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race brake fluid or standard?

Discussion in 'Technical and Troubleshooting Torque' started by phongus, Nov 6, 2010.

  1. Hello everyone...

    This may seem like a stupid question since it is in regards to brake fluid for my race bike. One would quiet simply assume that race brake fluid such as the Motul RBF 600 is the way to go. But with a price of $35 for the RBF against $16 for Motul DOT 4 standard, the cheaper option seems healthier for the ever dwindling bank account.

    I am not sure what the previous brake fluid was prior to my crash (since it all spilled all over the kitty litter), but I never felt any problems in regards to hard braking...either that or I just don't go fast enough. I hadn't changed it since I bought it 3 years ago and had done maybe 10 track days on it. Mistake and laziness on my behalf for not servicing it.

    Question is...would it be worth using the RBF over the standard, even though I only use the bike maybe 6-7 times a year on the track (less if I crash out)? After a quick google, some say that RBF fluid should be changed every month...to me that just seems expensive and some what unnecessary, however I am no expert. Would it be safe to run the RBF for a whole season without changing it every month? If so I think I may just go the RBF path.

    Thank you all in advance.


  2. Street brake fluid. Race brake fluid needs to be changed very frequently. They need to be changed very frequently (as you say every month at the latest) as they absorb water very quickly. Water in the brake fluid ruins the braking performance.
  3. Thanks toadcat...I was hoping I could run the RBF fluid and keep it for the year. It seems as though the RBF fluid has a high moisture absorption.
  4. For your kind of usage, I doubt if you'd have a problem with any modern street brake fluid in a modern braking system. With all due respect, if you're only on the track every couple of months, I doubt if you'll be going hard enough to boil it as long as it's changed yearly to keep the water content somewhere sensible.

    Your master cylinders and calipers will thank you for regular changed too.
  5. i use the top shelf motul stuff (RBF), and my braking performance hasn't got worse in the 10+ months it's been in the bike, including about 5000km, 6 track days and a second set of brake pads. if anything it seems to hold up better than the cheap motul stuff that was in the bike previous.

    if anything i'm riding harder, faster, and braking later... and never had an issue with brakes, including zero brake fade at the track.

    IMO, i dont think you should be tight when it comes to brakes, tyres or safety gear. $20 more is nothing in the whole scheme of things when it comes to racing, or high performance road riding.
  6. http://www.motul.com.au/fact_sheets/brake_fluid.html

    There is also now a new RBF660 Dot4 non silicon synthetic fluid with VH boiling point.

    As I understand it the thing that you must not do is mix fluid types, which for you will probably mean a complete strip and clean of the braking system.
  7. I'd go with the cheaper stuff, and upgrade if you have loss of lever / sinking lever / close lever issues.

    Like engine oil, it's better to get medium quality stuff and change it regularly, than exotic top shelf stuff (which may be very good) and never change it again.

    The higher grades of brake fluid, that work normally at v high temps, are insanely thirsty. They go off their advertised spec very quickly. They can be 'reconditioned' by draining them into a pot and heating (with a cooking thermometer) to around their rated temp. When I was pit crew for a go-kart team, we've had top shelf fluid come up below spec straight out of a freshly opened tin, and had to do this.

    For most people most of the time, normal mid price mid quality road fluid works fine, especially on a bike. The disks on a bike get pretty hot, but the callipers generally don't. (Alright, if you're an A grade superbike racer, that may not be quite correct, but if you're an A grader, you wouldn't be asking this question.) The hydraulic part of the brakes on most bikes would probably work at less than 100 C most of the time. What do you need DOT5+ brake fluid for?
  8. Thanks for all the replies :). I think I might just go with the standard DOT4 brake fluid for now and see how I go.

    Also I was never thinking of DOT5 brake fluid.

    Thanks everyone :)