Author Topic: Drum Brake Modification  (Read 1008 times)

scooterfan

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Drum Brake Modification
« on: September 19, 2020, 07:26:57 PM »
Since I bought my Agility almost two years ago I was never impressed with the drum brakes at the rear. The drum pads and the drum have been cleaned and sanded twice, but the result was never a big improvement.
So I had a look at a couple of Youtube videos and decided to do a modification with a slight difference myself.

Firstly, the rear disc pads have been cleaned with a fine sandpaper, and the glaze on the drum has been removed with sandpaper again.
Then a couple of grooves have been cut at an angle on both brake pads - in a way that loose brake dust will be guided  towards the outer (outlet) part of the drum. I thought cutting the grooves this way should make it easier to get rid of loose dust generated by normal friction.
According to some videos on Youtube grooves on the pads actually cause a better grip on the drum. I was not sure about this, but decided to try it anyway.

I then decided to try something different - sanding the bottom part of both pads down - in a way that the bottom part on both pads are thinner (more worn) than the upper part of the brake pads. the reason being - I noticed that when the brake lever gets pulled, the movement by the upper parts of the pads towards the drum are far more than the movement of the bottom parts of the pads.
Right or wrong - I thought if I left the pads as is there would be no guarantee that braking results would be better than when the top surface of the pads presses harder than normal against the drum. So the bottom part of the pads have been skimmed down to cause a better leverage on both pads.

Long story - but I am more than happy with the results. For the first time in almost 17 000km km covered by myself on the Agility, it can be stopped from 80km/H to Zero in quite a short distance - just by using the rear drum brakes !
 
I guess the lifespan of brake pads at the rear will be much shorter in future - but on a positive note, I think the disk pads in front should now last much longer. Simply because I always use both brakes at the same time, and the brakes at the rear now helps to brake the scoot more effectively.

A photo of the modified pads at the rear can be seen below.
Life is a journey. Just spend some time, and enjoy the trip.

CROSSBOLT

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Re: Drum Brake Modification
« Reply #1 on: September 19, 2020, 10:38:02 PM »
Nice job!
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
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Iahawk

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Re: Drum Brake Modification
« Reply #2 on: September 20, 2020, 02:13:15 PM »
rear drum brake improvement?....Nice!....I agree, mine is pretty worthless, too. It appears the shoes make contact with the drum on only a very small portion of the braking material. I like your idea to get around this by shaving down part of the material.

How did you cut those grooves? and was there a reason for the shape and spacing of them?

The timing of your post is great..I have a new set of EBC rear brake shoes out in my garage waiting to be installed on my scoot. Mine isn't due to worn out brakes (2900 miles on scoot) but due to terrible pulsation in the back brake. I've pulled the wheel and cleaned the brake shoes and drum and the first time the pulsation went away for a short time. The second time I did it the pulsation didn't change at all. (really irritating to apply rear brake and have it pulsate)

I'm hoping a cleaning and new shoes will solve the issue because the other alternative is that the rear drum is warped and if that's the case I'm screwed because I don't want to spend the money on a new rear wheel.
2010 People S200 - sold after 8 wonderful years!
2014 Ninja 300
1996 Honda Helix
1984 Honda Nighthawk 650

scooterfan

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Re: Drum Brake Modification
« Reply #3 on: September 20, 2020, 04:09:24 PM »
rear drum brake improvement?....Nice!....I agree, mine is pretty worthless, too. It appears the shoes make contact with the drum on only a very small portion of the braking material. I like your idea to get around this by shaving down part of the material.

How did you cut those grooves? and was there a reason for the shape and spacing of them?

The timing of your post is great..I have a new set of EBC rear brake shoes out in my garage waiting to be installed on my scoot. Mine isn't due to worn out brakes (2900 miles on scoot) but due to terrible pulsation in the back brake. I've pulled the wheel and cleaned the brake shoes and drum and the first time the pulsation went away for a short time. The second time I did it the pulsation didn't change at all. (really irritating to apply rear brake and have it pulsate)

I'm hoping a cleaning and new shoes will solve the issue because the other alternative is that the rear drum is warped and if that's the case I'm screwed because I don't want to spend the money on a new rear wheel.


The rear drum brake was pretty useless on my Agility as well. Quite dangerous actually - my driveway is quite steep and when the scooter has been rolling backwards the rear brake never worked at all. And when I was pulling the front brakes (while rolling backwards on the steep driveway) the front wheel always tend to lock. Then the scooter started sliding backwards and I had to do some gymnastics to keep the scooter upright.

I almost gave up all hope to get the drum brake work properly, but fortunately stumbled across some Youtube videos about drum brake   modifications. Some owners cut grooves at a 90 decree angle - others cut grooves at an angle as shown at my photo. I could not find any comments about the best way to cut the grooves - I just thought the way I cut it might help to direct brake dust to the open (outlet) side of the drum.

