Author Topic: Drum Rear Brake Frustration  (Read 453 times)

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Mad4Bullets

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on: June 05, 2024, 03:29:31 am
Hello, Over the winter I upgraded the rear drum brake on my 2014 Classic 500 from the flimsy factory version to the newer version with the thicker reinforced backing plate. It took quite some time to bed the shoes in and creep up on the optimal adjustment. I'm was very pleased with the improved braking.

Just recently I realized that the chain was too loose and I moved the rear wheel back one notch on each of the snail eccentrics. Now I'm back to square one with the rear brake, slowly creeping up on any appreciable braking action. I would think moving the axle one notch per side would keep everything pretty much as it was but no dice. I've heard the old timers advise you should step on the brake pedal to expand the shoes into the drum before snugging everything back up. Of course I neglected to take their advice. Any tricks of the trade out there? Thank you.


zimmemr

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Reply #1 on: June 05, 2024, 12:52:55 pm
Hello, Over the winter I upgraded the rear drum brake on my 2014 Classic 500 from the flimsy factory version to the newer version with the thicker reinforced backing plate. It took quite some time to bed the shoes in and creep up on the optimal adjustment. I'm was very pleased with the improved braking.

Just recently I realized that the chain was too loose and I moved the rear wheel back one notch on each of the snail eccentrics. Now I'm back to square one with the rear brake, slowly creeping up on any appreciable braking action. I would think moving the axle one notch per side would keep everything pretty much as it was but no dice. I've heard the old timers advise you should step on the brake pedal to expand the shoes into the drum before snugging everything back up. Of course I neglected to take their advice. Any tricks of the trade out there? Thank you.

I don't know if this will help you, but when I work on drum brakes, I always leave the axle nut loose, spin the wheel and apply the brake a few times. On the final spin I hold the brake on and snug up the axle nut. The theory is that it centralizes the brake shoes in the drum and centralizes the wheel on the axle. I was taught to do it that over 50 years ago, so I guess that make me an "old timer." ;D

FWIW it can be awkward, to reach the axle nut while holding the brake on, so a helper may make things easier.


Mad4Bullets

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Reply #2 on: June 05, 2024, 03:06:48 pm
I don't know if this will help you, but when I work on drum brakes, I always leave the axle nut loose, spin the wheel and apply the brake a few times. On the final spin I hold the brake on and snug up the axle nut. The theory is that it centralizes the brake shoes in the drum and centralizes the wheel on the axle. I was taught to do it that over 50 years ago, so I guess that make me an "old timer." ;D

FWIW it can be awkward, to reach the axle nut while holding the brake on, so a helper may make things easier.

Thanks. I'll keep this in mind for the next time around. I have helper.


allanfox

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Reply #3 on: June 07, 2024, 09:47:21 am
Not sure if your brake plate is the same as the earlier bullets with the sliding plate to centre the cam, worth doing if you didn't already do so, does make a difference.

https://messageboard.hitchcocksmotorcycles.com/viewtopic.php?p=7427


Mad4Bullets

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Reply #4 on: June 08, 2024, 06:03:33 pm
Not sure if your brake plate is the same as the earlier bullets with the sliding plate to centre the cam, worth doing if you didn't already do so, does make a difference.

https://messageboard.hitchcocksmotorcycles.com/viewtopic.php?p=7427

Thanks for your response. That's the backing plate design I upgraded. I had it set up so that the the nuts were tightened just enough to allow the cast brake cam shaft housing to float. This worked well, centering the brake shoes with each application, but required a lot of travel on the brake pedal. Plus, I found the brake assembly to be somewhat flimsy. I've kept it. Who knows, I may go back to it in time.


longstrokeclassic

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Reply #5 on: June 09, 2024, 11:36:27 am
Tightening up the spindle bolt with the brake very firmly applied and ensuring the brake arm is being pulled towards and not past 90* whilst applying the rear brake are probably the two most important things required to end up with a reasonable rear brake.

