Ceramic bearings for Commando.

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banshee880

banshee880

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Has anyone any experience replacing stock bearings with ceramic ones? As appropriate, I would like to do so to reduce parasitic loss due to friction.
 
banshee880 said:
I would like to do so to reduce parasitic loss due to friction.
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Fully ceramic bearings are rare and for very special applications*, you probably have hybrid bearings in mind where the rollers are ceramic. The reason to go for ceramic rollers usually is rotational speed as the centrifugal force of the rollers eats quite a lot of the load carrying capacity. The difference in friction loss is actually not that dramatic and certainly it will be hardly noticable on a Norton keeping in mind what kind of speeds the bearings reach.


Tim

* e.g. pouring juices through them and subsequently turning on the cap during bottling which is quite demanding due to the absense of regular lubricants and the presence of corrosives.
 
I'll be rebuilding a 24,000 RPM milling machine spindle with ceramic bearings today. Norton crank really isn't a good application for them, even if they were available.
 
concours said:
I'll be rebuilding a 24,000 RPM milling machine spindle with ceramic bearings today.
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That's what they were invented for ..... :wink:



Tim
 
Sidetrack. Thats a heck of a tank in banshee's avatar
I'd be a little nearvous of the mounting system - any stresses could produce a cracked tank, and .....

Nortons had a bit of bother finding trouble-free bearings for Commandos.
Going back into testing phase again just doesn't seem worth it.
 
I am a tournament bass fisherman and I've put ABEC 7 hybrid ceramic bearings in most of my Shimano reels. They are noticeably smoother and make for longer casts. Lightly loaded, high rpm usage. I can't see them surviving the pounding given by a Norton.

Jaydee
 
Hello Rohan. Like the AJS Porcupine and 7C Boy Racers, the tank is braced and the brace is fixed to the frame but I do understand your concern. Hopefully it will not be a problem. Time will tell.
Scott
 
Goodo... !
You planning to go cross-country without stopping ?

Enquiring minds are wondering what color it will be too.
 
Now that was a good one. No I won't cover the US with one tank but perhaps the Isle of Man with one tank per lap as the Porcupine did when everyone else needed to fill 1/2 way through each lap.

I will paint it black but because it is made of Norton and AJS ok, and then some Triumph parts, I will put AMC on the tank rather than AJS and have the script and stripe that is in gold on the original done in polished aluminum by polishing the tank and then taping it off before painting.
 
banshee880 said:
but perhaps the Isle of Man with one tank per lap
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One tank per lap ?
what ??

One tank per race perhaps.
Assuming not too many laps per race...
 
Sorry, my post wasn't clear. One tank of gas was needed for the 1949 Isle of Man 226 mile race course that required that the other racers to pit to fill up at least once in the race. The another strategy was to use the tank as a cowling. AJS management would not allow cowlings so the engineers came up with this idea of making the gas tank in a way that it could be used as a functional cowl.
 
At 37.x miles per lap of the IoM, you'd have to use an awful lot of juice to need to refill every half a lap. !!
(and since the pits are at the start/finish line, where could you refill it at half a lap ?).

The 5 gal tank on a manx will do 3 laps, so one refill for a 6 lap race.
It only needs to do ~25 mpg to do this, comfortably.

Someone hasn't done their sums right ?

Aha, we see you have edited your post, that sounds better.
 
Yeah I read it all years ago when deciding to build this bike. Clearly I confused a few points along the way.
 
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