Brake fluid and bleeding

[Nefarious]

Any tips on what brake fluid to use. Was thinking about Castrol SRF, but it's eye-wateringly expensive. Given that I'm pretty good about changing at least annually, sometime more often if there's a lot a trackdays, is there something a bit closer to "normal" price range that I should be considering too (e.g. Castrol Super Dot 4).

Also, could someone tell me the recommended bleed order for Cerb brakes i.e. fronts then rears, or FL-RR-FR-RL.

cheers

N

[TT Tim]

AP Racing make their own, I'd vouch that that will be upto the job.

Various fluids at various prices: AP Racing

Demon tweeks stock AP Racing fluids, link here.

I'm using the 'standard' 5.1 at the moment and so far, so good.

HTH

Tim

[Nefarious]

I notice that for the two "top" AP fluids they say the following:

[quote]It should be noted that before using AP Racing PRF660 fluid, any existing brake fluid should be drained completely from the brake system. The system should be thoroughly purged with new AP Racing PRF660 brake fluid and can then be filled completely with AP Racing Racing 660 fluid.
[/quote]

Does that mean that you're supposed to completely fill the system with new stuff, then fill again? Seems a bit of a waste?

Or can you just empty the reservoir with a syphon, fill with the new stuff and pressure bleed until it comes out whatever colour the new stuff is?

[TT Tim]

Nefarious said:

I notice that for the two "top" AP fluids they say the following:

AP Racing website said:

It should be noted that before using AP Racing PRF660 fluid, any existing brake fluid should be drained completely from the brake system. The system should be thoroughly purged with new AP Racing PRF660 brake fluid and can then be filled completely with AP Racing Racing 660 fluid.

Does that mean that you're supposed to completely fill the system with new stuff, then fill again? Seems a bit of a waste?

Or can you just empty the reservoir with a syphon, fill with the new stuff and pressure bleed until it comes out whatever colour the new stuff is?

The new stuff is clear(ish) anyway, so no difference, unless your seals are gone that is.

It's not hugely expensive and unless you're planning a lot of track time maybe not worth going OTT. All IMHO of course.

I pumped about a litre through I guess, when I refilled and flushed my system

Tim

Edited by TT Tim on Wednesday 30th April 11:15

[warpspeed]

I've used Halfwits 5.1 for a while now in the Chimp with no trouble. It's so clear and pale that it's easy to see when it starts to get cruddy. I'll be swapping the Cerb over to it when I get it back from RT.

[350Matt]

Some interesting info on brake boiling points;

Here are some boiling points for common fluids. The DOT 3, 4 and 5.1 numbers are STANDARDS and for a fluid to be rated as DOT 5.1 a fluid must EXCEED these ratings:

DOT 3 Dry: 205°C Wet: 140°C
DOT 4 Dry: 230°C Wet: 155°C
DOT 5 Dry: 260°C Wet: 180°C
DOT 5.1 Dry: 260°C Wet: 180°C

AP Racing 551 Dry: 275°C Wet: 150°C
AP Racing 600 Dry: 310°C Wet: 210°C
AP Racing Formula DOT 5.1 Dry: 275°C Wet: 184°C
AP Racing PRF 660 Dry: 320°C Wet: 199°C
Ford Heavy Duty DOT 3 Dry: 288°C Wet: 143°C
ATE Super Blue Racing Dry:280°C Wet: 200°C
ATE TYP 200 Dry: 280°C Wet: 200°C
Motul Racing Dry: 315°C Wet: 216°C
Castrol SRF Dry: 310°C Wet: 270°C
Performance Friction Dry: 288°C Wet: 140°C

Typically it will take an average car around 2 years for the brake fluid to contain more than 3% water. Heavy use of the brakes cause them to absorb more water.

Me I'm sticking with Halfords 5.1

Matt

[Byker28i]

I put halfords 5.1 through the clutch when it needed bleeding and did the brakes last year. Both times I ran about 2 litres through it just to be sure it was completely flushed through.