brake fluid...?

[peteA]

'Another' one of my winter jobs is to fit braided brake hoses to my cerb and I was/am going to replace the fluid at the same time.

I was going to use some brake fluid I already have but its DOT4 and I noticed having printed of the alternative parts list (very useful by the way - thanks to who ever pulled that together) states DOT5...?

I know a little bit about DOT5 fluid and know it cant be installed in systems designed for DOT4, etc but am suprised the cerb is DOT5.

Is the the cerb definatley DOT5? Its a 98 4.2 by the way in case that is important.

Thanks in advance.

[Nefarious]

DO NOT put DOT5 in it. DOT 5 is silicon based and is totally incompatable with all the rubber seals etc in the existing system (TBH, I think you'd struggle to find somebody to supply DOT5 outside a military base or somewhere inside the artic circle)

DOT 5.1 is what you're looking for - it's essentially the same as DOT4, but has higher wet and dry boiling temperatures. To complicate matters some DOT4's are better than some DOT5.1s (e.g. Castrol SuperDOT4), so go on wet boiling temp, rather than DOT number. If you really want the very best, then put Castrol SRF in, but be prepared to pay for it.

[peteA]

Nefarious said:

DO NOT put DOT5 in it. DOT 5 is silicon based and is totally incompatable with all the rubber seals etc in the existing system (TBH, I think you'd struggle to find somebody to supply DOT5 outside a military base or somewhere inside the artic circle)

DOT 5.1 is what you're looking for - it's essentially the same as DOT4, but has higher wet and dry boiling temperatures. To complicate matters some DOT4's are better than some DOT5.1s (e.g. Castrol SuperDOT4), so go on wet boiling temp, rather than DOT number. If you really want the very best, then put Castrol SRF in, but be prepared to pay for it.

Thanks nefarious - actually looking again the spares list states 5.1...I assumed, obviously incorrectly, that DOT5 & 5.1 were similar.

DOT4, DOT5.1, superdot4, SRF....nowts simple!

Thanks again

[peteA]

OK

Motul rbf 600 seems to come recommended - its about £10 per 500ml. The spec sheet states ''types of use - all types of hydraulic actuated brake and clutch systems requireing non-silicone synthetic fluid'' + '' Exceeds DOT5.1 and DOT3 standards also, except for viscosity at -40 Deg C (-40 Deg F) (Hopefully this will never be an issue...) Also. ''standards : FMVSS 116 DOT4 / SAE J 1703''.

Pretty sure this will do for me!

whats the braking system capacity?

[Nefarious]

System capacity is considerably less than 1L, but if you're bleeding it yourself, then don't be too wasteful or you'll run out! (i.e. close the bleed nipple as soon as the fluid turns clear).
The Motul stuff looks like a winner at that price (IIRC I paid £50+ for a litre of SRF)
Here's a link for some boiling point comparisons: http://www.volvoclub.org.uk/faq/BrakeFluidComparis...

[Nefarious]

Oh and while I'm thinking about it - don't make the same mistake I did first time - there are two bleed nipples per caliper.

[HRG]

I alternate between the ATE super racing blue and clear, that way you can tell when the whole system is correctly bled.

[Brummmie]

Dont go on DOT ratings, go on boiling point. Any good fluid will give this on the container. The good ones are 300+ C. The dry boiling point is when new and wet is when it is old and exposed to moisture. Hence why you should renew every once in a while.

[peteA]

Brummmie said:

Dont go on DOT ratings, go on boiling point. Any good fluid will give this on the container. The good ones are 300+ C. The dry boiling point is when new and wet is when it is old and exposed to moisture. Hence why you should renew every once in a while.

I printed the spec sheet off for motul rbf 600 and that states ''very high boiling point : 593 Deg F / 312 Deg C''....like i say, that will do for me!

To be honest, the standard DOT 4 stuff would probably do for me but I take the 'I dont mind spending a bit more approach for a bit extra quality' when i am replacing stuff.

Thanks again guys

[jesfirth]

Castrol srf 600 is the mutts nuts. I used to regulaly boil dot 4 and 5.1 fluids on the track in both my 400se and the cerb but have never managed to boil the srf 600 - and believe me I try

good for peace of mind