'53 Customline - Diff Gear Swap

[fredeuce]

I have a Ford style differential that was equipped with a 39/10 gear set. (3.9:1)

I am attempting to fit a later gear set that is 29/9 (3.22:1 ) to this early housing. I have discovered it does not fit and requires some relieving to get it to fit.

Clearly, there are different castings for these differentials.

Has anyone encountered this before ?

Has anyone relieved the housing for this purpose?

Is there a way of identifying these castings externally?

[pistonbroke]

Yes the casting is different for the later freeway fliers but, the whole third member will bolt into the 53 axle housing. Tim

[petehoovie]

Originally Posted by fredeuce

I have a Ford style differential that was equipped with a 39/10 gear set. (3.9:1)

I am attempting to fit a later gear set that is 29/9 (3.22:1 ) to this early housing. I have discovered it does not fit and requires some relieving to get it to fit.

Clearly, there are different castings for these differentials.

Has anyone encountered this before ?

Has anyone relieved the housing for this purpose?

Is there a way of identifying these castings externally?

[Newc]

52/53 Wagons use a different diff also Newc

[fredeuce]

After some closer examination of casting shown in the original post I had a look at another complete unit to ascertain if there was any difference. This unit has a 41/11 (3.73) gear set. Looking inside where my pinion is fouling I can see the casting is different and provides a relief in the area where the 9 tooth pinion fouls. Externally the casting is different around the filler plug area. See pictures. I am going to explore this housing and see if it takes the 9 tooth pinion.

[tubman]

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Given the scarcity of these rear ends, could you please define the years covered by "early" and "late"?

[petehoovie]

Originally Posted by fredeuce

After some closer examination of casting shown in the original post I had a look at another complete unit to ascertain if there was any difference. This unit has a 41/11 (3.73) gear set. Looking inside where my pinion is fouling I can see the casting is different and provides a relief in the area where the 9 tooth pinion fouls. Externally the casting is different around the filler plug area. See pictures. I am going to explore this housing and see if it takes the 9 tooth pinion.

[pistonbroke]

I think they were used from 49 thru 56

[tubman]

Originally Posted by pistonbroke

I think they were used from 49 thru 56

I knew that, but what differentiates between "early" and "late"?

[fredeuce]

Originally Posted by tubman

I knew that, but what differentiates between "early" and "late"?

Generally speaking I think you can define early v late as Flathead powered v OHV powered however the use of an auto trans also determines the ratio used so the line between the two categories is a bit blurry.

[tubman]

Originally Posted by fredeuce

Generally speaking I think you can define early v late as Flathead powered v OHV powered however the use of an auto trans also determines the ratio used so the line between the two categories is a bit blurry.

Now I'm getting confused. Is this an "early/late" (e.g. '49-'53 vs. '54-'56) or a "carrier break" difference? ("Carrier break" is were you need a different carrier for high ratios vs. low ratios.) Anybody know for sure?

Just tryin' to add to my store of "shoebox knowledge".

[Gene1949]

Kinda off topic but related. I would mag [particle] the axles. I broke 2 of them, one on each side.
And no, my 16 year old self wasn't present.