Drive side main bearing

[berger]

same here greybeard, don't know him but miss him.

[berger]

colsbeezer I don't know about oil slinger but my only advice on working a spare to measure the end float is get the micrometer on the bearings because I found out when using that method there was a small difference and the one I had eased the inner on to slide easily on the shaft was locking the crank and the one I was going to use didn't when I had got the shims correct. this lead me to get the mic out as they were the same bearing. I did have a japan made bearing for the crank and found it considerably tight on the shaft.  the two I have in hand now one is NF 206.E with 13 smallish rollers about 7mm long with the stepped cage . the other is USA made I think it says bower ku-1206-DJ and has 14 10mm long  rollers. they both slide nicely on the shaft BUT measuring them with Vernier there is a difference on the inner races width of 4 thou, probably more accurate with mic as I mentioned. Of course one has a thicker lip in the outer for the narrower rollers. apart from that it looks like the 10mm wide rollers will take more stick. IF you put your bearing on and as you say can't get anything behind it I am sure there is a puller and drawings on here that clamps on the rollers, you could use that method with maybe a soft metal cushion on the rollers

[Colsbeeza]

Hi GB. Sorry to cause undue angst. Anybody heard from Dutch yet.??
Thanks Berger. I know you went through this earlier in this post. I tried to use an old bearing which came out of the bike years ago, but different brand - an R&M. Dimensions all over the place - the Inner OD rollers included was much greater than the OE bearing.
Two suppliers I have contacted have an NF206 but seemed unaware of clearances and dimensions other than ID, OD and width. They all say they have sold 100s with no problems.
I do want to be comfortable with what I put back in.
For interest, I have attached an Excel Spreadsheet I muddled up today - A Calculation of Clearance vs Temperature difference between Inner & Outer rings. It suggests that a C3 clearance is required. Worth playing with anyway.
Why do I always go over the top.???
Col

[Swarfcut]

Col. Yes, the standard race is NF206  30 x 62 x 16 mm,  C3 grade as it needs a bit more internal clearance to allow for expansion because of its hot  running location. This clearance is to do with the actual internal relationship of the component parts. The external dimensions are the same as any other bearing of this size.

  This bearing has a twin lipped inner race, so the rollers stay in place on the inner race when the bearing comes apart. The problem with this design is that there ain't much to grip to pull the sod off the crank in order to add/subtract shims to set the crank endfloat.

 Alternative types of bearing offer an easier solution, where the outer race complete with rollers stays in the drive side case, and the inner race stays on the crank, as usual, but is easier to get a puller behind it without the caged rollers in the way.  If truth be known many standard bearings have been wrecked setting the endfloat, with pullers loading the rollers and bending the cage.

  NJ206 is the basic type, with a twin lipped outer race to locate the rollers, single lip on inner race abuts the crank web, and prevents the crank moving axially outwards, float  controlled as usual with shims behind this inner race and crank web.

 NUP206 has the same type of twin lipped outer race, a similar inner race, plus a demountable outer lip to the inner race to locate the rollers axially on the inner race, effectively limiting crank endfloat  to the allowed axial movement of the rollers, set by the manufacturing tolerance.

 Price levels seem to be competitive with the original type, and with the ease of setting the crank float (NJ206) or eliminating it (NUP206) are well worth a look if you decide to change the bearing. The cush nut has to bottom onto the drive sleeve and sandwich everything nice and solid. This is standard assembly practice.

 The original A7 Longstroke used a deep track ball race, and as such ran with no endfloat on the crank. Some forum members are successfully running with this type of simple ball race rather than roller mains. In the end its your compromise between cost, power, reliability, plus the type and amount of use the bike  will get. The cheaper ball race makes economic sense for lightly loaded low stressed motors.

 The crank web should have a clearly defined area for the inner race to seat. This may be worn away (cush drive nut too loose is the usual cause) and contributing to the bearing ending up too close to the web face. By convention, any markings on inner and outer races appear on the same side when the bearing is correctly assembled. By my reckoning the widest flare of the cage would be closest to the crank, narrowest flare towards the lip on the outer race. The line drawing above illustrates this.

 Swarfy.

[RDfella]

Cols - if your suppliers are unaware what C3 means, best not use them as clearly they're not familiar with bearings. As for tightness on shaft, why grind the inner race ID? Much easier to ease the shaft with a little emery paper.

