New Departure Model D Coaster Brake Overview




8/24/12-8/27/12

Coaster Brakes

I tend to do most of my work on the weekends, but I do slip a little bit in here and there after work during the week.  It seems the mosquitoes like it when I work late too. They make as good an assistant as any, seeing as the purpose of an assistant is get in your way 90% of the time.

I spent the first part of the weekend rebuilding a 1940s era New Departure Model D coaster brake. Most people are familiar with brakes that work by squeezing a lever on the handlebars, but for many years in the USA, the brake of choice was a foot brake activated by pedaling backwards. A coaster brake is ideal for a casual rider who doesn't go very fast, and for politicians, because they are good at back pedaling once you finally get them to start going forward.

When you pedal backwards, a threaded driver pushes together a set of metal discs, creating friction and slowing the back wheel down.  As long as you pedal/push in reverse, the brakes are applied. Of course, you can pedal forward and coast when you want to as well. All of the parts are inside the hub of the wheel, so they are impervious to weather.




As the brake gets used, the discs that rub together get worn, eventually crack, and then need replacing. This time around I had no broken ones, but plenty of wear. I have some replacement discs around, so I figure it's time to replace the old ones. The new ones are pictured below.


In order to prevent excessive wear and heat, a 90 weight heavy gear oil is used to lubricate the moving parts.  These brakes are interesting also in that they have a small oil filler cap, sort of like you would have a on car, so that you can add new oil to the hub every so often. It serves a dual purpose: keep the hub cool and free moving, while also making a mess of the repairman and his clothes. Remember that your shirt and the brakes will each share half the oil you use.





With the new brake discs in and fresh oil, the hub is reassembled. I will perform a final adjustment this week/weekend. I am also doing some cosmetic work on the bicycle, which will be described in another post. Unlike most other 60-65 year olds in the DC area, no Botox will be used.

2 comments:

  1. AnonymousMarch 27, 2026 at 8:09 PM

    How much gear oil do you use? I put my New Departure together with grease, and it barely stops. I've seen the little filler cap since I was a kid, but only saw people put 3in1 (light) oil in it, which sounds wrong. Please advise.

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    Replies
    1. The Bike ShedMarch 30, 2026 at 10:18 AM

      When I rebuild the hub, I liberally oil the discs. I have an old set of ND instructions but they only say "lubricate" the discs with oil (don't say exactly how much). So I give all the discs a coating of oil when I rebuild and use medium grease (Lucas green) in the main bearings. After that, it's a few drops per month through the port. A medium or light-medium oil is used. This could be SAE 30 weight motor oil, or a 80 or 90 weight gear oil. If all you can find is 3-in-1, use the Blue Bottle 20-weight oil. 3-in-1 black/red bottle doesn't last as long and tends to congeal in the hub. Keep in mind also that gear oil and motor oil use different viscosity rating systems. An 80 to 90 weight gear oil is roughly equivalent to a SAE 30 to 40-weight medium motor oil (in case all you can find is motor oil). Some sources say they grease the discs. This provides some lubrication but the Model D runs better with oil on the disc stack.

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