Brilliant rear drum brake

[dickie]

Last night I rode an old LI of mine. I was amazed at how good the rear brake was. When I sold it, the lad who test rode it for the buyer (who'd never seen a lambretta before) said it was the best he'd ever used. It was normal for me as it was my bike, but you get used to what you've got.

I did nothing really special with this brake. Makino 'race' shoes. GP cam. Decent quality cable.

BUT, the braking surface of the drum was in poor condition so I asked a mate to skim it in his lathe. This is what I suspect made the difference.

Just letting others know so they can try if they want.

I'm building a new bike at the moment and I'm going to rough the surface up with a dremel cutting disc. Hopefully it'll be the same.....or I'll scrap a brand new uni hub!

[Andyf]

I'm such a klutz, do i lathe it smooth or dremmel it rough?

[dickie]

I'm such a klutz, do i lathe it smooth or dremmel it rough?

Rough I reckon. My opinion, and it's not easy for me to check as it's not my bike any more, is that my mate was a bit hasty when he machined it. Thereby, slightly roughing the braking surface up.

Unfortunately, there's no way to know what he did now, because it was about 5 years ago now, but it's stood the test of time. It really is worlds apart from the typical lambretta brake.

[mikeyb1]

Brake drums and discs should be perfectly smooth, absolutely not rough. Smooth means more surface area for friction to do it's job. Roughing up the surface means that the linings (or pads in the case of disc brakes) only rub on the high spots and take a lot longer to bed in. Turning a drum in a lathe makes the friction surface smooth, but also concentric, which is just as important. In the good old days many garages had a simple lathe-like machine specifically designed to true up brake drums.

[dickie]

Brake drums and discs should be perfectly smooth, absolutely not rough. Smooth means more surface area for friction to do it's job. Roughing up the surface means that the linings (or pads in the case of disc brakes) only rub on the high spots and take a lot longer to bed in. Turning a drum in a lathe makes the friction surface smooth, but also concentric, which is just as important. In the good old days many garages had a simple lathe-like machine specifically designed to true up brake drums.

So you think that it's more concentric than usual? Surely, I'd feel some pulsing on other bikes if that were it? Also, my other lambretta and other people's that I've ridden aren't nearly as good. Everyone who has ridden it, is shocked by how good it is. Honestly, it's hard to put into words just how good it is, but the best I can say is that it's better than the hydraulic rear brake on my triumph tiger.

I don't have a clear explanation, but the lathe is the only difference I can think of.

[al pushpak]

I would say if it works for you mate that's all that matter's & at the end of the day its YOUR scooter to do with what you like

[dickie]

I would say if it works for you mate that's all that matter's & at the end of the day its YOUR scooter to do with what you like

Yes, I get that, but it's the technical aspect I'm interested in. Something is different about it and it's different in a good way, but I'm not really sure how.

I was hoping someone might have tried something similar and could shed some light on it. Seems not

[Hat]

Can only assume your rear hub braking face was out of true and the skimming has trued it up giving an increased braking area. Race spec shoes will help but won’t have a long life.