QR50 - Brake Shoe

Some of the elements of pulling the QR50 out of a pile of bits are specific to the bike, but most of them are very generic. The one that I am going to write about today is the fact that one of the brake shoes had lost it's lining. Now, relining brake shoes is something that I normally entrust to specialists but in this case, which such small loads and relatively little use I am going to try a DIY approach using JB Weld, a metal loaded epoxy with a tensile strength of 5020 psi and able to withstand 550°F.

Now, you can see from this picture that the shoes are rather corroded - if they have anything to do with the forks, they have been outside in the wet for a while:

The first job is to thoroughly clean off all that oxide on the wheel, and get the shoe back to bare metal.

After mixing the JB Weld in equal parts, in accordance with the manufacturers instructions, we spread it on the shoe thinly making sure that the whole area is covered. Then, apply the lining keeping it in the correct position and bind the lining to the shoe with tape.

I removed the tape after 6 hours, and left the shoe for a further 24 hours. I trimmed the edges of the lining and shoe to clean up the hardened squeeze out on the linisher, and the job is done.

QR50 - Front brake

The front brake of the QR50 is a 3" half width, single leading shoe drum brake, pretty straightforward:

The one I have is very standard and is even painted gold - I just have to clean it up, paint it and re-attach one of the linings:

I've not seen this spring arrangement before:

Half an hour on the wire wheel has it looking much better:

SQ4 Front Brake

As part of winter maintenance, I have my front wheel off for new bearings, a new tube and a look at the brake. It appears that I still haven't got it right.

Take a look at this, it is the leading end of the trailing shoe:

To me, this is indicating that I haven't got the adjuster tight enough - there is about 20-30% contact on both shoes, at the cam end - in both shoes, there is no contact at the adjuster end. Here is the leading shoe, trailing end:

In both cases you can see where the lining is worn by contact with the drum. The brake is nothing like as effective as the one on my W/NG, which is obviously a much lighter bike but the brake has much more feel. They are bedding in at the cam end (trailing end of the trailing shoe here):

I'm happy to see that the drum is nice and clean, with no trace of grease

Less happy to see the heat damage to the paint, but we will deal with that when the weather warms up.

Setting the drum up with emery tape and double-sided sticky tape in the traditional way results in much better contact. By the way, don't do this with one of the wheel bearings missing since the spindle, and the brake plate and shoes will not be concentric with the drum:

Set the brake plate up such that it is pulled down to the bearing and is held rigid (as far as possible with these pressed steel brake plates) - that way the shoes will be as cylindrical as possible. I've used a short tube spanner on the spindle to take the place of the fork leg, and I am holding the brake plate from turning with a tommy bar. I turn the wheel to sand the linings.

Start with adjuster backed off and gradually wind it in, turning the wheel a few times and then dismantle again for inspection. When your satisfied that the adjuster end of the shoes is ground down enough to fit the drum, put a bit of pressure on the brake cam lever and repeat. Stop when you have contact over most or all of the shoe.

Here's the leading end of trailing shoe:

Leading end of leading shoe

 Lots of dust after the process is complete:

Restore, Ride, Fettle, Ride, Fix at roadside, Ride, Fettle...

So of the course the latest little jaunt around the countryside heralded the same old problems with the front brake...

No obvious overheating this time, but only because I was watching for it and acutely aware of the vibration from the front forks. Resting my gloved hand softly on the lever, you can feel that sometimes it is tight and sometimes not. Sometimes there is a lot of play at the lever - I suspect it is not returning too well. Parked up, I backed off the cable a couple of turns and it felt much better.

So back in the workshop, the cable is obviously too long. It doesn't run down smoothly through the yokes, and it feels a bit dry:

We'll look at getting a new pair of shoe return springs, but for a start let's sort that cable out. No going back now:

This is how you fill up the nipple with solder. You want to avoid it running down the cable, and you need to be careful to avoid excessive heat.

More cable making information here.

Oh, and the speedo needle is sticking again:

But she still looks nice in period surroundings, albeit with a bit of PhotoShop!