LOL. .....I'm a gearhead. It's what I do.

 

Yeah! Finally, the dirty little pig's out.

 

Visual difference between a common C7AW-E 9-inch 3rd member (on the left) compared to a Daytona N-case 9-inch 3rd member (on the right).



Looking at the mounting bolt holes around the perimeter, just inward from the 9:00 o'clock, 3:00 o'clock and 4:00 o'clock positions, you'll notice there are depressions on the face of the C7AW 3rd member casting that the N-case doesn't have. The N-case casting is solid in these areas.

The C7AW casting has (3) horizontal ribs running across the face and (1) vertical rib running up the face of the casting. The N-case has (4) horizontal ribs and (2) vertical ribs.

If you look at the driving pinion housing --the area with the (5) bolts, just behind the driving pinion/U-joint flange, you'll notice the driving pinion housing of the C7AW casting has raised bosses under each of the (5) bolts. The Daytona driving pinion housing has a consistent 3/8" thickness all the way around, is smooth, and doesn't have the raised bosses under the bolts.

The Daytona version of the N-case has much larger driving pinion bearings than the regular production C7AW casting or the non-Daytona version N-case.

Notice the driving pinion housing on my non-Daytona N-case. Looks just like the regular C7AW's.



I'm not exactly certain when the N-case first went into production --possibly in the '62-'63 Galaxies (??) but, early N-cases didn't come with the large "N" cast onto the face between the ribs of '69 and earlier versions. The earliest versions also had very large differential side bearings (3.063" compared to 2.892" for later models). Casting numbers for the early N-cases were C2AW-A and C4AW-B --the 3rd member has to be pulled out of the rear end housing to see the casting numbers. The casting number is on the inside of the case. The "N" wasn't added onto the front of the N-case 3rd member castings until 1970 (and up).

My non-Daytona N-case came from a 1974 Dentside 2WD pickup. It came with a 3.70 ratio on a single track (open) differential. It's casting number is: D0OW-B.

My Daytona N-case came from a 1975 Ford F150 4x4 and has a Traction-Lok and 3.50 gears. It's casting number is also: D0OW-B. The main component difference between my two N-cases is the driving pinion support --one is much stronger than the other.

The factory 9-inch N-case is the ultimate in strength of the entire 9-inch 3rd member line.

 

2X on that HIO... Ultra is over the top. but I love it, and benchmark his work...

Baja

 

I got the old gear oil cleaned out of the housing sump. I chased the housing-to-3rd member studs with a 3/8"-24 die, wiped out the housing with acetone and also cleaned the mounting flange and studs with acetone.



A thin layer of Permatex Ultra Black RTV on the mounting flange.



Fel-Pro RDS 55074 gasket installed.



A thin layer of Permatex Ultra Black RTV applied to the gasket with a little extra dose around the base of the studs.



"Going up?" N-case being positioned into place with the floor jack, to slide the 3rd member over into the housing.



....and it's in there!





This weekends objective was to remove the stock 28-spline axles, axle seals and the stock C7AW 3rd member and install new axle seals for the 31-spline axles and get the N-case 3rd member installed. Looks like it's mission accomplished.

 

Over the top Ultra, over the top. Its a nice feeling though, to know that it is done right, and perhaps, with more care and detail that you could have paid someone else for. I love it, when the inside of stuff is "NASA" clean. For 35 years I worked with Nuclear Power, and refueled reactors. You are definitely Nuclear grade amigo..

Baja

 

I appreciate that, Baja.

I've just always been very particular about how I do stuff. I don't like do-overs and I have specific reasons of why I do things like I do.

That doesn't mean everything I do goes flawlessly or like I had planned but, it's not from a lack of trying to get it right --the first time around.

Anything worth doing is worth the extra time and effort put into it, to get a quality result.

However, I'm human just like everyone else and I don't own a Super Man suit complete with cape and, I'm not infallible.

 

Is that yoke flange nut not torqued down yet?

 

Ahhh, very observant there, weed hopper.

The N-case had a 1310 flange on it but, it didn't have the deflector on it to protect the pinion seal from flying debris.

I had a couple of 1330 flanges lying around so, I cleaned one of them up, removed the deflectorless 1310 flange and replaced it with the larger 1330 version.

The current drive shaft U-joint has the 1310 width along both crosses. I initially intended to remove that U-joint and get a hybrid U-joint --one that was 1310 on one cross for the drive shaft end and 1330 on the other cross for the flange on the N-case.

However, I've decided I don't want to have to take the drive shaft out and change U-joints. I've changed enough stuff lately and I don't want more added expense of a hybrid U-joint and fooling with changing it out. --I'm ready to get done with my projects and get the truck back on the road for some quality drive time.

I'm going to take the 1310 flange off the C7AW 3rd member I just pulled and put it on the N-case. This way, the drive shaft will connect right up and will be easier and simpler than swapping out U-joints.

 

3X Hio and Baja. I think Steve has the intelligence of a Brain Surgeon and the personality of a Gear Head.

 

My axle bearings arrived in the mail today. I took them out of their Ford logo boxes and slid one of the bearings onto one of the 31-spline axles, in preparation to press it on.

However, when I slid the bearing on, this is the sound I heard. (Go ahead. Click on the following link and then press the "Play" button and you too will hear the very same sound that I heard).

Sad Trombone

 

Dang. What does the bearing surface on the axles mic out at?

 

I put my caliper on the O.D. of the axle bearing journal and then I put the caliper on the I.D. of the bearing and the caliper said, "The I.D. of the bearing is exactly too damn big."

The 31-spline axle journal is about 1-17/32" (1.5313"). The I.D. of the bearing is about 1-5/8" (1.6250").

--I say, "ABOUT" because the battery in my calipers seems to have given up the ghost. I just had to put the caliper on the items and then measure the distance of the caliper points on a tape measure.

There seems to be forces in the universe conspiring against me at this particular moment in my existence, in keeping me from reaching completion of the tasks at hand on my truck. --I may have lost this particular battle but, the war ain't over yet.

 

Hence the name Ultra... nes pah?

 

Sometimes it's like that on these big government jobs. I THOUGHT the D0TZ-1225-A bearing was the right bearing for these 31-spline axles but, it turns out they're not. --they're just a bit too big on the I.D. for the O.D. of the axle journal.

However, I DO KNOW that a BCA 88128 YYN bearing will fit, since that's what was stamped on one of the bearings I had removed from one of the axles.