MTFCA Forum

Greetings everyone,
on my car, on the rear axle there is a washer on each side between the axle shaft nut and the rear wheel hub. I had always assumed they belong there, however I can't find any reference to them in the service manual and I haven't found anything searching the forums.
Without them, hub and nut would be too far inboard for the cotter pin hole and the castle nut to line up, so my fear is someone put them on to mask worn hubs / axle shafts...
Do you think I'm on the right track with that thought? Or maybe I'm overthinking things...?

Regards
Frank

Yes you correctly identified what is going on. If the hub is tight on the axle and there is no rubbing on the inside of the hub or brake drum you are fine, there is no problem to be concerned about.

Looks like some sort of external accessory brake also, so maybe it was needed for that? Otherwise, if the hub/axle was or is that worn I'm betting there's almost gotta be a shim in there too.

The wheels turn freely, no rubbing that I am aware of, and the stock handbrake works well. And yes, the car has a "Stronghold" auxiliary brake, which was apparently sold by Montgomery Ward and is very similar to the AC brakes. I guess it's possible that someone modified the hub to install those.
Well, I'll order the rear axle book, take the wheels off & do some careful inspecting and measuring...
Thanks for your help!

Frank

frank_w wrote: ↑

Fri Dec 29, 2023 9:29 am

The wheels turn freely, no rubbing that I am aware of, and the stock handbrake works well. And yes, the car has a "Stronghold" auxiliary brake, which was apparently sold by Montgomery Ward and is very similar to the AC brakes. I guess it's possible that someone modified the hub to install those.
Well, I'll order the rear axle book, take the wheels off & do some careful inspecting and measuring...
Thanks for your help!

Frank

Ur welcome, and since it appears you've not yet had the wheels off yet, again I'm betting you'll see some shims in there. Let us know and good luck Frank! I hear the weather in Germany aint been so good lately. Sorry.

To my shame, I have to admit I indeed didn't have the rear wheels off yet. (I'm still pretty new to the game.) But, I checked the axle shaft nuts for thightness regularly, so I knew these washers were there, but it didn't occur to me they don't belong there until recently. I'll wait for the book to arrive & will report my findings
Concerning the weather, we're having our share of floods at the moment... though most of it is up north and in the east, its not so bad in this part of the country. Would actually be warm and nice enough to go for a ride, if it wasn't for the all the salt on the roads.

Frank - it is good you frequently check axle nut tightness. Loose nuts are the number one cause of axle failure. When you check them, remember they need to be really tight - 90 ft-lbs (122 n-m) or so.

This is a subject I have long wanted to discuss. Earlier this year, I went through 16 rear wire wheel hubs to determine how they fit on the axle and why some people are using shims. I used a new axle shaft in my vise for testing. I numbered the hubs and documented the thread length protruding from each one. I found that most of them wiggled and did not go on as deep as they could. I used a coarse round file to "glide" on the inside taper to identify and remove anything protruding from the factory machining. I found burrs at the keyway, various lumps from galling, and most of all, a choking where the nut rides. That is evidenced by a dimpling of the hub face where the nut runs. I removed the all constrictions and found the hubs each went on to the same depth, fit snug and without wiggle.
This month, I disassembled over 60 rear wood spoke hubs and am now doing the same process on them. So far, I am finding the same thing. Now I am wondering if for many years, the need for a shim was partly misunderstood because of what I discovered and corrected on the hubs? I think a washer may circumvent this problem.

Washers are not a good thing unless they are hardened. They will creep over time which effectively reduces the thickness. So, you end up with loose axle nuts. I know because my car was fitted with washers to make the castellations line up. Needless to say I removed the washers when I realised what was going on. Use different nuts to get the castellations to line up. Washers and shims are probably one of the worst things you can fit to the axle. Shims are undesirable also because they break the tapered join between axle and hub.

Every Model A made had washers installed from the factory between the nut and hub. If you are worried about hardness, use them. The torque on the axle nut is the same.

Ok, I finally got around to taking the wheel off... first of all, no shims in there! But, the key was put in the wrong way: deformed key: I suppose that was what spread and cracked the hub: tapered portion of the the axle shaft.... looks... kind of ok I think..? I don't have the axle book yet, but found a drawing that states the diameter of the axle shaft before the threaded part begins at 3/4". I measured it and found it to be 0.03 undersize. The taper is even, without worn spots as far as I can tell.
So, I suppose it is time for new hubs? Also, I'm kind of concerned about the axle shafts. With the key deformed that way, it must have put a lot of pressure on the axle...

