Rear Drum Brake Centering

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Tornado

Tornado

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For most of the five yrs I've had my Commando, rear drum brake has been vague and requiring large angle of depressing foot lever before much braking action. If I adjusted the cable to where this lever angle was better, the drum would scuff significantly while rotating wheel by hand and could even be felt while coasting along. Had tried the method of keeping brake lever depressed fully while doing up the axle nuts, but no real improvement until just this past week. I'd had the rear wheel off to check the cush rubber and do some work on the speedo drive unit. When refitting, I was having trouble getting wheel hub fully seated into brake drum, the the drum showing excess wobble against brake carrier. Turned out the "paddle" on carrier was not fully engaging in the SA slot. Got it square and torqued up stub axle to full 70 ft-lbs while holding foot lever full on. Next test ride I found excellent rear brake function for first time. No scuffing at coast, minimal lever movement needed to give very respectable rear braking force.

I'm wondering it the cush rubbers might have been misaligned, hanging up the drum from proper fully square engagement with casrrier. The rubbers were all in great condition (replaced 5 yrs ago). But they could easily be removed/fall out when handling the removed wheel.

Norman Whites restoration book mentions there is a fairly involved procedure for centralizing the rear drum and says to see a specific chapter of the book, but alas I could see no further procedure for the rear in that chapter.
 
Loosen both sides of the rear axle nuts. Spin the wheel and step on the brake peddle, holding while tightening the nut at the brake drum side. Then tighten the other side. I believe this is in the owners manual, but after 48 years driving Commandos I tend to forget where instructions are.
 
Any poor brake requires full attention to find out what that problem is.
But I've never come across that one before.
 
Bernhard said:
Any poor brake requires full attention to find out what that problem is.
But I've never come across that one before.
Click to expand...
I guess in my defense here is that the rear always had this problem from when I got the bike, and lots of folks state the rear brake can be poor performer, so I was ignorantly blissful. Now it works with a fraction of the lever movement/foot angle to actually bring speed down very effectively. I need to re-calibrate my foot pressure on lever.
 
My rear drum brake was always very effective , with great feel and progressive… the front disk setup not so much , once I rebuilt caliper and installed the CNW master with SS line , was transformed , the old bike then had very good brakes not compared to a modern but good reliable, progressive smooth stopping power …. yours should be similar ….
 
ILLF8ED said:
Loosen both sides of the rear axle nuts. Spin the wheel and step on the brake peddle, holding while tightening the nut at the brake drum side. Then tighten the other side. I believe this is in the owners manual, but after 48 years driving Commandos I tend to forget where instructions are.
Click to expand...
This thread comes just right. First time out after rebuild I spun the rear wheel and heard a rubbing like it came from the chainguard, so off it came but it seems to lie with the brake-plate.
I will try the method above and hopefully it works.
Rear Drum Brake Centering
Rear Drum Brake Centering
 
ILLF8ED said:
From the riders manual says the same thing.
View attachment 94631
Click to expand...
I had a go at my rear wheel today and found despite going by the book I couldn't get rid of the scuffing between the plate and the wheel. I can only think that something has slightly altered after I changed the wheel bearings.
My single way out was to lay a 1mm shim between the brake plate and drum which worked very well and doesn'tput any load on the speedo take-off. No rubbing on the chainguard either but after torquing the engine for the first time oil pours out from behind the engine
 
Woody850 said:
I had a go at my rear wheel today and found despite going by the book I couldn't get rid of the scuffing between the plate and the wheel. I can only think that something has slightly altered after I changed the wheel bearings.
My single way out was to lay a 1mm shim between the brake plate and drum which worked very well and doesn'tput any load on the speedo take-off.
Click to expand...
Most bikes require one of part 21 and some with a slightly warped brake place require two: https://andover-norton.co.uk/en/shop-drawing/75/rear-wheel-drum-bearings Note: the picture is odd - it goes between the hub and brake plate.
 
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marshg246 said:
Most bikes require one of part 21 and some with a slightly warped brake place require two: https://andover-norton.co.uk/en/shop-drawing/75/rear-wheel-drum-bearings Note: the picture is odd - it goes between the hub and brake plate.
Click to expand...
robs ss said:
I see - that would have the effect of pushing the brake plate further out of the drum.
Thanks - didn't know they existed
Click to expand...
I have steel "valve spring shims" of the proper ID/OD in .015", .030" and .060" thickness.

Not sure what a letter posted to OZ would cost but I could drop one of each in an envelope and send it out in the morning if you like. PM me your address if you can't find some quickly.
 
If one can find valve spring shims with 13/16" ID and 1 1/4" OD they will work as a substitute for the Norton part-no: 06.7603
 
robs ss said:
I see - that would have the effect of pushing the brake plate further out of the drum.
Thanks - didn't know they existed
Click to expand...
Rob,
That spacing washer is listed as AR,(as required).It basically pushes the drum further out from the backing plate.Not every bike needs them. I have not had trouble getting them but have hardly ever used them if everything else is proper.Just my experience
Mike
 
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