Arc the rear drums?

Since I've got things apart to install new front and rear shoes, has anyone ever bothered to arc the rear drums. I get a tight spot rotating the rear wheel despite tightening the drum while tightening the spindles, in correct order, left first and right last. And the rear brake pedal feels like it's going down too much when there is no drag on the rear brake. It's actually always been like this, but I just ignored it. Could it be my drum is out of round or any thoughts would be accepted?

I had real good luck arcing the front original shoes, and now I have the RGM high friction ones, but have not done it yet. The originals are actually usable at this point and I had a Triumph guy comment on how good the front drum brake is.

Dave
69S

"arc the drums"
can you explain this term, I've never heard this term
are you talking about machining the actual drums?
are you talking about radiusing the brake shoes?

I assume he means milling the drum friction surface true round to match the shoes. The issue to concern is if the parallel lines that will be produced by the easy way to trim may remove more friction than returning. This is issue with disc rotors they found did a lot better if cross hatched flat instead of the spiral in cuter blade. First step is determine if not true enough already.

One source of rear brake drag can be against the drum face or the chain side backing mount plate. Check back plate thin spacer and witness marks on drum by paddle lugs. It is handy and fun to have rear brake lock up pretty easy.

I have had good luck just centralized the backing plate, but have always tightened the stub axle last (otherwise you can't get the brakes in the right location). Until I got the RGM high friction linings it always felt like the rear brake was as good as the front...

Can you make a spacer to eliminate the brake plate, use a dial indicator, and check to see if the drum is out of round ?

Greg

Steve,
Drum brakes. Arc the brakes, sand the shoes so they contact the drum more fully than just putting on the shoes and hoping they work. My original shoes were contacting maybe 2" total. Applying the front brake was kind of like dragging your feet at 60mph. When I sanded them down by putting #60 sandpaper on the drum and hand turning the wheel while tightening the shoe adjuster, I managed to get full contact on both TLS shoes. Made a huge improvement. They actually work now.

gir,
Are you saying you tighten the RS first and LS second. I always thought that lead to possibility of stressing the joint and spindle failure?

I would think if it were rubbing on the backing plate (the plate the shoes mount on, cover plate 06.0332?) I would hear it rubbing. I don't see any scoring and don't notice any rubbing on anything, but it may be a good idea to make a spacer and replace the cover plate to see what's going on. Would certainly be easy enough to see if the drum is out of round then. I think it's the shoes that are rubbing, whether it's the drum or shoes or how they are mounted, that's to be determined. There is a point when I can make it not rub by adjusting the rear brake adjuster nut.

Thanks for the ideas, I'll report.

I set up my brakes by aligning the wheels and then loosening the stub axle side nut. Spin the rear wheel and apply the rear brake. Push the stub axle against the adjuster and tighten the axle nut. Tighten the brake adjustment nut until the shoes rub a little. Set the wheel at the tight spot, loosen the stub axle nut, apply the brake and tighten the nut. Readjust the brake rod nut and repeat the process until you run out of beer or patience, which ever comes last. If the alignment is good, I don't think there should be much stress on the axle or joint.

The idea with the spacer was to see if the drum is out of round. You would have to remove the brake backing plate to get a dial indicator into the drum. The spacer is just to keep things from flopping around. Sorry if my description was unclear.

Greg

Greg,
No, I get your drift. I'll try it out. My only issue is that everything I have read about putting the rear wheel on/tightening all the parts, says to tighten the brake plate side first (LS) and then tighten the long bolt (RS) into the dummy spindle. It's always worked for me and I haven't had any problems, like some have. I'll play with it.

If it doesn't work out, I'll try the spacer to see if my drum is out of round, I could probably use a new one since the cogs are a bit worn, but it still passes the hobot test.

By the way, my wife was inducted into the Wall of Fame at the Moose Lake HS, MN just last week. And she came home with a terrible sinus infection, I'm sure from being in the airplane or the Mall of Americas (but I tell her it's god's retribution for leaving me for a week). She graduated from Moose Lake in 59 I think. Think Garrison Keeler. At least she had a good time with her brother in St. Paul. Trace snow there, eh? Two more months of good sledding!! It was 47 here today and a high of 30 yesterday.