Well the key is definitely junk. That's the easy part. Re the hub crack, unless I'm missing something, I can't see a crack in the picture. But the keyWAY in the hub looks to be "spread open" somewhat, making it junk. And if the keyway on the axle allows the key to "floppity flop" the least little bit, so is that axle. I subscribe to an age old axiom: "When in doubt, throw it out". Just an opinion, you'll get far more from here and maybe even better thoughts and ideas and expertise than me.

A washer is useful when you have tightened the nut and the split pin hole doesn't line up with the nut castellations.

Tim, there are two hairline cracks in the raised center part of the hub, going out from the square corners of the keyway at 45 degree angles. Concerning your comment about the axles, that is pretty much what I've been thinking... but, I don't have any experience with rebuilding rear axles. So, I fear I'l need to get some outside help for that...

Chris, I agree that would be one reason, but the washers in there were really thick. My guess is they were put there because when the wheel was on tight, the castellations on the nut were too far inboard for the cotter pin to engage them.

Are there any other Model T owners in your location or nearby? If so, they might know of a source of T parts in the area. Otherwise, they will need to be imported which would be expensive. I would suggest that you get the book on Rear Axle and follow it step by step to see what else might need replacement or repair. The parts you show look very worn and looks like the hub might have been crooked with the nuts on one side scraping something inside the wheel. I can see that you will need to at least replace your axle shafts and also the hub. Your wheel bearings might also be worn out and need to be replaced. I wish we lived closer, but too far for an old man like me to make the trip.
Norm

frank_w wrote: ↑

Thu Jan 04, 2024 11:37 am

Tim, there are two hairline cracks in the raised center part of the hub, going out from the square corners of the keyway at 45 degree angles. Concerning your comment about the axles, that is pretty much what I've been thinking... but, I don't have any experience with rebuilding rear axles. So, I fear I'l need to get some outside help for that...

Chris, I agree that would be one reason, but the washers in there were really thick. My guess is they were put there because when the wheel was on tight, the castellations on the nut were too far inboard for the cotter pin to engage them.

Frank don't let rebuilding..actually it's replacing..the rear axles dissuade you. Do note I used plural. Do them both while you have the rear end all apart. It ain't difficult. I did it on my former '15 with no problems with not even "the book" but I do recommend getting the rear axle book. I think it's orange. Getting the gears off the old axles is the hardest part and will require a good machine shops STRONG press! Mine needed a 60 ton press to get them off! Previously a fella did my very first rear axle job and those almost turned his 20 ton press into a pretzel!

But again it's not a bad job. You can do it.
Plan on replacing the inner sleeves too, whether they need it or not in my book..this will also give you a chance to thoroughly check the differential guts and I'm willing to bet there's babbitt thrust washers that need to be replaced with bronze anyway. Good luck and enjoy the ride!

I'm less inclined to think that the axles are junk. I do however question the lines/marks I'm seeing in the one photo. These areas are the classic spots for cracks to occur. Look very carefully in these areas. Also, as others have mentioned, be sure that the keys still seat reasonably well in the axle keyways.

The small cracks in the hub do not worry me. They are likely only present at the end of the taper, where the improperly installed key stretched the end of the keyway out. If everything is installed correctly, that area should see little stress and the cracks should not propagate. That said, the keyway also looks stretched open. If that's the case all the way through the hub, then yes, it's junk... Also, you have to check for a worn taper, also meaning it's junk.

If the castellations do not line up to insert the split pin, All you need to do is dress a little off the back of the nut with a good file. That way it will go on just a tad further to line up with the hole. Washer now redundant.

Allan from down under.

First of all, thanks a lot for your feedback & advice!

Frank don't let rebuilding..actually it's replacing..the rear axles dissuade you. Do note I used plural. Do them both while you have the rear end all apart.

That is what I'm planning to do - I haven't had the other rear wheel off yet, can't access it the way the car is parked now - but I suppose it will be the same or similar since it has the same washer under the nut. And since it looks like I'll have to disassemble the whole thing, I won't cut any corners & do it right the first time, so that I won't have to worry about it in the future. Concerning babbitt thrust washers - the last owner assured me that the rear axle had been gone over and the thrust washers replaced. That was one of the reasons why I hadn't bothered to take a closer look at the rear axle before. I should have known better...
The axle book is on its way. In the meantime, searching the forum has turned up lots rear end threads. Lots of good info, including a handy parts checklist.

The small cracks in the hub do not worry me. They are likely only present at the end of the taper, where the improperly installed key stretched the end of the keyway out. If everything is installed correctly, that area should see little stress and the cracks should not propagate. That said, the keyway also looks stretched open. If that's the case all the way through the hub, then yes, it's junk... Also, you have to check for a worn taper, also meaning it's junk.

Wow, you have good eyes! At the position you marked, the keyway in the axle is indeed spread open by 0.015. The rest measures at 1/4".