Brake Fluid change for a V7C - one way to do it.

[sign216]

I changed the brake fluid on my V7C, using a technique that's easy without too many special tools.

I captured it with photos, here: http://www.flickr.com/photos/sign216/sets/72157625625067451/

Joe

 

[Morizzi]

Thanks Joe,

You obviously went to a lot of effort.


I used to work with a very, very good classic car mechanic. He once told me just to syphon out the fluid from the reservoir and not to worry about the fluid in the line.

His reasoning was:

1. The volume in the line is fairly small and some will be lost when the caliper is bled anyway.
2. Easy, quick, no mess so can be done more regularly.
3. M/C's can become pitted on the inside surface where the rubber seals don't slide. If you push the piston past their normal range of movement the seals get chewed out by the pitting.

Just another perspective.

Rod

 

[sign216]

Rod, I've got to say that the lines need to be bled out. That's where most of the air bubbles are, and it's not too much work to do it right.

 

[Morizzi]

Joe,

I liked your post and stated so. I'm just offering another perspective.

For a new bike like yours then there is probably no pitting so it wouldn't be an issue. For older gear it may be different and if you are in a situation that you have no other means to bleed then pump away by all means but I've always been taught to minimise it.

If the brakes feel fine and it is just time to replace the fluid then do so by sucking out the reservoir and refilling. Forget the rest.

If you need to bleed then a simple pressure system or vacuum system will be able to purge the whole system without the piston needing to move.

I have a compressor at home. I just fitted a suitably sized lid that would screw onto the master cylinder with an air inlet and with just a couple of psi the job is easily done. Others prefer using a vacuum system. Just use the syringe you showed in the pics to suck the fluid through. Others use a syringe at the bleed nipple to push fluid through. It really doesn't matter which one you prefer as they all work.

I like the pressure system as I have older bikes with the linked system. One attachment and two of the calipers are under pressure and ready to bleed.

Cheers

 

[sign216]

Morizzi that's a good idea to use the syringe to suck the fluid out. Or a compressor to push it out. Would make the fluid drain in seconds.

Quickly sucking the fluid out is more likely to strip out the air bubbles, and that's good. I'll try that for next time.

Thanks.

 

[Morizzi]

Joe,

The key to success is 'slow and easy.'

You only want a couple of psi pressure. Any more and the fluid can splash around. The pressure system can be done with a tyre valve and hand pump if that is what you have.

Rush fluid through an air filled tube too quickly and it will trap air and make bubbles. Keep it slow and the forward edge of the fluid will maintain its integrity and purge the air before it. Same goes for the vacuum system. Use the syringe in a nice easy smooth motion and it will be done first time.

If it doesn't want to come through just give the M/C piston a jiggle or move it slightly. Not always needed but sometimes.

Glad to be of help.

Rod

 

[icenian]

A few years back, I bought a Mityvac hand held vacuum pump, with a brake bleed kit. It makes draining/changing/bleeding brakes a doddle, even if you've completely drained the whole system.

It's a great solution for someone who does this maybe a couple of times a year and doesn't what to spend a huge amount on tools. Only catch is that it's easy to use a bit more fluid than if doing in by hand, at least until you get used to it. Oh, and they're just a bit stingy on the amount of tube they supply, but it's not hard to fix that problem.

I can't see the exact one I have on the web site, but this one looks like a newer version of the same thing:
MV8020

40 UKP (~55 USD I think) in the UK, probably cheaper in the US.

 

[Holt]

A few years back, I bought a Mityvac hand held vacuum pump, with a brake bleed kit. It makes draining/changing/bleeding brakes a doddle, even if you've completely drained the whole system.

It's a great solution for someone who does this maybe a couple of times a year and doesn't what to spend a huge amount on tools. Only catch is that it's easy to use a bit more fluid than if doing in by hand, at least until you get used to it. Oh, and they're just a bit stingy on the amount of tube they supply, but it's not hard to fix that problem.

I can't see the exact one I have on the web site, but this one looks like a newer version of the same thing:
MV8020

40 UKP (~55 USD I think) in the UK, probably cheaper in the US.

- and, as I stated both before and elsewhere - if you're using a similar but compressor-driven gadget, you won't even get sore hands by all that pumpin' and pressin'. :mrgreen: