drum brake improvement

[bobdo]

Hello out there,
Still a rookie at this, here goes.. I think I'm in the right heading this time.
I'm looking to get the most stopping power out of my Knuckle's drum brakes.
I came across an aftermarket front backing plate on Ebay awhile back & didn't
get it. It supposedly had a dual cam action to it & used the stock drum. The lever was considerably longer. Has anyone out there used this & what did you think? The one on Ebay is long gone & I haven't seen or heard of one since.
Also, I've heard that there are brake shoes made of improved material of some kind. Any thoughts or leads appreciated.
Thanks, Bob

[Perry Ruiter]

The dual cam backing plate is from 45 Parts Depot in Holland:
http://www.45partsdepot.com/45parts/...all.php?cid=85
Good folks to deal with, but I have no experience with this particular product ... Perry

[bobdo]

drum brake improvement

Thanks Perry for the incredibly quick reply.
This is an interesting product. Hopefully
someone has some experience with it.
Thanks again, Bob

[len]

brake

I talked to a guy on one of the toy runs up here who had that brake mod. He said it works fantastic. Also you should give Gus Karnes a call at Utopian cycle he has some tricks to make those brakes work better with the stock parts.

[bobdo]

drum brake improvement

Len,
Thanks for the lead. I found Gus' web site, I'll contact him.
I'd like to keep the stock set up, at least for awhile. If Gus
has enough tricks to make me feel comfortable in todays traffic
I'll keep the stock set up indefinitely. Thanks, Bob

[61 panman]

Knuckle Brakes

Hi Bob,
Properly set up I have found out that Knuckle brakes can stop very well. You should have no problem locking the back wheel, if you cannot something is wrong, possibly grease on your shoes.
The front wheel is where it is important to carefully set everything up. YOu want to make sure you are getting full contact btween your shoes and drum.
A safe distance never hurt either.
Doug

[bobdo]

Drum Brake Improvement

Hello Doug,
Ya, my back brake skids along pretty well, heh, heh. It's the front
brake I'm interested in. I can't say its bad necessarily, I was just curious
about any tricks to optomize. I agree with the "safe distance" idea. Unfortunately,
I work in around a city, any safe distance & it is quickly filled cutting me off. I found its actually safer to follow the guy ahead a little closer than I normally would like. When you think about it, knuckle brakes were developed for dirt roads.
Thanks, Bob

[slowjoe]

take your drum,facing plate with the inners and brake shoes to a car brake shop and have them "arch" the pads. Some places do it for free if you buy there pads.

[bobdo]

drum brake improvement

Hello Slowjoe,
That's interesting. What exactly is "arching"? I'd like to be able to describe it to my friend who has a auto repair shop.
Thanks for the response, Bob

[slowjoe]

Thats when they grind the brake shoes in the backing plate to fit exactly to the drum. Might want to turn the drum too.

[bobdo]

drum brake improvement

Hello Slowjoe,
So the idea is to turn the brake shoes down mounted onto the backing plate in order to match the ID of the drum. I didn't know that was possible. Thanks for the information. I will have him clean up the surface of the drum also.
Thanks again, Bob

[AdminGuy]

Once the wheel is built skim the drum. Chalk it up and assemble axel. Make sure shoes are seated properly. Spin tire and apply brakes. Chalk will indicate high spots on shoes. You goal is full surface area contact. You can use a file on shoes. Just don't inhale the dust.

Get the soft pads.

Arching refers to a bevel trimming of the ends of shoe pad I believe.

Hand pack your bearings but don't over grease stuff for obvious reasons.

You can drag your rear brake a bit on inital test drive to get it beded in a little better. Not sure of contact? Take it apart and take a look see at wear pattern on shoe surface. Then you'll know if you've got it all on.

Hope my limited knowledge helps a bit.

[bobdo]

drum brake improvement

Hello AdminGuy,
That's all good safe advice, and what I've done in the past. I guess this
all started with looking for the unknown trick. I was going to ask my mechanic friend if he thought chucking up the backing plate & shoes was a good idea. If he
didn't feel comfortable with it, I was going with plan B, your suggestion. I'm not a gambler, especially with parts these days. I trust my file. I owe you for setting me back on track with a safe solution. I'll look for tricks somewhere else.
Thanks, bob

[AdminGuy]

Welcome. I think the trick your looking for (front cam) revolves around altering the cam to spread or put more pressure on the shoes (shortening it). If the cam flips after progressive pad wear - your in big trouble to say the least (insert massive legal disclaimer here) . I'd look at increasing the leverage, longer arm? Stronger muscle? Fred Flintstone acuation? just kidding.

