Replace hydro fluid

Tech Tech Help
1

For years I’ve been listening to Dave’s PSAs about replacing brake fluid, and ignoring it in preference of giving them a bleed now and then.

But one bike in particular is going ever shorter durations between needing attention and I think it’s time to replace the 7 year old DOT..

Having bled brakes as often as I have I could probably swap the fluid out blindfolded but now I’m doing this I want to do it properly.

Any tips and tricks for filling & handling syringes that people have good results from? Otherwise I was just going to go with full degassed syringe at the lever, all but empty at the caliper and push it through.

I don’t have a feel for the volume of fluid in the system. Is one syringe of fresh enough?

With DOT there doesn’t seem to be an obvious colour change either so I’m not sure I’ll know when I’m getting fresh fluid all the way through.

1 Like
2

Fluid volume is very small, you’ll be surprised if you haven’t done it before. One of my biggest pet peeves is folks pushing old dirt fluid up from the caliper, always drain old fluid from the caliper end.

3

My only suggestion is to hook up both syringes, but for the first step, close off the lever syringe by pinching the hose. Then pull a vacuum at the caliper, which will suck out all the fluid out of the reservoir. That way, you won’t have pockets of old fluid in the reservoir that will mix with the new fluid.

It probably doesn’t matter, but the idea of mixing old with new in the reservoir bugged me, so this seemed like a quick and easy step to incorporate.