Drivetrain Driver's Side Axle Shaft Not Seating Properly In Diff

Alpine615

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May 2, 2017
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Hey all, my name is Steve and I'm new here. Technically I do not own a Mustang II, but I have an 8" rear end from one that's going into my Pinto. I figured this would be the best place to get help. Thanks in advance...

I had the axles out to be drilled for 5 x 4.5" bolt pattern, with new bearings pressed on. The passenger side axle went in just fine, but the driver side will not seat all the way in the differential, which is a 3.25 ratio with posi. I removed everything from the housing, and noticed there are two gears in the driver side of the diff, and one is misaligned/offset with the other (see picture attachment). I took depth measurements from inside the differential and transferred them to the axle in Sharpie, so I know the misalignment is causing the interference.

Since everything spins together, I have been unable to align the two driver side gears - can anyone help explain how to turn one while preventing the other from turning with it? Thanks again...

 

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jozsefsz

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Aug 11, 2013
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Hi there friend, please excuse my ignorance as I've had my 8" rear apart exactly once to change bearings and set backlash so there are lots of other experts here who might chime in. I'm pretty sure there's only supposed to be one spider gear and one set of splines that the axle-shaft splines mate up with on each side of the carrier. Unless this is some exotic rear-end with which I'm not familiar. It would appear to me that your gear has fractured, perhaps due to the use of a too-short axle in the past or present? I could be completely wrong but do you have the same thing going on on the other side?
 
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Alpine615

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May 2, 2017
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To the best of my knowledge, this is a rebuilt factory unit with the Trac-Lok differential. After reading your reply, I got the idea to look through the Ford Master Parts Catalog. According to the diagram, it does appear that there are two toothed parts where the axle shaft splines should mate to. One part (4946) is called the 'Rear Axle Differential Gear Clutch Hub', and the other part (4236) is the Rear Axle Differential Side Gear, which appears to sit inside the Hub.

Still hoping someone out there can explain if it's possible to rotate one and not the other, without having to disassemble the thirdmember.

FMP Catalog.png
 

jozsefsz

Mustang Master
Aug 11, 2013
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Ah ok that makes perfect sense with the traction-lok which I don't have, and now know you have. :)

The II forum here is very quiet, you might have more luck posting to the classic 1st-gen forum as there are more folks there, and the 8" is common to us all (at least the carrier).
 

Alpine615

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May 2, 2017
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For anyone who comes upon this thread, perhaps with the same issue as I had, it was resolved. Click here for the solution.
 
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LILCBRA

I wish I didn't have all of these balls in the air
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Dec 6, 2005
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Sorry, I only really get the chance to check in on the forums on the weekends. I was going to suggest the same thing as horse sence - keep the other wheel from spinning and turn your axle in order to seat it in the splines. Happy to hear you got it sorted out!!