Front drum brake slipper

OK, working on the front brake to install the RGM high friction shoes and arc them. I cannot get the shoes into the drum with the sandpaper on the drum, they are expanded too far, even messing with all the adjustments I can. Can I reduce the shoe slipper thickness, item 28 here, http://www.oldbritts.com/1971_g17.html or what else are my options, besides taking the shoe assembly to a shop to have the shoes turned down? They almost go in. They may go in if I take the sandpaper out, I may try that first.

Dave
69S

You would be better off taking them to a shop anyway. Why do you want to arc the shoes to a drum that is smaller than your drum -by double the thickness of the sandpaper. Chances are they are that close when you get them. Jim

The RGM high friction shoes I put on the back were also quite close and am at the end of the adjustment. You might just have to run them in like the rest of us.

I believe by looking at the shoes, it looks like in a few hundred mile the surface will come smooth, my adjustment will loosen up and you will be able to continue your procedure.

OK, plan is right now after thinking (dangerous), take the sandpaper out and see if the shoes go in. If not, I'll take the slippers out and arc the shoes to get a bit of wear on them. If they do go in without the sandpaper, I'll probably just wear them in on the road.

I see your point Jim. That's been the local wisdom for a while, sand the shoes off the drum. It did work on my original shoes and improved the braking tremendously, but they were getting close to the rivets.

The other thing I noticed when I got them apart, the adjustment for the 2 shoes was out quite a bit. I had done the workbook procedure and had good braking, but apparently it was not right. I'm thinking I'm going to adjust the shoes so they contact the cams/slippers equally by adjusting out of the drum, where I can see what's going on. Then tighten up the shoe adjuster and centralize the shoes while tightening the brake and see if that helps too.

Dave
69S

You can just lay the shoe inside the drum and see if is arced close to correct. If they're close I just assemble them and figure it's going to be a couple thousand miles before I see full braking. If they aren't very close I would use a lathe and get them pretty close. It will still be some time before they fit perfectly. If your not turning the drum I would sand the hell out of it with 80 or 100 grit.

I always installed the brake assembly in the drum on the bench and put the axle through it with a tubing spacer so I could tighten the nut. Then I just used my fingers to apply equal pressure to both levers and adjusted the link rod till the pin would drop through the hole. Both levers should be at the same angle "close to 90 degrees" from the link rod. Then after re-assembling the wheel on the bike I would hold the brake while I tightened the axle nut.

I can't recall ever reading the official instructions. Just learned from an old fart.

I took the sandpaper out and cleaned up the drum with some #60. Can't even get close to putting the shoe assembly in the drum and I took the adjuster between the shoes off, so both shoes are tight against their cams. I guess it's off to the machine shop or put the sandpaper back in, take the slippers out and sand the shoes down a bit until I can get the assembly in. Supposed to snow tomorrow anyhow.

Dave
69S

DogT said:

I took the sandpaper out and cleaned up the drum with some #60. Can't even get close to putting the shoe assembly in the drum and I took the adjuster between the shoes off, so both shoes are tight against their cams. I guess it's off to the machine shop or put the sandpaper back in, take the slippers out and sand the shoes down a bit until I can get the assembly in. Supposed to snow tomorrow anyhow.

Dave
69S

Click to expand...

Well so much for quality control...Kind of like their belt drives- work great but some fettling required.

What's the part number on those shoes. The Ferodo GF1091 shoes or the 063417 RGM HIGH FRICTION SHOES?

They're marked RGM 060007. I got them from Commando Specialties. They're bonded not riveted.



