Is this a Model A rear axle?
- Thread starter Ziggster
- Start date
updraught
Well-known member
It's had both its balls cut off, so it might might have hydraulic brakes.
By 1930 you could replace your balls when worn out?
Joe K
Well-known member
Look to where the radius rods attach to the inside of the backing plates. If the "Y" at this location is forged (with reinforcing rib between the two attachments) then its 28-29, likely a 29. (28s frequently had the "single brake" system which have an "L" shaped end to the radius rod.)
If the attachment is done by a strap of metal doubled back on itself and the fold portion welded into the radius rod, then its a 30-31.
There was a short while during the change-over when Ford used up available stock making the 28-29 pattern stretch out into 1930.
There were some other differences between 28-29 and 30-31 relating to the location of the welded seam of the axle housing, but these are even more variable and probably paid less attention to.
Functionally, all "Model A" rear axles beyond single brake are the same. You can swap one for the other without concern. You may find a 4:11 ratio axle which might have been used on a pickup truck or station wagon. Most cars were 3:78. And, of course some have been retrofitted into 3:54 or even 3:27
Joe K
If the attachment is done by a strap of metal doubled back on itself and the fold portion welded into the radius rod, then its a 30-31.
There was a short while during the change-over when Ford used up available stock making the 28-29 pattern stretch out into 1930.
There were some other differences between 28-29 and 30-31 relating to the location of the welded seam of the axle housing, but these are even more variable and probably paid less attention to.
Functionally, all "Model A" rear axles beyond single brake are the same. You can swap one for the other without concern. You may find a 4:11 ratio axle which might have been used on a pickup truck or station wagon. Most cars were 3:78. And, of course some have been retrofitted into 3:54 or even 3:27
Joe K
1930artdeco
Well-known member
What is up with the lack of drums? You are going to have a hard time stopping with them.
Mike
Mike
Joe K
Well-known member
The only thing I can think is that the axle had been planned for a conversion to the 1932-36 braking system. Those drums are two-piece with a pressed steel center and a cast iron wear surface. I'm not aware that these could be "renewed" by exchange of the cast iron only.
We can't really see the backing plates but that might lend credence to the modification.
For a while I had planned an "upgrade" of Avatar to the hydraulic late 30s brakes. The dealers even sold a "kit" of sorts which included spacer rings, and a paper outlining where and how to modify the backing plate "holes" to make the bolts line up with the Model A axle housing. Also modify the backing plate to accept the interference with the Model A spring perch.
I did the mods - but when I was done it came to me how much of the backing plate I had removed - and how little was actually holding it. And I deferred on the substitution.
It also came to me that the pre-1947 Ford hydraulic brakes were not "self-adjusting" and would require periodic balancing and adjustment of a hydraulic kind. Not like a modern car does all this automatically.
It may stop better - but cast iron drums make that possible. And those now can be bought from Randy Gross all prepared for the Model A.
Joe K
rotorwrench
Well-known member
Model As have the top mounted spring. The model B changed all that but they are similar. Model As have the same axle shafts, carrier, center section, and bells. The early ones have different driveshafts & pinions. The early brake set up was already mentioned. Later one had separate E-brakes in the back.
I was just going to stick with mechanical brakes with my speedster build, but then decided to go with full hydraulic and self-adjusting. I recall watching some vids where folks said the earlier hydraulic brakes weren’t much better in terms of stopping than the mechanical setup. Got my loaded backing plates from Speedway, and they’re all warped. Not good.
https://youtube.com/shorts/YDmP_GSfD-o?feature=shared
I asked the seller about that and he never replied. Also asked him about the condition of the bearing hubs and told me I could come down if J wanted and have a look. Wasn’t going to drive over an hour one way just to see. Not sure what is wrong with folks if you’re trying to sell something and can’t be bothered to answer a few questions or do some checking for potential buyers.
