FAO Lee : Brake Fluid and Bleeding Clutch

[Doug_RS2]

Lee - Is the fluid you are using Castrol Super Response Dot 4 or Castrol Response Dot 4? I can't remember what you said!

This is a webpage doing some comparisons on brake fluid:

http://www.volvoclub.org.uk/faq/Brak...omparison.html

and this pic sort of shows how to bleed the clutch - which should be done when bleeding your brakes - the pic isn't very clear as it looks like the bleed hose is connected to the gear linkage thread - it is actually behind that.

I've asked before but can't remember the answers : Is there a specific order to bleed the brakes and do you need to do anything special becasue we ahave ABS - like bleed the brakes with tthe engine running?

[Lee]

Thanks Doug,

Super DOT4. SRF when the rear brakes are done. Few months yet!

Engine doesn't need to be running on our cars due to the ABS sytem config.

The pic makes it look like a PITA. I'll have a look next time I open the bonnet to see how easy it really is.

Always start with the longest from the master cylinder. True unless you have ABS, in which case it is furthest from the ABS unit. OSR then NSR then OSF then NSF.Clutch whenever due to the way it takes fluid from the reservoir on our systems. I am going to leave my clutch unbled since the Super DOT4 mixes OK with the previous stuff. SRF in not compatible so that will need a thorough flush and rebleed. I figure on wasting a lot of money by using 1 to 2 litres just to flush since it is so incompatible..picky maybe and expensive but it will give best performance.

Lee

[Doug_RS2]

Cheers Lee - It is a pain doing the clutch becasue you can't see what you are doing.

[newsh]

This could be useful, for the ur.

http://www.isham-research.com/quattr..._bleeding.html

[Doug_RS2]

John - that is new to me so I have some questions:

1. pump the brakes so they are hard - why?
2. proportioning valve? Where is that?
3. bleed the master cylinder? where is th enipple?
4. 2 to 2.5 Bar - that is high - I have read that it should be below 20psi for an eezibleed

[Doug_RS2]

And - why do you have to hold the brake pedal down?

[Lee]

@Doug, you obviously know this but just in case you don't. Your APs will have 2 bleed nipples per caliper. One on each side, ie one nipple per 2 pots. It doesn't matter which order you do them so long as you complete one corner of the car before moving to the next. I always aim for filling a small glass jar out of each corner, I guess about half a pint (1 litre to flush the system). Never let the master cylinder go dry otherwise you'll have to start again which is a PITA. Not done it myself but know people who have wasted hours for such a simple mistake.

[Lee]

The Sykes Pickvant bleed nipple spanner from Halfords is well worth the investment for a couple of quid. It is much better than a ring spanner which can easily damage a corroded nipple.

'nuff said. This talk of nipples is distracting!

[Lee]

Originally posted by Doug_RS2
John - that is new to me so I have some questions:

1. pump the brakes so they are hard - why?
2. proportioning valve? Where is that?
3. bleed the master cylinder? where is th enipple?
4. 2 to 2.5 Bar - that is high - I have read that it should be below 20psi for an eezibleed

This might have overcomplicated things. Some things don't apply in the same way to the S2. If you want, pick up the blower and I'll talk you through it on the S2. It's easy. There are many techniques to brake bleeding and I've tried them all with varying success on different systems over the years.

[Doug_RS2]

I thought you should bleed the nipple further away(can't remeber if that is inside or outside) so you don't risk introducing air to the one you have just bled. (on the AP setup)

I have the open-ended ring brake spanners.

[Doug_RS2]

Lee - I know there are different ways - I just like asking "why" to understand things more, rather than just doing it.

[newsh]

Sorry Doug, I may have confused things with that post and I can't answer all your questions either:wacked:

Pump the brakes to relieve servo pressure from the system?

The ur has a valve just below the master cyl that splits the pressure between front and rear. If there's a leak at the back it shuts off the back so the front still works.

On the ur the nipple is on top of the master in plain view.

Not sure about the pressure. I usually use the spare tyre.

Er, you can tell I've never done it on the S2.. Will be soon though as I got a grinding noise from the brakes just now on the way home, pads are gone I reckon...

[Mark Halligan]

Doug,

to bleed the clutch easier you can slide the gear linkage off of that shaft with the 10 mm nut if you want, just be careful not to lose the plastic bushings, its easy to re-install. It makes life a lot easier, done it several times myself.

Cheers,

Mark.

[Lee]

Originally posted by Doug_RS2
I thought you should bleed the nipple further away(can't remeber if that is inside or outside) so you don't risk introducing air to the one you have just bled. (on the AP setup)

I have the open-ended ring brake spanners.

True if the calipers are new and full of air. You are not worried about air lock removal...more the replacement of old fluid with new. Furthest nipple is probably wisest though, as you said, and this is the ouside one for us.

I know there are many ways but it helps to understand one way at a time and how different systems require a different approach. Our ABS actually simplifies things in many respects so just thought it might save you learning different ways that you can't apply to your car.

HTH. Lee

[Vagsport]

I've always bled brakes (even with new calippers which are full of air) by atmospheric pressure, i.e letting the fluid run out on its own. I haven't had any problems doing it this way. It takes a bit longer, though but very useful as I can do other jobs on the car while bleeding.

Siena