Author Topic: Can't fit rear brake in drum after fitting news brake shoes  (Read 1553 times)

Offline alexdecker

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Can't fit rear brake in drum after fitting news brake shoes
« on: November 19, 2023, 03:57:39 PM »
Hey all

Just installed new brake shoes from CMS bought specifically for my model. But after installing them, I can't make them fit into the actual drum. The brakes are fully retracted, but they just won't fit. Am I missing something here? Usually it goes in really easy and is actually slightly loose.

These are the brake shoes I bought: https://www.cmsnl.com/products/shoesetbrake-non-oe-kevlar_06430390405p/

And then I bought a new brake cam as the old one broke: https://www.cmsnl.com/products/camrear-brake_43141374000/

- Alex
« Last Edit: November 19, 2023, 04:19:06 PM by alexdecker »

Offline Johnny4428

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #1 on: November 19, 2023, 07:47:02 PM »
Hi Alex my new shoes I just fitted were a tight fit in the actuator recess, make sure they are seated properly, I would even take a file to the ends to make fit easier. And obviously make sure you have the right shoes.
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1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
1973 Honda CB750K3

Offline alexdecker

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #2 on: November 19, 2023, 07:50:18 PM »
Hi Alex my new shoes I just fitted were a tight fit in the actuator recess, make sure they are seated properly, I would even take a file to the ends to make fit easier. And obviously make sure you have the right shoes.

Hey, thank for the input! Can you elaborate what the actuator recess is?

Offline Bryanj

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #3 on: November 19, 2023, 07:54:18 PM »
The flat spots on the cam that the flat end of the shoe fits into

Offline alexdecker

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #4 on: November 21, 2023, 07:24:05 AM »
So found out these are Vesrah brake shoes. And they fit perfectly in the actuator recess. So I guess they just aren't a fit in general, or that CMS sent me the wrong ones…

Offline McCabe-Thiele (Ted)

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #5 on: November 21, 2023, 09:31:13 AM »
I'd check the part number of those supplied against the manual.
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http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline alexdecker

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #6 on: November 21, 2023, 04:09:47 PM »
I'd check the part number of those supplied against the manual.

Here is the part number of the Vesrah brake shoes: VB128S

And here is a picture where I have overlaid the new brake shoe on the old one. You can clearly see that the Vesrah shoe is quite a bit longer. No wonder it didn't fit into the drum.


Offline Bryanj

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #7 on: November 21, 2023, 04:20:17 PM »
You bought 750 ones which are bigger than 500/550 the middle part number should be 323 not 300

Offline alexdecker

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #8 on: November 22, 2023, 08:03:41 AM »
You bought 750 ones which are bigger than 500/550 the middle part number should be 323 not 300

Really? I know this might be misleading, but even on the packaging it says it should fit my bike?

Offline Johnny4428

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #9 on: November 22, 2023, 08:19:06 AM »
Just a thought Alex, is your rear wheel hub original or correct for your bike?
1952 Cymoto on Triumph bicycle.
1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
1973 Honda CB750K3

Offline Bryanj

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #10 on: November 22, 2023, 03:01:07 PM »
The cms link you posted says they are 750 by the part number, when fitted use a tape measure to measure the diameter of the shoes, there is also a max dia cast inside the drum.
Also has it been relined and machined too small?

Offline Oddjob

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #11 on: November 22, 2023, 04:56:45 PM »
I'm wondering IF the rear drum has been replaced by a previous owner as the 500/550 drums are renowned for cracking, maybe something like a CB500T was used instead.

Any pics of the inside of the drum and the drum in general Alex so we can see if it looks correct.
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Offline McCabe-Thiele (Ted)

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #12 on: November 22, 2023, 06:00:40 PM »
Would the inside diameter of a 500 brake hub be handy - it's just slightly under 18.0 cm between the inside edges of the liner measured with an expanding ruler. That probably 17.98 -17.99 cms.

Amended I can't read my stupid tape measure.
« Last Edit: November 22, 2023, 09:11:11 PM by McCabe-Thiele (Ted) »
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Oddjob

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #13 on: November 22, 2023, 06:34:40 PM »
Stamped on the inside of the hub Ted
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline McCabe-Thiele (Ted)

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Re: Can't fit rear brake in drum after fitting news brake shoes
« Reply #14 on: November 22, 2023, 06:49:01 PM »
If that's the case Ken then Alex should easily know if he has a 500 hub.

Only markings in my hub are E-7 & opposite B 1 3

My error it 18.0 cms less a tad not 8!
« Last Edit: November 22, 2023, 09:09:10 PM by McCabe-Thiele (Ted) »
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

 

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