head stock bearings on25DB

[mikerwt]

I've searched the forum but cannot find information on fitting taper bearings instead of cups and balls. Is it possible?are there drawings available?or is this a DIY modification?all information greatfully received.

[John Wakefield]

I dont think its possible to convert from balls to taper rollers as the casting for the taper roller head bearings is larger, ie there will not be enough metal to bore out the beam casting to fit the taper rollers. There are drawings of the two types in this thread http://www.greeves-riders.org.uk/for...+race+bearings

[mikerwt]

25db headstock bearings

thank you John
have down loaded the picture you suggested and think I can make some bearing holders that If measured carefully will double up as dust covers.I will have to sleep on this one for a bit.If I do eventually sort this issue out I will put drawing and bearing spec up on forum Thanks once again Mike

[dave higgins]

I bought a conversion kit from greeves motorcycles....it was rubbish!, but from memory, it consisted of a spacer to allow the outer taper race to fit into the h`/stock, & another shim/spacer to fit that sat between the id of the inner race & the top/bottom yoke boss.
Anyone handy with a lathe can make this in minuites, & do a much better job......

[John Wakefield]

thank you John
have down loaded the picture you suggested and think I can make some bearing holders that If measured carefully will double up as dust covers.I will have to sleep on this one for a bit.If I do eventually sort this issue out I will put drawing and bearing spec up on forum Thanks once again Mike

Unless the bearing tracks are worn & have to be replaced I would leave them as they are, new balls can always be obtained from a local cycle shop. Ball races are well adequate for road use, I think Greeves went for the Timkin taper rollers to handle the extra stress incurred on scramblers.

[John Pattinson]

Head Bearings

Hi Mike, I think the main problem with trying to replace head races with taper roller bearings is maintaining the correct distance between the yokes as there is much less distance to play with compared to the later Timkin type forks. I go along with John,s advice the old races are fine if you can get them...John P.

[John Wakefield]

Ball bearing head races

If you have access to a lathe you could make new races (see this link http://www.practicalmachinist.com/vb...-races-164446/ )
Lots of other motorcycles use the ball type races so it maybe that the size to suit Greeves are still obtainable. Cant believe that Greeves would have had a special size made. Maybe Bearingman can give some advice.

[dave higgins]

old waffle!

Bearing tracks are very hard...if you can machine it...it aint no good, bearing tracks are machined, hardened, then ground to the finished size.
Converting over to tapers is such an easy job, being made to sound hard, taper bearings are commonly available to suit & provide someone has basic turning ability on a lathe, then the job is easy, as for increasing the track & bearing height in the steering head, then this is only by a couple of mill & represents no problem to the security of the top & bottom yoke positions.

[mikerwt]

headstock bearings

Thank you for all the useful information. For the record I bought new cups and balls from greeves they look like they are just turned not ground and the issue I have is to remove any slack I can only just turn the bars perhaps they will bed in (he says optimistically)if I do a conversion in due course you will all hear about it.

[mikerwt]

cup verses taper

having ridden my greeves for a couple of miles I am not happy with the steering at all you either have slack or it is too tight frightening so some thing is amiss with my cups and balls ? plan "B" will be to go and talk to my friendly bearing company and see if I can get some thin enough tapers to allow me ro make suitable cup holders if I,m successfull I will put up the drawings and specs on the fotum!