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Dot 3 or dot 4?

Discussion in 'Technical and Troubleshooting Torque' started by thecptn, Oct 21, 2005.

  1. Hey all, went today to my yammy dealer and had 2 new rubbers installed, and had the front brake bled and drained, how ever after picking up my back, I noticed in the brake reservoir the new fluid was below the low level...which cant be good, so I asked the guy who did it, and he said some thing about the caliper being on an angle, so I took his advice, yet on my ride home, at every light stop, I couldn't get my eyes of the reservoir, im kind of paranoid now, the front brake works nice and solid, but id rather take no chances, and just top it off, how ever I don't know if the guy used dot 3 or dot 4, I don't know which to use or what exactly to do...great :cry: other than that he said my front caliper needed an overhaul as it may leak :? so any advice? top it up with dot 4? take it back and chew his ear off?

  2. I can't imagine a circumstance where having the fluid below the low level is a good thing...

    Theres some good stuff about brake fluid at http://www.xs11.com/tips/maintenance/maint1.shtml

    You can mix DOT 3 and DOT 4 without ill effects.
    The fluid he's used is almost certainly DOT 4 anyway...
    DOT 4 has a higher boiling point - probably not an issue in your case
    Putting DOT 4 into DOT 3 mix has no issue the other way lowers the boiling point of the DOT4 to the DOT 3 level.

    Personally I'd top it up with a good DOT 4 fluid.

  3. Thank you Tony, Much appreaciated mate. :D
  4. How a calliper being on an angle will effect the resevoir on a handlebar is beyond me :?

    The handlebar being on an angle could make a difference, but I doubt it'll push it below the low mark.

    I would have demanded it be filled to the proper level at the time, and never go back there again, doesn't sound like a competent mechanic to me.

  5. Yeah he seemed not too good, def not go back to him again, live and learn again, I got some dot 4 stuff, now the two screws on the resovoir wont budge! if I try it just chews it up and might end up with a threaded head, any way of getting it off?
  6. When I was changing brake lines and didn't know what I was doing I ended up rounding out the screws when I was trying refilling and ended up having to drill out the screws.

    I learn every time I do something bad. Ended up not being too much of a problem despite taking a couple hours of messing around to fix.

    When I was trying to find what to do once they started rounding, I read than an impact driver is good or you need lots of downward pressure and a well sized screwdriver (my method is screwdriver with vicegrips around the handle with plenty of weight on top of driver and turn driver with vicegrips). You can even hit the screwdriver with a hammer to loosen it if it is jammed in. Possibly can try WD-40 or somethign, but I find it doesn't help all that much.

    If worst comes to worst you may have to drill out the screw so that the head detaches from the rest of the screw and it comes out a bit easier (mainly if the head was holding on to tight I believe). Or that may not help if the screw has siezed for some reason. Warning... I ended up scratching the reservoir cap a bit, but I am clumsy. After this you would need new screws. Also I guess be careful about letting metal flakes fall into reservoir when taking lid off.

    Otherwise you could take it to a mechanic of sorts and they maybe can do something.

    *Not a qualified mechanic or anything, just options I tried
  7. damn it...dont wanna admit this..but I got the resovoir open, and to my suprise it was full! the thing is, the fluid was new and golden and imposible to see through the glass...ahh jeez.. :LOL:
  8. I think we now know why the level was so low :-k

    Jaycar are flogging off THIS DEVICE that is supposed to help in such things,
    be very handy in the future, cos just about every bleedin' screw on a bike guts stuck!!!!

  9. Do a search for "damaged screw" or "screw extractor" on eBay.