Selecting iron for brake drums

[4GSR]

If you decide to use the Durabar, get ahold of a Durabar Metal Center nearest you, and tell them what you need and have them to cut two pieces, one for each drum. Allow yourself about 1/2" on the length, maybe 1/4" and at least 1/2" on the OD to cleanup and get under the skin on the bar. It'll be a lot cheaper too, rather than going through McMaster-Carr IMO. If the metal center is near you, pick it up in person to save on shipping.

 

[kelfy]

Here's the car and the 110-year-old drum. Shiny outside surface is what the foot brake band grips.


There are thousands of cars of this era in operation today. (See www.hcca.org .) Modern materials and some modern components are regularly adapted to them to help them be safer on the road than the materials and designs that were available in 1913.

Some people drive them pretty hard. Professional restorers of really high-end cars fabricate cast-iron drums to support driving in modern traffic. I was just hoping to get some of my own understanding of the metallurgy related to this application, and perhaps commission my own replacement project in an informed way, rather than just saying "uh, make me some of whatever somebody else got."

 

[dian]

are the drums in the back?

if made from ci the ring will have to be considerably thicker, so the brake mechanism will have to be adapted. if modding is no problem, i would try and slap a set of disc brakes on there.

implemex, what im suggesting here: safer = weaker in this case. unlike with steels, moduli of cast iron correlate with uts. first hit: https://www.sonelastic.com/en/fundamentals/tables-of-materials-properties/ferrous-metals.html

together with higher conductivity because of the shape/structure of the carbon lamellae a lower modulus results in less thermal stress.

and i completely agree with you on casting: its an intricate process, solidification and transformations in ci are more complicated than in steel. little details might matter, like the way of stirring the melt or variations in chemical composition of the lining of one of the vessels. ci is appropriate for mass produced parts, where procedures have been worked out by experience and ingenuity. i always get very "curious" when hearing "i had this cast" unless its some ornamental piece.

btw, i wonder how much heavier ci drums of this diameter would influence drivability and acceleration (from what, 20 kw perhaps?) of the vehicle.

 

[john.k]

Fabricated steel is the only possible solution .....you can also go with a wear resisting steel for the friction part.

 

[Dan from Oakland]

Kelfy- I would suggest the 65-45-12 Durabar. It has a decent coef. of friction with woven lining and will be much better than the old steel brake drum. You end up with a lot of chips, but in the long run its still cheaper than getting two castings made. I feel your pain, I have an '11 Overland Model 59 that is going to get new brake drums pretty soon, so you are not alone, and they will be made from Durabar. Have you checked with your local Paige dealer? pretty sure they are out of stock!!

 

[kelfy]

Thanks Dan, that's very helpful. You do think ductile is a better choice than gray? I put on composition linings when I recommissioned the car, but eventually have supposed that their COF against steel ended up hurting the stopping even more. Hoping they will be appropriate for the iron drums.

 

[Mud]

How bad are the stock brakes with steel drums? I had a 22 Reo with a similar setup, external bands and internal shoes on steel drums, it's weakness was tire traction, the wheels locked up way too easily. I don't recall what lining was on it.

There's an Amish foundry in PA called Cattail foundry who will use OE parts and add to them to use for patterns, I've seen several replacement parts they have made for old iron. The handicap is they only communicate by USPS mail

 

[kelfy]

I live close to Cattail. It's a neat place, but when they do iron they pretty much melt whatever they have lying around.

If I could lock up the brakes, I'd know that I can use all the braking that is available to me with those little tire contact patches. But the current setup won't even lock up those skinny tires.

 

[Dan from Oakland]

If your current drums are physically ok you might try a different lining. There is a woven lining called Green Gripper that seems to work quite well on old band brakes.

Item # 4280, Green Gripper Woven (GGW) Non-Asbestos Material On The Rowland Company

Browse Item # 4280, Green Gripper Woven (GGW) Non-Asbestos Material in the The Rowland Company catalog including Item #,Item Name,Description,Specific Gravity (SAE J380),Gogan Hardness (SAE J379A),Minimum Tensile Strength (ASTM D638),Minimum Compress

catalog.rowlandcompany.com

 

[Donkey Hotey]

My opinion, PDOOMA:

Now that you've shared a photo and we can see the diameter of the drum, I would stick with the drums you have and focus on the lining, the band and the mechanical system actuating it.

You already have a large diameter friction surface. That translates into good mechanical advantage relative to the rolling diameter of the wheel. Changing the coefficient of friction of the metal side won't buy you anywhere near as dramatic a change as really applying the brake linings you already have.

There has to be some serious shortcoming in the mechanical advantage or the lining material if that diameter can't lock that wheel at will.

 

[tdmidget]

Here's the car and the 110-year-old drum. Shiny outside surface is what the foot brake band grips.
View attachment 409544

There are thousands of cars of this era in operation today. (See www.hcca.org .) Modern materials and some modern components are regularly adapted to them to help them be safer on the road than the materials and designs that were available in 1913.

Some people drive them pretty hard. Professional restorers of really high-end cars fabricate cast-iron drums to support driving in modern traffic. I was just hoping to get some of my own understanding of the metallurgy related to this application, and perhaps commission my own replacement project in an informed way, rather than just saying "uh, make me some of whatever somebody else got."

Is the thickness that we are seeing on the wear surfaces close to original or the result of many years of service and refinishing?

 

[EmGo]

I don't know why you guys are so set in this. A little over a hundred years of practice has shown that steel brake don't work for poop, cast iron is good. For street use probably even better than carbon-carbon because you dont have to pre-heat them before an emergency stop.