[muskrat]

G'day Fellas.
I believe the C3 code is for extra clearance due to the bearing being a tight (press or shrunk) fit in the housing and shaft. Outer shrunk into the case, inner pressed onto the crank. If either is an easy fit the bearing will have too much clearance. Heat the case to put in the outer and the inner race for the shaft.
The rollers can be popped out of the cage (easy with a plastic cage but can be done with a metal cage) and a bearing splitter/seperator used to remove the inner (a little heat on the inner race helps). If re-using the bearing mark each roller to go back in the same place and direction.
As already mentioned if a surrogate inner with a relieved inner surface is to be used to measure end float. Both the surrogate and replacement bearings must be identical.
Some times after measuring end float with a surrogate and then putting on the new bearing the shaft can lock up when the cases are bolted up. This is because the inner hasn't seated fully. After heating the inner and dropping on I have (ha, had!) a tube placed against it and tighten the cush nut on it till the inner cools.
That's how I do it but there's always other ways to skin a cat!
Cheers

[Colsbeeza]

Thanks Swarfy, That is a great summary of the options. This sketch from the web shows these details clearly. I was aware of these different types but had not got around to thinking hard about them.
The NJ seems a good choice. No rollers in the way for Inner removal. Unlike some of you fine surgeons I am too heavy-handed to avoid roller and cage damage. Unless it is an interference fit, boiling water and a thin wedge should hopefully get it moving outwards. The NUP inner would be the same to remove. As for ball races, I am trying to imagine how to fit it all together at once and heating it up at the same time. Likely have to put the bearing on the crank, then heat the case up and get it on quickly, making sure it is tapped home in the crankcase. Then getting it off again.??
I suppose that with the NUP, you would still need shims to ensure limited oil leakage from the timing side gap – ie the 1.5 thou would still be your aim.
RDFella - I would buy two bearings, one to grind the race Inner ID to use this inner as a spacer for shim thickness assessment- a surrogate in Muskys term, and store it later in my tools storage for next time. Then fit the unground one. Maybe buy a third for next replacement, as best to purchase the third to match the surrogate ( I like that word ).
Muskrat – I quite agree that the C3 rating is because both inner and outer are an interference fit, so reducing the clearance before heat is even considered. Impossible to calculate.  Assuming the C3 Clearance roughly equates to say a 20 DegC temperature difference between Inner & Outer rings (See my Excel Sheet), then it is likely that the installed clearance of the C3 bearing is down to Normal or C2. As the engine is warmed up, it is unlikely that there will be much Delta T Inner to Outer, as the bearing rings should warm up fairly evenly due to warming oil, and friction heat from the rollers would flow both ways. The inner can go nowhere, but the outer would expand outwards. So there would be some clearance reduction due to temperature.
Great ideas here for consideration – gotta go get some prices now.!
Col

[Swarfcut]

Col.  The ball race set up is a conundrum. Assembly is relatively easy. Heat case, freeze the race, drop into place squarely with a confirmatory smack. Use  the cush nut and a tubular spacer to draw the shaft into place. Dismantling is the awkward aspect. Usual assemblies of this type require a puller of some sort, but not excessive force. Drive shaft/wheel bearing replacement on FWD cars is a typical scenario. The shaft would be expected to pass out of the bearing rather than the race leaving the crankcase. But the real world isn't like that. More likely the approach is warming the case,  dropping the bearing and crank complete, bearing can then be pulled off the crank.

    From an engineering point of view I can't see why the inner race has to be a tight interference fit on the crank. A cush nut tightened down to some 60-75 ft/lbs onto the drive sleeve does not give much scope for the race to move on the shaft. Maybe it's belt and braces, assuming Mr Average would not tighten the cush nut enough.

   The single lipped roller bearings require shims to limit the crank float. The NUP type does not, but shims should be used to position the crank laterally, to ensure the oil pump worm is not offset to any degree. Without them the crank may end up too far to the drive side. In effect the starting datum for crank lateral location is the inner face of the timing bush. Without the outer lip in place, the NUP type will allow the same initial axial movement as the other roller types. The float can be set to the recommended limit to allow for expansion and when assembled with outer lip and cush drive tightened down, the float will disappear, but you know the crank has wiggle room for when things warm up.

 All later engines, '53 onwards,  have an oilseal outboard of the bearing, to separate primary and crankcase lubricants. All shims are the same size diameter, matching the inner race, and go between the inner race and the crank.

 Thanks for the diagrams, much better than a thousand words.

 Swarfy.

