I recently found (in a local farmers field) 2 ford 9 inch diffs, and I was able to get them both for $50. Now I am rebuilding them hoping to get one good one to use in my 52 M3.
They had both been lying there for a good 25 years so there is a lot of rusted nuts and bolts to deal with.
Needless to say all bearings will have to be replaced, and the pinion and ring need to be setup, this brings me to my question, does anyone know of or have a manual on a 9 inch diff, or specifically the torque specs required for rebuilding these units?

 

I have found you an answer, Ford 9 Inch Rebuild/Gear Setup .: Articles
All the information you should need

 

Excellent

That's why I love this site!

 

From my 64 Thunderbird FSM,

Differential Bearing Cap Bolts 70-85 ft. lbs
Differential bearing preload 2 1/2 to 3 notches tight
Diff bearing adjusting nut lock bolts 12-25
Ring gear bolts 65-80
minimum torque required to tighten pinion nut to obtain correct pinion bearing preload
175

This looks to be most of the important stuff. Hope this helps.

 

Are the gears themselves rusty?

 

Good point to emphasize....the information you are looking for would be in any Ford Car or Truck Shop Manual from the years where the 9" was installed. Best would probably be a late 60s early 70s (to 72) truck shop manual.

 

Surprisingly not, even though the pumpkin on one had a rust hole in it, there was still oil in one of them, and I will use the carrier from that one, it is also a 31 spline. The other is a 28 spline and had a little surface rust. I will be using the ring and pinion from it.

Thanks everyonr for the info

 

WHOA!

31 spline axleshafts: Some 1968/72 F100's with a 9" that has a 9 3/8" ring gear. ONLY five parts are the same as a 9 inch: Housing gasket, one pinion bearing & race, pinion seal and the retainer for the pilot bearing.

EVERYTHING else is different! All the specific 9 3/8" parts can be a real b!tch to find, as all are as obsolete as the dodo bird, and most autoparts stores (and FTE members!) are totally unaware this axle even existed.

Good luck finding axle seals for this puppy, not to mention the other parts. btw: Julie has one a these 9 3/8 inchers in her 1951 F1.
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31 spline axleshafts: Some 1973/79 F100/150's, all 1980/86 F100/150's. Since Ford increased the distance between the rear frame rails in 1973 to 37 1/2 inches, the axle housing is wider than was used on previous years.

Most people use the 1957/72 F100 9" in 1948/56 trucks because the housing is about the same width as the Dana 44. The rear frame rails of all 1957/72's are 33 1/2" apart.

9" F100 rear brake shoe width: 1957/67 F100 = 1 3/4" / 1968/83 F100 & 1975/86 F150 = 2 1/4"

And...You found these 9's in a field. How do you know they're even from an F100? They could be from a 1957/79 passenger car. The cars axle housing width will not be the same as any F100/150.

The 9" w/the 9 3/8" ring gear was also used in some 1966/73 passenger cars: Lincoln's, Continental Mark III's & IV's, some full sized Ford/Merc's and some Thunderbirds.

 

Rust hole in the pumpkin??? I know Ont has corrosion issues with road salt, but to rust thru the casting would require some ferocious "metal moths". I can't imagine ANYTHING being any good in that unit. You never want to swap a used ring and pinion into a different carrier. Even the best rear setup guy isn't likely to be able to match the existing wear pattern, so the rear will howl like a banshee until the gears fail. If you want a different gear ratio, either swap a complete carrier with the right gear ratio or replace the gears with a new set correctly set up. Setting up rear end gears is part science and a great deal of art/skill/experience, not to be taken lightly. If the axle needs any more rebuilding than new axle bearings and seals, IMHO junk it and find another.

 

...how kool......I gotta agree with NumberDummy on this one...

Check the width...flange-2-flange...axle bearing size as well as carrier bearing size...

...and above all else...DON'T believe "everything" you may find on "other"
websites regarding these rear ends......there are many "myths"
floating around started by "experts"...anyone can start a website these
days...

I found this out while trying to figure out "where/what" my Franken-Nine
originally came out of...

...the dude I bought it off of told me it was out of a '70 F100...then it
seemed it "may" have been a Galaxie/Torino rear 'cause of the "swedged"
area between the tubes & center section being shorter than the reported
longer ones that you hear were "supposedly" used in trucks......

...and it has 28-spline axles that were taperd about halfway down and I
was told they could NOT be resplined...






MY "truck" axles looked JUST like the ones on the left above...
...hhhmmmmmmm...

...LARGE axle bearings (3.15" ) , SMALL carrier bearings (2.891")
and it DOES have a drain plug on the carrier...



...the infamous C7AW case that was used "everywhere"...

Although I could NOT find the almighty "N" cast anywhere on this case I
gotta believe I have a high nodular iron case.

AND...it appears to have a Daytona pinion support and monster yoke...



And these are my new Dutchman 28-spline axles...I don't know what all
the big fuss is about monster spline count for a "street" style hotrod...



About $500 on my front porch complete...and I mean COMPLETE!

 

For what it's worth, I purchased a Differential Rebuilding CD from Techinical Videos.com (Part Number 16-1600) that covers all of the common rear ends and of course the 9".

It's really well done and the best part is that you and rewind as often as necessary to understand the rebuild.

 

What's the fail-safe method of avoiding these?Which years to use, I.D. numbers to use, etc.?

 

^ ^ The rear axle ID tag. The problem today is...many of these are missing. The Warranty Plate AXLE code also has the info, but because of swaps, who knows if the rear axle is the original...or not? ^ ^

F100/150 axleshafts are the same right/left. This is NOT the case with passenger car 9's.

 

Excellent point Bill!

I was thinking about my 9 3/8 when I recommended the late 60s early 70s truck shop manual for diagrams and specs because my manual has both 9" and 9 3/8" stuff in it. I guess I just slipped on mentioning that.

I believe (and please correct me if I'm wrong) but the only way to tell in the field (unless you find the ID tag and have th etag tables with you) is that the car rear ends have a 4 1/2 x 5 bolt pattern and the trucks a 5 1/2 x 5 bolt pattern.

If you want to know quickly, the main external visial difference between a 9" and a 9 3/8," look at the front housing ridges. The top right hand corner on the 9 3/8 is curved downward the regular 9" does not have this curve.





Note my 9 3/8 doesn't have the plug either. Mine is out of a '66-'70 "Big" Ford/Merc Car (WDT-F).

 

inre to 9 inch rear axles: 1957/79 F100's & 1975/86 F150's: 5 lug, 5.50" bolt circle pattern.

Some 1980/83 F100's have a 5 lug 5.50" bolt circle pattern, some have a 5 lug 4.50" bolt circle pattern. 4.50" Passenger Car wheels will not fit these F100's, because they will not clear the trucks calipers.

I knew about the ridge on the 9 3/8" being different on the pumpkin (carrier) from the 9 inch, but trying to describe same without posting pics is difficult and can be confusing.

Picturing the puppy is the way to go...thanks for doing this!

I dunno how to post pics (and parts catalog illustrations) and I do NOT wanna know! I'm besieged enough as it is.