Horrible experience: TLS brake locked

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Tom Bramler

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Hello all together,

I’m Tom from Germany and enthusiastic owner of a 750 Commando Roadster from 1971 which I completely restored 8 years ago and use regularly (besides 2 other British bikes). The bike has drum brakes and on the front wheel since 5 years I have a TLS-brake with stiffening kit on aluminium rims (from madass). The TLS-brake showed all this years an acceptable and predictable performance (much better than my old 650 Triumph).

But today I had a horrible experience: with the first very slight brake action the front wheel instantly locked up completely and I “kissed” the road (my first downfall after 45 years of motorcycling – I’m deeply depressed). Thanks to God I had good protective cloth and helmet, was not fast (50km/h) and there was no traffic. So the injuries at man and machine are manageable and I could drive the machine back home (trembling and with walking speed – and brake worked normally again).

I haven’t touched anything for at least 2 years with the front brake it always worked perfect. The last trip was about 4 weeks ago and I had no brake issues at all. During this 4 weeks the bike was standing in my dry and heated workshop.

Currently I completely lost my confidence in my beloved Norton. I think I need a few days of recovery before taking a closer look to the TLS brake – but I fear there will be no obvious mistake because it behaved normally after the locking. Have you any ideas what could have happened to the bloody front brake?
Kind regards Tom
 
Tom Bramler said:
Hello all together,

I’m Tom from Germany and enthusiastic owner of a 750 Commando Roadster from 1971 which I completely restored 8 years ago and use regularly (besides 2 other British bikes). The bike has drum brakes and on the front wheel since 5 years I have a TLS-brake with stiffening kit on aluminium rims (from madass). The TLS-brake showed all this years an acceptable and predictable performance (much better than my old 650 Triumph).

But today I had a horrible experience: with the first very slight brake action the front wheel instantly locked up completely and I “kissed” the road (my first downfall after 45 years of motorcycling – I’m deeply depressed). Thanks to God I had good protective cloth and helmet, was not fast (50km/h) and there was no traffic. So the injuries at man and machine are manageable and I could drive the machine back home (trembling and with walking speed – and brake worked normally again).

I haven’t touched anything for at least 2 years with the front brake it always worked perfect. The last trip was about 4 weeks ago and I had no brake issues at all. During this 4 weeks the bike was standing in my dry and heated workshop.

Currently I completely lost my confidence in my beloved Norton. I think I need a few days of recovery before taking a closer look to the TLS brake – but I fear there will be no obvious mistake because it behaved normally after the locking. Have you any ideas what could have happened to the bloody front brake?
Kind regards Tom
Click to expand...
Possibly a delaminated brake shoe or a broken piece of brake shoe got wedged in the wrong place at the wrong time?
 
Firstly, you’re a lucky man, this could have been a lot worse.

Yes, a broken / dislodged lining is most likely given your description of events.

Another common failure mode of drum brakes is, as the liners wear, they reach a point where under hard braking the cam can go ‘over centre’ and lock on. But as your occurrence was with “very slight brake action” I doubt this is the case.

By the way, this would certainly restore your confidence:
https://coloradonortonworks.net/cnw-brembo-front-brake-system.html
 
I would ask how long since you last rode the bike before this happened? As these twin leaders are self-energising, if there was a reasonable coating of rust on the drum inner face, first application could result in increasing friction, hence lockup. Glad you are not too hurt, must have been a real shock to the system.
Cheers, Martin
 
Glad you seem to be ok other than being a little rattled.
Take the wheel off and look at the brakes - in a few minutes you’ll have your answer as to why it locked.
 
Hello together, thanks a lot for your unbelieveable fast replies and helpful hints. This is really a wonderful forum!
Yes - fast Eddie is 100% right: I'm a lucky man! A few bruises and a bit of bent metal is nothing compared to what could happened....
I will have a look into the brake within the next few days and hopefully give you the solution for this terrible event.
Currently I have to calm down myself (with the help of a few beers :D) and even more my wife - she drives also a bike which I restored (Triumph T140V - fortunately with disc brakes)
Have a nice weekend
Tom
 
Happy no serious injury , you will find out the brake issue once you have time for a serious look .... sorry you had to discover your brake problem the hard way ...
 
Drum front brakes are for idiots. Back in the good old days of road racing, the combination of pudding-basin helmets and drum front brakes, killed many good guys. How many ways can a drum front brake go wrong ? I can think of about 5 ways without even thinking too hard. Disc brakes are actually sane.
I have watched a few Youtube videos in which guys were riding Commandos with no helmet, but with a drum front brake. Even at walking speed, that is dangerous.
I have only ever had one race crash in which I actually believe I could have been killed. It was caused by a drum front brake. If you get them good enough for racing, the slightest over-reaction can crash you. - They should be banned. A big drum front brake looks lovely, but they are rubbish.
 
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Tom... Twin leading shoe brakes have reputation for grabbing when cold... One persons grab might be anothers locking up... Cant say mine ever suffered from this with the original asbestos linings but with the now available kevlar caution on initial application is called for.
 
I had a similar brake set up on my AC. I used to get brake lock up at slow speeds when the friction material (bonded) came unstuck from the metal shoe.
I have also seen this on a Greyhound bus. The driver knew what was causing a rear wheel to lock up. He said a shoe lining had come off. Ever since then I used
riveted shoes and I actually added some rivets to the AC brakes when I re attached the friction material. No glue holds forever but a rivet will.
 
Yes I had a rear shoe lining come off and now always add rivets.
 
The TLS on our Atlas is ALWAYS grabby at the first application ,and my SLS is the same but less so. We test at 5mph before riding off. I think it the lining material /light rust.,never really needed fierce brakes back in the day, Not so many idiots on the road then.
 
norton bob said:
The TLS on our Atlas is ALWAYS grabby at the first application ,and my SLS is the same but less so. We test at 5mph before riding off. I think it the lining material /light rust.,never really needed fierce brakes back in the day, Not so many idiots on the road then.
Click to expand...

Why does this grabbing happen on front but not rear drums on our bikes!
 
Scary stuff!

Can you post photos of the brake linings?

Which brand are they and what is the condition of the cam surface? Do they spring back good when you operate the lever by hand?
 
"never really needed fierce brakes back in the day, Not so many idiots on the road then."

Yeah - on my original '71 Commando (drums) I never noticed anything bad about the brakes; they seemed to work like all brakes worked... ;) Never had any grabbing/locking up issue. I suspect, as others have mentioned, that some mechanical failure is the cause of the OP's problem. Glad it wasn't any more serious!

It will be interesting to hear what is found when the brake assembly is examined!!
 
jimbo said:
I am voting for drum rust
Click to expand...
I'll second that and the lockup happened to me once. It was a cold night and moisture must have been just right. The bike was parked for a couple hours when I continued my journey. The front locked up for a split second but I didn't go down. I babied the bike with the rear brake over to a nearby friend and spent the night rather that take the long drive home. Every time I tested the ft brake later that night it was super sticky and would lock up the tire at walking speed. The next morning when the air temp warmed up the ft brake worked fine and never locked up again. I use a disc now.
 
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