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Mad4Bullets

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Reply #6 on: June 10, 2024, 02:13:59 am
Tightening up the spindle bolt with the brake very firmly applied and ensuring the brake arm is being pulled towards and not past 90* whilst applying the rear brake are probably the two most important things required to end up with a reasonable rear brake.
Thank you. Just to clarify, when you say 90*. is that a reference to straight vertical then the brake is applied, or 90* to the angle of the brake rod when the brake is applied? I hope I've made that clear.


allanfox

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Reply #7 on: June 10, 2024, 08:39:53 am
Thank you. Just to clarify, when you say 90*. is that a reference to straight vertical then the brake is applied, or 90* to the angle of the brake rod when the brake is applied? I hope I've made that clear.

Your brake arm should be no more than around 5.00 o'clock when fully applied so you are pulling it on towards the vertical but never actually vertical. One fix I believe is to modify and fit a Redditch cast aluminium brake plate as they don't warp like the steel Indians ones, not tried it but will do if I ever see one.


longstrokeclassic

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Reply #8 on: June 10, 2024, 11:20:09 am
The latter, the 90* maximum is measured between the rod and the arm.
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Mad4Bullets

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Reply #9 on: June 10, 2024, 07:23:29 pm
The latter, the 90* maximum is measured between the rod and the arm.
Understood. Thank you. That's just about where it is now, so I'm getting the maximum leverage. I think I just need to loosen the spindle nut, apply the brake firmly (With my assistant's help) and tighten it back down.


rattonshaw

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Reply #10 on: June 11, 2024, 08:20:04 am
What is the logic for slackening the wheel spindle (axle), applying the rear brake, then tightening the spindle?  The rear wheel is a QD type so the rear brake drum assembly is rigidly attached to the swinging arm.  Loosening the rear wheel spindle will only free-up the rear wheel; the rear brake assembly and brake shoes will be unaffected. 

The position of the brake shoes relative to the drum is only influenced by the position of the pivot pin (non-adjustable) at the leading part of the brake plate, and the plate for the operating cam (adjustable pivot bracket with two bolts).  I can't see why freeing the rear wheel with the brake applied will reposition the shoes.  Am I missing something?


allanfox

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Reply #11 on: June 11, 2024, 08:46:17 am
Understood. Thank you. That's just about where it is now, so I'm getting the maximum leverage. I think I just need to loosen the spindle nut, apply the brake firmly (With my assistant's help) and tighten it back down.

If it is nearly at 90 degrees with the brake off I would move the arm back a bit as you could easily pull it over the 90 when applying it, it never wants to actually be at 90 degrees.


Mad4Bullets

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Reply #12 on: June 11, 2024, 10:06:27 pm
What is the logic for slackening the wheel spindle (axle), applying the rear brake, then tightening the spindle?  The rear wheel is a QD type so the rear brake drum assembly is rigidly attached to the swinging arm.  Loosening the rear wheel spindle will only free-up the rear wheel; the rear brake assembly and brake shoes will be unaffected. 

The position of the brake shoes relative to the drum is only influenced by the position of the pivot pin (non-adjustable) at the leading part of the brake plate, and the plate for the operating cam (adjustable pivot bracket with two bolts).  I can't see why freeing the rear wheel with the brake applied will reposition the shoes.  Am I missing something?
This is exactly what I thought originally, that if the brake needed to be applied, it should be done when snugging down the brake backing plate and snail on the right side of the bike. My bike is odd in that the snails are adjusted to very different points from side to side. This is done to get an equal measurement from the center of the swingarm bolt to the center of of the spindle on both sides. When I set the spindle/snail on the left side of the bike, the brake plate actually shifts a bit. It appears to even slightly bend the right leg of the swing arma a bit. That could affect the brake shoe/drum alignment I suppose. My only explanation is there's a built quality/alignment issue. Probably best to firmly apply the brake when snugging down the backing plate, and again when tightening the spindle nut. Probably wouldn't have these issues on a Japanese bike. I remember riding a Suzuki 250 TX years ago with a mechanical rear drum brake. The braking action was sublime on that little bike. Chalk and cheese to my Classic 500.


longstrokeclassic

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Reply #13 on: June 12, 2024, 05:41:24 pm
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« Last Edit: June 12, 2024, 05:59:56 pm by longstrokeclassic »
Motorcycle enjoyment can often be inversely proportional to capacity ridden.