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#142
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Sealed Bearings
"Phil W Lee" wrote in message ... "Ian Field" considered Wed, 15 Jun 2016 19:50:15 +0100 the perfect time to write: "Phil W Lee" wrote in message . .. "Ian Field" considered Mon, 13 Jun 2016 19:21:38 +0100 the perfect time to write: "Phil W Lee" wrote in message m... "Ian Field" considered Sat, 11 Jun 2016 22:12:40 +0100 the perfect time to write: "Phil W Lee" wrote in message news:s3polbl8655e1epl8u7jlbn94l5k5uc5nd@4ax. com... "Ian Field" considered Fri, 10 Jun 2016 19:09:02 +0100 the perfect time to write: "Joerg" wrote in message ... On 2016-06-08 19:27, John B. wrote: On Wed, 08 Jun 2016 12:45:58 -0700, Joerg wrote: On 2016-06-03 09:36, wrote: On Sunday, May 29, 2016 at 11:40:18 AM UTC-7, wrote: With all the bikes I have I also have a bike for which I built the wheels on old Campy record hub on the back and DuraAce on the front. After getting this bike back from a friend who was saving it for me while I was not in the best of health I rebuilt the wheels with new balls and Campy grease. I have mostly modern wheelsets from Campy or Fulcrum (the people who make the modern Campy hubs etc.) These wheels have sealed bearings. These sort of bothered me when I saw them because of the drag of the seals. You can tell simply spinning the wheels in a stand. But I imagined that with the weight of a person this would be insignificant. For the last couple of days I have been riding the old Look and in fact you CAN feel the difference between the open bearings and the sealed. It does coast much further and with less noise. Has anyone else noticed this? From the discussion it would appear that the lost of 2% of the pedaling energy in the wheel bearings doesn't appear to be noticeable to most people. Which brings up a point: Suppose someone will tolerate that, which sealed bearings are best? Requirements: 1. Industry standard, inexpensive, available everywhere. 2. Can be quickly exchanged without specialty tools. 3. The axles and hub surfaces the bearing touches aren't eaten away. 4. No finicky alignment. 5. QR not required. Actually, not even desired. Several of those requirements are self limiting, don't you think? Not really. Always look at automotive, they know how it's done. Mainly because if you want to sell a motor vehicle these days you must give a multi-year warranty. Car buyers do not put up with the typical one year on a bicycle. They also will not accept any chickening out like "Oh, but you must have used it on dirt roads too much and that's not covered". Can be quickly changed without special tools? Probably not, in all cases. Even in bicycle hubs that use the old cone and ball bearings you can't change the outer race. The BB bearings I roached into my old student's bikes could be swapped out with a simple punch and a hammer with some old jeans fabric wrapped around it (didn't have a plastic hammer), and for inserting you take sockets and a screw clamp. I didn't have sockets back then so I used chunks of pipe. These bearings weren't meant for bicycles but worked nicely, no more "ka-clunk" from down there. I bought them at a Timken dealer that catered to industry and farmers. From what Ian described and from what I saw on Youtube that seems to be similar with wheel bearings. Aren't eaten away? All joints that move wear so even a ball bearing is ultimately going to wear. The surfaces the bearings reside in or on shall not move or chafe. With proper bearings they won't. Finicky alignment? if there are two bearings on a single shaft then they must be aligned. If they are loose, or installed on flexible mountings of some sort, then the entire shaft will move. I don't know about bicycle versions but in automotive this is often solved by one (or both) bearings having slight tolerance in angle from straight. Or at least was when I still worked on my cars to such extent. Only fractions of a degree can suffice. Mostly no alignment was necessary but sometimes there was. You had to set them so they would not bind. But it was less work than adjusting ye olde cone-cup deal on bicycles. AFAIK: all ball type cartridge bearings have a very small amount of tilt play - its pretty much a fortuitous side effect that they can tolerate a small misalignment when 2 or more bearings carry a shaft. Most multi-cylinder motorcycles have shell bearings just like cars because cartridge bearings in the middle of the crankshaft would be a bit impractical. Generally small singles have cartridge main bearings - usually one of those will be a caged roller bearing. I always assumed that was to minimise crankshaft flexing. I'm not familiar with more recent designs, but it certainly used to be common to have caged rollers for main and big-end bearings. Of course, the down-side is that you must have a built-up multi-piece crankshaft in order to get the bearings into their correct locations, but you need to do that even on a single cylinder engine in order to fit the big-end bearing. The big end bearing was almost always a caged needle roller bearing as the big end ankle would be rather big with a roller bearing. That would be the small end, which of course is accessible by removing the gudgeon pin (wrist pin in USian). The big-ends and mains, being effectively non-replaceable (well, you could replace the crankshaft and con-rods, and sometimes get a remanufactured unit in exchange, but it was still vastly expensive), were usually much more substantial. Once on a motorcycle group, I commented that the police motorcycle on a 50s/60s police drama was pretty good at laying smoke screen - apparently those old ones had plain conrod bearings and needed a high oil ratio. Since that would mean pretty big carburetor jets, they couldn't have been very efficient. Older engines (and the oils they ran on) did have to run at higher concentrations, but I'm surprised that even with a high concentration it was possible to run a plain bearing, so would be interested to know the model concerned. The motorcycle in question could possibly have been a Francis Barnet. Then it used the popular Villiers engine - the first 2-stroke to actually supply the oil through a separate pump and along a hollow crankshaft to it's bearings and even up through a hollow connecting rod to the plain small end and out to the cylinder walls, although it was still a total loss system, with oil escaping from the bearings being (at least partially) burned. So yes, that 2-stroke was capable of using plain bearings, and did so. But not in an oil-in-fuel lubrication system. So