Saturday, November 5, 2011

More Brake work and It Lives!

Look at that lovely stainless steel gleaming
I got the master cylinders and rear wheel cylinders back from being re-sleeved - the front wheel cylinders had been done previously. The quality of the work is excellent so they should be right to last another 50 years. I sent them off to Leon, whose business is appropriately named Quick Service Brakes. He apologised about being too busy to get to them immediately but still only took just over a fortnight to do them. We discussed what to do about the reservoirs. The two ports in the side of the master cylinders need to be drilled after the sleeve is inserted. This is usually done by drilling right through the side of the reservoir and soldering the hole up afterwards. The alternative is to un-solder the reservoir and put it back on later, but this is labour intensive and adds considerably to the price. We agreed that I'd take the reservoirs off and put them back on myself. This gave me the chance to clean them up and repair them while they were off.
Hexagon top master cylinders - looking a bit better than in the 'before' photo
 I refinished the master cylinders, not by plating but by tinning them with solder. It may sound odd, but all of my research into how to replicate the original dull tarnished light grey finish drew blanks. Everyone I spoke to said something like, "maybe its zinc", or "perhaps its some kind of cad". I consulted a local plater and he said, "I don't know what it is and I can't  replicate it". The breakthrough came when I was heating up the spare one to practice on. As I heated it, little silver beads of molten metal appeared out from under the dull grey finish. Not just on the tin-plate reservoir but from all over the cast iron body as well. I didn't have it hot enough to melt zinc, so It must have been solder. Thinking about it afterwards it does make some sense. Solder typically oxidises to a dull grey white finish over time, and the body would have needed to be tinned in order to solder the reservoir on. After a soak in my derusting bath and a thorough clean, I painted them with Kemtex B916 tinning compound and heated them until it melted. A wipe with a clean cloth and they were looking much better. I just need to work out how to encourage the grey tarnish to re-form quickly now. Soldering the reservoirs back on was a bit tricky but in the end I was pleased with the result. The reservoir from the brake master was pretty bad so I replaced it with one off a spare. As a result its much shinier, whereas the pitted clutch one looks fairly dull. Hopefully they'll even out over time.

New pistons, seals, bleed screws, stainless sleeve - better than new.
I had to solder up one of the original tin master cylinder caps. It doesn't look as good as it might, but I had no choice it was badly corroded and pin-holed in several places. Luckily I managed to get a good nearly new cap on ebay, for the brake master cylinder because the one that was on there crumbles when I undid it.

I figured new clevis were needed after seeing the one that came out
I rebuilt the rear wheel cylinders using new pistons ( a slightly embarrassing story I may reveal one day) and new seals and put the whole lot back together again. The master cylinders went in reasonably easily. I used R clips on the clevis pins which is much easier than messing about with split pins.

It was when I went to bleed them that the problems started. Firstly I discovered that the thread for the bleed screw in the driver's side front whelle cylinder had stripped out. With some tools loaned to me by the local thread repair specialist, I managed to get it working again by drilling and tapping it for a helicoil. It worked OK but weeps a little unless the bleed screw is really tight. I'm either going to have to replace it with a bleed screw insert, or get a new wheel cylinder. Once that was repaired, I discovered a serious leak where the front brake line meets the brake hose on the passenger side. It meant that the radiator had to come out again in order to tighten it up. The tube nut on the end of the brake line has been abused over the years and is rounded off, which makes it nearly impossible to tighten. When I recondition the subframe the brake line will be replaced so it looks like new tube nuts are needed too.

Gunson's Eezibleed hooked up - the black hose gets pressure from the spare tyre.

I eventually got it all bled, I bought a Gunson's Eezibleed, and it was excellent. I bled both the master cylinders on their own first, then connected them up and bled the clutch and brake systems. It was so easy, I could hardly believe it. It took a couple of goes around, firstly before adjusting the brakes, then again afterwards. They'll need adjusting after they've bedded in but are pretty good for now.

I spent the afternoon madly working to get the Traveller running well enough to drive to MiniFest 2011 tomorrow. Big  Mini shows only come around every two years here so they aren't to be missed. I had a few small problems getting it started and running smoothly, but managed to get it to run well enough to risk the trip. It needs a thorough tune up, but should be OK. The brakes are a little spongey still but aren't as bad as I expected. The Traveller is unregistered so I organised a temporary permit which covers me for the duration of the event. Today's road testing was done on my personal test track, of course.

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