Snatching front brake(TLS)

[BSA500]

We now have a non snatching front brake(although a damp day will be the complete test of it). I had to shorten the outer sheath of the brake cable so it would reach???.

[duTch]

   
 

(although a damp day will be the complete test of it).

...I bet you're not really hoping for it...

 Good to hear you've had a win...  And a bonus extra life for the cable !           


 

[BSA500]

Yep a win but it still has a judder under braking. Not many places round here that can check and true up a drum

[Angus]

The A7 1961 just got MOT advisories on the braking effort fluctuating both front and back. I am told it is the drums out of true. Never had it before and have no idea of the cause.

[Butch (cb)]

I’ve got a couple of bikes where some years I get MOT advisories for fluctuating brakes and the next year I don’t. None of them are what I would consider to be dangerous in operation, though on my Guzzi V50 (just passed this very weekend with no advisory) it is bad enough that if I ride long enough before applying the brakes (foot – linked brake) I get a lot of excess travel first off due to pad knock off.

I guess that if it bugs you enough then it’s supposedly best to have the drums skimmed when the wheel is all built up anyway.

[BSA500]

Well now the weather is chilly the brake has gone back to grabbing like a ba****d again.

[DuncanF]

Found it on a Triumph once. What was happening was that the TLS brake plate, was being used on a non-TLS hub. If you do that, the brake linings will overlap onto the section of the hub, where the spoke abutments are. This causes "sharp" edges to come into contact with the brake linings. If you look at the pics, the "sharp" edges I refer to, are the recesses where the ends of the spokes locate.

A proper TLS hub, has a flange, and the spoke recesses miss the brake lining material. One way round the problem, is to cut a small slice from the linings, so they miss the recesses. If the shoes aren't pulling exactly square  to the hub surface, it could make matters worse.

I'm not saying this is definitely the problem here, but it was one I found.

[Greybeard]

Without reading through the whole thread again: Has anyone suggested chamfering the leading edges of the shoes? I needed to do this to mine when they started grabbing.

[Rocket Racer]

Looking at the images, it appears you are running a late 60's wide shoe TLS on an early non flanged drum: so the brake shoes are trying to grip on a non brake area of the drum (where the spokes come in). The non flanged hubs are designed for narrow shoes.
Unless I'm missing something to run that brake plate you need to change the front hub.

[Butch (cb)]

So the friction material on the shoes is wider than the drum brake area? Could/should/would you reduce the height of the friction material where it is currently contacting the non braking area of the hub ... or given that this is brakes we're talking of is that maybe a short cut to dusty death?

[Rocket Racer]

So the friction material on the shoes is wider than the drum brake area? Could/should/would you reduce the height of the friction material where it is currently contacting the non braking area of the hub ... or given that this is brakes we're talking of is that maybe a short cut to dusty death?

The original FWH iron SLS brakes with narrow shoes had a good reputation in period tests of the day, but were I understand prone to wearing out fairly quickly. So narrowing the shoes certainly an option.
Personally I would fit the later flanged hub designed for that brake plate. They are readily available 2nd hand.

The later TLS brake plate already loses any period authenticity, whereas the hub is quite subtle.
My SR has the later hub (note flange visible), with a modified SLS brake plate

[BSA500]

I have been using this hub for over 20 years and its only been grabbing like a bitch the last couple. Only when its cold/damp. I have found a firm to skim the drums(judders) and a firm that can reline the shoes with a lining suitable for a brake lever and not hydraulic.
 I will see where that takes me first 

[metalflake11]

I've experienced this three times over the years, twice on bikes, and once on a transit van. Just changing the shoes cured the problem straight off. I've got no idea why it happens, I only know the effect and the cure.

[BSA500]

I've experienced this three times over the years, twice on bikes, and once on a transit van. Just changing the shoes cured the problem straight off. I've got no idea why it happens, I only know the effect and the cure.

I still have the original shoes the plate came with. First I will compare/measure against the current ones and then prob get that pair relined. They are the rivetted type against bonded currently on the bike. Be interesting to see if they are in any way different.

[Greybeard]

Grabbing could be down to the lining being loose on the shoes