resurfacing drums/// brake lathe info

[Mitch//pa]

i have an ammco 4000 brake lathe,
resufacing / truing the front drums is no problem as the 1" arbor and standard race adapters work beautiful. the issue is the rear drums as the 1" arbor will not slide through the end of the hub as its 3/4" opening. after doing a little research i found that ammco sells an 11/16th" arbor which comes with all needed accy's. this setup will adapt to any ammco Models 2002, 3000, 4000, 4100, 7000, 7700 brake lathes. so for anyone looking to be able to do the rear drums a brake doktor is not needed. these ammco machines are easily available used and for good prices. just thought i would post this info as i hope it can help.
the part # for the kit is 9708 and i found the cheapest place to buy it from with free shipping, and dropped shipped from ammco so it only took a few days to get

[Mike]

Thank you

[BRENT in 10-uh-C]

Well, I don't have time at the moment to post a picture of mine but what I encountered is Yes, I can use a 11/16" shaft but how do I 'indicate' the shaft in relation to the hub so that I know they are parallel?

Several years ago I machined an adapter to fit the hub race area that has a .6876 hole however the outboard area of the hub is generally where you/I have issues. If you look at most hubs, you will notice the outboard area has been damaged either by use of the axle nut without a washer, --OR by a hammer. That means the opening is distorted and usually non-concentric which creates alignment issues with the cone. Add to that, the cone that slides onto the shaft usually is too large to slide into the hub to pick-up in the tapered area, thus again creating a runout issue.

Therefore I do agree that you can chuck it up and machine the drum with your set-up however I have found is afterwards when I indicate/sweep off of the hub race, and then sweep the newly machined brake shoe surface, they are at two different angles which creates shudder vibration when the brakes are applied. I am open to ideas on how you can correct this. I am not the only one as this topic surfaced on the old Fordbarn about 10 years ago and this is why I now do mine differently.

On my machine, I used a 1.250 truck-type arbor that I would normally never use and so I machined it with a taper where I can install the hub onto the arbor using the axle tapered area. This also allows me to use a small sweep indicator mounted on flex arm attached magnetically to the lathe carriage to quickly make checks. Now I can easily inspect for hub race wear (quite common) and also make sure the hub race is parallel with the axle shaft. I personally feel this method ensures the shoe surface is in proper alignment with the bearing and the axle shaft. Thoughts??

.

[Mitch//pa]

brent on this arbor the inner cone is part of the arbor. it tapers down to the 11/16th the arbor shaft size. the outside diameter of the cone is 2". the cone slides inside the bearing and seal until the small end of the cone contacts the area where the axle slides into the hub. the outer cone fits to the inside edge where the axle would come out and where the outside seal fits.

[steve s]

I thought I saw in the Gilmore Model A museum a display explaining that the steel Model A drums were never to be turned.

[BRENT in 10-uh-C]

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Originally Posted by Mitch//pa

brent on this arbor the inner cone is part of the arbor. it tapers down to the 11/16th the arbor shaft size. the outside diameter of the cone is 2". the cone slides inside the bearing and seal until the small end of the cone contacts the area where the axle slides into the hub. the outer cone fits to the inside edge where the axle would come out and where the outside seal fits.

Yes, you are correct but often times this area is damaged thus rendering the cone for the hub difficult to align precisely.

Again, how are you checking the inside of the bearing hub for wear? Most people do not realize this, but proper braking on the rear axle is crucial that the hub not be worn along with the axle housing race. That is why the shows on the rear end are mounted 90° from how they are mounted on the front.

Originally Posted by steve s

I thought I saw in the Gilmore Model A museum a display explaining that the steel Model A drums were never to be turned.

You probably DID see that however there are two exceptions to that. On a steel drum when a reinforcing band is installed, it generally distorts the drum from being perfectly round, so it needs to be trued.

On a new cast iron drum, after it is installed onto the hub and the studs swaged in, the drum needs to be trued to the centerline of the hub. Both of those procedures require machining on a lathe.

