Got lousy drum brakes? Fix 'em!

grandpaul

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It's winter, and you're probably not riding right now, so why not FINALLY fix those lousy drum brakes once and for all?

The best thing to do is to turn the drums using a simple wheel stand (jig). No need to even dismount the tire, as long as everything is reasonably well balanced. Have an assistant do the turning, or rig up a motor with a friction drum on it's spindle to turn it for you. An old style shoe polishing rig is the perfect thing, you can get them on ebay.

Get the drum spinning slowly and check it for a true inner face using a fixed wire pointer (or a dial indicator if you have one); this step is really important, you FIRST want the drum face to be nice and true. Mark high spots with calk on the edge of the drum. Use one mark for slightly high spots, 2 marks for her spots, 3 marks for really high spots.

Take an old brake shoe and line it with emery paper to use as a sander, hit the high spots a little at a time then re-check and see if they've become lower. If so, proceed; if not, sand a bit harder. Make nice sweeping passes at them starting to put pressure on as you arrive at the mark, then press hardest, then ease off. It might take a while, BUT ITS WORTH IT!

Once you've got the drum nice and round, time to fix the shoes. Set them in the drum one at a time, and look for obvious curve shape differences. Mark with chalk on the face of the shoe.

Use double-stick tape or wood glue, and stick a new sheet of emery paper to a disposable piece of plywood or board, long enough that you can kneel on it, or screw it into your workbench top if you use a topper of sacrificial material (or if simply don't mind screw holes in your workbench).

Work the shoe(s) gently, smoothing off the high spot(s), check against the drum to see that you've hit it right.

Gently color the entire surfaces of both shoes with light, even passes from a full stick of chalk laid across. You want the entire surface colored evenly.

Fit the shoes to the brake plate, and fit the plate up to the wheel, and put it back on the bike. Fix the axle in place snugly. Have your assistant turn the wheel at a moderate speed, then apply the brake gently for at least two wheel revolutions.

Remove and inspect: The chalk coloring on the brake pads should be evenly disturbed or gone across the ENTIRE faces. Any remaining chalk indicates a low spot on the shoe that the rest of the shoe needs to be reduced to. Drum should have a uniform appearance as well; if not, address it.

Once trued drums and good quality shoes are all properly arced, grease fittings serviced, good quality brake cable properly adjusted, and all lever pivot points lubed, you should have the best brakes that your particular bike will ever be capable of having.

If you haven't been trying to get them to work better by installing new shoes and cable(s), re-adjusting etc, (in other words, if you are going from really crappy brakes to totally nice ones) You are going to be AMAZED at the difference!
 
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If I had a nice Commando which had a drum front brake, I would just ride slower. Drum brakes are always unreliable. Discs are fit and forget. But discs look silly on a Commando. I have only ever had one crash which was not due to a drum front brake, but my own stupidity.
 
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Whilst, not to belittle grandpaul's post, IMO this just doesn't scratch the surface of putting right the faults of a drum brake.
I posted a previous post on how to improve the drum brakes, borrowing a small clock gauge mounted on a small magnet post attached to a metal plate on the forks would take out any guess work.
But it really is easy, once you understand it, and are knowledgeable enough to avoid the pitfalls.
 
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All of the big crashes I have had during racing were due to drum front brakes. When I set them up, I am not stupid. If a drum brake is good enough to race with, it is always dangerous. You only need to be a bit out of practice and when push comes to shove, you are down.
The worst drum brake is probably the Fontana copy which is used on the TZ350 and TR3 Yamaha. In Australia, the first road bike to have discs was a 500cc Yamaha. My friend fitted one of those front ends onto his TR3 Yamaha. He led his race and three guys crashed behind him, while trying to stay with him as he braked so late into corners.
 
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If you put a hard lining on the rear shoe of a drum brake, and a soft lining on the front shoe, You can have mediocre brakes for the whole of a 5 lap race on many circuits. With discs, there is none of that. They either work or they don't.
 

Onder

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Well it is either that or your iron disc exploding. Damn highways and byways here are littered with them....:)
 

Time Warp

.......back to the 70's.
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dtfg.jpg


dft.jpg
 
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In the UK if you do not have access to a mill or lathe then you can get close to arcing by buying relined shoes off Villers Services, Saftek provide the same service.

When you send your shoes in for new linings you can specify either

1. The model, in which case they put the standard lining thickness on.

2. You can give them the OD of the shoes without lining plus the ID of the drum, they then fit linings to account for any wear minus an allowance for the shoes not to rub when the lever is in the off position. Its not as good as arcing but close to it and leaves you with the option of still arcing the shoes but will likely little to need removing.

Their default road lining is the same as RGM use on their uprated Norton 7" rear brake shoes, a gold woven lining.

MZ Gold Woven brake lining.
 

L.A.B.

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All of the big crashes I have had during racing were due to drum front brakes. etc.etc......

I see you've slipped back into your old habits once again as this thread isn't about racing, the benefits of disc brakes over drum brakes or your exploits on a race track so would you please either STAY ON TOPIC or not post.

