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Re: Front Wheel and Brake Query

Thanks Ron. I know where the cone shape bearing goes, but it is a funny shaped spacer that looks like two spacers welded together; one with a smaller outside diameter than the other and another plain spacer.

Kind regards

Pat

ps It is a WM20.

email (option): sacombsashtrees@hotmail.com

Re: Front Wheel and Brake Query

Hi Neale

I would not know how to check if the drum is within limits or over size, as I do not know what was standard.

My micrometer goes up to a few thou over six inches.

Kind regards

Pat

ps It is a wm20.

email (option): sacombsashtrees@hotmail.com

Re: Front Wheel and Brake Query

Well I'm not sure what you have there Pat. Sometimes a picture tells a thousand words. This is what you should have. Ron

 photo Scan-130223-0002_zpsd8d14ae5.jpg

email (option): ronpier@talk21.com

Re: Front Wheel and Brake Query

Hmmmm! One of them looks like number 47.

Thanks Ron

email (option): sacombsashtrees@hotmail.com

Re: Front Wheel and Brake Query

Pat,

Re brake
Original lining material was 0.140" thick when new.

Your described symptoms suggest brake drum is oversize.

Original new drum 7.015"-7.020"

Max oversize 7.040".

It is possible to go beyond the max oversize, but at your own risk.
Non standard thicker linings can be fitted and machined to suit your drum.

Given that you are unable to measure the drum:
I suggest you locate a motorcycle drum brake specialist and use their services.
Local car brake specialists can bond new linings on and radius grind them, however the modern non-asbestos material generally used results in a woeful motorcycle brake and radius grinding is not what you need.

Seek a specialist who caters to the historic motorcycle racing scene, they will have good lining material and know how to machine the shoes in-situ on the brake plate.
Don't forget the shoe pivot is radius-adjustable.
Also, I have found many brake plates to be bent/distorted from 70 years of use and abuse.
The cam, pivot and assembled axle must be in the same planes in both directions.
And the anchor must properly line up with the shoulder bolt at front and stay at rear, if the brake anchor or stay has to be flexed to install, the cam, pivot and axle can be pulled out of line.

Any misalignment results in incomplete contact between shoes and drum and adds sponginess.

It is time consuming and if you can't do it yourself it is costly, but as with anything, close attention to all the details makes the the difference between poor and good performance.

Re spacer
Washers may be stuck together with rust or paint, or someone's bodge, but there are no welded spacers used in M20 wheels.

All parts books 1940-1948 list two 36-3528 washers fitted between speedo drive and fork (drwg #47).
Curiously, Russell Motors list claims only one 36-3528 per front wheel.

36-3528, Front Hub Spindle Locknut Washer is identical part and number to engine idler pinion thrust washer, its dimensions are: 0.640” x 1.250” x 0.125” thick.

I have determined that most probably BSA intended these washers to be used on an "as required" basis to make up for variations in the width of 1940 and later forks,i.e don't force the fork apart by using 2 washers if there isn't room, and don't spring fork blades together together with axle nuts it there is room.

Drwg #46 is 66-5524, Front Hub Washer (Speedometer Drive) (1) (goes inside speedo drive, 0.640” x 0.950” x 0.078” thick)




email (option): n.gentner@bigpond.com

Re: Front Wheel and Brake Query

Again, thank you for all your help.

This forum never ceases to amaze me as to how many people give up their time and knowledge to help others out.

Kind regards

Pat

email (option): sacombsashtrees@hotmail.com

Re: Front Wheel and Brake Query

Pat,

Happy to help others screw em together "proper".

Neale

email (option): n.gentner@bigpond.com

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