Damaged Hub Taper - Reamer?

[Biggles]

A rear hub key fractured, the hub spun on the axle shaft so both tapers were damaged. The axle shaft has been recovered by careful filing and lapping to a good hub which is now in use.

I would like to recover the damaged hub taper, but before lapping to a shaft the taper needs to be cleaned up so I need a 7 degree included angle spiral taper reamer.

Approximate dimensions need to be
11/16" diameter small end
1.1/4" diameter big end
4.1/2" long cutting section

Where can I find such a thing?

[JSeery]

You do realize that a tapered ream like that can be very expensive? I would think that a good machine supply should be able to provide one.

[cmbrucew]

Would not the refinished taper cause the hub/drum assembly to be too close to the brake shoes?
Bruce

[hotrodA]

A little smaller than your spec; the big end is 1.020, but it is 7* with long shank.

[JSeery]

They are sold by Speedway and on Amazon and ebay, etc. Most run the the $70 to $90 range for cheap ones and a couple of hundred for a quality one.

There could be several problems with this approach. One already brought up is moving the drum inboard. Another is the difficulty in attempting to ream a hole with a keyway in it. Is the drum that valuable? Hope you are running drum retainers with these!!!

[flatheadmurre]

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Reaming a keyway hole with a straight flute reamer is a challenge...preferable a spiral flute.

[Biggles]

Thank you for all the thoughts.

I expect it not to be cheap but it is a special Ford hub/drum and I have only one pair.
I agree - a spiral taper would be most desirable.
The Snap On repairman's reamer angle is not specified and as noted is too small. A Speedway item with its tight spiral would be ideal but at 1" is too small - the drum taper runs out to the full axle shaft diameter of 1.1/8".
Removing 10 thou from the taper would push the drum inwards by less than 3/16" which can be accommodated. I don't expect to have to remove 10 thou -just want to clean it up before lapping to a shaft.

[Mart]

Neil, would it be simpler/easier to maybe produce a lap to the same dimensions as the axle taper, and use that to lap it in pre lapping to the axle. maybe in aluminium, or some other softer material. that or an other wise unusable axle shaft, perhaps one with a damaged thread or something. I don't think you will find the ideal reamer, and if you had to have one made it really would cost a fortune.

Mart.

[Biggles]

Thanks, Mart, for your as always reasonable engineering thought and suggestions. An aluminium blank taper could be made, but what is the advantage of a soft material for such purpose? Intuition says that the blank should be harder than the subject piece so that the subject (the hub) is abraded to conform with the blank, as is the case with a standard axle shaft and hub when lapping.
Just searching for knowledge.

[Mart]

No Mate, it's the other way round. The gritty particles (grinding paste) embeds more readily into the softer material and can then more easily abrade the harder material. So an aluminium taper lap would work well on cast iron/steel hub.

I've never done this job, just trying to think it through from first principles.

I think in your case you will never machine the hub back to a perfect surface finish. What you might be able to achieve is knocking down any high spots and then allowing the remaining surface to be lapped as level as possible while allowing that there will be some remaining low spots or gouges.

It might be that judicious application of a smooth half round file could go a long way to removing the high spots and then a simple lapping operation could be all that is required to achieve the best practically achievable fit. Good new keys and hellishly tightened nuts should see old Boz running a nicely matched pair of hubs.

Mart.

[Biggles]

"Knocking down the high spots" is what I aim for, then usual lapping to a good axle shaft. I've come to the conclusion that a spiral taper reamer is probably not available (at any reasonable price) so careful work with a half round fine file is probably my best hope, with a next step of oiled wet-and-dry emery paper cut to shape and sandwiched in the taper between a good axle shaft and the hub, before lapping to a good shaft with fine grinding paste.

Wish me luck !

[Andy]

The hub could be cleaned up on a lathe. Set the angle on the tool post and bore it out a little. I would make a tooling fixture to bolt the hub to using the brake flange.
They used to sell shims to go in the taper to move the hub out. That would be nice to use and not have the hub too close in.

[hardtimes]

Originally Posted by Andy

The hub cold be cleaned up on a lathe. Set the angle on the tool post and bore it out a little. I would make a tooling fixture to bolt the hub to using the brake flange.
They used to sell shims to go in the taper to move the hub out. That would be nice to use and not have the hub too close in.

Such shims are still available , and if properly used they do as you say.

Besides good lapping /mating of hub/axle, nothing is going to prevent this from happening again...if proper torque (maybe 200 or so ft lbs ) isn't used.
Sounds like it is expected that the key is thought to be the 'thing' that holds/keeps such problems from happening...NOT SO !

[rotorwrench]

Repro hubs are expensive at 160 US dollars so that's a given. If a person spends a lot of time and money on a part that is getting closer to the dead zone, it might be less expensive in the long run just to replace the hub or hubs. It doesn't take too much wear before the drums or hubs are rubbing on something.

I like my wheels to stay on the vehicle. Even if you have the safety catchers, a busted axle or hub will still leave you stranded.

[Biggles]

I decided to give the job to a machinist who used high speed diamond to remove the high spots. A good axle shaft taper was used to turn a lap from aluminium, which was then used to hone the hub taper.
The hub and shaft are now rung (self locking) and I'm very pleased.

Thanks for all the interest and suggestions.

[JSeery]

Sounds like you found a good machinist!

[Mart]

Glad you were able to get it sorted out, Neil. Do you think you have achieved the required fit without creating a brake drum/backplate clearance problem?

Well done, though, glad it worked out for you.

Mart.

[Biggles]

Originally Posted by Mart

Do you think you have achieved the required fit without creating a brake drum/backplate clearance problem?

My instructions were to remove only the high spots, leave the gouges, and then hone to see what the finish looked like and felt like. As I said, it is rung so that's a good start. Now that I have it back some work with engineer's blue and more honing will improve the fit even more. So far I cannot measure any difference in the length of axle thread protruding.