped, the other one would have to turn twice as fast as it would if they were both spinning the same speed. This means that if you were stuck and spinning only one rear tire, and the speedo said 30 MPH while they spin, the moving wheel would actually be spinning at 60 MPH.

Suddenly, it seems like the axle should have had like 7.55's or something like that. Doh, guess I'll have to go drain the axle and pop the cover. Major pain in the butt for an axle that I may not even buy. Especially while lying in the dirt at a junkyard.

Thx for the responses, Jared.