That Dual from 45partsdepot is the obvious big upgrade for city slickers. That's a real nice piece of equipment. Keep orig. w/ bike.

Follow close and split lane on brakeing. A great way to meet women. You just look over smile and wave. Hummm.... I'm giving up my antique motorcycle dirty tricks now.

[Paps]

I can't see an easy way to arch you shoes by using your backing plate. Seems to me to be a much more difficult setup and you are less likely to get an accurate arching because of this. A lathe is certainly the most accurate way of obtaining 100% shoe contact for sure. Problem is though..........you will need to make yourself a fixture which will allow you to mount both your shoes in the correct location for arching them. This fixture will need the same fulcrum points as your backing plate and these fulcrum points must be mounted in the same locations as your backing plate has them mounted. In other words....your lathe fixture must duplicate the operating and location properties as your backing plate and must be much stronger too. It must also have a holding capability to clamp your shoes without distorting them in the proper location for arching. Your drums inside diameter is what you are trying to obtain for maximum braking in arching. This fixture will also have to keep the shoes square to the fixture face. A backing plate doesn't do this. Your drum squares up your shoes upon contact instead. You need a good round shoe surface in your drum to begin with. This fixture should also be cut to a known diameter on the outside. The outside diameter should be long enough to chuck up in the lathe and also long enough to stick out past the chuck jaws to allow an indicator tip to rest on it. This indicator tip room will be used to indicate the fixture into the lathe and it will also be used to setup your shoes for arching. Once you have all this...take an accurate measurement of your drum with a pair of inside mics or dial caliper. This is the diameter you will need to mount the lowest spots of your shoes at on your lathe fixture that you made for arching. You can find the lowest spots on your shoes after mounting them to your fixture by rotating the lathe chuck with an indicator setup on the lining of the shoes. Be sure you have the shoes located roughly where they will be in relation to your drums inside diameter for this operation. Mark the lowest spots with chaulk. These low spots will be your finishined arching locations. They will also be measuring points. You can adjust the shoes now to arching location. Remember the outside diameter of your fixture?? This will determine your shoe location for arching. Now setup an indicator with a magnetic base attached to your carriage {chuck side). Adjust the indicator plunger tip square to the fixture and lathe spindle centerline. Now bump and move the whole works in until the tip touches off of the outside diameter of your fixture just enough to move the indicator needle around .010" to .015". Adjust the dial indicator bezel to set at ZERO. Now carefully crank the carriage away from the fixture towards the tailstock end of the lathe bed just enough to put the tip of your indicator about 1/2 way across the width of the shoes mounted on your lathe fixture. DON"T DISTURB OR BUMP YOUR INDICATOR!!!! IT IS SET FOR MEASURING!! This indicator represents the diameter of your fixture when its' needle is on the ZERO mark on the indicator bezel. Take this measurement and subtract the inside diameter of your drum and then divide this number by 2. This new number represents the distance from the indicator tip when it reads ZERO to the finished surface of the shoes mounted on your fixture. If this number is say... 4 inches?? Then you need to mic between the indicator tip and the lowest chalk spot on your shoes until you have adjusted the shoe low spots and fastened them to that location. The low spot and the indicator tip must be parallel to each other during this micing. There are many ways to be sure of this with just common sense. With all of this said and done....cut the lining. Don't cut all of the high spots off until you mic the shoes from shoe to shoe 180 degrees apart and take a measurement. Record the measurement ! Now setup an indicator on the fresh cut shoe surface and set it at ZERO. roll the chuck until the indicator lands on a low spot. HOW MUCH DID THE NEEDLE DROP??? Multiply the drop reading by 2 and subtract it from the mic reading you recorded. Will this be finish drum diameter size?? If yes. finish cut to size. If no?? Reset shoes on fixture. I'M OUT OF BREATH !! Paps This is the most accurate way of doing it.