Comet Brakes

[Matty]

I have had my Comet for 58 years and the brakes have always been terrible - even with the original green linings and I know this has always been a problem despite the claims of the old road tests.

I had new linings a year or so ago and these were machined to fit the brake drums which looked fine.

Have done around 5000 miles since then and at first the brakes were very poor but I hoped they would bed in.

However they are a little better now, but still very poor - at slow speed they are not too bad, but after initial bite more pulling on the lever does not seem to give more braking, though they are not very spongy. It feels like brake fade due to heat, but I am sure this is not the problem for the low speeds and short distances involved.

I have tried a few theories such as shortening the trailing shoe lining, making the holes at the pivot pin a little elliptical so that the back edge of the shoe is used etc. but none of these ideas shows much improvement.

Is there a solution, (other than fitting discs - which I think is cheating), because at least two of my Vincent owning friends have exactly the same problem with both front and rear brakes.

Is there a magic lining material which would work better or is there some other fundamental problem please?

Matty

 

[davidd]

Matty,

I would think that there are some brake materials that are better, but it is very difficult to find a supplier. Vintage Brakes is quite expensive, but I have never been able to identify the material they are using. I think most of us would accept a little more wear for better braking at this point.

There are coatings that can be applied to brake rotors that increase the friction, but I am not certain that the technology is settled. The coating is ceramic, like Nikasil and they are currently using it on aluminum and titanium rotors to provide a more durable surface. It is also used to recondition large lorry brakes, which are drums. Maybe someone on the Forum knows about it?

David

 

[nkt267]

Matty,I use these people and have been very pleased with them
http://www.autoandindustrial.co.uk/
I have used other suppliers and even had my B33 fail the Mot a few years ago with new shoes that had been turned to fit..Also make sure that you drums have not cracked,a friend of mine had bad brakes and one drum had a crack near the edge that you could see opening when the brake was applied..John

 

[timetraveller]

If these are the original non finned Rapide/Comet brake drums (stretchy by now) and original steel brake plates (bendy) then that is probably the problem. Can you borrow a friends Shadow front wheel with known good brakes and try it for a few miles. If it is hopeless on your bike then it probably means that a combination of handlebar lever, flexing balance beam, inadequate brake cable and incorrectly angled brake arms are to blame. At various rallies over the years I have set up front brakes for people who had just about everything wrong. Please understand I am not saying that you have but some of the best braking figures ever achieved were on a Comet 60+ years ago.

 

[vibrac]

At Darley Moor Meeting last weekend the scruitineer said "your brakes are marginal" . I did the adjusters up untill the brakes were binding and I could hardly push it along and then he pronounced them OK, I was not worried they were new and had been just been turned to fit in my lathe using safteks substitute for AM4. after scrutineering I loosed them off, and as I expected after one good blast round the circuit and a good couple of pulls at the hairpin they worked a treat.

Much has been written on this subject.this is what I do.
1. Do what you can to stiffen up the pivot tube if you don't want alloy brake plates braze a triangle of steel alongside/between the tube and plate
2. Use a good lining and have it fitted to the shoe professionally I use saftek http://www.saftek.co.uk/ their turn around is only a couple of days.
3. Turn the linings to fit the hub use a minimum amount of packing on the pivot faces when turning
4. Always tighten the wheel spindle with the brake hard on
5. Don't overbrake Bramptons

 

[clevtrev]

Why tighten the axle up with the brake hard on ?

 

[bmetcalf]

braze a triangle of steel alongside/between the tube and plate

See attached from STOP:

 

[vibrac]

Why tighten the axle up with the brake hard on ?

I know Trev I remember your comments in Feb 2012 and I understand your point with regard to steel plates 1/2 spindles and axle holes. But it works for me, perhaps its because I dont have the E80 nuts up as tight as possible but I do ensure they are firm and flush to the axel ends so the final clamp is done by the fork ends and as your were told by some bystander at the time "it wont do any harm" certainly it always necessary on alloy plates