Servicing advice please.

I just popped to my local screwfix and bought the following:

As you can guess, I am getting ready to service my bike and give it (almost) a complete service. I want to replace the brake fluid and I have a few questions.

1. I want to flush the old fluid out and ideally take the calipers off for a rebuild. But I have no vacuum tools for this (and not prepared to buy any being the tightarse I am ). If the principle for bleeding the brakes is as I understand it, why can I not pump the old fluid out with the brake lever out the bleed nipple (into the bleeding kit I have above)?
   
   Surely that is the same principle as bleeding it, as it's removing the older fluid out the bleed nipple?
2. If I cannot do the above, I will just replace the fluid. Which is my next question. I see there are a thousand threads on this already, but all seem to use different tools.
   
   I know I fill the bottle in the picture up with brake fluid (there is a pipe in the kit I bought which is submerged in fluid). Then connect one of the valves to the bleed nipple, and pump the old fluid out (keeping the reservoir topped up with new fluid) until eventually the new fluid is shown through the clear pipe (as stated in the Haynes manual). Is that it? It seems pretty simple...

If I happen to get air into the system, can I bleed it out by just pumping the fluid out and keeping the reservoid topped up?

And is there any tips/tricks I should look for? My preferred choice is to rebuild the calipers. Which leads me onto my next question - there seems to be loads of parts from wemoto ranging from replacement nipples to piston and dust seals to "Rebuild Kit Brake Mastercylinder" to "Rebuild Kit Full Seals Caliper Front/Rear".

I presume I need the last one (I see the front covers both calipers, hence the £50 tag - if someone could confirm.

[johnnyrod]

First off, if the brakes aren't binding then don't waste your time and money on stripping the calipers, it will achieve exactly nothing. Not sure what the feeler gauges are for, valve clearances and/or plugs I presume. Anyway I think the bottle is for the old fluid but I've never used one of those so I can only assume. Yes if you let air in then you just flush it through, new in at the top, old out at the bottom. Yes you can also do this to empty the system but really you'd first use the pressure to pump the pistons out of the calipers (but you don't need to unless stripping them, obviously).

All you really need is an 8mm spanner, a bottle of clean brake fluid, and an empty bottle. These vacuum/non-return valve jobbies are nice but not essential. When you pump the brake lever, it pushes fluid, when you release, it sucks it back again, until it's almost at its rest position. At rest it allows fluid to flow by itself in and out of the reservoir, so there is no pressure in the system and it tops itself up automatically. As you pull the lever, the first thinig it does is shut off the reservoir, then it pressurises whatever is in the cylinder/calipers/lines. No mystery really but if you know that then you can figure out how to go about it.

Hope this helps

[yorkie_chris]

Originally Posted by johnnyrod

First off, if the brakes aren't binding then don't waste your time and money on stripping the calipers, it will achieve exactly nothing.

Preventa-what-tive maintenance?

[timwilky]

Originally Posted by yorkie_chris

Preventa-what-tive maintenance?

+1, I would advise calipers are stripped/rebuilt at least every 3 years/10,000 miles. there is no schedule as such. but you need to know your brakes are gong to function properly when needed in anger.

You would be surprised just how much crud builds up on the pistons over time. This tends to adhere to the dust seals and pulls them out, wedging between the piston/caliper. Also the calipers float on mounting pins. you do not want these to sieze as you are then pushing against on side of the disc and not squeezing it. (although others will probably disagree, clean the pins/caliper and re grease with LM).

Remove your pad retaining pins, apply a little copper grease to the blind hole/pin and reassemble. Saves hours of heartache for 5 minutes work. I know of Suzuki owners who do this within hours of buying a brand new bike.

A day in the workshop every couple of years is time well spent

[yorkie_chris]

If you ride all year round I would advise stripping calipers 2 or 3 times a year.

It costs about 4.1p for the grease and brake fluid, mad not to do it when avoiding it can cost you £100 for new pistons and seals.


Tim, I think LM grease is safe on the slider rubbers. (for anyone else reading those are NOT the caliper seals)

[timwilky]

Cheers Chris, I have read of people suggesting rubber and copper greases for this purpose. Probably armchair internet mechanics. but hey this is a virtual world and everyone is an expert. I know what I do/use. Some trust me and I advise from experience not by google.

[yorkie_chris]

The sliding rubber (not the one that's just a cover) is one of the worst parts of these calipers, you get corrosion inside caliper which squeezes the rubber and locks pin in place. You need to pull rubber out and clean bore with round file, or some emery, or anything and apply bit of grease to prevent reoccurance.

