H: Hubs, Wheels and Tyres A bit of a puzzle

[powella]

Sitting here on this ex - milking stool ( repaired ) I am looking at the two Brake Drums you see in the Photo`s.

Both are Plain Vincent , have 10 holes and are " normal " thickness and outside diameter.

However the left Drum has every other hole at 5/16 inch , the remainder at 1/4 inch : 10 holes at 5/16 inch on the other Drum.

The Hub Diameter on the L/H Drum is 2 inch , the other at 2.3 inch with the god awful thin bit which can crack !

What`s the story , what machine did the left hand Drum come from ? Someone from around the world in Vincent land has the answer.

 

[TouringGodet]

Lots of people converted 5 hole drums to 10 holes, that might explain the 5/16 vs 1/4 discrepancy. Not sure about the hub diameter difference.

 

[greg brillus]

Series "A" drum perhaps. Are the 1/4 holes in the left drum threaded or just plain holes.......?

 

[davidd]

Having had the plain drums shatter in use it is a little difficult to understand why the heavier 10 hole hub would be used in combination with a weak drum. The increase in the center hole is a mystery to me also.

Having changed those ten little bolts and nuts quite a few times, I thought the earlier owner might have enlarged every other hole on both the drum and sprocket using just five bolts. Again, it does not make much sense to be using such weak drums for side car work or racing where gearing changes happen quite often.

David

 

[Peter Holmes]

I have posted this before, but a good few years ago, when I used to visit Furness & Searle, and they built wheels for me, they advised me never to use extreme force when putting in the hub bolts, get what you can in easily, then run a correct size drill through the rest of the holes.

 

[macvette]

Having had the plain drums shatter in use it is a little difficult to understand why the heavier 10 hole hub would be used in combination with a weak drum. The increase in the center hole is a mystery to me also.

Having changed those ten little bolts and nuts quite a few times, I thought the earlier owner might have enlarged every other hole on both the drum and sprocket using just five bolts. Again, it does not make much sense to be using such weak drums for side car work or racing where gearing changes happen quite often.

David

I found out the hard way that the recess in the sprocket and the drum flange are not necessarily compatible. The recess on the sprocket has a radius the drum flange doesnt always have. The consequence is that the drum flange is distored on tightening and fails through the bolt holes. My rear drum ( series D) grenaded at 60mph, locked evedything solid and caused loads of damage. The new drum and sprocket had the same issue so I radiussed the drum flange so it sat completeley flat. Its not obvious unless you check carefully

 

[Robert Watson]

The large bore hubs are post war, the smaller bore are prewar series A ones. You can use the post war on the prewar hubs but need to turn up some spacers.
As for the hub bolt holes, somebody has been busy with a drill...............

 

[greg brillus]

The reason I asked if they were threaded is perhaps to wind in 1/4 bolts to press the drum off the hub. In reality you should align as many bolts as you can by hand pressure or light tap with a soft punch and hammer, the other holes you should use a 5/16" parallel reamer. When restoring bikes or most other machinery where paint and plating obscures various holes, it is far better to use reamers than drill bits, as the less metal removed the better.

 

[Albervin]

I certainly hope you do not plan to use either drum!