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Steering box upgrade.

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The box is bolt-in but the pitman arm is different and should be replaced with an XJ/MJ pitman arm.


As to whether the ZJ box is an "upgrade," it depends on your usage. The ZJ box has a faster ratio. That's a good thing for street driving on stock or near-stock size tires. But the ZJ box is not any bigger or stronger than the XJ/MJ box. Running a quicker ratio with large tires, especially if you do rock crawling, is very hard on the box. If anything, a rock crawler on very large tires should be going to an 18:1 ratio box rather than a quicker ratio box.

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Quick Q...


The TJ guys bolt on Dodge Durango boxes.... do those work on a XJ/MJ also?



The main feature (of both the ZJ and the Durnago boxes) is the quicker ratio, they are not any stronger.


The 'durango box' will bolt up to the XJ/MJ as does most Saginaw steering gears.


Saginaw makes a couple of different size stearing gears. The ZJ uses the same piston size a the Cherokee/MJ. The durango uses a 1/2" larger pistion and has more power but because of the larger pistion it turns a little slower (a higher pressure pump helps this). The Durango gear is 'stronger' in regards to turning because of this.


The durango box works well but there are some issues. Since the piston/gear is larger the gear must be spaced an addition 1/4" from the frame (in addition to the alloy spacer already there) and longer bolts are necessary. The BIGGEST issue with the Durango boxes is the turns from lock to lock. The Durango box has inconsistently come with 3 and 3.5 turns lock to lock. A XJ/MJ requires 3.5 turns lock to lock for a normal turning radius and this is even more crucial offroad. If you get a box that has 3 turns lock to lock you must open the gear up and rebuild it and remove the limiting spacer on the inside and grind the inside the main cap a little bit. This is a very easy thing to do and rebuild kits are available at Napa, O'Reily's, etc. The process can take less than two hours the first time one does this.

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  • 5 years later...

  I'm bringing this one back from the dead but it looks like I'll be in the market for a new steering box soon.  I changed Georgia's pressure & return hoses last night (crusty OE hoses) and found some metal in the return line at the box.  I don't have any issue with her steering at the moment but if I have to score a JY box I might as well upgrade if the opportunity presents itself.  I did some research and found the following, courtesy of Hollander:

-551-1353 box Fits 84-95 XJ/MJ.  This should be what's on the truck now. Either an ES or EK code, not sure which I have.

-551-1688.  '96 only. Not sure what's special about it

-551-1742.  '97-01 XJ. 

-551-1690. ZJ steering box listed as '96-98 per Hollander


  I looked up the Durango box as well but forgot to write down the P/N.  I was very surprised to see 3 different options for XJ steering boxes.  Anyone have an insight as to what makes the '84-'95, '96, and '97+ boxes different?  I was thinking that,for 98% street driven MJ, a relatively low mileage XJ box of any year would be fine.  Thoughts?

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I was very surprised to see 3 different options for XJ steering boxes.  Anyone have an insight as to what makes the '84-'95, '96, and '97+ boxes different?


I'm pretty sure they changed the style of fittings in the box where the hoses connect. Don't remember what year that happened, though.

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I know the '98 ZJ box uses M16 X 1.5 and M18 X 1.5 threads on the box.  I put one in my '69 GM A body and had to source a bunch of things from the local hydraulic shop.


 Here's the how to I followed:



It looks like I could use an 800 series 12.7:1 ratio box from a '96-'98 ZJ and everything would fit.  I'd also drop from the current 14:1 ratio to 12.7:1. 




 I don't necessarily mind the 14:1 ratio.  Still don't have any idea what's different on the 2nd XJ boxes though

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