Fixing N360 guide slot wear.

[Oran]

Will do that and the bronze bushings arrived yesterday, so I should be able to do it this weekend. It looks like I will have to invent some way of pulling the ends off the planet axles. That will be an interesting challenge.

[Oran]

I've successfully fitted the bronze bushings, so I now have a unique hub. One that will survive longer under my abuse hopefully.

The planets axles were easy to take apart as the ends are a push fit. Someone had the sense to put a 1.5mm hole in the end so I could tap the axle out using a snapped off drill bit, see photos.


With the ends removed the axles were 1.5mm shorter and I was concerned this may cause a problem. So I pushed the axles a mm out of other ends so that they are all now within 1/2mm of the original length. The bushings are a perfect fit on the axles and rotate freely. The O.D of the bushings is 8mm and the slots are 8.6mm so this is also a good fit. The bushings should rotate in the slot so mustn't touch both sides. The original ends are 8 - 8.3mm with a 9mm O.D O-ring.



It looks like there is good chance the bushings will preform correctly. The axles are polished steel and should rotate nicely inside the bushings. The guide slots are mat aluminium so I,m hoping the bushings will roll with minimal wear. The vast majority of the wear should therefore be concentrated on the I.D of the bushings. The question know is will they stand up to the loads and how fast will they wear?



Initial testing has gone very well. Although at the moment the hub is installed temporary on an old maintain bike so I can't shift ratio whilst riding. The usual bike is in bits having it's frame painted. I took it for ride up a hill a few times whilst cranking the pedals hard and at times broke the min sprocket ratio rule. Performed normally and nothing has broken yet. My initial impression is that it's more efficient, particularly it low sprocket ratios and high torque situations. The normal squishiness feels a lot smoother and that less torque is being eaten up inside the hub. It's early days and it could just be because the hub is new, or its a warm day, or I was feeling enthusiastic. A bit to good to be true if it really had increased the efficiency. Time will tell and I still have to test shifting under load. I'm expecting it to be easier to shift. In a way it has already been shifting under load as that is what the squishiness is. Interestingly there is no auto shifting even with no cables attached, I was expecting it having freed up to planet axles.

[Normand_Nadon]

WOW! THat is what I call Impressive!!!

Do you have the brand and part number of your oillite sleeves? I will be taking my hub appart sometime this summer...

Did you refilled the hub using the same fluid or did you try the Santotrack one?

[Oran]

If they do the job it will be.

I took a brand new hub straight from the box and the only thing I did was swap the planets and their axle's for the modified ones. I would rather treat the traction fluid experiment as a separate project. If the fluid wasn't right and the hub slipped it could damage the polished surfaces. What I could do is use the worn out hub with the new planets as a traction fluid test hub.

I wouldn't be too quick to modify yours yet. Wait until I've done a few hundred miles and assessed the wear rate. The part number is AM050804 and brand is Oilite if you want to get some.

[Oran]

My bike is now back together and looking very smart. A few new parts including a chain, the old one had done over 5000 miles (8000km) since I got my first hub. The modified hub is performing well so far, it's hard to tell if it's any different from an ordinary hub. It is noticeably more efficient but that's probably because the stator is unworn. A new chain also improves the efficiency. Shifting under load is a little easier but not as much as I had expected. It's hard say if this is all due to the bushings or other factors.
So far I'm very pleased with the result. My only concern now is the bushings are not meant to be used like wheels. Could they fail from fatigue and if so how will the hub react to a badly misaligned axle.

Time to do a few more miles and find out.

[Normand_Nadon]

I don't see any reason why oilite seals could not be used as "wheels" the outer and inner material are the same and the rotation is really not that important...
As long as the needle bearings in the balls are working fine, keeping them from spinning the axles, I don't see what couls cause a problem... and between you and me... It is surely a lot better than using a o-ring as a wheel!!!

[Oran]

Well said, I don't know why I'm worrying. Especially as the hub has just survived the ultimate test.
I took my trailer to collect some cable that had been found on a beach clean and was destined for the bin lorry. It was in the most enormous knot which took a few hours to sort, the sea has a habit of doing that.
I took the following photo at the top of one of the hills on my way home.
I hit the bottom of the hill at 17 mph and by half way up I was down to walking pace and cranking the pedals with all my strength at only 30 rpm. That's about as much torque as I will ever be putting through the hub.



I weighed the cable at 65kg (140lbs) and it’s a fibre optic cable of some sort. I have no idea what to do with it I must have about half a mile of it.



I stripped back the various layers and the core is made of plastic and doesn’t seem to transmit light. Maybe there is a very thin glass fibre within it but I haven’t been able to find it.

[Normand_Nadon]

wow! that is a cable! There is a fiber in the center of the last transparent plastic bit... it is so small it can barely be seen with the naked eye.

A fibre won't transmit light unless it is correctly jointed (fused) with a terminal. If the cable was twisted what so ever, the fiber might be broken inside... the bending radius is about 8-10" normaly

[Oran]

You know how I said I thought the modification had increased the efficiency but couldn't pinpoint why. I put it down to the hub being new and unworn. It occurred to me today that the wear is coursed by friction obviously. Friction wastes energy and where's that energy coming from? I know that it took hundreds of miles to remove the metal. However the axle ends are rounded and smooth and not designed to cut metal so the frictional force must be quite large. In high torque situations this friction is occurring during every pedal stroke which must add up to something.

Maybe now I have the worlds most efficient hub, probably by only 1/4 of a percent. The gain it efficiency will however be greatest when the hubs overall efficiency is lowest so the benefit will be disproportionately large.

[Oran]

First one hundred miles completed successfully and nothing to suggest anything is wearing out fast. I haven't opened it, I'm going to wait until 500 miles as that's the distance my first hub had done when I opened it. That way I can make a comparison with the photos I took.

I'm always expecting something to go badly wrong, like it's a precision engineered thing that's going to get messed up by changing one thing. The reality is that it's pretty basic engineering, however there's no doubt that some aspects of the design will have required extensive research.

I should complete the mileage in the next month and will post an update then.