turning brake drums on conventional lathe

[Standing Elk]

Curious if any of you have turned brake drums on a conventional lathe, specifically rears. If so what sort of fixture did you use to mount the drum / hub assembly in the lathe? I am assuming that you would need to have the wheel bearing in place in the hub and index from it in order to insure the inner surface of the drum would be be cut concentric to the inner bearing race on the axle. Pictures would be helpful if anyone has some. Thanks

[Tom Wesenberg]

I've turned brake drums on my 12 1/4" Craftsman lathe. It's just a matter of making special cone shaped adaptors to fit the hub of the brake drums, and no bearings are installed.

[WHN]

I took the last set to a truck brake shop. They did all four for $50.00 on a true brake drum turning machine.

[George Miller]

For the back drums I use the end of a old axle shaft in the chuck.
The front I turned down a shaft to fit the bearing races in the hub.
The easy way is take it to some one that does that kind of work.

[Charlie Stephens]

Try calling all of the local Model A and Early V8 clubs in your area and find out where they go to have rear drums turned. It would be easier to drive 100 miles than to do it yourself.

Charlie Stephens

[Y-Blockhead]

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I read in the Service Bulletins that "Under no circumstances must any attempts be made to turn brake drums ... ", page 514. Are we saying it is OK to turn Model A drums?

Just asking for future knowledge, I have Cast drums.

[Patrick L.]

I think its fine to turn the original steel drums as long as they don't go more than .030" oversize. The steel drums are what the service bulletins refer to. I've seen some of these drums over the years that you could darn near see through.
The cast drums can be cut, but, I'm not sure what each manufacturer specs are. Generally .060" over is the limit.

As said about the lathe. Making/finding an arbor would be the way. But,usually there is an old repair shop in the area that would have a drum lathe gathering dust in the corner. Someone in the shop should remember how or be able to figure it out.

[Standing Elk]

The drums are new cast drums with zero wear. The problem is that when they were trued initially after having the hubs installed I believe one of the rears is slightly out of round on the ID. This causes the car to brake unevenly on that one wheel. All the local "modern" shops say they can not chuck them in their newer brake lathes. Just exploring the possibility of fixing the issue myself. Sounds like I will be better off having them done where I had the initial work done. They're a good bunch of guys.

[WHN]

Originally Posted by Y-Blockhead

I read in the Service Bulletins that "Under no circumstances must any attempts be made to turn brake drums ... ", page 514. Are we saying it is OK to turn Model A drums?

Just asking for future knowledge, I have Cast drums.

I have been told the same by many people.

I can tell you that cast drums can be turned. I have had them done, with no adverse affects. You do need to have metal left on drums that will allow them to be turned.

I had new brakes put on my wife’s car this past summer. The dealer said that they no longer turn rotors. They wanted to put on new pads and rotors. I took it to another shop and saved $700.00. Had rotors turned and new pads installed. Enjoy.

[48fordnut]

My machinist used a special set up to turn mine on his lath. 250 mile round trip otherwise.

[Patrick L.]

Originally Posted by Standing Elk

The drums are new cast drums with zero wear. The problem is that when they were trued initially after having the hubs installed I believe one of the rears is slightly out of round on the ID. This causes the car to brake unevenly on that one wheel. All the local "modern" shops say they can not chuck them in their newer brake lathes. Just exploring the possibility of fixing the issue myself. Sounds like I will be better off having them done where I had the initial work done. They're a good bunch of guys.

OK. When installed the drums should be cut with the hubs to true them up. Maybe something happened, like maybe one got forgot. STUFF happens at times.

[Patrick L.]

Originally Posted by Standing Elk

The drums are new cast drums with zero wear. The problem is that when they were trued initially after having the hubs installed I believe one of the rears is slightly out of round on the ID. This causes the car to brake unevenly on that one wheel. All the local "modern" shops say they can not chuck them in their newer brake lathes. Just exploring the possibility of fixing the issue myself. Sounds like I will be better off having them done where I had the initial work done. They're a good bunch of guys.

OK. When installed the drums should be cut with the hubs to true them up. Maybe one got forgot or some such thing, STUFF at times. An out-of-round drum can pulsate.

