Model 20 Brake Lining?

Am I correct that the Model 20 takes 3/16" brake lining? I put that on my brake shoes, but can't quite get the drums over it. It's a tight fit, anyway. I'm wondering if the ridges in the drums might be stopping the assembly. I thought to grind down the lining a bit, but the brake Technician I called said he can't do it on a circular shoe, plus a 5/32" lining might be too thin. I could turn down the drums a bit, but they're not real thick. Any ideas appreciated!

Here are some measurements I took:

Old linings: approx. .189" thick

Drums: about 7-15/16" I.D. & 8.25" O.D.

Original thickness of drums (the unworn ridges) = .119"

Drum thickness at brake contact area: .081" (= .038" ridge height/wear)

Phil

I got some nice tips from Gary Hoonsbeen of the HCCA. He noted that the tight-fitting brake drum is a common brass-era problem, and that the drum should be turned down just enough to even it off. Afterward, some chalk applied to the drum will show the high spots on the lining, which can be brought down with a belt sander. My next step is a trip to the machine shop.

Phil

I've hesitated to post on this topic, since what we do is silly.

Put new linings on model 20 Hupp, shoes would not fit in brake drums. These were old linings, sure there was some interesting asb.... Stuff in there....this was 20 years ago, we put on little white masks and put the hand grinder to them, made them fit...

In the 60's and back, could get asbestos in a pail, you mixed water with it and smeared on small boilers for insulation....I did this on a 50 hp boiler for a cattle feed ( range cubes) processor for a few years...owned by my father...

Our local hardware store sold paper bags filled with asbestos powder, probably for the purpose you describe, David. I recall sanding drywall seams, laden with asbestos, protected by a bandana over my mouth. I'm sure we could describe our adventures with mercury, also!

Phil

G,day to all. Well said David . Its a wonder we aint all dead from asbestosis. The white mixture was known here as monkey **** and was used to lag the steam pipes in hospitals and navy ships. Back to business! Check that the end of the shoe that goes onto the cam has not been built up and if so grind it off. If still in trouble put on your mask and with a coarse belt on your linisher take a bit of lining off. I would not turn out the drum but would grind out the unworn 1/8 on the open end remembering what you take away you cant put back, at least not without some swearing. Max Burke Nulkaba 2325 Australia

G,day again To save time take off the brake band and place it in the drum . Adjust it as previously mentioned until the gap between the ends is a fraction more than the width of the flats of the cam. You may have to trim the unworn ridge in the drum between the shoes and the open drum end may be worn more than the inner. You are probably doing this anyhow and its unlikely that the new lining will have asbestos but it may be new old stock! Max Burke Nulkaba 2325 Australia

I ended up turning down the drums slightly to remove the ridges. The right drum works well, but the left only worked on the hand brake. The inner (foot break) portion had deep wear the lathe work didn't remove. Therefore, I brought the drum to a nearby thermal (metal) spray shop which will add some thickness to the drum. We'll see if that does the job. Don't ask me if this will work. The guy said they use a copper/nickel mix to spray brake drums. The process uses two sprayers with the two metals directed at the part. Here is a video the shop made:

http://www.reneuxit.com/vid/thermal_sprays.html

Phil

G,day to Huppers. Phil a few years ago we picked up a Hup 20 rear axle assembly that had a pair of heavy cast shoes in each wheel with wide cams. each cam, be it hand or foot, operated both shoes using all of the available drum surface. I intended to cast the shoes in aluminium and use the system but as it was only about fifteen years ago there's still hope that ill do it when I run out of jobs. About thirty years past we bought the remains of a 1916 Hup N that had been made into a truck with a side valve Ford engine from a bren gun carrier and massive back springs. Well the drop arms on the footbrake at the rear had bolt on extensions to make them 2 1/2 inches longer. We used them on our N and copied them for the 32 and both 20cars cant say it doubled the efficiency but it made the brakes no worse. Still waiting for a mod 20 driver to tell if they can skid the wheels on a hard surface at any speed at all, just in a test mind you. Friend Edgar has always said that's what broke his crankshaft, but i'm yet to see one that would shear off a 3/8 bolt. I have heard of a pair of cast iron drums in service but don't have any test reports. Yes, we do have a Tapley brake test meter. We are going to use it in a club event to sort out the facts and the skites. Max Burke Nulkaba 2325 Australia.

I've wondered if one could "build up" a standard early steel brake drum with body filler or the like and then use it as a pattern to cast the drum in iron.

Phil

The hopeful conclusion to my Model 20 brake drum & lining restoration: To recap, I removed the oil-soaked brake linings and replaced them with riveted 3/16" woven linings. They would not enter the brake drums, so I turned the drums slightly to remove the heavy scoring. The right shoes fit nicely, and have good braking action. The left side also fit, but had lousy braking. Also, the left drum was more heavily worn, and I couldn't turn it down enough to get it totally flat. I then had the left drum metal sprayed at Reneuxit, a firm here in West Chester, PA. This brought the drum walls close to what must have been their original thickness. Unfortunately, my new 3/16" linings now were too large to fit, and I determined that 5/32" linings were needed. With linings that thin, I thought they should be bonded rather than riveted, so I sent them to Rochester Clutch & Brake in NY. Got them back today, and they seem to fit...

Total cost: don't ask.

Phil