[Mitch//pa]

Originally Posted by BRENT in 10-uh-C

Yes, you are correct but often times this area is damaged thus rendering the cone for the hub difficult to align precisely.

Again, how are you checking the inside of the bearing hub for wear? Most people do not realize this, but proper braking on the rear axle is crucial that the hub not be worn along with the axle housing race. That is why the shows on the rear end are mounted 90° from how they are mounted on the front.





You probably DID see that however there are two exceptions to that. On a steel drum when a reinforcing band is installed, it generally distorts the drum from being perfectly round, so it needs to be trued.

On a new cast iron drum, after it is installed onto the hub and the studs swaged in, the drum needs to be trued to the centerline of the hub. Both of those procedures require machining on a lathe.

i would think if the end of the hub was damaged i could clean it up enough to get the cone in. if not i would worry about that bridge when i get to it. the drums i cut today turned out great so i wanted to just let everyone know of a way to do this on an ammco
thanks

[BRENT in 10-uh-C]

Originally Posted by Mitch//pa

i would think if the end of the hub was damaged i could clean it up enough to get the cone in. if not i would worry about that bridge when i get to it. the drums i cut today turned out great so i wanted to just let everyone know of a way to do this on an ammco
thanks

I know it sounds like I am being argumentative but that is not my intent. How did you check to see if the hub bearing race is parallel with the shoe surface? For example, if the cone does not totally center on the outboard side by the axle nut, .005" off-center there will likely transfer to .035-.040 run-out at the brake shoe surface because of the diameter.

I think it was Will Cronkrite who actually machined a gauge to drop into hubs to check the wear. I use inside micrometers but both of us have found many hubs that are worn. My theory is when they were run dry of lubricant (or used poor quality lube) all the years, they don't just wear to a larger diameter but in actuality they wear the hub race at an angle because the hub is pivoting off of the axle shaft that is anchored in the differential. Now when the weight of the vehicle is on the drum, the bearing causes the hub to skew but when the brakes are applied, the shoe pushes in a different alignment over the direction of the drum. This causes a chatter and pulsation.

Again, I am not saying you can't use an Ammco unit, I'm just saying that I have experienced issues when I was trying to center on cones. When I finally broke down and made a shaft that would spin the drum off of the axle taper in the hub, now everything is in true parallel again. If I need to true the bearing race surface, I remove the arbor from the brake lathe and install in my Southbend lathe. I use a live center on one end and chuck the arbor in the other end. I use a small boring bar to reach inside the bearing area and make a cut or two. (Remember that factory spec only allows for .005 wear on the hub race as per the Svc. Bulletins!!) Then I usually just cut the shoe surface while I have it mounted to save time and that way I know both the shoe surface and the bearing surfaces are parallel with each other. Then it is all about using a good bearing to bring everything back to near-center during operation. If the bearing race is worn, I just machine it to accept a sleeve (race) and then order an undersized bearing from the parts vendors.

.

[ctlikon0712]

Brent, I follow what you are explaining and it is a good point that I hadn't considered. Thanks for bringing it up. Mitch thanks for posting your solution to your problem too. Brakes are such a convoluted mystery to many, I'm glad there are some that can explain and are willing to help others.

[Ken Ehrenhofer]

Hi Mitch,
Thanks for posting this is the same set up I have and it works great. I see two washers What are they for?
Do you know where to get the sanding drums for the arcing machine?
Do they make the belt for anti vibration? I see something on you photo?

[Mitch//pa]

Originally Posted by Ken Ehrenhofer

Hi Mitch,
Thanks for posting this is the same set up I have and it works great. I see two washers What are they for?
Do you know where to get the sanding drums for the arcing machine?
Do they make the belt for anti vibration? I see something on you photo?

