Spanner wrench for Ford 9"?

I'm going to be tackling my first rear end...ummm yeah not that kind, a Ford 9". When i bought it, it already had new Yukon 5.13's. I picked up a Yukon Grizzly locker to replace the factory limited slip. I've done lunchbox lockers in D30's and 8.25's along with shafts and whatnot but thats the extent of diff work.
Anywho, from what i gather i'll need some sort of spanner wrench for the side adjusters, what have you used or better yet have you made one? Shouldn't be too hard, just a couple bolts welded to a bar???
Any tips on tools required or procedure for the Ford 9" big bearing, 31 spline?
Thanks!! -B

I made a real simple one just as you stated - a couple of 1/2 20 bolts (i think - can't remember much these days) welded to a small bar or flat stock. Worked just fine as you don't need to crank them a lot.

The 9 is a great diff. I run one in the buggy with the same gears. One tip i would offer is to eliminate the crush sleave. There are plenty of kits out there that replace it with a spacer and shims. With off roading, you can easily bang the yoke/driveshaft and alter your pre-load by compressing the crush sleave. Ask me how in know.....

Make sure you check the housing carefully. Where the pinion support bearing rides is known to break. Make sure that is intact and the bearing is good.

If you are planning for some serious abuse, i would think about an aftermarket case. Stock cases are relatively weak when pitted against big sticky tires.

Thanks for the tips! :0)
Here's another question, how much power is lost switching from the 8.25 to the 9"? is it enough to notice? its mentioned in the Differential Guide that one of the reasons the 9" was discontinued was due to the offset and the power needed to drive it because of this. For example the hypoid offset of the 9 is 2.38", and the 8.25 is 1.5".
From looking at the shear size of this 9", i have a hard time believing its rating of 35" tires! lol Whats your opinion of tire size for the big bearing 9" 31 spline and the hp d44 30 spline?
Thanks again, -B

As for a spanner wrench, I always just use two screwdrivers. I've just never gotten around to making a spanner wrench, but the screwdrivers work just fine. The 9" and the 44, if built well, can easily hold up to 37/38's especially under a light vehicle like the cherokee.

boomhauer said:

Thanks for the tips! :0)
Here's another question, how much power is lost switching from the 8.25 to the 9"? is it enough to notice? its mentioned in the Differential Guide that one of the reasons the 9" was discontinued was due to the offset and the power needed to drive it because of this. For example the hypoid offset of the 9 is 2.38", and the 8.25 is 1.5".
From looking at the shear size of this 9", i have a hard time believing its rating of 35" tires! lol Whats your opinion of tire size for the big bearing 9" 31 spline and the hp d44 30 spline?
Thanks again, -B

Click to expand...

Power loss? i don't think you would ever notice or feel a difference.

As far as axle strength vs. tire size - it's tough to say. Are you talking about a 30 year old stock 31 spline? If so i would say 35-36 is the max i would run. I grenaded 31 spline 44 shafts pretty regularly with 37 inch MTR's.

Now if you are upgrade to an alloy shaft, then your safety margin would increase. That said - i would still keep the max as previously stated to the 37-38 range.

I personally run 39's on my 9. But it's built to the hilt with an aftermarket chuck, 35 splines and a Daytona bearing support. That's the beauty of the 9. you can upgrade it for just about any abuse.