Filler nut on differential

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Rt.146
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Filler nut on differential

Post by Rt.146 »

What size is the filler nut on a 66's 390 differential?
RAVEN
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Re: Filler nut on differential

Post by RAVEN »

Believe it is a male 1/2" socket square drive. Just insert the square ratchet drive or extension and away you go!
CDN Member since 1975 #2086
Flock: 1964 Landau Original Family Owned
1964 Sr Convertible "RAVEN"
Past: 2003 Blk Lab "RAVEN" "RIP"Nov 15/17
1964 Lincoln vin4Y86N00007
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Rt.146
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Re: Filler nut on differential

Post by Rt.146 »

Thanks for the reply, though that nut at least on mine is over 1" I just do not know how much over 1" maybe 1 1/2" I don't have a socket that fits, I'll get one if I find out the size.
RAVEN
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Re: Filler nut on differential

Post by RAVEN »

I think you will find that it is a plug, not a bolt, and no socket is necessary, only the ratchet or breaker bar square drive.
Unless the P.O. did a change out.
CDN Member since 1975 #2086
Flock: 1964 Landau Original Family Owned
1964 Sr Convertible "RAVEN"
Past: 2003 Blk Lab "RAVEN" "RIP"Nov 15/17
1964 Lincoln vin4Y86N00007
1964 Red Convertible
jtschug
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Re: Filler nut on differential

Post by jtschug »

Some have a plug in the carrier housing on the driveshaft side of the axle. This is an internal square drive plug. Not all have this.

All the original axles had a large fine thread drain bolt on the rear side of the axle housing. This is like a 1 3/8" hex head. I don't know the exact size. My largest wrench is 1 1/4", this is a little bit bigger and my biggest Crecent wrench will fit it.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
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Alan H. Tast
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Re: Filler nut on differential

Post by Alan H. Tast »

jtschug wrote: Fri Dec 20, 2019 12:44 pm Some have a plug in the carrier housing on the driveshaft side of the axle. This is an internal square drive plug. Not all have this.

All the original axles had a large fine thread drain bolt on the rear side of the axle housing. This is like a 1 3/8" hex head. I don't know the exact size. My largest wrench is 1 1/4", this is a little bit bigger and my biggest Crecent wrench will fit it.
Huh? I don't recall any large-headed bolts, just the drain plugs. You're talking about a Ford 9-inch housing? Are you thinking of the pinion nut at the front of the center carrier? Pictures please?
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
jtschug
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Re: Filler nut on differential

Post by jtschug »

Now that photobucket doesn't work anymore, how do we post pictures on here?

I have the axle out of the car, so I can take a picture of it, I just don't know how I would post it. I actually have two original '66 axles I can snap, a 28-spline and a 31-spline. The both have the large hex-head drain plug on the rear of the axle housing.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
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Alan H. Tast
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Re: Filler nut on differential

Post by Alan H. Tast »

When you were typing in your message or reply, did you see the two tabs below the message box called "Options" and "Attachments"? Hit the "Attachments" tab and the button "Add files" will show up. Hit this button and a file browser should show up as a new window on your screen that is looking at your computer - find the file you want to attach, select it and hit the "Open" button. The picture should load and give you a place to insert a file comment/capton and buttons to either place the picture inline
Raven - Tulsa 2018 Undercarriage Judging
Raven - Tulsa 2018 Undercarriage Judging
or delete the file. Once you're finished with your message hit "Submit". I just did this on my computer.

Voila! No more reliance on Photo-suck-it.
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
jtschug
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Re: Filler nut on differential

Post by jtschug »

Here is a picture of the oil fill plug with a hex head on the rear axle housing
Attachments
Rear axle plug.jpg
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Rt.146
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Re: Filler nut on differential

Post by Rt.146 »

jtschug wrote: Sun Dec 22, 2019 10:11 pm Here is a picture of the oil fill plug with a hex head on the rear axle housing
That is the one..
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Alan H. Tast
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Re: Filler nut on differential

Post by Alan H. Tast »

Well...this is an interesting wrinkle that requires some digging into master parts catalogs, master cross-reference books and Obsolete-Supersede-Interchange (OSI) volumes to see if part numbers show up for the 3rd-member housing and the drain plug, and in service bulletins to see if they make any mention of it. Looking into service bulletins/TSBs and websites dedicated to Ford 9-inch rear axles may yield some additional info, too. We also need to find the corresponding part numbers for the housings to determine when the larger hex-headed plug was introduced/used.