I just used a sharp knife to cut the grooves. Was planning to use a hacksaw, but could not find it. The grooves were widened with folded sandpaper. The pads are quite soft - so it's quite easy to cut the grooves.
I just cut 3 grooves on each pad - one groove has been cut halfway between the top an bottom part. The other two have been cut toward the top an bottom end.
I noticed some people cut 4 grooves on each pad. The grooves on my pads are quite long - if it was shorter I would probably have cut a 4th groove as well.

The wear on my scoot's pads were uneven as well. I don't think there is any reason to worry about a warped drum on your scooter. I think the way the brake pads work is actually the cause of uneven wear.
I think the slightest uneven wear actually prevent the brake not to work properly. That's part of the reason why I decided to shave the pads down at the opposite side where most wear usually seem to take place. 

This mod actually improves the riding experience on my scoot completely. Stops suddenly became much quicker and i think a lot safer. We often have loose gravel on our tar roads and I was always dead scared of the possibility of pulling the front brake on loose gravel....

Anyway - should you decide to try this mod, it will be interesting to hear about your experience.
Life is a journey. Just spend some time, and enjoy the trip.

Iahawk

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Re: Drum Brake Modification
« Reply #4 on: September 21, 2020, 01:29:26 PM »
Anyway - should you decide to try this mod, it will be interesting to hear about your experience.

Scooterfan - great info! I think I will give cutting grooves a try. I may have found some of the same videos you saw on youtube showing people cutting grooves in their brake shoes.

I pulled the rear of my scooter apart last night (took a lot pf photos to document, as there isn't much info available on the S200s) and also practiced cutting a few grooves into my old brake shoes. I used a hacksaw and you are right, it was much easier than I anticipated. My cuts weren't as nice as yours so I have a little more practicing to do!

I should have time this evening to put the new shoes on and get the scoot put back together.

Do you have any concern over the brake material crumbling or deteriorating at a faster rate after the cuts?
2010 People S200 - sold after 8 wonderful years!
2014 Ninja 300
1996 Honda Helix
1984 Honda Nighthawk 650

scooterfan

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Re: Drum Brake Modification
« Reply #5 on: September 21, 2020, 04:15:04 PM »
Hi Iahawk, no I’m not too concerned about pads crumbling. The groove depth on my scoot’s pads are about halfway down and the knife cuts were “clean” - there are no loose bits on the pads. The pads still look rock solid.
I expect more than usual wear on the pads but I’m not too concerned about it. As mentioned - the front brake pads on my scooter should now have a longer lifespan. So I think in the longer term there should be no extra money to loose. I think having better and safer brakes is worth any extra expenses anyway.
Life is a journey. Just spend some time, and enjoy the trip.

Iahawk

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Re: Drum Brake Modification
« Reply #6 on: September 21, 2020, 11:36:42 PM »
All right, I'm getting closer! I disassembled everything last night, made the cuts in my new EBC shoes, reinstalled the shoes and put the scoot back together. About an hour to tear it apart and a little bit longer than that to put it back. The exhaust gave me a few issues getting the holes all lined up.

I wanted to take it for a quick ride down the street just to see if the brake pulsation was gone. It won't start. If fires up and runs for about a second and dies. I tried starting it about 20 times and same thing happened.

Crap. time to take the seat and bucket out, unhook carb, clean jets (I'm guessing it's the pilot) and reassemble it all. 

I'll do that tonight and hopefully get a chance to ride tomorrow (it's 6:30 PM, here).

To be continued...(attached a pic of the new shoes)
2010 People S200 - sold after 8 wonderful years!
2014 Ninja 300
1996 Honda Helix
1984 Honda Nighthawk 650

Iahawk

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Re: Drum Brake Modification
« Reply #7 on: September 22, 2020, 01:21:35 PM »
hmmm...thought I posted a follow up last night (?)....got carb cleaned (pilot jet was completely clogged..last ride was only 2 weeks ago..), scoot started and ran fine and took it for a short trip down my street. Brake pulsation is gone and the rear brake feels much more effective.

I'll take it on a longer ride today to get a better feel for the new rear brake. Again, thank you, scooterfan, for motivating me to get my rear brake shoes changed.
2010 People S200 - sold after 8 wonderful years!
2014 Ninja 300
1996 Honda Helix
1984 Honda Nighthawk 650

Iahawk

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Re: Drum Brake Modification
« Reply #8 on: September 22, 2020, 08:41:01 PM »
took a 27 mile ride this afternoon..beautiful sunny,warm weather!

It feels like I'm riding a new scoot. The pulsation is completely gone and I have much more rear braking ability. It made me realize how unpleasant it had become to ride the scoot with the rear pulsation. I ended up mostly using front brake only and this isn't ideal for slow speed maneuvers.

Something else is improved but I'm not sure why. Previously if I was at a stop and had only the rear brake applied the whole scoot vibrated badly. Since changing the rear shoes there is no difference now (in vibration) if I hold only the front or rear brake. The extreme vibration is gone.

So all in all a very positive improvement with the new brake shoes.
2010 People S200 - sold after 8 wonderful years!
2014 Ninja 300
1996 Honda Helix
1984 Honda Nighthawk 650

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