Moose Lake ? 1959 ? Her graduation class must have had 30 people in it. What did she do to get on the Wall of Fame ? Even getting close to the Mall of America makes me sick... people here are starting to worry about the lack of snow. It was dry going into the fall and we have had less than two inches of moisture since August. We are about 10" short and facing a forecast of a hot dry summer.

Do you find that the RGM brakes are a little grabby at times ?


Greg

On the back brake it is also good to drill the backing plate out another 1/32 it gives it room to not fight you so bad the new alloy ones already come like that. Sand them in just a bit after they have this freedom it does make some difference.

DogT said:

Since I've got things apart to install new front and rear shoes, has anyone ever bothered to arc the rear drums. I get a tight spot rotating the rear wheel despite tightening the drum while tightening the spindles, in correct order, left first and right last. And the rear brake pedal feels like it's going down too much when there is no drag on the rear brake. It's actually always been like this, but I just ignored it. Could it be my drum is out of round or any thoughts would be accepted?

I had real good luck arcing the front original shoes, and now I have the RGM high friction ones, but have not done it yet. The originals are actually usable at this point and I had a Triumph guy comment on how good the front drum brake is.

Dave
69S

Click to expand...

Yep, making sure your drums and shoes are round is a good thing. I have had a few of my drums machined and had dramatic improvement in braking. Arcing the shoes is also important but you want to start with a round drum.

norbsa48503 said:

On the back brake it is also good to drill the backing plate out another 1/32 it gives it room to not fight you so bad the new alloy ones already come like that. Sand them in just a bit after they have this freedom it does make some difference.

Click to expand...

What do you mean 'drill the backing plate out another 1/32'? Enlarge the hole the spindle goes through?

I'll try Greg's method first if that doesn't work, check the drum for run out.

She was the first woman photographer hired by the Washington Post Co. She worked there over 40 years. Lots of people think it was Jakie Kennedy, but she was never really hired, they just used some of her stuff. There probably weren't even 30 people in her class.

Dave

It could be that your drums are not concentric; the only way to test this is with a clock gauge mounted on the wheel spindle or frame.

Setting up the brake shoes to run true to the drum/wheel, would mean mounting the drum on a mantle and machined in a lathe. But if you are like me and don’t have access to a lathe, don’t bother, the shoes will wear to the drum with use.
For beast results have the shoe as close to the drum, within .020 tho inch or more, using homemade brakeshoe spaces, to keep the flats on the pivot pin as right angle as possible, and the brake arm to also be at right angles when on fully.
Look up brakes in;

http://files.me.com/davefriesen/1ii7ja

Vintage Brake has some tips on their site. It's interesting what he said about the grease vaporizing from the felt seals contaminating the shoes.

http://www.vintagebrake.com/tips.htm

Yes just that simple drill the axle hole for just a bit more clearance this has been a well known mod for years nothing new.

I'm sure the powder coat didn't make the hole any larger. I'll try it.

Dave

I binned the rear drum brake plate and fitted a 2LS hydraulic plate off the RH side of a mini. Had to shave the shoes down width ways to fit in the drum deep enough, weld a boss in the middle and slot the plate to clear the swinging arm. Master cylinder is off a Triumph Herald. Works a treat and been on there about thirty years now.
I know, what's a Triumph Herald?

Triumph Heralds, Vitesse'e and Hillman Imps are collectable's this far south in the planet!!!!
How about some pics of your setup?
Regards Mike

There's no way I'm putting any Mini parts on my Norton. Nuff said. The original rear brake I can lock up easily with control, so what else is needed?

Dave
69S

Played with the rear brake today. I remembered that it always seemed to make a difference how the wheel was attached to the drum, that is there are 3 positions because of the 3 studs. Don't know why that should be, but it seems like it. So I went through all 3 positions, the same time adjusting the LS spindle while tightening the brake. Don't know if it was just going through the procedure 3 times, but on the last position, it seemed pretty acceptable to me. Goes from no rubbing shoe to drum to full contact in 3/16" travel on the cable, measured from the cable end holder on the swing arm to the adjuster. That gives 1" travel on the pedal, which feels acceptable to me. I probably could close up this travel by arcing the shoes, but I think I'll go on to the front brakes now. At least it seems a whole lot better.

A nut driver sure saves a lot of time on the rear brake adjuster nut compared to using an open end spanner 1/2 turn at a time.

Then you have to loosen everything up to get the chain back on. ugh.

Dave
69S