Brake Master Cylinder Rebuild and Stoppers

Discussion in 'General Tech Talk' started by RacerX74, Jul 13, 2018.

  1. RacerX74

    RacerX7406 R3

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    Anyone attempted this ? is it a easy job ?

    Do I have disassemble the whole twist grip ?

    I'm done with these Rubbish brakes they need bleeding every 200 miles or so .

    Also after market calipers best I can find that are acutely available are Pretech

    Anyone know of another brand ?
     
  2. TURBO200R4

    TURBO200R4stand up straight and grab the world by the a$$

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    mine has always worked good except for a while they had air in the one on top (handle pulled to far)
    so while working on tire i moved the right front piston all the way out when i got the tire on pump the handle and applies real good. 40,000 miles will stop on a dime and give u 9 cents change.:thumbsup:
    i guess i should say when the bars get up to about 130 degrees the plunger seems to stick for a couple of pulls then works good.
     
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  3. rash_powder

    rash_powderSupercharged

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    I had a 03 Sprint that always had soft brakes. Corrected it by pulling the pistons from the caliper and carefully polishing away a ridge of muck that had built up where the seal sits on the side. Re assembled with silicon disk brake grease. I also cracked the caliper open just enough to get some fluid to come through. Not sure the caliper did anything, but the piston definitely would have been leaking air. From then on I had one finger on the lever brakes!
     
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  4. barbagris

    barbagrisMad Scientist

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    Mate - if they are lasting 200kms - pretech's are not the answer. They just aint bled or you have a duff seal or return spring in the M/C, or something not moving as it should.. Mine (09) will near stand on it's nose with short levers too. I changed the front hoses when I put new bars on - 35K kms ago. Nowt else. Oh I did use Dot5 fluid. Pretech's are nice though. Very very nice. If you do the M/C - be gentle knocking the old out and new in.
     
  5. RacerX74

    RacerX7406 R3

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    Ok all done would have replaced the calipers but no one had any in stock so a 2 to 3 week wait ! I was more than ready to pull the trigger on Pretech' as they come in a awesome gold finish ...saved some money I guess .

    So I found some enthusiasm and did it myself .

    I stripped the calipers and master cylinder piston / seals and and replaced all the seals and fitted new EBC pads .

    I found 2/3 mm of thick black sludge in back of both calipers and in the master cylinder I guess just a result of twelve years moisture build up ?

    After a bit ( a lot ) of cleaning all eight piston came up like new and so did the master cylinder with no signs of pitting anywhere.

    The paint on the calipers makes them look a bit tired but they are in good condition for there age and I didn't want to wait to paint them or get the powder coated as it is still summer and I want to ride .

    Done 100 or so miles on them and they are 100% better without all the muck in there and so far the lever has stayed consistent I assume the pads may bit a little more as they bed in .

    Thing number 1 the circlip that holds the master cylinder piston in is a motherf****r to get out I would advise buying a proper tool for this as I had adjust ( with a grinder ) a pair of universal circlip pliers in order to get in there .

    Thing number 2 although it stops now at rest I can still pull the leaver all the back to the grip / stop of course if I did this when riding it would I guess lock the front wheel but I have never had a bike where this can be done before .

    Thing number 3 I have individual HELL brake lines already so its not the pipes ….and yes I bleed them I bleed them fast I bleed them slow I reverse bleed them I vacuum bleed them I left them over night under pressure I tried the forcing the pistons back trick BUT still I can pull that lever all the way back to it stop .

    Thing number 4 Turns out Rockets or mine at least has 83 mm mounting centres for the calipers which yes you guessed it almost no other Triumph has I know this because I tried to source some already refurbed calipers and all they had were 90 mm fitment .

    Thing number 5 I assume later ABS equipped models have a different master cylinder at least as some report on here awesome brakes .NOT my 06 as I now have replace every seal clip washer and pipe and they are still only acceptable and really good maybe triumph didn't want super sharp brakes ! anyone else got an 06 ? what your brakes like ?
     
    Last edited: Jul 20, 2018
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  6. Jason Jurgens

    Jason JurgensOns gaan nou braai...

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    I have to say, when I bought my 06, they did all the fluids. The front brake was good but I could also pull the lever almost all the way to the grip. So I got some cable ties, pulled the lever a few times then pulled the cable ties so that the lever was almost against the grip. Left it overnight and now it only travels about half way pulling it as hard as I can. Made a huge difference. ONLY DO THIS WHEN THE BRAKES ARE COLD!
     
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  7. barbagris

    barbagrisMad Scientist

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    YUK. Two Thirds or two to three? - 2-3mm is straight up ridiculous. I've stripped the callipers on loads of bikes and cars with way more years and never seen that much. That much and the system will simply not even try to work. Good job you took a look.

    A final bleeding trick that sometimes works when others fail.

    Bike on sidestand. Full left lock. This way the fluid openings on the M/C to reservoir are higher than the top banjo. Remove Lid.

    Agitate the lever really fast but not overly firm - Imagine Flamenco hand clapping - 1 hand on bar end the other on lever end. Try not to spill fluid. After 10 or so pumps PULL the lever hard back for 30seconds or so - release fast - wait a couple of seconds - Now with fingertip pressure pull back the lever very slowly and slightly and more often than not a flurry of tiny bubbles will flood out of one of the fluid orifices. Let them rise.

    Sometimes even with all new components some "yuk" seems to come out too. This may be bubbles so fine they are in emulsion or some residue in the pipes - I have never bothered to ask.

    Just repeat until there are no more. Depending on where the air has lodged it can take a few repeats - but never had any over 10. Even on linked brake Guzzis with 6 part brake bolt up rubber and metal tube lines. And after the lever is SOLID. My old 1979 Guzzi front now comes on so fast I can barely get a firm grip as the levers are not adjustable and I have small hands.
     
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  8. Claviger

    ClavigerHP Junkie extraordinaire

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    Will be doing the same, just on my Daytona, which shares brake systems. I have a crap lever. But, they do work. Just not confidence inspiring.
     
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