[RDfella]

Agree with swarfy. Having the bearing anything more than a push fit on the shaft makes no sense from an engineering point of view. Just makes life more difficult for the fitter. Ease the shaft so you can just push the bearing on and off by hand is my advice.

[Colsbeeza]

Thanks Swarfy,
 That all makes sense, and I forgot about the importance of getting the oil pump offset right. Thanks for the reminder.
The NJ type is appealing. Do you know where I can get an NJ206 with C3 clearance and a metal cage.? Some of the supplier websites do not explain what the cage is made of. I might be a bit out of touch with modern plastics, but a metal cage feels more secure to me long term, particularly because in the NJ type, removal of the cage and rollers to remove the inner from the crank is not required. With luck, I hope it will be a long time before next stripdown.
And thanks RDFella for the advice for a push-fit onto the crank. I'll check that out with the new bearings when I get them. I have read up on the opinions for this, and I know it should not have free play on the shaft, but there doesn't seem much advantage in having it so bloody tight that you need to destroy it or the shaft to remove it providing the cush nut is on very tight - 65 ft-lb or impact driver. Ideally I'd like to warm it up a little to push it on without hammering - water at 80 DegC  would suit me.
Col

[Swarfcut]

Col.  Not much help as you are halfway around the world, but these nice folks are worth a look as regards specs, brands etc.

  https://www.bearingboys.co.uk/?gclid=EAIaIQobChMIn7SJ9O3k6AIVSYBQBh3z4QH8EAAYASAAEgKldPD_BwE

 Sign of the times and progress that metal cages are being replaced by moulded components, but the materials chosen will be well capable of performing in the working environment we have.

 RD...Good to know you view the fit of the inner race in the same practical way.

 Cheers.

 Swarfy.

[BSA_54A10]

FWIW we made up a plug out of Plasti Bond to be a dummy bearing so it was a sliding fit on the crank.
A simple machining job that even I could get right to +/- .0001" assuming my .0001" micrometer is in fact accurate as I do not have a calibration block for it.
We used this to set the end float & it appears to have worked cause the bike has not gone bang ( yet ) .
I was going to use a lump of plastic but we decided the bog would be harder so less likely to get compresses .
We did the same for honing the timing side bush making the hole in the plug a light press fit onto the hone.
Thus we could bolt up the cases and make sure the ( as we could ) that the hone was true to the cases.
labled them both and dropped them into the , never to be used  again special tool box .
Interestingly the new bearing was nowhere near the same width of the bearing that came out but judging on what the rest of the engine looked like would not be surprised if he pinched it from a shopping trolley wheel.

[Colsbeeza]

Hello Trevor,
That is an interesting approach. Where do you find micrometers to 0.0001"? I have seen them advertised, then they say the accuracy is +/-  0.001". ??? I'd like a set that says 0.0001" +/- 0.00005" eh?? My machining skills are a little lacking.
Swarfy - I picked up some NJ206 C3 bearings today, Japanese NTN. I ordered steel cages, but when I drove over to pick them up, they had Polymide/fibreglass cages. Good for -40 Deg C to 120 DegC.  If my engine gets to 120 DegC, I think I'd have more to worry about than the cages. The head office had misread the order ??? The sales guy convinced me talked me into  *roll*taking them. He said that industry customers say that they are much quieter and minimise abrasion of the rollers from the steel.!! I doubt if I'll ever see the difference. Anyway I thought I'd better get with the times and give them a go., beats going back for a second trip.! He dropped the price so I got an extra set.  I dunno  - I just get this mental picture of the crankshaft lying at the bottom of the outer ring, and all the rollers at the top*grins*.
Colin

[Swarfcut]

Col. Good call there. When everything is back together, make sure the drive sleeve splines are proud of the splines on the crank, otherwise the cush nut will bottom on the end of the crank splines, rather than tightening drive sleeve, bearing inner race and shims against the crank web. An unlikely scenario, but these machines have suffered to some degree over the years from less than ideal engineering skills, so wise to check everthing. Shims are available  to aid primary chain alignment. They go between the drive sleeve and the cylindrical spacer that the oilseal runs on.

 Cheers.

 Swarfy.

[RDfella]

Colsbeeza - MSC, the firm I get my engineering supplies from, lists micrometers graduated at .0001" starting at around £25. Those are 'normal' mikes, as opposed to digital. I don't trust digital as Idon't find them accurate. Having said that, it's possible to read a normal mike to around a quarter of a thou and that's adequate for lathe work. Tenths micrometers are usually reserved for cylindrical grinding etc.
Have a good day.