Most Popular "78" Transmission Case?

[Fred A]

Over the years I've heard so many opinions about which variant (recently learned cool word) is the strongest. Beyond the mythology that comes with old Fords, I'm putting together a few in each desirable gearset. This is to be a best of the best. There must be at least four types that I can think of without comparing stock. Any favorites? Thanks: Fred A

[Tim Ayers]

So I've learned something new over the past year. The back portion of the #78 cases have two different dimensions. The "shorter" of the two is approx. 1.5" shorter and is best to use when using a #78 case with a '32 K member.

I've always read and been told that a full bottom rib, #78 case is the best case. Full rib cases are getting tough to find.

I'm really curious to hear what others say about this; especially our resident guru MacVP.

I would think any #48/#78 case that still has good thrust bearing surfaces is a good starting point.

[pistonbroke]

The #78 case with the full length rib is a thicker casting but I'm not a engineer, to say it's the best is for someone with more knowledge then I. Tim

[JM 35 Sedan]

The #78 case with open drive rear bearing retention parts that I just recently built for use in a 50/51 Ford pickup has a slightly deeper area that will accept a 29 tooth cluster, when compared to the #48 case. It does have a thicker area cast along the outside bottom of case. I'm not sure how much stronger this feature provides in a #78 case. I think with enough hot rodding abuse, I could put the cluster thru the bottom of the case as easily as I could on any of the earlier cases, jmho.

[Fred A]

After reading Tim's response, I dashed out to the chicken house and measured my V8 and B cases overall. The B cases, always longer, are 14 5/16" overall. My V8 cases ranging from a '33 numbered, Model 18, to a 48, some long rib 78s to late postwar pickup numberless all measured 11 5/8 overall. Didn't find any different in my stash.
The 29 tooth cluster issue is not the only limitation early on, as the later cases could clear larger and larger clutches. Fun stuff eh? Good Luck: Fred A

[JM 35 Sedan]

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Originally Posted by Fred A

After reading Tim's response, I dashed out to the chicken house and measured my V8 and B cases overall. The B cases, always longer, are 14 5/16" overall. My V8 cases ranging from a '33 numbered, Model 18, to a 48, some long rib 78s to late postwar pickup numberless all measured 11 5/8 overall. Didn't find any different in my stash.
The 29 tooth cluster issue is not the only limitation early on, as the later cases could clear larger and larger clutches. Fun stuff eh? Good Luck: Fred A

The 48 cases will also clear up to an 11" clutch but it is somewhat of a challenge getting the 29 tooth cluster into a 48 case.

[Tim Ayers]

I'll measure and take a few picts of the portion of the #78 cases I have to show the area I'm taking about. It only may be an issue when transplanting into a '32 K member.

To be clear, all #78 cases will work with a '32 K, but the more shallow ones work better.

[Juergen]

I don't know how one measures strength, but it is easy to measure weight. I initially thought that later trans would weigh more due to bigger clutch areas, deeper valleys to accommodate larger gears etc. Here is what I measured: 18- case 25.7 lbs; 48-case 24.55 lbs; 78-case with 48 emboss 23.04 lbs; later 78- case (deep for 29 tooth cluster) 26.95 lbs and post war (pickup with big bussle)28.6 lbs. The only cases I found that were broken had a crack through the input bearing area.

[transbytip]

The full length webblng on bottom arent all 78 cases i had a 100 percent stock 36 that had the full lengrh webbing with the serial no. of car on the case it was the 48 case.I have a full webing case if inst.e-mail [email protected] Cliff

[Tim Ayers]

Originally Posted by transbytip

The full length webblng on bottom arent all 78 cases i had a 100 percent stock 36 that had the full lengrh webbing with the serial no. of car on the case it was the 48 case.I have a full webing case if inst.e-mail [email protected] Cliff

That is correct. I have a full length rib #48 case as well.

[JM 35 Sedan]

Originally Posted by transbytip

The full length webblng on bottom arent all 78 cases i had a 100 percent stock 36 that had the full lengrh webbing with the serial no. of car on the case it was the 48 case.I have a full webing case if inst.e-mail [email protected] Cliff

Originally Posted by Tim Ayers

That is correct. I have a full length rib #48 case as well.

Some of these feature differences can be attributed to Ford using different manufacturers to supply the same castings.

[Fred A]

One could ask if ford needed different manufacturers for a design with similar if not exact matters of part's fit from '37 to '51. Many of the differences could be caused by subtle strength and economy considerations. The latest 78 cases in some ways resemble the evolution of the side shift cases of the same years. Good luck: Fred A

[rotorwrench]

Any 78 case that passes dimensionally checks and has no cracks is good in my book. This is a light duty design so differences in castings likely don't make that much difference in strength.

The late LaSalle 3-speed was what folks looked for if they wanted more strength back in the day.

[jimvette59]

I have a Lincoln 48 case with the full length webbing. This Lincoln case is perfect inside and out. I also have a 78 case with a short webbing. I didn't check the others I have.