Dave
69S

I had the same problem with my front brake a few years ago. After sanding both the drum and the new shoes, I blued the drum, looked for contact points and sanded the new shoes again. If the slippers are keeping you from working on the brake than i would take them out for a short period. Lube the contact points and reinsert when you are done. I did not send my brake out to be arc'ed but I would like to see the contact profile after having it done.
Mike

If the shoes are turned on the backing plate to the true diameter of the drum you will have 100% contact the first time the brakes are applied. You will have full braking power after a short break-in. I really works wonders as far as getting rid of that squishy feeling at the lever. It's really cheap and easy if you can find an old bike guy with a lathe. Jim

i did just that on the domi-featherlastic ( not a caferacer -topic )

Re: not a caferacer

Postby lynxnsu » Mon Oct 03, 2011 11:17 pm
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i have been working on the front wheel/brake
the inside of the drum was somewhat scored so i machined that out and have done the brakeshoes as well
the lathe was driven at 250rpm and the shoes were 'loaded ' with a feelergauge of 1mm before turning them down at the same diameter as the inside of the drum

i found that if you simply fit the drum on the spindle in the lathe that it tends to vibrate , so i made up 2 cones that are a snug fit over the spindle and actually seize the drum on the spindle by tightning down

My lathe doesn't have enough swing to mount a drum with rim mounted.

The last few drums I have trued were done on my mill. I run a bolt through the bearings into a block that is bolted to the table. Then I push the tire up again the chuck on my 4th axis.[positioner] Then I start the positioner turning and come down from the top with a 5/8 inch diameter long carbide in the quill. Works great. Jim

DogT said:

... Can't even get close to putting the shoe assembly in the drum and I took the adjuster between the shoes off, so both shoes are tight against their cams.
Dave
69S

Click to expand...

Got anything big enough to accurately measure the drum and the assembled brakes ? I have been running the RGM shoes for a couple years. When I took the front wheel out last week, the brakes wouldn't drop into the drum. I thought 'WTF ?!' When I put the axle through the hub and the brake plate, they dropped in, i.e. they had to go in very straight.

Greg

I've had good luck with a local clutch and brake company. All they do is brake work, and specialty clutch re-lining. There is not going to be a shop like this in every town, but there are a few out there. I just took in a 69 Harley front wheel, and they riveted on new linings (softer compound) turned the drum, and arced the linings for a very reasonable $33. I also had them bond on some new linings on my Velo, and I just dropped the shoes off, and they did those with a softer lining for $26. Hate to sound like a fussy snob, but that Velo twin leader has all kinds of clips, shouldered bolts, and lots of fiddly little things that I wanted to assemble myself. The Harley stuff is stone primative, and they did a nice job. Did a little of my usual checking with light sandpaper on the Velo, and it needed very little addtional work, was fairly close and made good contact, so I didn't take it and the rim back down for any lathe work. I don't know how many of shops like this are out there, but they've always done good work for me. The Velo linings were what I refer to as "Emgo" linings, and came with the brake plate. That black-gray stuff that is hard as a rock, and no amount of arcing is ever going to make it into anything other than mediocre. This place has lots of Ferodo signs on the wall, but I have no idea what actual brand or grade these linings are. They are not quite as soft as the RGM linings I have on my '72 Norton front, but for being locally available off the shelf, they are very good. One day turnaround on both projects. Used by a lot of /2 BMW riders in the area as well.

Well, I sanded the shoes down a bit by hand and I finally got them to go into the drum with sandpaper back in it and no slippers on. I'm going to sand them down enough just to get the shoes to fit into the drum without the sandpaper, with the slippers and no rubbing and let them wear in from there. When I think about it, like Jim says, doing it this way means the arc of the shoes is going to be actually a smaller circle than the drum, but only by less than .025 on each side.

I just don't know any shops around here that I would trust and every time I take something in, it's an arm and a leg. Besides I like doing this.

I had good luck with my originals, arcing them this way. When I started out with the originals I had maybe 2" of contact on one shoe, I got nearly full contact on both shoes and had acceptable braking as opposed to dragging my feet.

I think I'm about there. Hasn't snowed yet, but my neighbor ran over her old dog a while ago and I had to help them load the poor dog into the car for a trip, most likely it's final one. ugh.

Dave
69S

Well, I finished. The adjusters are sure screwed into their holders to give some slack to the cable. Seems fine, but won't be able to tell until I get it out. I'm sure it will be good. It feels tighter.

Dave
69S

Dave
What the heck are slippers? When you were talking about snow I thought "Well maybe Dave rides in his slippers". Then I thought nobody but Hobot could be that crazy.
Bruce
69S

item 28 here http://www.oldbritts.com/1971_g17.html

Why are you dragging up these old posts?

Dave
69S