Do I really need to change my fluid.

Hi guys,

I'm off work early today so I will finally have time to fit my lovely new HEL Brake lines.

What I need to know is, do I really need to use new fluid? I've heard that water can get in through the standard lines, so once its out, it should never be used again.

What fluid should I replace it with? which grade DOT? and what make should I get?

Ta very mooch!!

Absolutely you must change it - kind of impossible to change brake lines without changing it!

Any DOT4 will do.

[rictus01]

Indeed you should change it, brake fluid is hydroscopic and will absorb atmospheric moister,as the basic principle of brake fluid is to transfer pressure from the master cylinder to the caliper(s) both air and water will increase the compressibility of the fluid (brake bleeding removes air to get rid of spongyness as in air).

for normal use any DOT 4 rated brake fluid will be more than enough.

Cheers Mark.

oh yes, cheap as chips so why not

[BillyC]

By changing your brake lines, you'll have to re-bleed your brakes anyway - what exactly were you planning to use to do this?

You're going to have to flush your brakes anyway - so you'll end up replacing most of what's in there anyway - so you might as well do the whole lot.

These are your brakes, and they're the only thing that'll stop your bike at your command. Don't cut corners for the sake of £6 of brake fluid!

If you want to be extravagant, use DOT 5e (edit: I meant DOT 5.1) fluid -the type compatible with ABS. It has a higher boiling point.

[jambo]

Originally Posted by sdusk

If you want to be extravagant, use DOT 5e fluid (the type compatible with ABS). It has a higher boiling point.

DOT 5 is incompatible with DOT 3 and DOT4 fluid. It is used by racers but for reasons discussed to death should not be used on road bikes (Short answer is it does NOT absorb moisture, so water collects in the system). DOT 5.1 fluid is a higher rated DOT 3/4 type and is fine to use, if a little expensive from some outlets.

In short DOT 5 probably not what you're after
DOT 4 or DOT 5.1 are fine.

[rictus01]

Originally Posted by sdusk

If you want to be extravagant, use DOT 5e fluid (the type compatible with ABS). It has a higher boiling point.

CAUTION!!!!!!

As your system was developed for DOT 4 that's what you should use, you're unlikely to overcook it even on the odd track day, however if you must use a DOT 5 or 5e fluid be aware they are silicone based and not glyco based (as DOT 3 & 4 are), you can't mix the two so you will need to dismantle the whole system and clean everything (may also need to change any seals as well). also the silicone based stuff is more expencive.

I'd not use silicone based fluid in anything bar a race bike and then only if it was an all new system.

Cheers Mark.

rictus01, DOT 5e (edit: DOT 5.1) is NOT silicone based, and can be mixed with DOT3 or DOT4.

DOT 5 (Silicone) should not be used in this application.

Please do not confuse the two.

Please excuse my brain fade above, I meant DOT 5.1 (not DOT 5e). Got network cables on the brain today...