Re: Commando Main Bearings with a Nourish Crank

The "superblend" bearing, or whatever you want to call it, is probably as good as you can get for a Commando engine. I rebuilt my bottom end last year and put the old Superblends back in.

As the Nourish cranks are very rigid its possible that the shaped rollers are not really needed. Standard rollers would suffice?. On balance I would probably stick with what is known to work.

Superblend bearings do not have shaped rollers, Superblend is purely referring to the crown on the very edge of the roller which is on all roller bearings, the rest of the roller is parallel. The amount of crown is determined by the load and specifying a roller for a heavier load gave a larger crown which had the benefit of coping with a whippy crank. SKF 'Superblends' are not known as 'Superblends' by SKF, this was a marketing term that Norton and RHP came up with and has caused confusion ever since. To get any SKF roller bearing in 'Superblend' form you add E to the end of the bearing number, so NJ604 becomes NJ604E, if its being used in high temps then also specify a brass cage instead of the std nylon cage. The E stands for extra or extreme duty bearings.

So "superblend" bearings are not sold by SKF however they do supply bearings with rounded crowns and extra rounded ones for HD use which may be beneficial with whippy cranks although it probably does not apply with Nourish cranks. HMMMMM!,we have not really answered your question. Bearing in mind (pun!) that the bearing size in use was orriginally specified for a 500cc motor thats now an 920 I would plump for the extra/extreme duty and brass cages.

But adding some extra crown at the edge is not shaping the roller, it remains parallel along the length of the roller. For all the extra cost vs dismantling cost I would fit them too, I have them in a B44 as a test and no issues.

If Mick Hemmings did the crankcase work I should think if there were any issues with the main bearings he would have let you know. If the bearings were in good condition when you re-assembled it, I should think there is nothing to worry about. Main bearing failure is almost a thing of the past. Lower compression, better oil and other improvements have solved the early problems.

NJ306E C3 on Drive Side

High capacity ball bearing on the less loaded timing side (extra balls) to give positive crankshaft location, required as the timing end of the crankshaft drives the oil pump worm and timing gear sprockets that drive the chains, and also allows the drive side roller bearing to run without lateral "wobble" plus a bonus of lower friction too and being a ball bearing, can handle all the "whip" it might encounter...(if any) ....No discussion from me on this recommendation.

See attached image of bearing:

Les