Rear Axle Hub Key
 

I'm assembling my rear hubs after taking them off to grease the wheel bearings. I wasn't paying much attention when I removed the keys, but now notice each one has a chamfered end.

What is the correct way to install the key on the axle? Where does the chamfered end belong: facing up or down; toward the end of the axle or toward the differential?? How far into the threads of the axle does the key extend? Pictures would be helpful.

Many thanks!

Re: Rear Axle Hub Key
 

I don't have a photo handy, but the chamfer faces out and up.

Tom Endy

Re: Rear Axle Hub Key
 

i had the same issue and tom.W helped me out with it. although i think they would work either way he mentioned that the chamfered side of the key should face the backing plate or inside and chamfer against the axle...
i had them facing out and up

Re: Rear Axle Hub Key
 

this is off the brattons site

Re: Rear Axle Hub Key
 

Mitch is correct, as you can see if you look closely, the keyway ends in a radius at the inboard end.

Re: Rear Axle Hub Key
 

Anyone for inboard and up?

Re: Rear Axle Hub Key
 

Re: Rear Axle Hub Key
 

You can crack a hub if you are not careful on this.
On every tapered axle I have ever worked on (tons over the years, all makes) I put the taper in and down, since the broached slot ends in a taper.
I only partly start the key, install the hub carefully, get the hub all the way on, and some of the key is still protruding. Then I put a small screwdriver on the key and gently tap it inboard until flush with the hub, allowing of course for the special 5/8 grease seal. This way I know exactly where that key is and I am satisfied that it is not inboard too far, 'cause if it is you won't be able to tighten the hub properly and also run the risk of splitting the hub when you go down the road.

I only wish Henry had made the threads 3/4 inch like all the other makes I work on instead of 5/8; 3/4 inch would have stood up better to all the torquing that goes on over the years. Lots of stripped 5/8 threads out there.

Anyway it works for me.

Re: Rear Axle Hub Key
 

Ok, thanks guys. I'm now noticing that the key length is shorter than the slot in the axle, so it's possible to insert the key and not have any of it extending into the threaded part of the axle end. Is this a problem?

Seems like the physics of the thing should work so that as the axle nut is tightened the washer pushes against the outboard end of the key to lock it into the hub as the inboard end of the key (with the taper) presses into and upward against the taper of the broached axle slot.

Re: Rear Axle Hub Key
 

"Seems like the physics of the thing should work so that as the axle nut is tightened the washer pushes against the outboard end of the key to lock it into the hub as the inboard end of the key (with the taper) presses into and upward against the taper of the broached axle slot. "

yes, and don't forget the special 5/8 grease seal, there is a recess machined into the hub to receive it. It somewhat resembles a garden hose rubber washer in size and shape

Re: Rear Axle Hub Key
 

Tbird: Gotcha! Thanks to all for the lesson!

Re: Rear Axle Hub Key
 

I do it like tbirdtbird does. Afordman31

Re: Rear Axle Hub Key
 

Make sure the axle end and hub are free of grease and oil,it must be assembled dry or the hub could ride up the tapered axle and split!

Re: Rear Axle Hub Key
 

Thanks Rocket! I'll be sure to clean the grease from the key and out of the keyway before reassembly. And just for future reference, anybody reading this thread can do a search using the term, "axle key" to find other interesting and informative tips on the subject..... Thanks Barners! :)

Mike

Re: Rear Axle Hub Key
 

free of grease is good; you actually want the tapered hub very tight on the tapered axle; it is the taper that grips. If the key is installed properly the hub cannot split. The foot-pound torque rating for the axle nuts is 90-100. Check'em once in a while, keep 'em tight

Re: Rear Axle Hub Key
 

I'd like to hear back from Tom Endy and see if he concurs with all the different opinions.

Tom is the author of the "Differential Bible" as far as I am concerned and I thank him for his many well researched articles and contributions to Model A owners.

Re: Rear Axle Hub Key
 

Tom is the best by far; I was surprised at his answer. But I work on many many different makes of vintage (and I mean old old vintage) vehicles and that is how I was taught by the old timers, many of whom are now passed.

Re: Rear Axle Hub Key
 

I have never removed a rear drum from a Model A and found the taper facing in and down. This morning the owner of a local Model A repair shop came to pick up a rear axle assembly I had just finished for him and I asked him how he installs the keys. He said he installs the keys with the taper up and out, but he grinds a small taper on the down and inboard side of the key to match where the axle tapers. He said that this prevents the key from riding up and jamming the drum. He also felt it was important that there be an up and out taper on the key to facilitate installation of the drum.

For my part I never knew there was any question how they installed. All I have ever seen are up and out and I installed them that way on any Model A I have ever worked on and never had difficulty.

What some have said here does make sense. Maybe grinding a separate taper makes sense.

Tom Endy

Re: Rear Axle Hub Key
 

As long as you have a method of not having the key jam the drum I doubt it makes any difference, since the taper is what does the real work.