MJ Gears and Years

[89 MJ]

Because we all know that there were a lot of gears that you could get in an XJ/MJ during their production, I think it would be a good idea to come up with a list of gears that you could get and the years that you have found them in for future reference. Please include other years and gear ratios that you have found over the years.

 

4.56 198?-1992? 4 cyl auto MJs (maybe XJs too?)

4.10 198?-1996? Typically found in 4 cyl, 5 speed MJs and XJs, and some 86s (no idea on 97+)

3.73 1984 (found in an all original 84 XJ)

3.55 1984?-2001 4 cyl 4 speed MJs and XJs, 4.0 auto MJs and XJs

3.07 1987?-2001 (4.0 5 speed XJs and MJs) (89eliminator's 88 4.0 auto, fuel mileage package?)

[89eliminator]

you can get 3.07 in Auto 4.0s as well.  my 88 had it.  

[89 MJ]

9 minutes ago, 89eliminator said:

you can get 3.07 in Auto 4.0s as well.  my 88 had it.  

Interesting, that must have been some sort of fuel economy package. I'll add it to the list.

[eaglescout526]

I can just copy paste all the ratios for each year from starparts and drop them in. Course do we want each MJ year or do we want to look back to 84 and forward to 01?

[89 MJ]

5 minutes ago, eaglescout526 said:

I can just copy paste all the ratios for each year from starparts and drop them in. Course do we want each MJ year or do we want to look back to 84 and forward to 01?

I am thinking 84-01 would be great. Lots of us have XJs or MJs swapped with later model parts. Thanks!

[eaglescout526]

Alright. I’ll just run each ratio and just list it’s years available. 

[Pete M]

21 minutes ago, 89eliminator said:

you can get 3.07 in Auto 4.0s as well.  my 88 had it.  

 

that is so much against the grain that I'm going to need to see some paperwork before I would add that to any list. 

[89eliminator]

3 minutes ago, Pete M said:

 

that is so much against the grain that I'm going to need to see some paperwork before I would add that to any list. 

 

i mean i owned it 15 years ago so i don't know what paperwork I'm going to get lol.  but it was verified by opening the cover.  who know if it was factory but it showed no signs of being swapped out

[89 MJ]

5 minutes ago, 89eliminator said:

 

i mean i owned it 15 years ago so i don't know what paperwork I'm going to get lol.  but it was verified by opening the cover.  who know if it was factory but it showed no signs of being swapped out

Unless the whole axle was swapped. 

 

11 minutes ago, eaglescout526 said:

Alright. I’ll just run each ratio and just list it’s years available. 

Sweet! Thank you, no rush. 

[Pete M]

"paperwork" can be the digital variety of course.   far too few of us still have build sheets and window stickers.   is the vin in the registry?  I've got 0 info to support any 4.0/auto coming like that from the factory.    fwiw I blew up and replaced my axle in '98 when the truck was all of 10 years old.  dana 35s truly suck. 

 

I need a time machine...

[89eliminator]

4 minutes ago, 89 MJ said:

Unless the whole axle was swapped. 

 

 

thats what i was getting at.  u-bolts and such had same amount of rust as everything else

[89eliminator]

5 minutes ago, Pete M said:

"paperwork" can be the digital variety of course.   far too few of us still have build sheets and window stickers.   is the vin in the registry?  I've got 0 info to support any 4.0/auto coming like that from the factory.    fwiw I blew up and replaced my axle in '98 when the truck was all of 10 years old.  dana 35s truly suck. 

 

I need a time machine...

no pics and no VIN registry  

[89 MJ]

44 minutes ago, 89eliminator said:

 

thats what i was getting at.  u-bolts and such had same amount of rust as everything else

Very interesting. 

[Pete M]

still could easily have been swapped out early on.  maybe someone was trying to hyper mile?  who knows.   without any official info it's hard to say.  

[derf]

I have also heard of 3.31 gears being optional in the early years.  Rare in the XJ/MJ but possible.

[eaglescout526]

Derf is correct on the 3.31. Probably as rare of an option as the 4.56. 

[omega_rugal]

5 hours ago, 89eliminator said:

you can get 3.07 in Auto 4.0s as well.  my 88 had it.  

 

really? how did it performed? are you sure it came factory?

[89 MJ]

4 hours ago, derf said:

I have also heard of 3.31 gears being optional in the early years.  Rare in the XJ/MJ but possible.

Interesting. I’ll add it to the list tomorrow. 

[Eagle]

The '86 XJ hulk I have out back has 3.73 gears. 2.8L auto.

 

[Pete M]

car-part.com can help you with what ratios were available each year.  search MJ rear axles if you want to weed out the XJ stuff

[cruiser54]

18 hours ago, Pete M said:

 

that is so much against the grain that I'm going to need to see some paperwork before I would add that to any list. 

Agreed. Of the 13 Comanches I had as demos at the dealership, I personally ordered about 10 of them. 3.07 with auto was never an option. 

[89eliminator]

20 hours ago, omega_rugal said:

 

really? how did it performed? are you sure it came factory?

it sucked lol.  no I'm not sure it came from the factory that way.  was just how it was when i bought it.  

[ghetdjc320]

Let us not forget about YJ axles. 3.07-4.10. 3.55’s originally in my 88 with BA10/5 and 4.2

[billyblankss]

On 12/21/2020 at 12:47 PM, Pete M said:

"paperwork" can be the digital variety of course.   far too few of us still have build sheets and window stickers.   is the vin in the registry?  I've got 0 info to support any 4.0/auto coming like that from the factory.    fwiw I blew up and replaced my axle in '98 when the truck was all of 10 years old.  dana 35s truly suck. 

 

I need a time machine...

 

I have an 88 sport truck with Dana 35 and 3.07 in the rear. 4.0 inline 6 engine.

 

Went wheeling yesterday and had a blast but got stuck once had to winch out... But my buddy's wrangler on 35s had no issue. My axle just barely stuck on that rut. I'm running 33s. 

 

I really didn't want to regear because I assume it's at least a grand but idk .

[Pete M]

10 minutes ago, billyblankss said:

I really didn't want to regear because I assume it's at least a grand but idk .

 

it's worth every penny.   it'll put a huge smile on your face each and every time you punch the gas.   

 

just don't regear a dana 35.  invest your cash in an axle that will last.