Rear Brake Reservoir blue?

Hello all, I noticed that my rear brake reservoir fluid has turned a dark blue on my 2020 V4, approximately 1700 miles on the bike. Contacted the dealer and they said that this can happen due to heat or sunlight and should not affect performance of the rear brake... Has anyone else experienced this? Thanks in advanced

Will post pictures sometime today.

Yes, it is a very well known “issue”

Blue? You're lucky mine went black. What I'd give for a lovely shade of blue...

It happens to everybody, no exceptions - ah, unless you don't ride it. The heat from the engine and exhaust cooks the fluid. On mine it occurred on the third ride, approx 250km on the odometer. On that ride I was in traffic, occasionally stopped at lights, so heat built up and, oila!, black rear brake fluid. My normal rides are open rural roads, lots of flowing cooling air but one slow ride turned the rear brake fluid black. At the 1000km service they didn't touch it, not worried.

Anecdotal, so don't take this as definitive, but my experience was that from new the rear brake had no feel and - worse - hardly did anything to slow the bike. Scared the crap out of me pulling up in traffic. Whether it was due to the pads bedding in or changes to the brake fluid I soon noticed much improvement. Today with 1200km on the clock I'm very happy with the rear brake performance and feel, black fluid and all. Unlike many sportbike riders I actually do use the rear brake very frequently. My solution for the black fluid, which is on it's way in the mail, is a small sized reservoir sock to cover it up. Ducati sells them if you want "Ducati". I'm opting for Brembo ones - a biggy for the front brake and two small for clutch and rear brake. Oh, if you're a demon braker the front reservoir will also go black, cooked as the calipers do their thing, and in that case you might feel some mushiness. Depends what type of rider you are.

There is a Canyon Chasers Youtube from 2 years ago that discusses cooked brake fluid on Ducatis and suggests changing to a fluid that has a higher wet boiling point. Problem is it's very expensive (it was US$70 for a pint(?) bottle). Socks are cheaper. I'll post a link if I can find it.

Edit: found it...


In the comments I asked if Dot 5.1 was a good option. The answer was "no". The stuff he is suggesting is much better.

Do the socks block heat somehow? Or just sunlight? My fliuid in the back is dark as night.

Use aluminum or gold foil on it. Wrap it up

the crappy fluids they use from factory were brown under 10 miles. I have around 600 miles on her now with Motul 5.1 still perfect. Order and replace fluid. Take the rear galloper off and flip upsidedown while u vacuum bleed. I like fresh looking fluids. Upgrade from 5.1 is RBF660 but it’s double the price

I use the RBF 660 and it takes a while for it to turn brown. I remedied that by going with a smoke reservoir lol. Outta sight outta mind.

Reading as much as I could...it turns out there are several things including sunlight which affect the colour, but colour is not necessarily an indicator of brake fluid performance. Short story, in our case the rapid and early blackening most likely comes from rubber components leaching impurities into the fluid. This is normal but some fluids and some rubbers are more prone. It may be exacerbated by heat (in my case the rear is black but front is clear) but the heat alone is not the culprit. It looks bad but rubber leaching does not affect performance. Changing to a different grade of fluid does not necessarily mean that heat was the original problem - the new fluid may be less reactive to the rubber.

Would be interesting to hear from anyone who has changed the brake lines to a different material. Also anyone who has done several bleeds sticking to a standard Dot 4 fluid - does the blackening slow down?

It’s just from heat. I have blisters on my inner right calf after riding in shorts. Yes colour doesn’t indicate if it’s beat or not but for those of us with specific disorders, toasty looking fluids are unacceptable

Thank you everyone! I'll look into getting the 5.1 ASAP to do the change, because it does look a little bad having it so dark.

I did 5.1 this time around. We’ll see how many miles until I need to renew. Next time around will be RBF660, but for now 5.1 is looking great well past 600 miles vs the fluid delivered with the bike didn’t make it much past 50 light duty, break in miles

If its lasted that long it should still stay clean I imagine.

Totally. I don’t mind bleeding it every so often but not after every ride with the terrible factory fluids. I’ll keep an eye on the mileage and color but for now I’m very impressed

I've used RBF600. The dry boiling point is a little lower than the 660, but the wet boiling point is the same.

Wait! Our bikes have rear brakes?

castrol SRF
the wet boiling point is prob higher than the dry boiling point of crappy stock fluid

gold

“I’ve used my rear brakes 3 time and all 3 times I crashed”

I have two liters of RBF660, waiting for me to decide on new rear reservoir, if I am upgrading the caliper and also to bleed out the clutch when I change the slave. Have a CNC slave sitting on the projects bench waiting for me to quit being lazy...

WyldCFH said:

I have two liters of RBF660, waiting for me to decide on new rear reservoir, if I am upgrading the caliper and also to bleed out the clutch when I change the slave. Have a CNC slave sitting on the projects bench waiting for me to quit being lazy...

Click to expand...

Why the new slave? Have you had any clutch issues with your 2020?

My Rear Brake Fluid turn dark, and I don't even ride it (only 4 miles on the odometer from the dealer, bought the bike in February, and I believe Ducati build my bike in November 2019).
I did warm the bike up every 2 or 3 weeks though, but I don't think it get hot enough to cook the rear brake fluid...
(oh, its very smelly too when I drain the rear brake fluid to remove my rear brake caliper)...