I did find illustrations in the '60-'64 "Blue Bible" that show a pipe plug with recessed square socket being used on Equalock differentials while open/conventional ones didn't. More info is needed from cars, through, to determine when the rear housing plugs were used.
60-up full/mid-size/compact + T-bird - non-locking rear axle - 9" Ring Gear w/ no rear plug (from 60-64 "Blue Bible")
60-up full/mid-size/compact + T-bird - non-locking rear axle - 9" Ring Gear w/ no rear plug (from 60-64 "Blue Bible")
60-up full/mid-size/compact + T-bird - Equalock rear axle - 9" Ring Gear w/ small pipe plug (from 60-64 "Blue Bible")
60-up full/mid-size/compact + T-bird - Equalock rear axle - 9" Ring Gear w/ small pipe plug (from 60-64 "Blue Bible")

And there is an illustration of a rear axle used on 427 full-size Fords with a larger hex-headed plug. This also shows up in the 1965-72 Lincoln-Mercury MPC illustrations.
63-up full-size 427 - DAPCO No-Spin rear axle - 9" Ring Gear w/ rear Hex plug (from 60-64 "Blue Bible")
63-up full-size 427 - DAPCO No-Spin rear axle - 9" Ring Gear w/ rear Hex plug (from 60-64 "Blue Bible")
70-72 Mid-size/Cougar - DAPCO No-Spin Rear Axle - 9" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)
70-72 Mid-size/Cougar - DAPCO No-Spin Rear Axle - 9" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)

While I don't have digital copies of the '65-'72 Ford Car MPC Illustrations sections, I do have them from the Lincoln-Mercury MPC (which pretty much tracks the same for these). There are some additional drawings showing the hex-head plugs on open- and Equalock-type axle housings:
65-69 full-size - Equalock - 9" Ring Gear w/ small pipe plug (from 65-72 L-M MPC)
65-69 full-size - Equalock - 9" Ring Gear w/ small pipe plug (from 65-72 L-M MPC)
68-70 Mid-Size/Cougar/Comet & 70-'72 full-size/Continental/Mk III - Traction-Lock 8"/9"/9-3/8" Ring Gear w/o drain plug (from Sec 40-p 7 65-72 L-M MPC)
68-70 Mid-Size/Cougar/Comet & 70-'72 full-size/Continental/Mk III - Traction-Lock 8"/9"/9-3/8" Ring Gear w/o drain plug (from Sec 40-p 7 65-72 L-M MPC)
65-72 full-size/Continental/Mk III - Open and Equalock Axle - 9-3/8" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)
65-72 full-size/Continental/Mk III - Open and Equalock Axle - 9-3/8" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)
65-72 Mid-Size/Cougar - Equalock & Open Rear - 8"/9" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)
65-72 Mid-Size/Cougar - Equalock & Open Rear - 8"/9" Ring Gear w/ rear Hex Plug (from 65-72 L-M MPC)

Another explanation may be that it's related to the 9-3/8" vs 9" ring gear/housing, which began to be used in '66 and was somewhat unique for use in the 'Birds and full-size cars with larger engines like the 428. Note that some of the '65-'72 L-M illustrations do list the 9-3/8" ring gear's usage.

Does this plug or procedure on how to refill the rear axle happen to show up in the '64, '65, '66 or '67 Thunderbird Shop Manuals?

And, can members take a few minutes to look under their cars, get a picture of their rear axle housings to show what they have plugs in theirs and post them along with the build date for their car and axle code off the data plate, plus tag numbers from their rear axles (which should be on the front side of the differential and held in place by one of the nuts for the center carrier)?
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
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RedBird64
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Re: Filler nut on differential

Post by RedBird64 »

Hello there Allen,
I have a reprint 64,65 FFM and this is the only image I can find - which isn't very conclusive but looks more to me like the square drive style:

Image

I guess since the fluid was "Lifetime", they figured there was no reason to go into any detail about changing it!

FWIW, my car has the square drive & the body plate says Date 18M, has no code for the diff but it's an "open" design. Panels are stamped 12 3 3.

Sorry but I'm a wimp and I'm not getting under there - it's too cold! ;-)
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
P47JUG
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Re: Filler nut on differential

Post by P47JUG »

All, My 65 TBIRD Landau, build date 9/22/6, has the pipe plug with 1/2 inch square indent.See pix below.
Merry Christmas & Happy New Year ! Charles Slack P47JUG Giddings, Texas.
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TBIRD DIFF IMG_8237.JPG
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Alan H. Tast
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Re: Filler nut on differential

Post by Alan H. Tast »

P47JUG wrote: Thu Dec 26, 2019 4:24 pm All, My 65 TBIRD Landau, build date 9/22/64, has the pipe plug with 1/2 inch square indent.See pix below.
Merry Christmas & Happy New Year ! Charles Slack P47JUG Giddings, Texas.
What's the axle code on your data plate? Is it a non-locking/open (number) or Equalock (letter) code? I assume build date is early, i.e. 9/22/64.
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
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redstangbob
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Re: Filler nut on differential

Post by redstangbob »

I have the same as p47jug, and a 65 SL I know has the same. 3.0:1 open
It's gonna be cool when it's done
And now it's really cool !!



59 convertible
58 convertible
65 hardtop
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