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1/22/2013
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AU
Edited Date/Time
1/20/2021 8:38am
Hi Guy,s i like to get your ideas on Front drum brake performance, tip's and idea's,
I am talking very early eighty's single leading shoe, i wish for easier pull and more bite / power.
Are there better shoes to purchase, different compounds.
Are open bike wheel / brake combo's more powerful than, say a 125's,
Do different cables make a difference, OEM vs aftermarket
Any other tricks or tips
No double leading shoe suggestions please, not class legal.
Thanks Mark
I am talking very early eighty's single leading shoe, i wish for easier pull and more bite / power.
Are there better shoes to purchase, different compounds.
Are open bike wheel / brake combo's more powerful than, say a 125's,
Do different cables make a difference, OEM vs aftermarket
Any other tricks or tips
No double leading shoe suggestions please, not class legal.
Thanks Mark
Rough up the drum with a porting sanding tool on a cordless drill.
Using sand paper taped to the drum arc a set of EBC G compound to insure full bite.
Lightly rough up the brake pad either with sand paper or I lightly sand blast them
I look for Teflon lined brake cables to ensure I get the most power from the brake lever to the drum
If need be find the longest brake drum lever but I've found that most of the late 70s are pretty long.
Install everything and do some hard embedding stops to adjust the cable/arm for max throw on the lever
If that doesn't work you can try a newer roller bearing clutch perch turned upside down to get even more power.
Good luck
After that, a longer brake arm for more lavage, a new cable (I like OEM for some brands, aftermarket for others) and careful assembly so the shoes hit the drum squarely for the most contact.
The simple way to do this is to loosen off the axle clamp bolts and the axle a little. Spin the wheel (in the same diection as it would be if you were riding) and then grab a handfull of front brake and hold it on. If your on your own use a zip tie to keep the front brake applied. If you have a small child, wife, girlfriend, mistress, cleaner, dad or general dogs-body on hand, they can keep the brake applied for you. Tighten the axle, then the pinch bolts. Realese the brake and adjust. The drum should now be centred in the hub.
Stevie
He should have know.
The Shop
As Klemm points out, it wasn't a computer machining those hubs back then, it was Aki or Ake or Heinz or Jaroslav, and it might have been Monday when yours was made, so it's worth checking whether the drum is truly concentric with the axle. If you have a stock SLS that has never really satisfied you, it seems worth the trouble to investigate. I would never have thought of it, and even Klemm is candidly a little embarrassed that he spotted the problem by chance rather than realizing abstractly that he should check it if he was optimizing a wheel. He describes it much better than I have if you scroll down the Bighorn page to the chassis part at Klemm Vintage Bighorn setup
That is a very informative site IMO: Klemm does things his way, but don't forget he was the guy who built the CZ that Rex Staten holeshot the world on twice at the 1975 Carlsbad GP, and probably would have won if the CZ factory had not forced Staten to use stock forks, etc.
The only thing I'd add is that I used to move my brake perch in towards the center of the bars as far as I could and still keep a comfortable distance for reach. Even an extra 1/2 " will give more leverage. Someone already said this, but I also used to add a 1/2 "or so to the brake arm at the drum. Add as much as you can without throwing the cable housing holder too far out of alignment. I'd want the cable to still have a pretty straight pull.
RB
One thing I'll add is to check the contact patch of the shoes against the drum.
ride the bike, grab a handful of front brake and then investigate what the shoes look like.
I'll take a course file and rub down the contact areas(high spots) to even out the shoes, then ride and test again.
the object is to make sure the shoe has full contact against the drum surface.
As Stevie said center them up u can test and look for high spots, if not equipped with tooling.
Goog luck
I recall what I think was originally the 1972 Yamaha 250 conical hub as the 1970s standard for light weight and stopping power when people were changing front hubs for better braking on Maicos, etc. But my impression is that all the Japanese brands and Husqvarna had strong & light SLS fronts at the end of the 70s, KTM or Maico being less consistent/needing more setup, and Can Am prone to fading. Sometimes larger brakes on larger displacements. Choosing a non-stock front might come down more to ease of adapting and availability of good shoes as pointed out above, and you might want to make sure you'd really optimized the stock brake before you gave up on it.
What bike did you make those shoes for?
Pit Row
Does a shorter brake lining give the drum's rotation better leverage on the leading shoe? Perhaps enough to offset the loss of lining area? Or is it the opposite--does it reduce "drum rotation effect" to keep the leading shoe from being too grabby?
I am fuzzy on the physics of it.
Got my first pair of EBC shoes for a project for which I also have NOS Yamaha shoes. The EBC seem rather precisely sized to the drum: with the actuator on the stock spline position, you have to crank the adjuster 20 mm before you even get contact, but this has the cable & actuator pulling just to the desired 90° angle for max leverage.
The Yamaha shoe linings are much thicker, and the cable & actuator still at a relatively acute angle when contact begins. It's like the stock shoes are meant to get stronger as they wear, but the EBC are going to start at their strongest and lose effectiveness as they wear--make a good initial impression & then require replacement sooner. . . .
That said shoe contact patch actually is less relevant in braking force and is more relevant to heat dissipation, dust/dirt removal. Friction materials plays the largest role in braking performance and fade resistance.
Honda always had small drums and pads when you compared them to Yamaha and even Suzuki but they worked just as well.
Those of us with Can Ams have to go the relining route as there aren't any off the shelf shoes for the Girling brake drums of the 70s.
When the leading shoe have shorter brake linning, it is to reduce "drum rotation effekt", dont know the words in english, maby "servo effekt" or "Self-reinforcing"?
I have problem with my DLS brake on my CR480 -83, the SLS on my CR250 -79 have better braking power.. Have to look closer on the construction of the shoes (ebs)
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