If I had a nice Commando which had a drum front brake, I would just ride slower.

That's probably the most useful thing you've said in this thread as we don't all ride on race tracks which you don't seem to understand.
 
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Acotrel said:

"Discs are fit and forget"

and in another thread:

"Humidity during storage can be a problem if you have disc brakes"

err..... so which is correct ?
 

Carl H

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It's winter, and you're probably not riding right now, so why not FINALLY fix those lousy drum brakes once and for all?

The best thing to do is to turn the drums using a simple wheel stand (jig). No need to even dismount the tire, as long as everything is reasonably well balanced. Have an assistant do the turning, or rig up a motor with a friction drum on it's spindle to turn it for you. An old style shoe polishing rig is the perfect thing, you can get them on ebay.

Get the drum spinning slowly and check it for a true inner face using a fixed wire pointer (or a dial indicator if you have one); this step is really important, you FIRST want the drum face to be nice and true. Mark high spots with calk on the edge of the drum. Use one mark for slightly high spots, 2 marks for her spots, 3 marks for really high spots.

Take an old brake shoe and line it with emery paper to use as a sander, hit the high spots a little at a time then re-check and see if they've become lower. If so, proceed; if not, sand a bit harder. Make nice sweeping passes at them starting to put pressure on as you arrive at the mark, then press hardest, then ease off. It might take a while, BUT ITS WORTH IT!

Once you've got the drum nice and round, time to fix the shoes. Set them in the drum one at a time, and look for obvious curve shape differences. Mark with chalk on the face of the shoe.

Use double-stick tape or wood glue, and stick a new sheet of emery paper to a disposable piece of plywood or board, long enough that you can kneel on it, or screw it into your workbench top if you use a topper of sacrificial material (or if simply don't mind screw holes in your workbench).

Work the shoe(s) gently, smoothing off the high spot(s), check against the drum to see that you've hit it right.

Gently color the entire surfaces of both shoes with light, even passes from a full stick of chalk laid across. You want the entire surface colored evenly.

Fit the shoes to the brake plate, and fit the plate up to the wheel, and put it back on the bike. Fix the axle in place snugly. Have your assistant turn the wheel at a moderate speed, then apply the brake gently for at least two wheel revolutions.

Remove and inspect: The chalk coloring on the brake pads should be evenly disturbed or gone across the ENTIRE faces. Any remaining chalk indicates a low spot on the shoe that the rest of the shoe needs to be reduced to. Drum should have a uniform appearance as well; if not, address it.

Once trued drums and good quality shoes are all properly arced, grease fittings serviced, good quality brake cable properly adjusted, and all lever pivot points lubed, you should have the best brakes that your particular bike will ever be capable of having.

If you haven't been trying to get them to work better by installing new shoes and cable(s), re-adjusting etc, (in other words, if you are going from really crappy brakes to totally nice ones) You are going to be AMAZED at the difference!
Hi, OK, Can you send a E bay item # for the Shoe polishing thing. Id like to look it over CH
 
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If you put a hard lining on the rear shoe of a drum brake, and a soft lining on the front shoe, You can have mediocre brakes for the whole of a 5 lap race on many circuits. With discs, there is none of that. They either work or they don't.
Yes you are right - but here, or at least Joe Dunphy did, he fitted HARD green racing linnings on the FRONT, and softer linnings on the rear.
You've got them back to front, - must be going senile in your old age!
 
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Acotrel said:

"Discs are fit and forget"

and in another thread:

"Humidity during storage can be a problem if you have disc brakes"

err..... so which is correct ?
If the pistons didn't seize in their calipers down under like they do in the UK then I might believe it. . . . .
 

gortnipper

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A good way to bed the shoes after you have ascertained the drum is true is to cut some rough sandpaper so that it fits in the drum, and the ends butt together. I use a bit of double stick tape to secure the ends to the drum. Assemble the brake plate in and put the wheel on the bike. Have someone spin the wheel while you apply the brake, on and off, on and off, etc. Take it off and inspect the shoes to see when you get to the point where the high spots are all down and the wear is even. Clean up everything real well, and then grease the appropriate parts.
 
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Nothing of value to add, so here's a story.

I have skinny little 7" drum brakes on my version of Norton. Cleaning them up and doing a light sand on the drums and shoes helps a lot. They are adequate on the street if riding at the speed limit and maintaining the 1 car length per 10 MPH to the car in front rule they taught kids in driver's ed a little more than half a century ago.

I also keep my idle as low as is possible without killing the motor when the motor is fully heated up. That way I get a slight advantage slowing down using compression braking. The little brakes I have don't hold stopping power long when pushed. Front shoes are soft, and rears are hard. I do have to remember use both front and rear brakes. The front brake doesn't get it done alone unless I'm pushing the bike around in the garage.
 
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A Norton Commando is quite fast, but most guys probably do not ride them fast. So the standard drum front brake is probably adequate. If you are the sort of person who gets silly, you would probably be able to buy a Japanese disc brake set-up for about $500. You can easily spend that on a drum brake and get nowhere. I don't think I ever use the back brake. If you are on a lean, that can drop the bike.
 
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