Welcome back folks, if you recall in the last post (hahaha like anyone reads these), I mentioned that I burned everything I own to the ground. Today, speaking from a cosy Starbucks between the joys living in my car (I have found a nice spot on in a forest car park that seems to have a lot of friendly people who like to look in each others car windows when it gets dark) and you will find out why…

Brakes are one of the fundamental parts of any vehicle, they slow you down and if you’re lucky, allow you enough time to think about what you would have done differently in your life before careering straight on at that corner… If anyone has ever had any experience where your brakes fade or are not working like they should then you will suddenly never take them for granted again.

I thought I would give a quick BRAKEdown (see what I did there…god I’m hilarious) to show you how they work, or in the case of my shitheap of a bike, don’t work.

The crudely drawn sketches below show all the fundamental components in a braking system. The principle is to use a pressurised fluid system which forces fluid through a hose to the calliper, which  moves a piston against brake pads which press on a disc (which is directly connected to the wheels), slowing your wheel down thus avoiding impending death…..and breath

High level brake overview
Crudely drawn sketch

The reservoir is used to ensure the system is topped up with fluid. Brake fluid is incompressible (it’s also the most corrosive stuff known to man….I should have used this to strip my tank in rather than that useless Nitromors), which means when it is under pressure it transmits the force you apply through your brake lever to the piston at the calliper.

Detailed drawings
Crudely drawn sketch 2

The reservoir is connected to a master cylinder which is what generates the pressure in the system to move the piston. When you haplessly grab a handful of brake lever, a small piston within the master cylinder will move. This movement of the piston shortens the reduces the overall volume of the system. By having a fixed volume of fluid forced into a smaller volume, the pressure of the system increases.  This piston is on a spring, so when you are done shitting yourself and let your fingers off the brake, the piston moves back to its original position letting the brakes off.

This pressure then transfers down a brake hose.  I didn’t know exactly what these were made of but judging by the PayPal invoice to HEL hoses tonight, I am assuming its solid fecking gold. These better be good! But these are a critical part of the system and have to put up with a lot of movement, and the elements, which in Scotland can be as much as 4 seasons in one day. These are connected via a banjo bolt to a calliper. The banjo bolt allows fluid to pass through the centre through an orifice in the side of the bolt.

The calliper is where all the magic happens. This takes away the fear and allows it to start dissipating. The calliper has essentially a housing for the piston, brake pads and nipple (hehe) which is mounted over the brake disc. The piston slides in and out (oh god) of a sealed hole in the calliper depending on what pressure is in the system. This forces the piston on to the brake pads which are made of a highly heat-resistant abrasive material. These apply friction to the brake discs. The friction that is generated causes heat. Discs have holes to help cool and dissipate the heat, as well as preventing any fluid build up in wet riding conditions (apparently…fairweather rider over here). The nipple allows for the brake system to be bled of any air in the system. Air in the fluid system is bad, as this is compressible and means the piston will not move like you want it to, meaning you will career straight on at that corner. It also happens that bleed nipples are cut from the same cloth as exhaust studs i.e. fiddly, weak bastard components regardless of how much to plan around them being assholes will still end up being assholes and cause you to burn your possessions to the ground…

 

So onto whats wrong with mine – many years of sitting exposed to the elements has not been gentle…try everything. The reservoir is goosed, someone kindly rounded all the bolts off for me to make dismantling impossible without damaging the plastic reservoir pics below….the studs this sit on are also seized and attempted removal caused them sheared flush…even if I could rescue this part the master cylinder is clogged with whatever gunk the brake fluid has decided to morph into over the years. The rear master cylinder is in better condition and a rebuild kit has been ordered for it. The hoses are rusty, the pads are all shot but at least the discs look ok…this is before we get to the callipers.

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There are three callipers on my bike, so three chances to get things wrong. The key things to achieve by stripping –  getting the notoriously bad bleed nipple removed, getting the pistons which had seized in place removed, restoring the sliding surfaces for the pads and piston back to normal.

There are various ways recommended to remove the pistons. Ideally, the best way to do it would be to use the existing fluid in the hydraulic system and keep pumping the brake lever to cause enough pressure to loosen the rust and press the piston out. Caution is needed here not to be stood in front of the pistons trajectory as it comes free and hurtling towards you like a 30mm bullet. As mentioned my brake system wasn’t functioning well enough (at all) to do this. I used a combination of heat, shock, shouting and a vice-grip adjustable locking pliers. Initial attempts were futile, but if all else fails, find a bigger lever! See pictures below…the pistons eventually became free, although there is slight damage to the lip this method is fairly successful. due to the corrosion and state of the sliding surface, I am replacing these anyway so was less concerned about the damage caused by heat and 10ft lever bar.  See pictures below…

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Onto the bleed nipples…knowing these are notoriously difficult to get out (my dad inadvertently taught me every swear word under the sun when he last had issues removing one of these back in the mid 90’s). Due to their position, they are exposed to all elements, seldom looked after and are made of the same material as tin foil (probably). They corrode quite badly.  Knowing this, i took several precautions to make removal less painless. I applied several rounds of heat with the blow torch, used trusty WD-40 to try and release the threads, left sitting for a few days, shocked the nipple with some gentle persuasion with a hammer. Having done this, I knew it was coming free… I put the spanner on and it snapped flush with the caliperthe first prssure applied…*face palm*

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Not to worry, this is the most common way these fail, knowing this I have a set of EZ-outs.  These are meant to rescue you when stuff like this happens. They are a hardened steel threaded tapered shaft (hehe) with a left-hand thread..they are also pretty terrible. You have to drill a hole in the remaining bleed nipple (easily done as there is a hole down the centre) to allow the EZ out in. Then you unscrew, the left-hand thread tightens against the remaining material and voila it comes free….except it didn’t…the EZ out, which I think was made of some kind of chocolate, broke flush the exact same way as the nipple…ARRRGGH

Hardened steel component inside of a heavily rusted nipple does not make for easy drilling out. NOT TO WORRY, I HAVE A WELDER WHICH WILL HELP ME. in the past, a last ditch effort has always been to weld a nut onto whatever stump was left to then get a bigger spanner on and then release. Using my new found welding skills, I tried for about an hour to get the nut welded on, but for whatever reason, it would not stick well enough to allow enough force to release…definitely not user error…honestly!

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Anyone who has been in this position before will share the frustration, it’s SO ANNOYING. After 2.5 hours in the freezing cold garage enough was enough, it was time to create some warmth…GOODBYE SHITTY YAMAHA PROJECT BIKE AND EVERYTHING ELSE  I OWN WHILST I’M AT IT.

Being less dramatic,  I was left with two options, either send the caliiper away to get spark eroded, a costly yet effective process for this kind of issue…if it had been an engine block then this would have been the choice, but the economics don’t add up. I managed to get another calliper on ebay from a breakers yard for £40 delivered. It was for a larger XS1100 but it is the exact same calliper as on my bike, so not the end of the world…

My next post will look at the stripping, painting and rebuilding of the brake system…I have actually spent a fair whack of money getting these back together. Parts for old motorcycles are not as cheap as you think…I will do a proper tally once I have them complete….they are such an important part of the bike that you want them to be as they were when they came out the factory. My concern is that this may not actually lead to good brakes…1970’s technology vs modern day….I may have been cheaper looking at some of the upgrades like using a more modern bikes braking system but I will bury my head in the sand with that one and look at that idea on future builds….once i rebuild my house and garage again….

To be continued,

Struan

 

 

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