[Synchro909]

I've never turned a steel Model A drum but I've done every cast iron one I have. Speaking with a machinist friend, he says that the steel drums are a #$%^ to turn. In the last couple of days, I've installed new CI drums on the rear (no swaging) and turned them to suit the hubs. One was 0.010" out of round, the other 0.012". I used a conventional lathe with an arbor made for the job.

[Tom Wesenberg]

The original steel drums were formed by rolling the steel into shape, and this will leave a hardened surface from the rollers. Turning or grinding this surface will leave you with a bit softer surface as well as thinner. That's why it's not recommended to turn them. I'm using original never turned drums, but it's well known cast iron are better and will have less expansion from heat created during braking.


I drove a Model A with poor brakes, and when going downhill, I had to run a red light at the bottom of the hill due to brake fade. Just lucky no cars were crossing at the time.

[Terry, NJ]

I didn't see any reference to this, but when your turning them, Wrap a long rubber Bungee around the outside dia. of the drum. Brake drums tend to chatter a lot and the rubber will hold the vibration down. You must have a good live center, well engaged with the center hole. Keep your speed and feed down and it should be all right.
Terry

[big job]

Terry is correct. We use a dead center in the chuck (small end) and a live large bull center into the other side then driven with a 'dog'. All you want to do is just clean it up, make
it round again cause you ain't stopping a loaded dump truck either LOL

[BRENT in 10-uh-C]

Originally Posted by Standing Elk

The drums are new cast drums with zero wear. The problem is that when they were trued initially after having the hubs installed I believe one of the rears is slightly out of round on the ID. This causes the car to brake unevenly on that one wheel. All the local "modern" shops say they can not chuck them in their newer brake lathes. Just exploring the possibility of fixing the issue myself. Sounds like I will be better off having them done where I had the initial work done. They're a good bunch of guys.

The issue with modern brake lathes is most do not have a small enough arbor to go thru the end on the rear drum.

Years ago I tried making an arbor out of an old axle like George did and when I got the drum mounted into the lathe, the drum faced the wrong way so I couldn't get my cutter in. Now that arbor is a huge drift punch.


One of the biggest struggles most have with accurately machining/turning rear drums is being able to mount it between true centers. More often than not, the end of the hub has been distorted/mangled/peined by the end of the axle nut so that if you use a centering cone (-or a live center), it likely will be off-center because of the burrs or mangled metal on that end.

One other check that many overlook is the hub bearing area of the hub. If the axle housing races are worn, -which a right many are worn, then the hub bearing race is likely worn too. This is usually caused by using poor quality grease back in the day, ...or more likely no grease at all. What this ultimately affects is the rear brakes because the centerline of the brake shoes are no longer in the centerline of the drum. In other words, if the brake drum is now rotating 0.020" - 0.030" higher due to a worn axle housing race and/or a worn hub race, then you effectively have one shoe braking and one not so much. The equalizer in the brake cam will compensate a small amount however you still are losing braking efficiency on the very axle that Ford designed to carry the majority of the braking.

[SAJ]

I have turned both cast iron and original steel drums. For rears I used a stub cut off an old axle to fit into the taper. To ensure the other end of the axle stub sat centrally in the bearing bore I made a mandrel that was a sliding fit onto the protruding axle stub and also slid into the bearing bore. Otherwise the taper did not locate it accurately in the bearing bore for an unknown reason. I made a quick dead centre to grip in the 3 jaw and fit into the axle centre hole and drove the drum with a piece of key steel slotted between 2 chuck jaws and clamped to the axle nut. Looking at my photos I cannot figure why I did not just grip the axle nut in the 3 jaw,which would be accurate enough and possibly better than using a mangled centre in the end of the axle.
I used a low speed and pieces of large inner tube stretched over the drum to stop it ringing and chattering with a tungsten carbide tip in the tool.
I have done many drums like this. Next time I will use the tidier set up of gripping the axle nut directly in the 3 jaw.
Front drums are easier. I cannot find a photo of the set up but I use a live pipe centre in the inside bearing bore and the outside is gripped in the 3jaw internally.
When swaging a new drum onto a hub, I face the hub first using the same mounting method. I note it is really easy to distort the hub flange face when removing old swaged studs. I cut the swage off with a hole saw sized as a neat fit over the studs. Even tapping the old stud out after the swage is removed can distort the hub flange. So a bit of bending work with a crescent spanner, hammer and dial gauge to straighten it roughly before lightly truing it by turning is called for, so as not to take too much off the flange, which is quite thin anyway.
SAJ in NZ

