AL BARKER wrote:Really interested in the tapered top bearing set-up... I've ordered the SKF 32006 to see if I can figure out how it will fit... I realise that more machined parts will be needed.... any advice F+F....
I need to clarify here.
I used a 32006 for my lower steering bearing conversion on my TS1. The forks are not Lambretta. They are custom made.
The machined bearing boss at the bottom of a lammy steering columb is nominally 36mm Dia. A 32908 bearing has an internal ID of 40mm. This is the bearing used in the SIP conversion kit. It has the advantage in that it will pass over the steering stop tag that is welded onto the steering columb. I'm assuming that the kit must also include a 2mm thick split bush to take up the slack between the inner bearing race (40mm) and the boss it mounts onto (36mm)? TBH the details available on this product are a bit thin and the kit still retains a ball thrust race bearing at the top.
The new SIP bearing carrier that sits into the bottom of the steering tube has an external dia of 66mm (the exposed part) which I think is only a couple of mm larger than the old dust cover was, so it has no impact on anything close by it.
However, the bearing carrier for a 32006 would have an OD of 60mm which is too big for an upper bearing carrier. It would rub and deflect the control cables.
A better solution would be to use either a 30Y/48KS, 48KS/30K, or a 48Y130YM1 bearing. These are all 30mm x 48mm so the bearing carrier OD can be reduced down to 52mm. Any bigger than this, the bearing carrier will foul the steering lock pin casting on the lower headset. The above bearings are 12, 13 and 15mm thick which offers a bit of scope should you find you're running out of locking thread. You could resuse your old locking washer and locknut. You will need a second locknut tho. I think dust seals are available?
Ian Frankland used to do a neat upper bearing Taper roller conversion kit. Alas, no more it would appear. 4 years ago the top bearing carriers were available and not the bottom. Today the bottoms are availabale but not the top ones.
So, bearing carriers are commercially available for the bottom race (albeit as part of a complete kit of parts) but I think the top carrier is something you would have to get made to spec if you want taper roller here. Easy done with a lathe.