Axle key to keyway fit

[BlockBuster]

Gents-

Thanks for all your help over the last several months. My rearend is rebuilt using Mr. Endy's disertation, my flywheel trued and installed, engine, clutch and transmission installed and I now have a roller to push around this winter.

When installing one rear hub to axle, the axle keyway and key fit was just a tad bit loose. There is no tapping the key in; it falls into place with no resistance. However, the keyway is true and not wallowed out, otherwise I never would have installed it. I tried two new keys and they're equally loose. I'm talking a couple thousandths the length of the keyway. Is it prudent to buy oversized key stock and massage it to fit? Peening the edges of the keyway doesn't seem right. Any and all information appreciated.

[Brendan]

sounds like you have a bad axle. I pulled the threads off an axle in my car, found 2 new axles and I checked the threads and the key slot first

[Tom Wesenberg]

If you have the axle and hub taper clean and dry then I'd assemble it and tighten the nut to about 100 foot pounds or a hair more, and not worry about the slightly loose key.

[glenn in camino]

Many years ago I had a restored Model A with a worn axle keyway. solution--I welded a small bead on each side of the lower half of a key and filed it to fit the keyway. It worked fine for years until I sold the car.

[Pete]

If you can lap the hub to the axle and get at least a 90% surface, clean everything super dry with acetone or lacquer thinner and assemble it. Tighten the nut to AT LEAST 100
ft lb.

[Marco Tahtaras]

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Although it wouldn't be my choice, Tom is probably correct and there should be no problem. I drive the cars a bit different than most so I'd be a bit uncomfortable.

If it's a new key I'd not take anything for granted and check it. I believe they were precisely .250". It sounds easy to get correct but don't assume anything the way supplies are sourced today.

Now, if your axles exhibit any taper in the keyway (which can be measured) but show no raised lip from the damage, that would typically mean the axle key was sheared and the drum spun. doing so would level the surface but leave some level of scoring around the taper.

[BlockBuster]

I'll measure up those keys. If the new keys are as good as it gets and I use Tom's advice, could I use a drop of Loctite to keep the key from riding up the keyway?

[larrys40]

It can't hurt.. but the loctite probably isn't going to make a difference if the mechanical fit of the axle/key to Hub isn't tight and good. Make sure the hub keyway is tight as well., Torque to 150 ft lbs. Recheck torque after 25-50 miles.
It should be OK.

Larry S.

[Marco Tahtaras]

The key way is tapered as is the key. It can't migrate far.

Pete made a very good point about lapping in the taper. At least check it with bluing to start. The taper is what really does the work.

[BILL WILLIAMSON]

Marco is correct, tapers have a tremendous gripping characteristic. I sheared a key once, & limped GENTLY home, by just tightening the axle nut "REAL TIGHT" with a breaker bar & a cheater pipe. The drum comes off easy after shearing a key, another time, I found a large rusty nail beside the road, poked the drum on & drove in the nail. Bent it back & forth to break off the head, tightened the nut & drove GENTLY home.
Old Chevys were NOTORIOUS for breakin' axles, usually happened when backing up. Chief said Uncle Doe carried 2 extra axles in his '32 Chev coupe, enough tools to change one, & a long wire thingy, with a "LOOP" on the end to pull out the broken STUB! Chief made the LOOP thingy for him.
My friend, Vern, broke an axle in his '29 Chev. on a run up in our Gold Country, found a blacksmith who welded the axle with a water pipe coupler, straightened it in his "V" blocks & he's STILL runnin' it, for 5 years! Same car broke a PITTMAN shaft, in TRAFFIC!!!! But I WON'T get into that story.+*^@#%## Bill W.

[Pete]

Sorry guy's, but the keyway is straight as is the key itself.
When tapered keys are used as in mill shafts and sprockets, the keyway in the shaft is straight and the keyway in the hub is tapered as is the key itself. The taper is usually standard SAE 1/4 inch to the foot. The key sometimes will have a hook on the big end to facilitate easy removal.

[Marco Tahtaras]

Originally Posted by Pete

Sorry guy's, but the keyway is straight as is the key itself.
When tapered keys are used as in mill shafts and sprockets, the keyway in the shaft is straight and the keyway in the hub is tapered as is the key itself. The taper is usually standard SAE 1/4 inch to the foot. The key sometimes will have a hook on the big end to facilitate easy removal.

Maybe my description was less than Ideal but If I recall correctly the bottom of the keyway in the axle tapers out at the inner end and of course the keys are shaped to accommodate that.

[Pete]

Originally Posted by Marco Tahtaras

Maybe my description was less than Ideal but If I recall correctly the bottom of the keyway in the axle tapers out at the inner end and of course the keys are shaped to accommodate that.

Roger on that.