Forum home Mountain biking forum MTB workshop & tech

Changing brake fluid

dogboy73dogboy73 Posts: 440
edited May 2010 in MTB workshop & tech
I'm not exactly sure what type of brake fluid I have in my Avid Juicy 3 brakes. They can be used with Dot 4 or 5.1 fluid. I understand you can't mix the two how do I flush the existing fluid completely out & then add new 5.1 fluid? Do I just use a bleed kit & flush everything through a few times? Or do I need a seperate bleed kit for each type of fluid?

Posts

  • ratty2kratty2k Posts: 3,872
    they can be mixed.
    My Pics !


    Whadda ya mean I dont believe in god?
    I talk to him everyday....
  • diydiy Posts: 6,473
    Just flush it bottom up through as per the bleeding process then do a second bleed.

    Personally I prefer 5.1 as it seems thinner and is easier to de-gas. Obviously don't buy cycle brake fluid when you can get car/motorcycle fluid for 25% of the price. Its the same stuff in a different bottle.

    When selecting 5.1 which is very similar to 4, make sure you don't buy 5 by mistake which is completely different and wont mix
  • ratty2kratty2k Posts: 3,872
    Only problem with buying car fluid (it is the same stuff) is volume. You end up with 1/2ltr stuck on a shelf for the thimble full you need in the bikes system.
    De-gassing is IMO a complete farce. You dont de-gas a cars brakes...
    5.1 is better, with a higher boiling point. But in a bike situation, barely relevant for most people.
    My Pics !


    Whadda ya mean I dont believe in god?
    I talk to him everyday....
  • dogboy73dogboy73 Posts: 440
    Cool. Cheers for the replies.

    Found this cheap bleed kit on e-bay. No fluid but the kit looks the same as the official Avid one;
    http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
  • nicklousenicklouse Posts: 50,675 Lives Here
    except the Avid kit comes with more tools and spare parts.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • dogboy73dogboy73 Posts: 440
    nicklouse wrote:
    except the Avid kit comes with more tools and spare parts.
    ........ and costs more than twice the price!
  • dogboy73dogboy73 Posts: 440
    ......... actually the proper Avid kit comes with a nice bottle of Dot 5.1. Finish Line 5.1 costs over a tenner anyway. Suddenly that cheaper kit on fee-bay doesn't look like such a good deal :oops:
  • diydiy Posts: 6,473
    I have the avid kit - paid 25 quid for it, from the pic in your link, I would say the non SRAM kit looks just as good. The only thing to check is that the syringe seals can take some pressure.

    Personally I get much better results from degassing the fluid first. Car and motorcycle brake systems don't work the same way as Juicy's. I don't find the gas in the system comes out naturally. Its largely because the components are so small. But also because the design is a bit pants from a maintenance point of view.

    You'll need about 200ml of fluid to flush both brakes and then about 100ml to do the final bleed.

    CRC do 1/2 a litre of rock oil 5.1 for 8 quid.
Sign In or Register to comment.