I've got new formula brakes, and I'm replacing the hoses with Goodridge hoses. I've got an Avid bleed kit, which came with a small bottle of dot 5.1 brake fluid. The brakes were initially filled with dot 4.

My questions are –

Is it worth swapping the dot 4 for the dot 5.1? Will there be a performance benefit?

If I do swap, how do I flush the old dot 4 out of the system?

How careful do I have be about making sure the two fluids don't mix?

Wouldn't worry too much, both types will mix. When you bleed using the kit, it'll flush it through anyway.

Wouldn't worry too much, both types will mix. When you bleed using the kit, it'll flush it through anyway.

Err – everythign I've ever read says don;t mix them.

Err – everythign I've ever read says don;t mix them.

DOT4 and DOT5.1 are completely interchangeable.

As simondbarnes says. No problems with just flushing it through with 5.1 after swapping the hoses.

Yup – can mix fine but you can flush out the system with 5.1 – you can't use DOT 5 as its completely different – perhaps the confusion above?

Dot 5.1 higher boiling point.
Dot 5.1 and 4 are interchangeable, but it's good practice to flush all the old stuff out anyway.
It's dot 5 that's not compatible with 5.1 or 4 I seem to remember.

It's fine to mix them but you might as well flush out the 4 and stick in the 5.1.

jackal's right

How do I flush the old fluid out of the caliper then?

If you attach hoses at both ends you can just push on the caliper syringe and flush the old fluid out through into the lever syringe, then take off the lever syringe, squirt it out and dispose of it.

Probably best to flush it with a bit of new fluid though to get all the old stuff out.

you got a bleed bottle with your kit?

Two syringes with the Avid kit.

What is a bleed bottle?

http://209.85.229.132/search?q=cache:JvDI9SrLBWEJ:www.formulabrakeusa.com/wp-content/uploads/2009/01/bleed_instructions_final.pdf+replacing+the+fluid+in+formula+brakes&cd=2&hl=en&ct=clnk&gl=uk

That any use?

Foxyrider – Member

Yup – can mix fine but you can flush out the system with 5.1 – you can't use DOT 5 as its completely different – perhaps the confusion above?

Whoops – sorry! 😳

http://www.formula-brake.it/en/support/download/12

try that too has some pics

Thanks for that, just what I was looking for.

np