Single row roller bearing - fitted to the inner of the two driveside mainshaft bearings in the crankcase on all SOHC engines, both International and Manx models. This listing is for the Non-C3 (standard tolerance) version of the high quality RHP brand, as the original C3 tolerance are now unobtainable.
This roller bearing can be found in both lipped and un-lipped type, these are the un-lipped version. It does not make any difference which type is fitted - but obviously you must ensure you fit the original inner mainshaft spacer in place - between roller bearing and ball bearing - and ensure the spacer results in the roller inner race sitting approximately central in the outer race (this can be done before assembling the crankshaft, by just placing the spacer in place on top of the ball bearing with the drive side crankcase lying flat, inner bearings sitting uppermost). It is always good practice to have the roller inner race running as central as possible to the outer race, while ensuring their is some positive clearance between inner side of roller and flywheels, once the crank is locked to the timing bearing.
We also sell driveside mainshaft shims (Item 0262 and 0262b) for this purpose
Background on the difference between 'C3' fit and 'STD' fit bearings (these bearings are 'STD' fit):
If you have already looked at the detail description for Item 0019 (and if you have not already done so - we suggest you read the bearing background in that detail listing)- you will know that the original fitment in Norton SOHC engines was this same bearing - made by RHP or their predecessor - Hoffman, but in a looser 'C3' tolerance.
These 'C3' fit bearings from RHP have been obsolete for many years and remaining supplies held by bearing stockits have been virtually used up in the last 15 years, with our last stock being sold in 2020. Theye are now virtually unobtainable (although I may be able to obtain a small quantity by Special Order - but at an extremely expensive price) - but instead can still offer these RHP 'Non-C3' tolerance version.
These are still manufacutred to the same high quality by the original RHP manufacturer, but slightly more care should be taken when running in your engine after first fitting - to allow the bearings to bed in, as they will have a fractionally tighter tolerance than the C3 version.
However, I have also heard a counter argument from other well known Norton engine builders that says - as original Norton crankcases have nearly always had replacement bearings fitted over the years - so the crankcase journals start to loose their 'interference fit' tolerance, and therefore the need for fitting 'C3' type bearings also diminishes. I can see the logic to this argument - particularly as many Norton original engines used to spin their bearings anyway, but I will leave the choice with you. However, I know for my part - I will be fitting this bearing into any future engines I build for myself, and just ensure the crank spins freely and the journals are in good condition on engine assembly.
As a final point - many owners over the years did not know that Norton engines were originally fitted with C3 bearings (or sometimes called 3 spot bearings in older times - as sometimes the outer ring of a C3 bearing had 3 dots stamped on it) - so you may find that your engine has already been re-fitted with 'Std' tolerance bearings anyway, and the tolerance difference is minimal. Normally if a bearing does not have 'C3' or 3 dots ground on the outer ring information, it is a standard bearing.
Sorry these are not cheap - but as at Feb 2021 these are now obsolete too and are getting just as difficult to source as the C3 type. Therefore the price I am having to pay to source them reflects this. Again - the supply is also very limited . . . and once they are gone they are gone! (the minimum batch quantity for RHP to make a new batch would be prohibitive for us).
We do occasionally get stocks of these bearings from cheaper (normally 'offshore') brands. If you are prepared to use non-RHP brands, email us on sales@racingvincnent.co.uk and we can confirm availability - we normally have at least one of these cheaper bearings available in stock.
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