Brake drum issues - Hitchcocks Forum

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Brake drum issues#8817

By Lord-Toady - Mon Sep 17, 2018 7:58 am

- Mon Sep 17, 2018 7:58 am #8817

Hi I have noticed the brakes on my 91 Bullet 500 are not quite right although they do work. When I bought the bike the rear brake was set up so it was far too sharp and would lock the wheel at the slightest touch and the front brake was far too weak. I adjusted the rear brake and put a new rod on as the old one was bent up and set it so I have alot of brake pedal travel which I like. The problem is when braking especially when the bike is cold and I start the run the rear brake doesn't do much and then gets to a point where it makes a loud metallic growl and then locks the wheel. It does it a couple of times normally and then it is ok and the braking is progessive however I have noticed it has started doing it a bit more recently when I am riding normally.

The other thing is my front brake this one works ok and doesnt have the growling issue and doesnt lock the wheel however it works well stopping the bike from going forward but is useless stopping it from going backwards. If I am on a hill it doesnt work and the bike rolls back unless I am really heavy handed with the brake lever. This isnt so great as I mainly like to ride the country lanes in the South Downs so I deal with hills alot.

Admittedly since owning the bike (about a year now and doing about 2000 miles) I have not had the brake drums apart to inspect them so am thinking that maybe they need some attention, perhaps new shoes and a new heavy duty cable for the front and replace some of the front braking arms etc with new shiny bits from our hosts.

Any advice would be great.

Brake drum issues#79199

By Beezabryan - Mon Sep 17, 2018 8:45 am

- Mon Sep 17, 2018 8:45 am #79199

A couple of thoughts if I may.
By the very fact that both shoes are leading Twin leading Shoe brakes only work efficiently one way - forwards.
Time open up the drums and at the very least wash out the accumulated crap, the rear in particular sounds bad.
Shiny new bits will not improve matters

Brake drum issues#79200

By ric - Mon Sep 17, 2018 9:56 am

- Mon Sep 17, 2018 9:56 am #79200

"When I bought the bike the rear brake was set up so it was far too sharp and would lock the wheel at the slightest touch"

It sounds like the brake cam bush (part No.801040) was incorrectly positioned along its horizontal axis or has suffered creep from not being secured correctly.

Brake drum issues#79201

By Lord-Toady - Mon Sep 17, 2018 10:04 am

- Mon Sep 17, 2018 10:04 am #79201

Thanks for your replies, I think the first thing I should do is open things up and take a look and at least clean everything up with some brake cleaner.

Brake drum issues#79202

By mart - Mon Sep 17, 2018 10:12 am

- Mon Sep 17, 2018 10:12 am #79202

see this article for front brake set up.
http://www.hitchcocksmotorcycles.com/pi ... -08-17.pdf
especially the bit about drilling out the top trunion which allows independent adjustment of the shoes. I get it as close as possible in the w/shop then go for a ride and experiment with small adjustments to the top arm, on the go. (It took a while but I ended up with an excellent brake. once your new shoes have bedded in adjust again.

Brake drum issues#79203

By Wheaters - Mon Sep 17, 2018 10:56 am

- Mon Sep 17, 2018 10:56 am #79203

Hi, The front brake, as already stated by Beezabryan, is a twin leading shoe type (which is why there are two brake levers on the brake plate itself). This has the advantage that in normal use, both shoes tend to "self servo" / pull onto the drum, improving their efficiency and reducing the effort needed at the lever.

This has the unfortunate side effect that if the bike is moving in reverse, it becomes a twin trailing shoe brake, so both shoes "self servo" away from the surface of the drum. You then need an almighty pull on the lever to get anywhere near the same braking.

I have a sports/trials car that was was designed to use TLS (Leyland Mini) front drum brakes. Same problem. Failing a steep hill section on an off-road trial was a nightmare because there was little or no braking in reverse to stop the car rolling back. I cured that by designing and fitting a disc brake setup. This gives equal braking forwards or reverse because there is no self-servo effect on a disc brake, although the pedal effort is higher than with TLS drum brakes (and this is why modern cars have a vacuum servo).

There is a clue in that last sentence.... a front disc brake is a "parts swap" retro-fit to many older Royal Enfields.

Built like a gun... could go BANG!

Brake drum issues#79204

By Lord-Toady - Mon Sep 17, 2018 11:08 am

- Mon Sep 17, 2018 11:08 am #79204

Thanks Wheaters it sounds like the front drum performance is reverse is normal then and nothing to worry about I will just live with it. I don't want to fit a disc because I went out of my way to get an old kickstart bullet with a front drum as I like the old style look.

I like the trials setup, my bike is getting closer to a trials bike all the time, I have the wide trials bars that our hosts do and a set of longer shocks on the back. My front spokes are rusty and I am considering going for a 21" front wheel at some point and maybe eventially the 18" rear with a chunky tyre.

Brake drum issues#79206

By enfield_trials - Mon Sep 17, 2018 11:46 am

- Mon Sep 17, 2018 11:46 am #79206

@Lord-Toady
that why i love Royal Enfield. you can transform them to your taste.. easily , just play with wheels/handle bar/petrol tanks. they look equally good.