[Synchro909]

Originally Posted by SAJ

I have turned both cast iron and original steel drums. For rears I used a stub cut off an old axle to fit into the taper. To ensure the other end of the axle stub sat centrally in the bearing bore I made a mandrel that was a sliding fit onto the protruding axle stub and also slid into the bearing bore. Otherwise the taper did not locate it accurately in the bearing bore for an unknown reason. I made a quick dead centre to grip in the 3 jaw and fit into the axle centre hole and drove the drum with a piece of key steel slotted between 2 chuck jaws and clamped to the axle nut. Looking at my photos I cannot figure why I did not just grip the axle nut in the 3 jaw,which would be accurate enough and possibly better than using a mangled centre in the end of the axle.
I used a low speed and pieces of large inner tube stretched over the drum to stop it ringing and chattering with a tungsten carbide tip in the tool.
I have done many drums like this. Next time I will use the tidier set up of gripping the axle nut directly in the 3 jaw.
Front drums are easier. I cannot find a photo of the set up but I use a live pipe centre in the inside bearing bore and the outside is gripped in the 3jaw internally.
When swaging a new drum onto a hub, I face the hub first using the same mounting method. I note it is really easy to distort the hub flange face when removing old swaged studs. I cut the swage off with a hole saw sized as a neat fit over the studs. Even tapping the old stud out after the swage is removed can distort the hub flange. So a bit of bending work with a crescent spanner, hammer and dial gauge to straighten it roughly before lightly truing it by turning is called for, so as not to take too much off the flange, which is quite thin anyway.
SAJ in NZ

I use as specially made mandril with a taper to match the on eon the axle, oly cut the other way. It is inserted into the hub through the bearing. The smaller end goes right through the hub with about 3 or 4 inches of parallel shaft protruding which I hold in the chuck. The taper is enough to hold it together while it is machined. Instead of the cyliinder running inside the hub bearing, I use a live centre.
A friend has fitted Flat Head Ted's brakes and has found that without enough return spring tension and the drums turned accurately, they drag. Seems they like a bit of runout to push the shoes off the drum. Moral: Perfect isn't always best.

[BRENT in 10-uh-C]

Originally Posted by SAJ

I have turned both cast iron and original steel drums. For rears I used a stub cut off an old axle to fit into the taper. To ensure the other end of the axle stub sat centrally in the bearing bore I made a mandrel that was a sliding fit onto the protruding axle stub and also slid into the bearing bore. Otherwise the taper did not locate it accurately in the bearing bore for an unknown reason. I made a quick dead centre to grip in the 3 jaw and fit into the axle centre hole and drove the drum with a piece of key steel slotted between 2 chuck jaws and clamped to the axle nut. Looking at my photos I cannot figure why I did not just grip the axle nut in the 3 jaw,which would be accurate enough and possibly better than using a mangled centre in the end of the axle.
I used a low speed and pieces of large inner tube stretched over the drum to stop it ringing and chattering with a tungsten carbide tip in the tool.
I have done many drums like this. Next time I will use the tidier set up of gripping the axle nut directly in the 3 jaw.
Front drums are easier. I cannot find a photo of the set up but I use a live pipe centre in the inside bearing bore and the outside is gripped in the 3jaw internally.
When swaging a new drum onto a hub, I face the hub first using the same mounting method. I note it is really easy to distort the hub flange face when removing old swaged studs. I cut the swage off with a hole saw sized as a neat fit over the studs. Even tapping the old stud out after the swage is removed can distort the hub flange. So a bit of bending work with a crescent spanner, hammer and dial gauge to straighten it roughly before lightly truing it by turning is called for, so as not to take too much off the flange, which is quite thin anyway.
SAJ in NZ

I love the impromptu lathe dog in the first picture.


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