Anyone have a 9" center section laying around? Could I get a couple measurements please? Could you take 2 measurements for me? I would like to know the spline depth on each side from inner most side (close to the center pin) to the case as shown.
This is an odd ball rear 9.375 - Most often refereed to as a 9 3/8 center and sometimes a 9 1/2.Anyway I'm comparing a standard 9" to it.
I slid my tape in to hit the pin,then brought it back out so as to hook it onto the end in there.Please do the same.
Thanks!
Ford 9 3/8

Passenger: (roughly) 6 & 1/4 inches.


Drivers: (roughly) 4 & 1/2 inches.



The reason I'm asking is,some claim these things are offset differently than a standard 9" and some say they're the same and are simply interchangeable (the housing must be notched if placing one of these inside a standard 9" housing,while the standard 9 bolts right into the 9 3/8 housing) with direct axle shafts and bolt in and go,while others claim the offset is so different,that when you place a 9" into a 9 3/8 housing,the stock axles become slightly too tight on one side,while the other now doesn't slide in far enough to be safe.To the unsuspected shade tree (like myself) because it works in driving the wheels,he may not know that one side is too tight for comfort (possibly now dangerously rubbing the pin?) and the other just barely slides inside the carriers splines,making a stripped out axle and or carrier splines possible.

 

Wow.Really? No one has an old 9" carrier laying around in their garage? To be clear,I'm not looking for the odd ball 9 3/8.This I already have as shown and measured.Just the good old school,common as dirt ford 9"

 

I don't have my differential installed in the 9 inch carrier, but I measured the spine offset to the end of the inner bearing race on each side. One side is 3 3/4", while the other is 2 3/4". I hope this helps.

 

Cool thanks! If you happen to remember though,please do take the measurements once you get your carrier together before putting it in your housing.

 

I measured my 9", and the depth is 3" on the short side and 4 1/2" on the long side.

 

WOW! Holy smokes.Big and indisputable difference in the offset between the 9 3/8 and the standard 9.Thank you my friend.I really appreciate it.

I mean even if you inserted your tape all the way until it hit,or brought it back out to just touch the full depth of the splines doesn't even matter,as that little 1/16 or 1/8 of an inch or whatever it is,is trivial next to the 6 1/4 & 4 1/2 of the 9 3/8 center to the 4 1/2 & 3 of the standard 9.

That pretty much seals the deal, that those who swap these two pumpkins between housings are supposed to use custom length axles.At least on that one side.


So let's see here.You set a 9" center inside a 9 3/8 housing then,and the passenger side axle,the long one,would have went inside a 6 1/4 and now only needs to go inside a 4 1/2. I've not heard anyone claim it doesn't fit! Surprising it goes in all the way and makes you wonder if it should be cut at least 1/4 for good measure? You'd want to measure with the 9" inside the housing to see but like I say,no ones ever mentioned that side has ever bothered anything.
Now you take the drivers side and it used to go inside a 4 1/2 depth and now it only has a 3" to work with so this axle is longer than required too.

OK so what gives? Why are some claiming an axle is too short when doing this? If anything 9 3/8 axles are now longer than needed on each side with a 9 center section,right? You may or may not need to cut some axle length off to avoid bottoming out and make sure your not too close for comfort.That's free and easy!


Let's go the other way,
You take a 9 housing,notch it so the 9 3/8 center can go in and now you have a depth of 6 1/4 where you used to have 4 1/2". This makes this oem 9" axle too short.It probably doesn't go inside the splines at least an inch.Right?
You have on the other side 4 1/2 where you used to have 3". This may or not be ok.It too may be too short but so long as it still goes inside the splines an least 1 inch you'd be ok.Again you'd have to measure with the center in there to know.

So it's when you set an old 9 3/8 center inside a 9" housing is when you come up short on axle length correct?
Am I thinking this through correctly guys?

 

I'm wondering where the positions of the side gears are on each of these diffs. Assume that they are in the same relative position, and the only difference in their overall widths are where their bearings are, then they should both use the same axle shafts as long as the shafts stay with their housing.

If the side gears, or whatever keeps the shafts from pushing in too far, on the 9-3/8 diff are further apart than those on the 9", and you jam it into the 9" housing, then you would need to shorten the shafts that were in the 9" housing.

Does this seem right, or did I miss something?