Superblend bearing profile

kommando said:

If you read the Nasa pdf it states that more crowning is added to the rollers as the capacity is increased, so by using a higher than needed capacity you get more crowning eg taper or chamfer at the edge. So the NJ 306E came with more crowning out of the box and luckily coped better with the roller inner twisting due to the centrally unsupported crank acting like a skipping rope at high revs. The NJ306E is mentioned in the oct 71 factory service sheet along with 5 other bearings, so it was available before the R&M 6/MRJA30 but not yet recognised in Sept 72 as being equivalent in durability.

Click to expand...

Well so far I have not found a Norton bearing with any crowning. I do know that some of the early roller bearings were crowned.

Crowning generally increases the tolerance for misalignment but decreases the radial load capacity due to reduced contact area. Jim

Measurements trump theory every time on the edges, but regardless the NJ 306E was in their hands and being fitted before the R&M was seen as the sole solution, then later on they must have found it also worked with the advantage of being in the catalogue as a std item.

One thing that's slightly puzzling, according to the Norton literature and the words of John Hudson etc., the pre-Superblend was supposed to have been the "MRJA30". The so-called Superblend having the "6" etched on, thus "6 MRJA30"
According to J M Leadbeater's notes (http://a20b767e.magix.net/#xl_xr_page_93), the brass cage MRJA30 was the 8/MRJA30 which had 11 rollers, the 6 MRJA30 having 13, however, every picture of a brass cage "MRJA30" that I've seen so far, (including the one in Jim's video) where all rollers are visible show 13?




http://www.ebay.ie/itm/TRIUMPH-T100-500 ... 19ef8fe82f
http://www.ebay.co.uk/itm/NOS-RHP-BEARI ... 0736940126
http://www.ebay.co.uk/itm/NOS-RHP-ROLLE ... 0715198075
http://www.ebay.ie/itm/NOS-1970-Triumph ... SweW5VZ02D

I am capable of counting rollers...well I was in those days decades ago!! I bought boxes of bearings ex Norton factory 8MRJA30 and 6MRJA30 (8 bearings to a box) From memory £12 for the roller bearings. Boxes containing the old Atlas brass caged ball race timing side bearings were £8 a box.
In fact I sold probably my last 6MRJA30 bearing to a friend restoring a 500 Dommy a couple of weeks ago ...it cost him £10 so after 30-40 years I actually made a slight profit for once rather than the usual loss.Mind you he does me favours in return so everything sort of evens out over the years.
One dealer bought a few 8MRJA30 bearings and at the time flogged them at £12 each...yet another thieving greedy b*****d.