Copper grease has been known to make these rubbers swell, not sure though. Not worth risk. Probably to do with the type of oil used in the grease.

[TheRamJam]

Brake bleeding is relatively simple. I replaced my stock hoses with HEL lines with nothing more than an 8mm ring spanner, some clear tubing, a beaker and Motul Dot 4.0 brake fluid. Took me a few hours but its working great and good feel at the lever. Will do pads next month.

First off i had to get the old fluid out. This is done by pumping the lever a few times then holding the lever back and and undoing the bleed nipple. Repeat until reservoir is empty and there is no resistance when the lever is depressed. Old hoses off and new lines installed. Rear brake is really easy. Top up reservoir with new fluid, put some fresh fluid in beaker and connect the clear tube to bleed nipple and the other end submerged in beaker. Pump the leve about 10 times and hold. Release nipple then tighten. Repeat this process until you can see clear fluid with no bubbles coming through the tube. NOTE: Make sure you keep an eye in the reservoir always keep it topped up.

The front takes a wee bit longer but the process is the same. First bleed the Master Cylinder then the left caliper then the right caliper using the process explained above. Once done check the system for leeks and good feel from the levers when depressed. Freewheel the bike and apply the brakes before going a test run. Stick to 30 ish for then come back and re-check for leeks and check the fluid levels.

Job Done

Originally Posted by johnnyrod

... Not sure what the feeler gauges are for, valve clearances and/or plugs I presume. Anyway I think the bottle is for the old fluid but I've never used one of those so I can only assume. Yes if you let air in then you just flush it through, new in at the top, old out at the bottom. Yes you can also do this to empty the system but really you'd first use the pressure to pump the pistons out of the calipers (but you don't need to unless stripping them, obviously).

Thanks Johnny - you certainly did help. You're right, feeler gauges for both of those.

Originally Posted by timwilky

+1, I would advise calipers are stripped/rebuilt at least every 3 years/10,000 miles.

Exactly my thinking - at least I can keep them in good order and hopefully see any problems on the horizon.

Originally Posted by yorkie_chris

If you ride all year round I would advise stripping calipers 2 or 3 times a year.

It costs about 4.1p for the grease and brake fluid, mad not to do it when avoiding it can cost you £100 for new pistons and seals.


Tim, I think LM grease is safe on the slider rubbers. (for anyone else reading those are NOT the caliper seals)

Cheers Chris. Looking at brake fluid was what drove me to do it (strange reasoning ). It's near pennies for a bottle!

Originally Posted by TheRamJam

Brake bleeding is relatively simple. I replaced my stock hoses with HEL lines with nothing more than an 8mm ring spanner, some clear tubing, a beaker and Motul Dot 4.0 brake fluid. Took me a few hours but its working great and good feel at the lever. Will do pads next month.

First off i had to get the old fluid out. This is done by pumping the lever a few times then holding the lever back and and undoing the bleed nipple. Repeat until reservoir is empty and there is no resistance when the lever is depressed. Old hoses off and new lines installed. Rear brake is really easy. Top up reservoir with new fluid, put some fresh fluid in beaker and connect the clear tube to bleed nipple and the other end submerged in beaker. Pump the leve about 10 times and hold. Release nipple then tighten. Repeat this process until you can see clear fluid with no bubbles coming through the tube. NOTE: Make sure you keep an eye in the reservoir always keep it topped up.

The front takes a wee bit longer but the process is the same. First bleed the Master Cylinder then the left caliper then the right caliper using the process explained above. Once done check the system for leeks and good feel from the levers when depressed. Freewheel the bike and apply the brakes before going a test run. Stick to 30 ish for then come back and re-check for leeks and check the fluid levels.

Job Done

Thanks a lot for the comprehensive explanation . I presume if I have one of those one-way bleed systems (i.e. one that does not allow air to be drawn in) I do not need to redo the bleed nipple up after each squeeze of the lever? ... I will have to check whether mine is one way or not.

When you say to bleed the master cylinder... how do you do that? I thought it was just the calipers that needed bleeding?

Finally, when you say keep the reservoir topped up, I presume that's once you're done with whatever maintenance you're carrying out on the brakes, and ready to top up the new fluid?

Cheers

[Sid Squid]

Beware clever bleeding tools, they should work as you say; one way valve only allows movement in one direction.
The gap in the threads of the bleed nipple will feel different, and air will be sucked back through there when you release the brake lever.
This can sometimes be alleviated by wrapping a few turns of PTFE, or a smear of some heavy grease around the threads of the bleed nipple.
Some bleed nipples are available which have a sealing material on some of the thread.

It's just easier to do it manually though.