Ken,
This setup is actually sold for doing small foreign car drums. The washers are to just go under the nut to take up space if needed. All i used was the outer cone to center it and one small spacer. I did not need the other spacers or the washers and as with all lathes yes i used a brake drum silencer band to prevent chatter. In the photo the drum was actually spinning so its a little blurred. To answer your other question no not sure

[Ken Ehrenhofer]

Ok without the washers it is just what I use......Thanks

[Mitch//pa]

Originally Posted by BRENT in 10-uh-C

I know it sounds like I am being argumentative but that is not my intent. How did you check to see if the hub bearing race is parallel with the shoe surface? For example, if the cone does not totally center on the outboard side by the axle nut, .005" off-center there will likely transfer to .035-.040 run-out at the brake shoe surface because of the diameter.

I think it was Will Cronkrite who actually machined a gauge to drop into hubs to check the wear. I use inside micrometers but both of us have found many hubs that are worn. My theory is when they were run dry of lubricant (or used poor quality lube) all the years, they don't just wear to a larger diameter but in actuality they wear the hub race at an angle because the hub is pivoting off of the axle shaft that is anchored in the differential. Now when the weight of the vehicle is on the drum, the bearing causes the hub to skew but when the brakes are applied, the shoe pushes in a different alignment over the direction of the drum. This causes a chatter and pulsation.

Again, I am not saying you can't use an Ammco unit, I'm just saying that I have experienced issues when I was trying to center on cones. When I finally broke down and made a shaft that would spin the drum off of the axle taper in the hub, now everything is in true parallel again. If I need to true the bearing race surface, I remove the arbor from the brake lathe and install in my Southbend lathe. I use a live center on one end and chuck the arbor in the other end. I use a small boring bar to reach inside the bearing area and make a cut or two. (Remember that factory spec only allows for .005 wear on the hub race as per the Svc. Bulletins!!) Then I usually just cut the shoe surface while I have it mounted to save time and that way I know both the shoe surface and the bearing surfaces are parallel with each other. Then it is all about using a good bearing to bring everything back to near-center during operation. If the bearing race is worn, I just machine it to accept a sleeve (race) and then order an undersized bearing from the parts vendors.

.

brent i hear what your saying an no i did not check the hub bearing race specs.
i can say that i am very happy with the way the drums cut with this arbor set up and after installing the drums today and adjusting the brakes i had a nice even turn of the wheel with no high or out of round spots from the drum. i realize that with the car in use the forces maybe different on the hub bearing then just hanging in the air. i would like to see a pic of the arbor tool you made when u get a chance.

[Mitch//pa]

Originally Posted by Ken Ehrenhofer

Ok without the washers it is just what I use......Thanks

ken i am happy to hear that it has worked good for you also. i was really happy today with the way the drums turned out.
mitch

[KR500]

Before Ammco lathes and I use one myself, Barrett recommended arrangement was a turned down arbor at the outside of the drum. Model A rear drums are best turned with an adapter which can be made on a lathe which centers the drum with the rear inside bearing installed in the hub which fits snugly. This is what Barrett utilizes. A tapered outer cone goes on the outside but as mentioned the drum should be indicated to be sure any dame which has been done to the outer portion of the hub does not adversely affect mounting. Also Model A steel drums can be turned but do not attempt with a carbide tool bit use high speed and don't turn beyond a safe limit.

[supergnat]

KR500,
I have a Barrett. What kind of tool bit should I use and where can I buy one? My lathe came with some triangle shaped bits but I do not what material they were made from. One of these days I will take a sample of a drum I cut to Mitch for his opinion on the quality of the cut.
Thanks,
Supergnat

[Mitch//pa]

Originally Posted by supergnat

KR500,
I have a Barrett. What kind of tool bit should I use and where can I buy one? My lathe came with some triangle shaped bits but I do not what material they were made from. One of these days I will take a sample of a drum I cut to Mitch for his opinion on the quality of the cut.
Thanks,
Supergnat

do a slow cut and it should be fine. since you just got the unit ck the runout on your arbor before you cut the drums. otherwise they will cut wrong if it is bent

[ctlikon0712]

Those triangle bits are carbide inserts, they can be rotated for a new cutting edge.

[Mitch//pa]

Originally Posted by ctlikon0712

Those triangle bits are carbide inserts, they can be rotated for a new cutting edge.

if their like the ammco bits upside down also 6 sides