I cant for the life of me insert the shaft into the clutch rollers, ive lightly greased them onto the shaft to try to assemble and also put them in the hub and tried that, its a new clutch hub, original shaft, 22 new rollers, its so close its annoying
any thoughts? tricks?
email (option): taybrig@shaw.ca
Hi there,
I assume you're talking about a wm20?
If so, then check the size of the rollers. They should be 1/4 by 1/4 (if I'm in error someone will correct me). I was recently sold a set that were 1/4 by 5/16 which were labeled as being for the WM20, and had the right part number. The vendor had made a mistake.
The technical section has great advice on clutches, as I recall.
And - perhaps this is a stupid point - do check that it is 22 rollers that are required. I'm away from my files (I'm presently self-isolated/quarantined) so I can't easily check. My faulty memory says 21??
Best wishes, Allan
email (option): allanmatchless@yahoo.com
My parts list says 22 rollers.
email (option): petercomley@web.de
I had the same issue when it came time to replace the clutch hub and clutch basket on my M20. To start, I decided to use the single spring clutch as issued from the WD. I reused the 22 rollers, measured each one with a micrometer to insure they were all as good as new. Since I don't have a lathe, I decided against shaving the inside roller race of the clutch basket. Instead I honed down the clutch hub roller race with a diamond sharpening stone. You can get a set of these at Harbor Freight for about $10 in the US, or a two sided diamond hone at Lowe's hardware, a product by Smith's, about $12 US.
I stripped down the clutch, but re-installed the clutch hub on the gearbox input shaft. The hub fixing nut need not be torqued to spec, but tight enough to prevent the clutch sleeve from wobbling when the gearbox shaft is rotated and lateral force is applied to the hub. With the gearbox in 4th, I used the rear wheel to rotate the clutch hub. I wet the hone with water periodically, and applied the hone to the roller surface, keeping it flat to the surface. I checked the fit with the clutch basket and rollers about every 10 minutes of honing. I used the coarse side at the start and the fine side of the hone at the end of the process. When the hub finally slipped in freely, but still snug when in place (no lateral play), that was the end. The honing took about 30 minutes, and I figure I removed a few thousands off the race. I didn't measure before or after. It works OK in use with no issues so far.
Make sure you use some stiff grease suitable for bearings when assembling the roller assembly for keeps. I also made a leather "gasket" placed in between the inner and outer clutch baskets upon final assembly to prevent the roller grease from contaminating the dry clutch disks. The rollers are in pretty tight with little room for the grease, so it has a tendency to squeeze out both ends of the roller assembly with use.
Good luck with your project.
Dave W.
email (option): dwdiak4@gmail.com
thanks guys...i will continue tomorrow, they are the correct size and theres 22 of them as per the parts book
email (option): taybrig@shaw.ca
Forgive me Dave W. but I can't see any reason why you would need to remove any material from the races to enable a clutch to be reassembled with all the same parts that you stripped. The parts were machined to the correct tolerance at the factory, and fair wear and tear would increase those tolerances anyway????? Ron
email (option): ronpier@talk21.com
Morning all,
Sorry to hijack the thread slightly, but how are the rollers lubricated? Is it purely from the grease they are assembled with?
Thanks in advance,
Gino.
email (option): gino_kerekes@yahooooo.co.uk
Gino, grease on assembly and then a small amount of oil from the chain will find it's way to the rollers by running down the back of the clutch. Ron
email (option): ronpier@talk21.com
Ron
Who says random parts are universally interchangeable? I worked in a machine shop for years and found that bearing parts are not necessarily interchangeable. In fact ball bearing manufacturers routinely sort machined balls by measured dimensions specifically for individual race components. Bearing assemblies are sold as within spec assemblies, not parts. Same with firearms. Manual fitting is still needed to tune the assembly for proper functioning.
Hence my experience in having to fit the m20 clutch roller assembly. If your experience is otherwise, then count yourself lucky. I was taught to hand fit and test all mechanical assemblies before use. So my experience indicates that craftsmanship is still valued in a world of CNC machining and laser precision.
Dave W.
email (option): Dwdiak4@gmail.com
Dave firstly I think I missed that you were installing brand new parts? Never the less, BSA machined parts with an upper and lower tolerance as stated in the standards book. I agree that BSA did select parts on assembly to get the best fit and would have measured them to determine this.
The difference between the upper and lower tolerance for these clutch parts is just 0.0005" (1/2 thou) If both components were at the upper tolerance for instance, it would still give 0.001" (1 thou) clearance overall for the 1/4" rollers.
It concerned me that you that you removed several thou with a honing stone without measuring anything and suggested it as a remedy. I do agree that fitting the two together with the tighter tolerance can be tedious and I've know a roller to inadvertently tip over, which you can't see once assembled......So you take it off to check and start over again:persevere:
Ron
email (option): ronpier@talk21.com
any thoughts? tricks?
You say that the clutch hub is new, is that NOS or is it one of the newly made clutch hub. If so when fitting to an original shaft then this will be your problem. If you can assemble it and the unit feels clicky as you turn it then the clearance if any is too tight. This will need honing if possible, if not and its not too tight you can assemble it and add i very small amount of very fine grinding past and turn by hand. Wash all parts out and try the fit again with a bit of oil. Only try this if your fit is only a little on the tight side. If too tight then you will have to get it honed.
Tim W
email (option): t.j.walker@btinternet.com
Must admit, I wasn't considering after market parts with a poorer tolerance threshold. :thinking_face: Ron
email (option): ronpier@talk21.com
I'm pretty sure that in some cases (timing gears for example) BSA 'selectively assembled' critical parts, matching tight upper, mid and lower limit parts to produce the optimum fit...This method can produce fits that are incorrect when the required final tolerance is very small and the parts are not 'selected' to match each other...
I have had this problem more than once with timing gears when I have had a full set of NOS components for the timing side but the final gear mesh was too tight at assembly...
Equally it would have been the case with less critical parts that they would have been toleranced to produce a dimension that would have fallen between a minimum and maximum clearance. They would have then been selected randomly from within that range of sizes for assembly, producing a final clearance that would vary slightly but would still fit together in every case, being neither too tight or too loose for the application...
So, the manufacture of replica parts can be problematic when it comes to parts that were originally selectively assembled if all the tolerancing information is not available and only one of a pair or group of matching parts is being produced...This may well apply to the clutch sleeve, rollers and clutch bearing track which, being a bearing, may have been matched for a close and constant fit...
These days with CNC manufacture where machines can even adjust themselves to maintain very accurate dimensions over a production batch these tolerancing methods are less prevalent but in the past where it was actually physically impossible for a machine operator to produce everything to exactly the same size it was a subject in itself...Tight tolerances took more time to produce, required more complicated inspection procedures and resulted in more reject parts that fell outside the limits...
When, as part of my apprenticeship, I was being trained to do job layouts that detailed the manufacture of a part to guide the machinists on the production floor I was constantly told...'Don't over tolerance when it isn't needed!'.....Ian
email (option): ian@wright52.plus.com
Thanks Ron!!
email (option): gino_kerekes@yahoo.co.uk