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DOT 5.1
hi guys,
just wondering if anyone has any experience with using standard moto/car 5.1 brake fluid instead of the original Avid fluid.
this is for a set of XX brakes and Avid recommend using only their own branded fluid....
thank you
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Works fine so long as you use matching dot oils. From memory dot 4 and dot 5.1 are compatible but dot 5 is not (?)
Yeah. No problem with the car brake fluid. Like Flynny says, get the numbers right.
I have a bottle that says compatable with dot 3, 4 and 5.1 but NOT 5.
it's 5.1 only for the XX. I have an older set of Elixir CRs on another bike and from memory they're compatible with 5.1 and 4.
I was just wondering if there could be a difference between Avid 5.1 and standard Moto 5.1
and you guys have just answered that so standard fluid it is...
thank you
Extract from Brake company web site:-
"DOT 5 is a silicone based synthetic fluid originally designed for use in military and government vehicles where regular maintenance could be problematic. Although not hygroscopic in the traditional sense, water molecules will still find their way into your hydraulics creating globules rather than being suspended as with traditional DOT 3/4 & 5.1 fluids…the end result is the same: contamination. DOT 5 Silicone was never intended for serious high performance application."
FWIW
In theory you shouldn't even mix brands, let alone dot types. In car high performance applications this is very important, however with bikes it's not as crutial. In saying that, the volumes in a bike system are so small vs the cost of a decent quality brake fluid, just flush the system and make sure it's all clean.
... you're saying that there ARE differences in quality regarding different brands?
that's really what I was trying to figure out. obviously I wouldn't mix different DOT numbers.
it's just that original Avid fluid is quite hard to come by - if you don't want to wait for your LBS to order it in or order it online yourself....
I've always understood 5.1 to be the performance specification, hence you can choose any brand. If that's not the case I don't think that there would be much in it. I've had a set of Hope for 10 years which I've just used with whatever 5.1 I could get hold of, usually from the motorbike spares section. I mention that they're Hope because they tend to be a bit sensitive to imperfect setup and used to be known for overheating on Alpine descents. As I understand it this is why 5.1 was specced because it dissipates the heat better, which may be why your trail designated brake uses it. Hope moved to heat reduction measures in later brakes.
Given the motorbike quantities you're forced to buy, the tiny capacity of mtb discs, and that an opened bottle may go off within a year or so, I always fully flush the old fluid out whenever I bleed my brakes.