Technical Shoebox and mid 50s Ford axle interchangeability

Hi,
I'm currently trying to overhaul my '49 Ford Tudor Sedan stock rear end.
I would like to know how interchangeable the differential parts are from 49 onwards.
Specifically the diff carrier unit, differential gears and ring and pinion sets.
NOS Internal parts for these axles are pretty hard to come by so it would be helpful if I knew I could fit parts for later cars and not just up to '51.
Can anyone help me with this information?

 

I usually drain those, and then transplant them directly into the metals recycling bin.

They are not particularly strong, and neither are the ones made in the next revision, and, as you have noticed, the parts are not exactly easy to acquire.

 

IIRC there are some internal differences between the years '49-56, but the complete pumpkin assemblies swap. But even parts for the later units are hard to get; I'd swap in a later rear and eliminate the problem.

 

Thanks folks for those really quick replies.
The reason I asked was that some NOS ring an pinion sets have appeared for 51-55 axles and I wondered if they would fit.
The car is bone stock and I'm trying to keep it that way if possible.

 

like you noted - these ring and pinions pretty much from 49 to 56 interchange....57 FoMoCo went with the 9" rear end....lots should be available - the T-Bird's 55/57 are mostly kept stock and parts are available for them.....good luck keeping it stock...I do well with my Studebakers.....that little Dana 44 was still be installed in mail Jeeps for a long time......
'

 

Thanks for that.
When you say 'pretty much interchange', and Steve also referred to some internal differences - do you know what those differences are?
I wondered if is is safe to assume that if the pumpkin assembly is a straight swap from 49 to 56 then things like the pinion bearing sizes and pinion length would be the same and also that the diff carrier and therefore differential gears and the ring gear would be the same.
I am aware that even within the 49-51 range there are differences in the spacer on the pinion but the pinion itself has the same dimensions.
Do you know if the only internal differences would be relating to the pinion spacer?

 

Nope, that's not safe to assume. The fact that you're finding ring and pinion sets listed for '51-56 (but not '49-50) tells me that there's enough internal difference to preclude interchange. It's been years since I messed with these, but the guy I dealt with in those days for OD trans rebuilds told me the early rears had issues that Ford addressed in later years with upgraded parts but still didn't get the results they wanted, so the 9" was designed. The Dana that Ford used for the 'heavy duty' applications then wasn't a Dana 44 either; it was a Dana 42 which while very similar to the 44, has little interchange with the 44 and is another orphan as far as parts are concerned.

 

If you have to put in a later rear, look at Ranger or early Explorer rears. Cheap, 56 to 60" wide 4.5" pattern.

 

and the station wagon rear is a whole 'nother ball of wax. not real strong, geared low, hard to find parts and a "spreader" tool is needed to get the gearset out.

 

Thanks all,
It's much appreciated.

 

Just thought I'd update this thread now that I've done a bit more work and the rear end is back together!
It might just be useful for someone else down the line although in the US I think you have a better chance at locating one of the narrower 8 or 9 inch axles and I can see that would be a preferable swap for many.

Here's my story though:

I went back and hit the books and purchased a collection of bits.
First as few facts:
1 - The differential carrier is the same part from 49 to 56, and so is the differential case.
2 - I was aware from my 49-51 shop manual that the drive pinion was changed in late 49 - this change was in the method of adjustment - early - shims placed between the rear bearing cup and diff carrier - late - shims placed on the drive pinion itself behind the bearing. Shop manual states that early and late pinions are interchangeable.
3 - Differential spider gears are sold as 51-56 but my shop manual is silent about the differences and interchangeability.
4 - Gear sets - ring and pinon are also sold as 51-56.

So - I figured that since the diff carrier and diff case are the same part then the internal diff spider gears would have to fit despite any differences to earlier models. Also, since they don't interact with any other parts other than the axle shafts, they should work.
The ring gear would have to be the same in terms of fitting since the case is the same throughout 49-56. I assumed then that the drive pinion would be the same dimensionally throughout the period 49-56.

As luck would have it some new old stock parts turned up on ebay (always amazes me that!): Spider gears for 51-56 and also a gear set - ring and pinion with shims for 51-56.

So I took the risk, purchased the parts and examined them.
The spider side gears are slightly different - deeper gears on the later ones but since they have to fit the same case, the thrust washers are thinner to compensate. They all went in fine.

Ring gear fitted fine, unsurprisingly.

The pinion, as I expected, had the later adjustment method but the bearing journals, splines etc were exactly the same as the early pinion but the bearing spacer was different as the pinion shaft was a slightly different profile - different taper between the front and rear bearing journal. That was fine though since all the later parts go in as a complete unit.

The only slight pain was that I had to take a guess at the shim thickness in order to fit and measure the pinion depth. I didn't get it right first time so had to pull the bearing and replace with a thicker one.

That was it - all back together and on the road - drives as it should - huge relief!

I appreciate that most folk would swap out to an 8 or 9 inch but in the UK there just is not that stock of axles available and so I would have been looking at narrowing an axle. And since this is a restoration I was very reluctant to do that. Sensible if I was changing the engine etc but I'm not. This thing is on its stock flathead and crossply tyres so it will never get stressed.

Thanks again to everyone who responded to my original post.

 

Thanks for all the work you've done and then getting back to us. Information like this is hard to find and good to have.

 

Thanks for that - I'm happy to provide it. It's all for the cause and knowledge is power after all.

 

This thread is mess. The OP comes on a hotrod forum and says hes going to restore the car, then he posts under custom cars

 

What caliber was the gun held to your head while being forced to read this thread?

 

9mm

 

Glad we got that settled.