I guess we're both kind of right. Oil in fuel just doesn't work with plains. But plains were used in a few 2-strokes. I should have remembered the Villiers 2-stroke pump-lubricated design, and I'm kicking myself, as I should have - my uncle had a fanny barnet - which was even an ex-police one (he'd had to modify it to put the civvy spec pillion seat and rear footrests back on, which were absent on the police spec model). The ex-plod 750 Commando I bought years ago had to be upgraded with a civvy seat - but the rear pegs were on it. In plod form is was technically a Norton Commander, and the 750 would have been a MkII (the first version being the 650). That would have been a much later bike though, and by that time the police were only using motorcycles for traffic duty, not general runabouts for "bobbies on the beat" in rural areas. So it was a much smaller market for the manufacturers, and only the bare minimum of modifications were made. The single seat was a requirement as the police were never authorised or insured for passengers. I don't know if you ever had reason to notice, but the electrical system was upgraded to cope with the radio and additional lights/siren, as well. The much older Fanny Barnets and BSA bantams were bought in huge numbers to allow ordinary country coppers to cover several villages in their beat, but were barely able to transport the rider, never mind a passenger! I think the 175cc Bantam was the last 2-stroke used by the police, and the 0-60mph time of that needed a calendar to measure, even fresh from the workshop with a downhill stretch and a following wind! The Commando, by comparison, was a fine motorcycle for it's time, suitable for pursuit and escort work (although as you no doubt discovered, a bit heavy on the maintenance requirements by modern standards). The back wheel was a PITA and the speedo pickup on it tended to get misaligned and ruined. Apart from that, everything was fine till it holed a piston. While doing the overhaul during repair, I discovered some **** had put tyre goo in the sump to stop oil leaks. The pushrod tunnels had been cast too close to the holes for the cylinder head bolts, so reassembly didn't go quite as planned. |
#143
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Sealed Bearings
On Thu, 16 Jun 2016 20:08:24 +0100, "Ian Field"
wrote: When the Allies overrun occupied Europe at the end of WW2, they captured among other things; the design for a small 2-stroke motorcycle. AFAICR: the Harly Davidson version was named the Chipmunk. Well amazing as it may seem, your memory is faulty. The first Harley 2 stroke seem to have had only a model number, the Harley S-126, Unamazingly at all your brain is completely faulty - I never said it was their FIRST 2-stroke. And you're also too ****witted to understand the meaning of: "AFAICR". Strange but prior to posting your little gem of wisdom you seem to have deleted the portion of my post that demonstrated how faulty your recollection actually is as there never was a Harley Davidson 2 stroke motorcycle named the Chipmunk as you fantasized. Ah well, as they say, "never attribute to ignorance what can be explained by malice". -- cheers, John B. |
#144
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Sealed Bearings
"John B." wrote in message ... On Thu, 16 Jun 2016 20:08:24 +0100, "Ian Field" wrote: When the Allies overrun occupied Europe at the end of WW2, they captured among other things; the design for a small 2-stroke motorcycle. AFAICR: the Harly Davidson version was named the Chipmunk. Well amazing as it may seem, your memory is faulty. The first Harley 2 stroke seem to have had only a model number, the Harley S-126, Unamazingly at all your brain is completely faulty - I never said it was their FIRST 2-stroke. And you're also too ****witted to understand the meaning of: "AFAICR". Strange but prior to posting your little gem of wisdom you seem to have deleted the portion of my post that demonstrated how faulty your recollection actually is as there never was a Harley Davidson 2 stroke motorcycle named the Chipmunk as you fantasized. Ah well, as they say, "never attribute to ignorance what can be explained by malice". You combine the two............. |
#145
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Sealed Bearings
"Phil W Lee" wrote in message ... "Ian Field" considered Thu, 16 Jun 2016 20:16:15 +0100 the perfect time to write: "Phil W Lee" wrote in message . .. snipetty In plod form is was technically a Norton Commander, and the 750 would have been a MkII (the first version being the 650). That would have been a much later bike though, and by that time the police were only using motorcycles for traffic duty, not general runabouts for "bobbies on the beat" in rural areas. So it was a much smaller market for the manufacturers, and only the bare minimum of modifications were made. The single seat was a requirement as the police were never authorised or insured for passengers. I don't know if you ever had reason to notice, but the electrical system was upgraded to cope with the radio and additional lights/siren, as well. The much older Fanny Barnets and BSA bantams were bought in huge numbers to allow ordinary country coppers to cover several villages in their beat, but were barely able to transport the rider, never mind a passenger! I think the 175cc Bantam was the last 2-stroke used by the police, and the 0-60mph time of that needed a calendar to measure, even fresh from the workshop with a downhill stretch and a following wind! The Commando, by comparison, was a fine motorcycle for it's time, suitable for pursuit and escort work (although as you no doubt discovered, a bit heavy on the maintenance requirements by modern standards). The back wheel was a PITA and the speedo pickup on it tended to get misaligned and ruined. I hadn't heard of that particular problem, but then, I never owned one myself. Apart from that, everything was fine till it holed a piston. Low on fuel when it went? That was often an interesting "feature" of fuel starvation, if the engine was already running fully warmed up and at high load. The holed piston had partially collapsed, so I suspect lubrication failure had been the root cause. The piston was designed with relief cut outs so that could happen without breaking up completely and causing a lot more damage. It got me home, and the faulty cylinder even fired if I kept the revs up. As I mentioned in an earlier post - some **** had put tyre goo in the sump to stop oil leaks, that probably had something to do with it. |
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