Braking issues

Discussion in 'Mech Tech' started by the 3 crispies, Jul 21, 2018.

  1. still struggling with brakes, have sorted issue with leak from reservoir feed pipe but I used some old brake fluid the other night and the brakes are real poor, the pedal is nearly on the floor. I presume it must of absorbed too much moisture whilst in shed. Other than replacing fluid again is there something obvious I am missing which could result in such poor pedal.
    I altered the length of the free play on the pedal but returned to original as this made no difference, there are no leaks, MC is new and all brakes are now disc set up.
     
  2. Put some new fluid in, and give everything a good pumping through. Obvious, but I’d think you’ve still got air in the system. Is the pedal spongey?
     
  3. Did you bench bleed it ." If not,,.? What you need to do is take the lines off the master and have someone pump the brakes with your fingers on the holes . Then reconnect . It's messy ,,,This is the only way to get a motorbike front wheel .master cylinder working and some cars are the same . You won't get the pressure without doing it .
     
  4. not spongy, thats the thing doesnt need pumping just goes to floor when foot is on it.
     
  5. took the MC off to purge it originally but it was leaking through badly fitting feed pipe.
     
  6. Dubs

    Dubs Sponsor supporter extraordinaire

    Carefully clamp both rear flexis to disable the rear brakes, and see if the pedal travel returns to normal. If it does you know it's something to do with the rears.
     
  7. redoxide

    redoxide Guest

    Discs all around ? have you fitted a disc disc master cylinder.. you may not be getting sufficient shift of fluid to work the rear disk set up with a disck drum master.. Just a thought
     
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  8. mikedjames

    mikedjames Supporter

    Most likely you need to bleed it using something like the eezibleed pressure bleed system to push a lot of fluid through from the reservoir - you most likely have a bubble or two in the pipework where you disconnected components that should be full of brake fluid and you need to push those bubbles several metres through the system.
     
  9. bled system by gravity and still the same :( , noticed a very few air bubbles but in fluid there was still some microscopic ones. Tried clamping rear hoses fella but fitted braided so didnt want to damage them and still the brake is the same. Getting to be a issue as supposed to be going abroad in it in 2 weeks,:oops::oops:. will try as @mikedjames and eezibleed it on Wednesday.
    Other than that the lower reservoir connection to upper was leaking but stopped by tightening clamp and could this be sucking in air.????
     
  10. Dubs

    Dubs Sponsor supporter extraordinaire

    Leaking between the reservoirs won't get air in the master cylinder. If it is air still in the system then the easy bleed will sort it out.

    My ever so helpful tip of the day is, never start *****ing about with your van before a planned holiday.. :hattip:
     
  11. I fitted the Porsche 944 M/C on my all disc setup ...
     
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  12. great tip and wasnt planned but the MOT man put paid to that. lol
     
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  13. redoxide

    redoxide Guest

    the standard master cylinder probably wont shift enough volume to the rear brakes .. The rear caliper needs a lot more fluid than the small slave cylinders in the rear drum.. Best to fit a more appropriate master cylinder for a disc disc set up.. as per IHUs post above .. or fit a willwood residual pressure valve to the rear main brake line which will maintain pressure on the rear brake ... from memory I think a disk will be 2lb and a drum 10lb.. stops the fluid returning along the brake line as the pads relese from the disc.. which could be your problem.. as the drum disc master probably wont have a factory fitted residual in the master cylinder chamber serving the rear drum brake..
     
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  14. Have you any idea which type. ? Any mods to fit ?

    Sent from my SM-J510FN using Tapatalk
     
  15. My worry was this will do more research as found demon tweeks do 2 and 10 psi was hoping new MC would cope

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    Last edited: Jul 24, 2018
  16. page 5 of my build thread ....its the alloy 944 one and it was a bit of a pain to fit ... I can`t remember what a bay M/C bore sizes are is but 944 one was different ..you should still get brakes tho with the bay one ..I went 944 as I`m using front and rear 944 calipers
     
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  17. A 944 master cylinder is 23/19 as opposed to the bay 19/19 jobbie so I guess it puts more to the fronts !
     
  18. any pics ???
    cheers buddy, Schofields are sending us another MC :), got to have another go tomorrow, also got eezibleed kit. yeah bay one should be ok just hope Im unlucky and had faulty one before...........
     

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