If it helps......................
Here we are with a few methods that we have come across in our time to get the best performance from your brakes and options on how to sort them out with simple tools or more drastic measures. There are many methods abound and all have there own merits, but folk law states that skills take time to build themselves up and after 2 ½ decades of messing with bikes we have certainly had a few cool eureka moments in this area.
At the top of our bleeding success story’s chart is a tool that will cost you less than ‘one spondooly!’ Yep, that’s one measly UK quid! I suggest that you check out the local car parts suppliers and look for an “Orange Tube” in a transparent packet.
It’s about 8 inches long with a metal plug in one end. Near the plugged end you will find a split, note: this does not mean that it’s faulty but is essential, because it has been made with cars in mind. You have to carefully extend the split by another ¼ inch for use on bikes. This simple tool means that you don’t have to worry about keeping the lever held in or the tubes end submerged when you are tweaking the nipple.
Talking about nipples, you should always have caps on them at all times. You’d be surprised at how much air leaks out of them, and they stop the shite from getting in as well.
Additionally. Regardless of what bleeding method you are using it is a good idea to unbolt the caliper and hold it above the master cylinder to promote the air to rise into the caliper's exit bolthole. Tapping the m/c, the lines, and also the caliper with a spanner a few times helps things along.
Those vacuum bleeders are cheapish and are worthwhile investing some coin in as they will pay for themselves over a few short years. If you spend a few more quid then Snap-On gear is the way to go but in the end, an effective £1 gadget can’t be sniffed at.
This is how I usually set about bleeding a difficult system. Firstly I remove the m/c banjo from the m/c and fill the reservoir up – and replace the lid. With a thumb over the banjo hole, gently pump the lever slowly increases the pressure on the thumb until the fluid and air squirts out. The use of protective rags on the bike is a prudent move here. When no air seems to be leaking out, fasten the line in place carefully as we want to minimise the inclusion of air.
The next stage involves removing the calipers banjo and elevating the line above the m/c. With fore finger and thumb sealing the banjo fitting the lever is again slowly pulled until the line end has the same effect as the m/c earlier. Fix the line to the stopper and do the same to it via the nipple. It is always a good tip to manually fill the caliper with fresh fluid via a syringe before hand. Install the brake system again and you should be able to bleed the system as usual after all that. Remember NOT to let the pads close down to far during all bleeding procedures when the calipers are off the disc. Saves a ball acher trying to fix the situation after the deed is done.
“None of that works so now what’s wrong” you may ask…!
“Personally I’d go the whole hog and restore your stoppers from scratch.”
“How do I get the pistons out then smart arse?” you excaim!
Well, if trying to push them out using the bikes own system fails then there are different ways of doing this task. The first one is to try and get the pistons out using quite a lot of compressed air. Beware though because this method can serious hurt you, unlucky astronauts or anybody else who happens to be passing by.
Other old dudes swear by fitting a grease nipple to the banjo bolt and pumping the stopper full of grease. This overly messy solution does actually work and it also happens to rate low on the fatality/loss of limbs scale.
“OK, but they are still stuck solid!”
Right… Grip the caliper or caliper halves somehow and drill the centre of the piston to suit a 6mm tap. Fit a 6mm bolt into the hole and simply jack the piston out. If the thread strips then tap out to 8mm and repeat the steps. This method shouldn’t fail to release even the most stubborn items. But you really must remember that the holes in the pistons will have to be welded on one or both sides to prevent fluid seepage after they have been fitted to your bike! TIG or MIG only here as arc is too barbaric and we want minimum heat and no warpage. Best if you enlist the help of a local professional for this job.
I won’t go on about the merits of different brake fluids as they have been mentioned in CMM before. With this in mind I have to say that the stoppers lifeblood is scientifically termed ‘Hydrophilic’ which means that it likes water if ya put it simply. Never the less…If you bandy it into the convo in the pub then folks will think that your either very clever…. or a rite bore!
Different ppl have an opinion about how often the brake fluids should be replaced but once a year should be fine. Just bleed away until fresh stuff flows outta the bleed nipples. A caliper overhaul once a year or more frequently should be undertaken as a matter of course on some models like the Yamaha LC’s units.
Ok… so we have the calipers stripped and the pistons and seals sat on the bench. You can look smug now because the hard part is over, but the seal grooves and other moving parts need looking at. A point worthy of note is that seals and pistons can actually be used again if they aint too far gone. Please be careful though until you have confirmed trust in the overhauled brakes. Considering the relatively small cost of replacements I’d advise going for new bits with a ‘very careful’ install.
To clean the piston and the caliper I usually use ‘scotch-brite’ to get the crap off and then I use a special tool that Harry Triples invented. It’s a cheap screwdriver that has been ground into a scoop shape with a sharp end. This allows you to get at most of the corrosion outta the seal channels. If you have a ‘pound shop’ or ‘Wilkinson’s’ then look out for a pack of 3 brass wire wheels and an adapter for a drill. Give the slots a few passes with the wheel and that’s them sorted.
Now lets focus on the caliper bodies themselves.
A must in any workshop is the presence of ‘brake cleaner’! Aerosols are the easiest to use and on the odd occasional the ‘pound shops’ stock them.
Firstly you want to use fine emery paper or fine wet and dry on the shafts and flat mating surfaces - don’t go stupid here! Clean all the parts with brake cleaner and wipe them clean. Pay particular attention to the threads in the nipple and banjo boltholes, and also the bolts themselves.
Now the seals need to be fitted and coating them in brake fluid is the first step. It’s really not that difficult to fit them if you take a little care to ensure that they are correctly seated. Wet the piston and gently push it in as far as it will go – sorted. On some models the two caliper halves need to be bolted together and with the body o rings in the right spot. Don’t forget to treat all the fasteners with a bit of ‘copper grease!’ If there were 10 commandments for workshops then ‘you must use copper grease’ would be number one.
The jobs almost a good ‘en and its time to fit the pads.. I suggest that you loosely fit them in the caliper body and fit the holding pins. If the pads catch then slightly file them until they are free. Fit the pads and shim pads if you have them and insert the copper coated holding pins home. Fit a split pin or ‘R’ clips if applicable and things are coming to an end.
Assembling the units you will need quality grease on the slidey bits, and that doesn’t mean the crap you can buy at Tesco or a discount crap goods store. A tub of Silkolene red grease will last you ages and is water resistant too – it will also last you for ages and all for just over a fiver, and the same for copper grease too, an essential!!
Ardon...............
