Camchain and tensioner seen up close in a cutaway bike engine

Home Repair And Restoration

Brake Fluid Change

Job Date - Monday, February 11, 2019

By Pocketpete

Ren has kindly made an early morning dash over the M60 to help with a brake fluid change.

I have watched a few videos online and there are a few methods which seem to get the job done. One where the oil is removed by syringe and then clean oil injected via the bleed nipple. Seems to work ok.Another system where a pump is used to suck out the oil. They all seem to do the same thing - which is change the fluid.

A cup of tea to start and then we are off. I'm rather disappointed, no stripping of cylinder heads. Instead we have a small spanner and bit of pipe. 

It's off with the rubber cap. No need to drill out any of the bleed nipples on my bike they open quite easily. Then it's pump the brakes, hold, then release the bleed nipple. Continue until the reservoir is empty-ish and top it up.

Ren does this 2 or 3 times then adds a top up and stirs the remaining fluid. Then he repeats the process again and is finally happy we gave changed the bulk of the fluid. Obviously the ABS may hold little somewhere.

He then cable ties the brake lever back which he leaves for 30 minutes before capping off and replacing the screws. He thinks this removes any remaining air bubbles. Seems nice and firm at the lever now.

The front brake lever is zip-tied on and the master cylinder is open

The same process for the rear. The oil is pretty dirty and seems to clean up nicely.

So it's a simple process, one I could certainly do now I've seen it done. Ren's pretty good at these repair thingys. All I have left to do now is clean the brake callipers and pistons. I'll also clean the bike and start preparing for touring Scotland in may.

On e rear brake's bleed nipple a pipe flows to a used milk bottle

A final big thanks to Ren, his help is invaluable to someone of my meagre mechanical talents. Bacon and egg butties are prepared and more tea. We have a lengthy chat about why no one who has a bike can agree on anything.

What oil to use?
What coolant to use?
How to do the brakes?
What chain to use?
How to clean the bike?

Indeed nearly anything biking means diametrically opposed views...

We investigate the benefits of a relay system for the electrics which I find really interesting. Eventually Ren departs to another appointment.

Another very interesting day. I'm sure I will be able to do this job in future and I'm happy my bike is well prepared for the spring.

Still no reply off Honda yet regarding my coolant issues though.

In a world with a million different ways to do the same thing - why not share your ingenious tips here on Bikes And Travels? Contact

Reader's Comments

Ian Soady said :-
Cable tying the brake lever? Snake oil in my opinion. Consider how the master cylinder works. When the lever is released, there is a tiny hole that allows fluid (better not to call it oil in case of confusion!) to pass between the reservoir and the operating volume forward of the piston. This also of course allows air bubbles to pass upwards and that's how any remaining air should be eliminated from the system.

When you operate the brake (or tie the lever back) this closes off the tiny hole. So how does the air pass up into the reservoir? Magic fairy dust seems the only answer......

By the way, I use a vacuum pump for bleeding brakes - see link below. The linked brakes on the Guzzi can be a real pain using traditional methods.
16/2/2019 12:31:15 PM UTC
Upt'North said :-
Well done Skipper, very neighbourly. You know it's only 4 hours to Northumberland if you're short of things to do. Re. tying the lever back, I've never done it, or indeed needed to do it but the practice seems to be used and recommended a lot by owners of Honda CBS/ABS owners. If memory serves me correctly I think it is recommended that the lever is tied back overnight for best results.

16/2/2019 3:07:29 PM UTC
Upt'North said :-
Your almost there John....All the hoses have bends, elbows, pipes, banjo fittings, as you stated, compressing the fluid, while it does make the bubbles smaller, and easier to break loose, there's more.....think of it this way...they are under pressure, gathered near all the corners where they are trapped (refer to your ink in the line example) and then while under pressure, they gather, join forces, making bigger pockets of air, and are sitting ready like the guys wearing white suits in a Woody Allen movie etc. Its when they are released, that the pressure flushes them by the areas that can trap them....
We'll see how many folks are old enough to catch my Woody Allen comment.

So, I think what this geezer is saying is bleed it, leave it under pressure and the bubbles will migrate upwards towards the blocked port, release in the morning and Robert's is your fathers brothers as it will pop out of the cleared port. Or it's witchcraft.
16/2/2019 3:16:22 PM UTC
Ren - The Ed¹ said :-
Ian - knowing full well how a brake system works the whole tie the lever or weight the footrest baffled me beyond belief. Rubbish, nonsense, codswallop and all that! But when I was struggling to bleed the front brake on the SLR650 I tried it. The SLR is as simple a set-up as you can get. Master cylinder up high, one single pipe to one single calliper. Could I get a good lever? Hell no. Then I was reminded about the nonsense of loading the lever. In desperation I tried it and left it overnight. Hey presto, go figure, what the deuce and all that.

I explained to Pocketpete on the day that it makes not sense.

However I daresay Upt'North's potential explanation is the only one I can think of that makes any sense. Something about the compression causes any air to "migrate" up to the master cylinder where it can be released into the space above the fluid level.
16/2/2019 6:07:50 PM UTC
Ren - The Ed¹ said :-
Oh and Upt'North. I'd consider your abode a little too far for a day trip to fix your Pan. If however there was accommodation... Hehe. Be warned though, you could end up with some DIY handguards and questionable sprocket practices.
16/2/2019 6:10:20 PM UTC
Pocketpete said :-
Good job I checked the brakes one of the pistons on the front was sticking I've not noticed any problems braking but one was not moving freely it was covered in crud and not moving well as the other.

I cleaned them up with a tooth brush and carefully turned the pistons the bottom one turned easily the top one was much stiffer. I gradually eased them out as far as I dared the top one was really covered in crap and had a large patch of black tar like stuff stuck on one side it wouldn't come off with the brush.

After a search on the internet I decided to use some fine wire wool. This eventually got it off. I kept turning the pot and it was filthy at the back once I had cleaned it off it seemed to move in and out much better I used rens method with a metal ruler between the pads to move the pistons in and out.

I also notice the rubber o ring on the pad retaining pin was perished going to have to get a new one. God it has just corroded to brittle mess of rubber. I've fit it back without the o ring but I will have to order one. Cant believe so much crap was stuck in there.

Front done I will do the back next weekend. Hope that's better.
17/2/2019 5:00:53 PM UTC
Upt'North said :-
Pete, an old thick shoelace moistened (nice word) with brake fluid and pulled around the surface after being wrapped around the piston does a good job. No chance of scratching it either.
17/2/2019 5:55:25 PM UTC
Ren - The Ed said :-
Oh I say Upt'North, that's rather clever.

Question - we all know brake fluid ruins paintwork and plastic. I have to presume the paint actually on the brake calliper is not affected (effected?) by the brake fluid?

Remember peeps - keep brake fluid away from everything other than brakes.
17/2/2019 7:49:20 PM UTC

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