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Posted

Did the automatic mjs and 5 speed mjs with the 4.0 have the same speedometer gear? I went to hook everything on the trans of my 87 my 5 speed 2wd w/ 4.0 and the gear was missing

Posted

They're swappable, but not the same, as the auto and manual used different axle gearing.  If you put a gear out of an auto into a manual, both with factory axles and wheels, your speedometer(and therefore odometer) will be incorrect.

Posted

Here, this might help.  Unfortunately I don't know actual tooth counts.

 

4.0 + 5 speed = 3.07 gears

4.0 + auto = 3.55 gears

2.5 + 5 speed = 4.10 gears

2.5 + 4 speed = 3.55 gears

2.5 + auto = 4.56 or 4.10

 

There were slight variations on the types of gears used, but I think you'll be fine if it's close in year.

Posted

eBay... seriously.  It's where I got mine.  Just as an example, if you've got a 4.0 with auto, 4.10 gears swapped in running 31-32" tires, you want a 37 tooth speedo gear.

Posted

There are long and short shaft gears depending on the year (probably all the same with MJs and XJs though).  If you can't find the gear with the correct length shaft, they can be swapped.  This is usually an issue when you put larger tires on.

Posted

My mistake my truck is an 88. Don't know about shaft length its a Peugeot ba10/5 trans with 235/75 r15 tires and 3.07 gears

Posted

Refer to these links. Not sure if it matters with it being a manual or automatic, but I'm pretty sure you need a 29 tooth gear, long shaft.

 

Long shaft is for cable driven speedometers, short shaft is for the electronic driven speedometers.  Yours is obviously cable driven being an '88.

 

http://jeep-xj.info/HowtoSpeedoGears.htm

 

http://www.quadratec.com/jeep_knowledgebase/article-46.htm

 

I would also like to mention for peace of mind that I used these exact charts to determine what speedometer gear I needed when I put my 4.10's in with 31's and it is within 1 mph of my GPS at all speeds up to 75 mph (that's the fastest I've went with a GPS in my Jeep).

Posted

Long shaft is for cable driven speedometers, short shaft is for the electronic driven speedometers.

 

Not true. 91-92 and some 93 models used long shaft speedo gears; all had electronic speedometers. Manual or auto transmission does not matter. The correct speedo gear tooth count is determined by tire diameter and rear differential gear ratio. Also the plastic gears themselves are the same for all. You can swap the shafts between the gears easily.

Posted

 

Long shaft is for cable driven speedometers, short shaft is for the electronic driven speedometers.

 

Not true. 91-92 and some 93 models used long shaft speedo gears; all had electronic speedometers. Also the gears themselves are the same on all. You can swap the shafts between the gears easily.

 

This is because the early electric speedos were just an electronic adapter that attached to the sender the exact same way the cable did.  The later ones were integrated, which I believe is when they switched to the short shaft.

Posted

 

Long shaft is for cable driven speedometers, short shaft is for the electronic driven speedometers.

 

Not true. 91-92 and some 93 models used long shaft speedo gears; all had electronic speedometers. Manual or auto transmission does not matter. The correct speedo gear tooth count is determined by tire diameter and rear differential gear ratio. Also the plastic gears themselves are the same for all. You can swap the shafts between the gears easily.

 

 

 

 

Long shaft is for cable driven speedometers, short shaft is for the electronic driven speedometers.

 

Not true. 91-92 and some 93 models used long shaft speedo gears; all had electronic speedometers. Also the gears themselves are the same on all. You can swap the shafts between the gears easily.

 

This is because the early electric speedos were just an electronic adapter that attached to the sender the exact same way the cable did.  The later ones were integrated, which I believe is when they switched to the short shaft.

 

Well, I just learned something new then lol.  I was (mis)informed last year on another forum about the speedometer gears apparently.  I guess it pays to do a little more reading.  It even has a breakdown for the different years in the first link I posted... :doh:

 

But thank you for the clarification. 

  • 7 years later...
Posted

Does anyone here have a big ole stash of these guys laying around? Just swapped my gear ratio and need a 32 long. Trying to avoid buying a new one if possible. Can mail the old one back to add to the stash. If someone hasn't become this person yet, someone should (I don't have a garage or would be happy to)

Posted
1 hour ago, Gubachoo said:

Does anyone here have a big ole stash of these guys laying around? Just swapped my gear ratio and need a 32 long. Trying to avoid buying a new one if possible. Can mail the old one back to add to the stash. If someone hasn't become this person yet, someone should (I don't have a garage or would be happy to)

 

you should probably post up in the classifieds :L: 

Posted
5 hours ago, fiatslug87 said:

Oh, I don't remember having any black ones, green, yellow orange is what I remember.

Well thanks for looking. I appreciate that. 

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