Brake fluid replacement

[popularh14]

Just about to do the above for the first time and I wondered if it would be possible to gradually add new fluid to the reservoir whilst pumping the old fluid out the bleed nipple and avoid having to do any bleeding after? Difference in colour should show when all the old stuff is out the system.

Any comments/experience gratefully received.

Ta

[sirch345]

That's exactly what I usually do to replace the fluid. Using a different colour fluid makes it easier to see when the new fluid has reached the bleed nipple, although I usually managed with the standard colour fluid DOT4,

Chris.

[VTR Phoenix]

Yes, just pour in new fluid in reservoir and bleed through caliper. Be careful not to let the level get low or you'll risk drawing air into the system. Also don't mix DOT 4 with DOT 5.1 as they don't mix. As long as you know what you have in there then use the same fluid.

[alanfjones1411]

I do exactly the same

[Jonesey]

Yep!

[popularh14]

Cheers guys, good know my thinking was not way off. Brakes are getting a bit spongy so I figured it was about time the fluid got changed - its about the colour of a nice pint of bitter now so prob a bit aged!!

[popularh14]

Oh just a thought - does one side have to be done before t'other or are they as broad as they are long?

[Jonesey]

Not if you're just flushing fluid through- makes no difference.

[Demonic69]

If you're doing it on the side stand I'd bleed the lower one first

[budd]

. Also don't mix DOT 4 with DOT 5.1 as they don't mix. As long as you know what you have in there then use the same fluid.

This isn't true,while you are right to say under no circumstances mix silicone and glycol based fluids it is actually the other way round and DOT 5 which is silicone based and therefore not compatible. Glycol based DOTs 3, 4 and 5.1 can be safely mixed if required.
Bottom line DOT 5.1 is OK while DOT 5 is a big no no.

Just a quick word on choosing an appropriate fluid, the best fliud for the Storm (and any other bike with normal brakes) is DOT 4 any will do the job but it is possible to get high boiling point fluids eg Motul RBF 600 which offer superior performance and high resistance to boiling than regular DOT4 however there is a ‘but’ a higher boiling point typically means they are more hygroscopic (absorbs water)and therefore need changing more frequently.
BTW all glycol based fluids are hydroscopic so all require regular replacement (something that is very often neglected) but to maintain their high performance spec higher boiling point (racing type) fluids need slightly changing more often. So my recommendation is for normal road use any decent DOT 4 will be spot on, although for very fast road/track then a higher boiling point DOT 4 may be worth considering.

What about DOT 5.1 ? I hear you ask, surely being a ‘5.1’ it must be better than 4? yes and no. Yes you can use DOT 5.1 it is totally compatible with DOTs 3 & 4 and as a slightly higher boiling point than DOT 4 (see note below) however DOT 5.1 was designed for use in modern ABS systems and as a result is thinner to allow it to move easily through all the ABS valves and actuators etc even at very low temps. In a normal non ABS system you don’t have all the gubbings found in ABS systems so a thin fluid is of no benefit so a normal DOT 4 (as recommended by the manufacturer) is preferable.
NOTE All the DOT specs are MINIMUM specs so it is quite often the case that a high quality DOT 4 vastly exceeds the specs of a cheap one and something like Motul RBF 660 (DOT 4 ) easily betters DOT 5.1 re boiling point.

[popularh14]

Cheers Budd

Interesting stuff! Well it is to me at any rate cos I love a bit of techy info.

Just to muddy the waters a little the Dot 4 stuff I bought recently says "Ideal for vehicles with ABS". Maybe they've made a low viscosity Dot 4 maybe.