Scottish Headstock Bearings

[IanCordes]

It will be good to see how it looks when it is done!

Ian C.

[IanCordes]

Ian
Mine is 1960 and when I looked in the parts listing it does show 34 Balls (17 upper and lower) but there is no way you can 17 in the upper race and as I said the 2 races are of a slightly different OD but there is no slack in the steering and they pinch up correctly so must have been changed at some time in the past

Hi Peter. Maybe someone found a close match on, say, a metric set? They may have had to machine the I.D. to fit, but, as they say, if it ain't broke, don't fix it!

Ian C.

[Stuart Baskill]

They are an interference fit on spigots; see photos. The cups on the bottom yoke are thicker than those on the top, but that will be obvious from the spigot depth. See photos; partly masked up ready for blasting & painting. You just have to persuade them off! They are likely to resist.... Ian C.

The bottom yoke is a taper bearing type and the top a ball bearing in this picture.You can remove the bearing centre from the yolks as they are brazed in.Then replace with another centre for ball or taper bearings.Taper bearings will increase the gap between yolks.I altered taper to ball bearings by turning down the centres and brazing back in.

[IanCordes]

Hi Stuart. I agree it is possible to change the bearing cup spigots. Here is one I prepared earlier! This for a taper bearing crown plate. What wouldn't be so easy though is to change the corresponding one which is cast into the alloy headstock on the cup and ball type bearing. This one is for a newly made-up crown plate.

I can see why you might think the bottom yoke spigot shown previously is for a taper bearing, but that is not the case. When I bought the TCS it was more or less a loosely assembled basket case, which I have stripped for renovation. The top bearing is the thinner one, which can also be found on the TA and SA models top and bottom, but this TCS had the thicker bearing on the bottom yoke. I had no reason to question its originality. The dimensions of the thin cup spigot are 0.938" diameter, 0.3" deep. My TCS bottom one is 0.938" diameter, 0.4" deep, to allow for the thicker bearing. This compares with 1" diameter, 5/8" depth for the taper roller Timken bearing spigot.

To underline all this, checking the part numbers for the different models shows that the TA and SA models; also the DB roadsters; have only one part number for their top and bottom bearings, as you would expect; M/F10-A. The TCS however has a different part number for top bearing; M/F10-B; and the bottom bearing; M13/F10. As we know, M13 is the model designation for the TC & TCS models, which concludes that the thicker bottom bearing was introduced on the TC/S models. In fact, that would turn out to be the only model it was fitted to, as the next trials model, TD, next scrambler, SC, and next roadster, DC, all were equipped with Timken bearings, the days of cup and ball bearings being resigned to history, at least as far as Greeves were concerned.

There maybe some of you thinking blah blah, we know that(!), but I didn't, Stuart didn't, I suspect there are plenty who didn't, and it may at least prevent people from buying the wrong bearings.

Ian C.

[Stuart Baskill]

The more discussion the better.I am not an expert on anything.I did have a late 1959 20SA that had taper bearings fitted on ball housings.I think it was original as the gap between the yolks was larger than usual as the fork tubes fitted snugly because they were longer.Stuart

[IanCordes]

Thanks to Colin, who has amended the title of this thread, to aid in searches in the future. It always helps if the header accurately reflects the subject matter!

Ian C.

[Colin Sparrow]

I can't take credit for that, really can I Ian, seeing as how it was your idea?

[IanCordes]

Haha! Ah well, I couldn't have done it without you, Colin!

Regards

Ian C.

[Vexis]

Well all arrived back and assembly begun.The bearing in question, fit nicely together and contain 17 balls top and bottom the cup length is .250" each one. They are both the same on the top race and the bottom.Onwards and Upwards... Vex

[IanCordes]

Looking good so far. It looks as though it is a TAS frame. You may want to turn the chain guide around, though!

Ian C

[Vexis]

Haha I’ve set it out trying finding the right bolt sizes. Think it was held together with what ever came to hand previously. Eye opener how much old BSF threads are costing. Wish I had kept all mine that were kicking around years ago.

[IanCordes]

Very true about BSF fasteners. It was recently pointed out to me by a member (Simon!) that AF are a fraction of the cost. Different spanner set needed of course, although the bolt diameters are right. I bought a zinc plating kit to restore my old fasteners; way too expensive to buy; way too time consuming to do!

Ian C.