Forum

[another Allan]

Hi OPM. Are you saying that you found that the drum was oval, so you addressed this by filing the shoes, or have I misunderstood?

[Mark B]

The 2LS brake on my 500 is very effective. At the risk of explaining how to suck eggs etc, if you hold the brake firmly on when you tighten the nut on the spindle that will ensure that both shoes are as well centred in the drum.

[PeteF]

Mark, the front brake plate doesn't float so how can your method work. Am I missing something?

[Old Plonker Mike]

Hi Allan, I replaced the front wheel to deal with the out of shape drum.
I filed high spots off the shoes linings to make them fit the drum better (same idea as arcing/turning, but slower and using a file and no big micrometers).
Mark, I am happy to be reminded of the simplest of things in case I missed one. Often I find a mistake that I just cant believe I could make. I can be a bit overenthusiastic (or impatient as other people call it).
In my investigations into brake material, I have found Ferodo 2520v which seems to have everyone raving over it. I read the friction graphs and it looked good, but then much the same as everything else Mu values between 0.4 and 0.5. It is usually the high temperature performance that people are after, but its just the first bite that I want. I am now looking for someone who will attach it to some shoes (preferably with glue and not in the USA).
I just contacted a chap who tells me this is no longer used, but he can do all the fitting work and has material he trusts, so I will visit him and get some shoes made up and turned to fit my brake plate and drum, and see what happens.

[Mark B]

It certainly improved the 2LS shoe on my Morini dramatically, so I did the same thing when replacing the front wheel on the Bullet; as that brake was working very well anyway I probably made no difference to the set-up...

[another Allan]

Thanks for the clarification, Mike.

[Alan R]

Hi Guys---------Mention of dear old "Moo" ie}----Mu, reminded me of far-off Apprentice days including slow Brit bikes ( for an L driver that is )..."Fast" girls and a rapidly evaporating pay packet ( once a week---in a Brown paper envelope )....We must remember that it is a constant figure for the Co-Efficient of friction between two materials....a change of either materials yields a new Mu ............If the drum is oval then it's the drum that needs to be rectified first--- either a new lining or the existing one turned and trued to a concentric setting.....The overall diameter will have changed so new, oversised shoe linings will be needed here...then machined to match the new Drum dia..

[Old Plonker Mike]

Well, I now have my relined shoes, with nice sparkly black linings courtesy of the nice man at classic brake services at Whaley Bridge (which also afforded me a nice drive out). It was very noticeable that after arcing/turning one shoe's lining was much thicker than the other. This seems to indicate some notable tollerance issues with my brake plate and or shoes. This will probably explain why arcing or turning is more important to some people than to others, depending on how the tolerances add up in your brake parts. I have also realised that it is not clever to shuffle the brake parts, and need to mark them all up so that the shoes always return to their matched brake plate and always in the same position (or better still don’t take them off).

Braking is improved (even though I was not sure at first). After a hundred miles or so of bedding in on just normal use, I noticed that I am only using two fingers now for braking, and not straining all the tendons in my forearm. I am also pulling up early at junctions, always a sign of good brakes. I noticed that I am nearly bottoming out the front fork too, but think that is more to do with nice new soft springs. I think both my new linings and the ones from Hitchcock's like to be warmed up a little. I find them both unenthusiastic at first, but after a few miles of use they seem to perk up a bit (unless it is me getting used to heaving on the lever). I have managed to provoke a squeal from the front tyre (its only an SM), so I think I have a brake now that could lock the front wheel.

In answer to MarkB and PeteF, I appreciate that the front brake is not designed to float, but if you release the locknut on the brake plate you will likely find a generous amount of "float". The procedure from MarkB is useful to make sure you start with the brake in its optimum position. I suspect that the braking forces might be enough to re-arrange things anyway, but no harm starting out with it in a good position. Fractions of a millimetre do count (as do whole ones).

I feel much safer now, so thanks to all. I will update if there is any further development over the next few hundred miles, but I seem to have a functional brake now.

[stinkwheel]

I actually DO leave the brake on my 350 bullet slightly floating after experiencing extreme frustration with the braking efficiency. Allowing it to effectively self-centre moved it from dangerous to adequate.



I simply backed off the dome-bottomed pressure plate retaining nut about half a turn from fully tight. I fitted it with threadlock and when I fit the front wheel, I pull the fork legs together tightly against the wheel nuts using a camlock strap before nipping up the clamps. There is no way it can come undone like this.



The one thing that made most difference to mine was changing the lever. I'm currently using an upside down clutch lever assembly off a GPZ500s instead of the standard brake lever. It's span adjustable and has the pivot/fulcrum located further from the bar giving much more leverage. The clutch idiot switch makes a way more effective and reliable brake light switch too. Standard barrel nipple fitted right in with no alterations.

[Old Plonker Mike]

Stinkwheel, thanks for that, I am glad someone else found the "float" useful. I have been considering rearranging the brake plate to make the "float" available/useful. I might also look out for a GPZ500 clutch lever.
I have a couple of issues with the front wheel design at the mo. The tolerances on parts are seemingly very free. I have two bake plates that differ in thickness by 2-3 mm at the point that they are clamped by the cone shaped nut. Fitting the thicker of the two requires the forks to be splayed to get the wheel spindle in, which will not be good for fork performance. I cannot understand this design with the clamping nuts (speedo and brake plate) butting up against the fork legs. My Bonneville for example has a reference surface (nut) on one side of the shaft that is pulled up to the fork with a nut outside the fork, accurately setting the position of the wheel relative to that fork. The other fork leg then clamps on to the spindle where it touches, ensuring no stress or bending in the fork legs. With the Enfield design, I see no problem if there is clearance between the fork legs and the clamping nuts, but if the nuts are touching, it surely guarantees misalignment of the forks.
On the plus side, I was taking out my machine with the new brakes, and faffing about with some carb tuning, and the engine misbehaving a bit, I was trying to pull out at my road junction and got a bit flustered, and ended up grabbing at the new front brake, which firmly planted the fuel tank into my nuts. I take that to mean the front brake is now working very nicely. Thanks to all who contributed.