Axle keyhole too wide

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Posts: 255
Joined: Tue Jan 22, 2019 8:16 am
First Name: Richard
Last Name: Gould
Location: Folsom, CA

Axle keyhole too wide

Post by rgould1910 » Tue Oct 22, 2019 10:58 pm

I purchased a new rear axle from the supplier in Texas about 7 years ago. It was the axle that is machined the entire length. I needed that feature because it was to be used in a Perfecto. Now that the Perfect is in the car and I am installing the hubs, I see the keyway is too wide. It measures .256". The key measures .248" wide. What do folks do , if anything, to get a better fit. The axle on the other side was recently purchased from Langs and the key is a light press fit requiring tapping with a small hammer to seat.

Posts: 2699
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
Location: Clark, WY
Board Member Since: 2005

Re: Able keyhole too wide

Post by Scott_Conger » Tue Oct 22, 2019 11:16 pm

If you are unable to make a key for yourself, call these folks and see what they can do for you regarding an oversize/stepped key: ... 201%2F4%22
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!

Posts: 1312
Joined: Sun Jan 06, 2019 7:21 pm
First Name: Allan
Last Name: Bennett
Location: Gawler, Australia

Re: Able keyhole too wide

Post by Allan » Wed Oct 23, 2019 7:18 am

Hayes wire wheels are notorious for flogging out the keyway in the hub. Before I came up with a way to machine them out and replace the centre with a good section from a Ford hub, I had custom made keys milled. We began with 3/8" keystock, milled them to 1/4" on one dimension and then milled the width to that of the hub keyway. Depending on the width of that keyway, that section which fitted into the axle keyway was milled from either side, so the key ended up being a stubby T section.
In your application that stubby T would be upside down, but seeing you only need an extra .006-008" it could be milled on just on side.
Hope this helps.
Allan from down under.

Posts: 611
Joined: Sun Jan 06, 2019 11:57 am
First Name: Adam
Last Name: Doleshal
Location: Wisconsin
MTFCA Number: 23809
MTFCI Number: 1
Board Member Since: 2000

Re: Able keyhole too wide

Post by Adam » Wed Oct 23, 2019 11:13 am

In other bad news, I remember inspecting and rejecting some supposedly “Texas” axle shafts a customer wanted me to install several years ago. They were fully machined from one end to the other, the bearing surfaces were not ground or polished (the lathe turning marks were quite visible), and they were way too soft. A hardness check showed about Rc25 and they should be Rc50. The bearing surfaces were too soft and too rough to be acceptable. My opinion is they likely wouldn’t have lasted very long before the bearing surfaces deteriorated beyond their useable limits. Maybe only a few thousand miles.

Topic author
Posts: 255
Joined: Tue Jan 22, 2019 8:16 am
First Name: Richard
Last Name: Gould
Location: Folsom, CA

Re: Axle keyhole too wide

Post by rgould1910 » Wed Oct 23, 2019 11:36 am

Thanks for the information, fellas. I'll put it to good use. Adam, I hear you loud and clear. I remember the flack about these axels a few years back. I am hoping the one I have will hold up. If not I am looking at a Perfecto tear down and axle replacement. My tooling is not accurate enough to machine a bearing surface for the third axel bearing used on the Perfecto side so I'll have to rely on a third party to do the work. Not an encouraging thought.

User avatar

George Mills
Posts: 167
Joined: Sun Jan 06, 2019 12:32 pm
First Name: George
Last Name: Mills
Location: Cherry Hill NJ/Anona Largo FL
MTFCA Number: 29497
MTFCI Number: 10032
Board Member Since: 1999

Re: Axle keyhole too wide

Post by George Mills » Wed Oct 23, 2019 2:41 pm

I think I'd resort to a custom key at this point. (Anyone ever heard of file-to-fit? :roll: Only kidding)

FWIW, back in the day before standards existed the general accepted shop practice was to make a 1/4" key at 1/4 FULL which went on to mean 0.251/0.250 in those companies that stayed in the replacement parts business...

Today that is an oversized key...but not then.

The shaft and arbor in generally acceptable shop practice was to mill at 0.249/0.250...

In the era it WAS an expected metal-to-metal to slight force fit as part of the inherent way to design and manufacture things requiring keys. (If it got dicey as to load expectation and load shock, the general common practice was to go to a gib head key arrangement.)

Oh, and when it came to material for the keystock? A medium carbon steel that would have had a tensile yield of greater than 65,000 psi ( I think this is 1035 or better today?)

Just sharing...if I don't write it down somewhere...someone will have to go and do all of the extensive research into common shop practices in the early 20th century all over again.....

Post Reply Previous topicNext topic