Slimline Featherbed. Gone for taper roller bearings - purely because they're abouta third of the price of the stock cup, cone and ball bearing set up. No problem in that except they stand about an eighth inch proud of the frame neck which gives a gap between the yokes and the frame which would leave the bearing be open to the elements. I can only see a way round it is by making a couple of new covers with slightly valances sides which drop over the frame neck slightly and thus cover the gap. Has anyone else come up with anything better please?
You can use the standard Commando head stock bearings as they fit in and they are so much better than the cup and cone type. I have done this on all my featherbed frames, and they are also a good up grade for the G15, N15, AJS 33 AMC duplex frames.
Don't you need a spacer on the steering stem with the Commando type bearings as they're non-adjustable? I agree they're a better solution that either cup & cone or taper rollers.
Fitted taper bearings 25 years ago ,regularly spray in the gap with spray grease .Still fine never need adjusting.
Many thanks Tony.
The question was not answered regarding use of commando bearings in a featherbed frame - is a spacer required?
I'm thinking of going this route with my slimline featherbed.
This works in a similar way to the spacer between the hub bearings by ensuring that the inner races are very slightly further apart than the inner sides of the outer races so there's no end force on the balls (although of course there is on the bottom bearing in the Commando steering head setup). So I do think it's necessary. You could calculate the length by measuring carefully between the outer race abutments and making the spacer a few thou longer. I don't think the length would be absolutely critical as the top bearing is only coping with sideways forces - unless you make a habit of doing wheelies.....
When I bought my second Commando some previous owner had actually replaced the originals with taper rollers for some inexplicable reason. It worked much better once I'd installed the correct version.
Thanks Ian, just what I needed to know.
RGM sell the spacer tube part 100006. £5.90. Not worth making your own.
That would be the right length for a Commando. Featherbed is probably different......
RGM appear to sell two types. 100006 for the Dommie and another for Commando. Look up 'spacers' and they are both on page 4.
I have recently purchased a new featherbed frame for my Manx, manufactured on Ken Sprayson's original jig, and have fitted taper roller bearings which I filled with grease. I was concerned as to whether there should be a spacer and spoke to a couple of very knowledgeable racers and tuners. They say that the spacers are not required with taper roller bearings and they don't know anyone who uses one..
I have however, fitted a nilos ring to the top of the top bearing to prevent contamination from dirt or water.
The bearings is a Timken 30205 and was bought from a local supplier. The Nilos ring is 30205A and was purchased from simplybearings.co.uk although I am sure there are other suppliers.
The bearing measurements are 25 x 52 x 16.25
looks perfect David. As you say, if they're available, why make one? I had a plunger bearer bar made for my ES2 then discovered RGM had them - I hadn't even looked. However, the one I had made was cheaper and made out of excellent quality HT steel so probably a better item.
With respect to taper rollers, there is of course no need for one - indeed nowhere to put it.
My PO fitted taper rollers so they stay. I don't know if he changed the frame but they seem to fit. Just don't do as I did and over tighten. Rollers can (maybe should?) normally be preloaded. I left mine too tight although it did not feel like it, but it badly affected handling until they were backed off a bit.