Mystery brake drum

[hennesse]

Can you identify this mystery brake drum?

It was found in a pile of K parts. The bolt holes match up with a K rear hub. The 46 tooth sprocket (odd) is non-removable (even odder) - it is part of the drum casting.

Mystery brake drum

DMH_006679.jpg (81.26 KiB) Viewed 14893 times

I guess it must fit some kind of K or XL, but I've never seem anything quite like it. Have you?

[EKHKHK56]

Nice high speed one. 49 I think is normal highest. No stampings on it Dave? Racing goodie of some sort.

[thefrenchowl]

Is it 8 inch? If not, it is a Triumph rear drum...

Patrick

[hayleyl]

Hello Gents, I agree with Patrick, looks like a pre unit Triumph rear brake drum to me. Cheers Hayley.

[hennesse]

The drum diameter is only 7 inches.

It must be coincidence that the bolt hole pattern is the same as a K/XL, and that's how it ended up in a K pile.

[thefrenchowl]

No coincidence here, Dave,

The front forks and triple trees are slightly beefed up versions of the Triumph as well, front 1/2 drum is derived from BSA front drum, etc...

Harley bought and had a look at a lot of "lightweights" from GB to save on development costs to create the midweight K which was all unchartered tech territory to them...

Patrick

[EKHKHK56]

Yes industry follows itself! Say Patrick I was wondering about tall gearing on your Bonneville Bike. About what sprockets do you run for that? Erik

[thefrenchowl]

Hi Erik,

I run a Metisse rear wheel, 18 inch.

That's the 2nd buy I made when I arrived in GB back in 1984, has served me well over the years. All alloy except disc rotor which is cast iron. (1st buy was a Colin Lyster 19 inch front wheel with twin discs, calipers and master cylinder, all in magnesium, a beauty. Similar set up was used by Lance Weill on the XLRTT he raced in GB in 1966 and 1967...)

The Metisse is a race wheel and came with all the alloy sprockets from 38 up to 49 in 1 tooth increments, 12 in all...

I gear 34/59 and 24/38 for Bonneville, I have had made 2 new sprockets just in case, 34 and 36...

I have cut in half the most likely to be used, 34 to 40 for quick ratio change without dropping the wheel off the frame...

Patrick