How to put an oil port into an internally geared hub

December 23, 2010

I had an SRAM i-Motion 9 internally geared hub. It died. I replaced it with a Shimano Alfine 8 internally geared hub. Both of these hubs are really well sealed, and come pre-packed with grease (come to think of it, the SRAM was pretty lightly lubed in there). Other hubs, for example everything from a Sturmey-Archer 3-speed, to a Rohloff 14-speed, come with an oil port, so you can add and replace the lubricant pretty easily, and the oil has a bit lower friction than grease. So, some people put oil ports in their sealed hubs. I decided that I wanted one, too.

However, I was a little nervous about tearing apart my hub, and just putting a hole in it. Things could go wrong. So I practiced on the old SRAM shell (3 times), and for the rest of the world’s edification, I made a movie of one of the practice holes. One take, 17 minutes long. 13/64″ drill, 1/4-20 tap, nylon license plate nut.

I’ve since done my real hub, and it now has about 2 tablespoons (30ml) of Mobil 1 synthetic ATF in it. The process was pretty much like this video, except that I was much more careful about the metal bits (which are, however, aluminum, and should get eaten like chewing gum by the hardened steel gears). In the Shimano hub, there are some hardened steel races set into the hub shell itself; don’t try to drill through those. Notice also that I was pretty gentle with the steel punch; you want the tiniest little pit in the surface.

If you try this yourelf and screw up your own hub, don’t come crying to me. Nonetheless, here’s photos showing how to dismantle your hub — you only need to remove the complicated guts, in order to mutilate the hub shell. I think the grease seal may be reverse-threaded; just be aware of this possibility.

Update: I don’t know that I recommend this after all; I could never get the hub to stop leaking oil, even when I only put about a tablespoon (15mL) in. Couldn’t bring it in doors, had to keep cleaning off the brake rotor, just didn’t do what I wanted. I shot some grease in instead.

6 Responses to “How to put an oil port into an internally geared hub”

  1. Bicycler Says:

    where exactly did you drill?

    • dr2chase Says:

      I don’t recall exactly; definitely not near the hardened track on the inside of the hub shell, and far enough from the edges that it wasn’t too hard to do the work or access the plug.

  2. Bicycler Says:

    thank you for the information. I have a pristine Alfine and will attempt to drill it prior the first ride, hoping that the tapping will be successful. I have never before tapped aluminium.
    Grease is probably not the best lubricant for gears, since the grease is just pushed away from the teeth after a few turns. Gear oil should be much better.

    I figured that Shimano possibly didn’t have a really good sealing that would withstand overseas shipment and didn’t want to spill oil when they transport the hubs to the vendors. The reasoning being that Shimano itself recommends oil for successive maintenance jobs. Who knows.

    Doing Internet research, I found many postings recommending ATF. I think the origin of using ATF is just a guy that happened to have spare ATF fluid. Others read about it, did the same and ATF established itself 🙂

    ATF is often much less viscous than real high-viscosity gear oil. Gear oil like 80W-140 should leak far less and provide excellent lubrication.

    I’ll share the result of the experiment 🙂

    • dr2chase Says:

      Gear lube can be really stinky, and if it drips it make stinky drips. Synthetic ATF is all the lubrication you need for a bicycle hub, if you can keep it in the hub. I converted the video to a form that will play (youtube): https://youtu.be/Zr_WMbcVSrQ

      • Bicycler Says:

        Thank you a lot. I was searching Google for a copy of this video for hours! Thanks, man! Very nice. I guess it will be helpful for many people.

      • Bicycler Says:

        Hello, I did the drill & tap and used the highly stinky gear oil.
        Fortunately, all oil is still inside the hub. Who knows for how long it will last.

        I used a plastic screw without any sealing, but with a good amount of grease on the threads.

        Apparently the threaded black plastic cap that is fitted right above the big right-hand cup&cone ball bearing seems to be THE most important piece that keeps the oil inside. I put a good amount of grease inside the plastic cap and its threads. If it is tight, the exit on the right hand side will be approximately as high as the elevated, smaller ball bearings on the left-hand side of the hub. Thus, no oil will spill out, as the black cap turns with the hub shell and doesn’t move while cycling.

        Just for clarification, I am talking about the threaded black cap that needs a special opening tool, if one was to listen to Shimano’s advise. Not the other black cap without a thread, which is fitted between the cap I am talking about and the sprocket.

        Anyways, cycling has been very fun and the hub shifts as quick as any well-adjusted derailleur I had.

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