Water-Cooled Sturmey Archer Drum Brakes

I’m in the middle of running a test to water-cool my 90mm Sturmey Archer drum brakes.

A few people in the German recumbent forum use water-cooled drum brakes in their velomobiles, so it wasn’t my idea. Velomobilize in Austria already offers water cooled drum brakes for velomobiles.

Since I live in a fairly flat area, I’m not so much interested in actually cooling the brakes, but to clean-out the dust from the brake pads before it sticks to the pads and glaces over. That’s normally the point when the brake performance deteriorates.

test set-up with 60ml syringe

As you can see, the test set-up is pretty crude. The water goes from the syringe, through the silicon tubing, to both drum brakes. Despite its Jerry-rigged appearance, it works rather well.

A little squirt of about 20 ml of water is enough to wash-out the attrition from the brake pads and to restore brake performance. Maybe a second squirt is needed (while applying the brakes) and the brakes immediately work like new again.

At first, I was a little concerned that the dirty water coming out of the drum brakes will spray around and freckle in my face, but even going downhill at 50 or 60 km/h it doesn’t.

Next, I have to find a small tank and do a proper install. I’m planning to use a fuel tank for RC planes and a clyster ball as an air pump. You press the clyster ball, the pressured air goes into the sealed water tank and pumps the water trough the tubing into the drum brakes. Easy peasy.

Update 2018-08-16
After testing the water-cooling with the syringe for a week, I did install the RC-fuel tank and the clyster ball ‘air pump’ yesterday. The clyster ball is zip-tied under right hand side of the seat, the tank is on the left. I just have to grab under the seat and pump 1-2 times. Works even better than imagined. Photos follow tomorrow (I hope).

Update 2018-08-19
Some images:
clyster ball air pump

the water tank (RC plane fuel tank)

As you can see by the dirt on the hub, there is quite some crud washed out of the drum brake hub by the water.

drum brake plates with RC hydraulic nipple

Found these little M3 nipples for RC hydraulics at Ebay. The hollow M3 screw is pretty fragile and I’ve already broke one when tightening it slightly too hard. My other drum brake plate sets will get these nipples with a bigger M5 screw.

Update 2018-10-17
So far, water-cleaning the drum brakes ‘on-the-go’ works splendid. When the drum brake performance starts to deteriorate after a couple of weeks (I ride around 320km per week), a few pumps on the clyster ball and some subsequent braking restores braking performance almost immediately. Only downside: the hubs get pretty dirty on the outside.


quite dirty after running 3,120km with water-cooling

The M5 nipples are not as tiny, but much more sturdy than the M3 nipples.
So far, so good. I’ll have to see if the water inside the drum brakes leads to some undue corrosion in the long term.

Update April 2019
I’ve added water cooling to the drum brakes of the Milan as well.


Milan front suspension strut

The DIY brake cable adjuster of the Milan drum brakes is described here.

Update December 2019:
Since cutting some notches into the brake pads, water cooling (or cleaning) isn’t necessary anymore. Braking performance improved quite noticeably as well!

Milan_Nuten in Bremsbelägen

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5 Responses to Water-Cooled Sturmey Archer Drum Brakes

  1. Rinus says:

    Hello Marc,
    I wonder,is this waterinjection done with hot brakes ? Do they wear faster when using this method ?
    great blog ! and love the e-milan ! Will do a similar conversion on my E-waw

    • Marc says:

      Hi Rinus,

      You want to use the water cooling to prevent the brakes from getting hot. So, you inject water into the drums just before or/and while you are braking hard (in front of a curve, going downhill for instance). So far, I’ve only used water cooling regularly in my trike and it doesn’t seem to change the wear behavior.

  2. linius says:

    Allright, interesting! Thank you for the info. I have an average of 40km with a maximum of 47km/h and flat ways. So my 70mm brake drums are at the moment still suffucient.

  3. taylor says:

    Would love more info on cutting those slits and the resulting cooling and better braking. Also I thought these were sealed?

    • Marc says:

      The slits in the brake pads don’t offer any cooling. They enhance braking performance.

      Actually, I’m quite hesitant to go too deep into improving or servicing drum brakes on this blog. If a person who has only faint or no practical knowledge about mechanics messes with his brakes unsupervised… Well, that could quickly end in a disaster.

      The drum brakes have a simple one stage labyrinth seal, to keep dirt and rain out. If you squirt water inside through a hole in the brake plate, the water runs out relatively unimpeded. If the drum brakes where properly sealed, the wheels couldn’t turn.

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