TLS Setup

Beach · Apr 12, 2015

I have a TLS setup on my Atlas, but the brake when applied ,stays on , the brake dragging.... I wondered what the tips are for setting these up....To adjust the linkage I put both shoes levers against the brake full on and adjusted linkage accordingly...Not quite sure what I have missed...

wilkey113 · Apr 12, 2015

You may have tightened the axle while the whole set up wasn't center. Normally I'd keep the whole set up somewhat loose, spin the wheel, apply the brake. This helps to center the assembly, and then start to tighten the axle. I generally do this several times as I snug up the axle nut.
And then adjust the linkage accordingly.

Of course, this is assuming that your wheel was laced and trued, and then the drum surface relined. Your hub could be slightly out of wack, and contribute to the problem.

texasSlick · Apr 12, 2015

My TLS is centered per wilkey113, and clearance set so 50 - 60 % of lever travel results in "hard" brake action. Check that shoes retract crisply in static mode ... no binding or hesitation.

Slick

dynodave · Apr 13, 2015

??? high cable drag or shorty cable and too tight turns....lack of cable oiling
Lube the bushes on the 2 cam shafts

Bernhard · Apr 16, 2015

Disconnect cable and push brake arm on by hand, if the brake won’t release, you may have 1 or 2 seized pivot pin(s) between the pin and brake plate, a common occurrence when it is not regularly cleaned & greased.

triumph2 · Apr 16, 2015

Is the cam going over centre to the point the springs can't pull the shoes back? It is possible to add shims to the shoe ends to fix this.

acotrel · Apr 16, 2015

triumph2 said:
Is the cam going over centre to the point the springs can't pull the shoes back? It is possible to add shims to the shoe ends to fix this.

If the cam goes over-center you have crashed big time. The linings should be machined to fit the drum with the cams fully backed off - no shims. If in doubt buy yourself a disc brake. I'm still carrying injuries from the last time I crashed using a drum brake.
It is difficult to control the self-servo effect of a TLS drum brake.

texasSlick · Apr 17, 2015

acotrel said:
If the cam goes over-center you have crashed big time. The linings should be machined to fit the drum with the cams fully backed off - no shims. If in doubt buy yourself a disc brake. I'm still carrying injuries from the last time I crashed using a drum brake.
It is difficult to control the self-servo effect of a TLS drum brake.

Alan:

I do not doubt for one moment of your unhappy experience with a TLS brake. I have read several of your posts telling of difficulties controlling the braking effect of the TLS. With each reading, I have reflected on my personal experience with my TLS. I think it time to say something.

My TLS is well behaved, giving me braking power proportional to applied lever effort. There were two or three times I had adrenaline pumping situations where I grabbed all the brake I could ... I had no brake shoe grab, lockup, or self augmenting action during those panic stops. Moreover, I do not believe a disc would stop me any shorter from any legal highway speed (one time stop).

So why the difference between your experience and mine?

Possibly:

1) design difference between one brake plate and another, especially in the cam profile. IMO, this is not likely to be much of a factor.

2) there exists a critical coefficient of friction between brake shoe material and drum lining material that creates the self augmenting feedback that leads to grabbing and un-controllability. IMO, too "sticky" a brake shoe material could account for this effect.

My "gut" recommendation to anyone having grabbing with a TLS is to try a "harder" shoe material.

FWIW, my TLS is pictured below. I think it is a Dunstall. I installed it in the late 60's .... my memory does not stretch that far back to be sure what it is.

Slick

Rohan · Apr 17, 2015

Triumph BSA 8" TLS. New in 1968.

Not much brake lining left in that photo...

acotrel · Apr 20, 2015

The brake which crashed me big time at Phillip Island in about 1970 had a home-made backing plate which created too much self-servo. The first thing I knew about it was when the brake dragged and self-steered the bike taking me off into the trees during a race. On the next corner it worked perfectly even though it was after a very long high speed bend. On the next corner - I was approaching at about 90 MPH and I lightly touched the brake and it locked immediately throwing me down the road on the non-skid surface. What happens is the leading edge of the lining can heat up and become sticky. Some of us used to taper the leading edges right back to get better heat distribution. Some people even used a section of harder lining at the leading edge of the brake shoes. One of the worst drum brakes for locking was the single sided manx Norton Brake. I had a photo of a mate of mine on a 1961 Manx with the wheel locked and turned with the front tyre smoking. He broke his collar bone into several small splinters and never raced bikes again. They are really a bastard of an idea, and the combination of pudding basin helmets and drum brakes was deadly in the old days - think about why so many guys got killed in road racing in the old days. These days I use two Lockheed calipers and two Suzuki discs on the front - it is unbeatable. These days there is no good reason to use a drum front brake on any bike - they should be banned along pudding basin helmets. Motorcycles are for enjoying not getting killed on. Why would anyone want to race a bike and have anxiety about using the front brake ?

acotrel · Apr 20, 2015

I think I've had about five very high speed crashes while racing. It has been the drum front brake every time - who needs THAT ?

Bernhard · Apr 21, 2015

acotrel said:
The brake which crashed me big time at Phillip Island in about 1970 had a home-made backing plate which created too much self-servo. The first thing I knew about it was when the brake dragged and self-steered the bike taking me off into the trees during a race. On the next corner it worked perfectly even though it was after a very long high speed bend. On the next corner - I was approaching at about 90 MPH and I lightly touched the brake and it locked immediately throwing me down the road on the non-skid surface. What happens is the leading edge of the lining can heat up and become sticky. Some of us used to taper the leading edges right back to get better heat distribution. Some people even used a section of harder lining at the leading edge of the brake shoes. One of the worst drum brakes for locking was the single sided manx Norton Brake. I had a photo of a mate of mine on a 1961 Manx with the wheel locked and turned with the front tyre smoking. He broke his collar bone into several small splinters and never raced bikes again. They are really a bastard of an idea, and the combination of pudding basin helmets and drum brakes was deadly in the old days - think about why so many guys got killed in road racing in the old days. These days I use two Lockheed calipers and two Suzuki discs on the front - it is unbeatable. These days there is no good reason to use a drum front brake on any bike - they should be banned along pudding basin helmets. Motorcycles are for enjoying not getting killed on. Why would anyone want to race a bike and have anxiety about using the front brake ?

Tapering off the leading edge on a drum brake on any motorcycle is vital, if you don’t want it to grab hard and if you are really unlucky lock up. The Joe Dunphy brake that I had relined with oversize Ferodo brake linings where filed down at a shallow 30 degree taper on the leading edge, and I do the same thing whenever I check the brake linings.
As for using drum brakes for period racing, if you preferred to use discs you would be put in the non-period class, here in the UK.

TLS Setup

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