Help Needed - Rear Brake MOT Failure

  1. Newbie Joined: Sep 2012 Posts: 10
    #1
    I am a Saxo owner living in France. Car failed its Controle Technique (French MOT) on the rear braking efficiency balance. Left brake OK but right-hand not good. RH Wheel cylinder not working properly so had it changed. Re-tested the car today and it got the same failure. Its a 2002/3 Saxo 1 litre. The original wheel cylinder was a Bosch(?). A mate in UK supplied the replacement as most Citroen bits in France are dearer than UK!

    I expected the retest to be OK and, if anything, show the right to be slightly more dominant as it had the new cylinder. It does not make any sense to my limited knowledge. Does anyone have any ideas please?
  2. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #2
    Is your brake bias valve okay mate?
  3. Newbie Joined: Sep 2012 Posts: 10
    #3
    Ah!! I said that I had limited knowledge and you have just exceeded it!! What and where is it please?
  4. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #4
    At the rear above the passenger wheel mate.
  5. Established Member Joined: Sep 2010 loughborough Posts: 2229 1988 ford fiesta mk2 1.4- 2001 black saxo furio (d
    #5
    you don't have abrake bias valve on a drum axel. are the shoes free or even saying that are they adjusted correctly on that side.

    also is it the foot brake where it's failing or on handbrake efficiency could need a cable that side if it's the handbrake.
    or saying that is it bled up correctly after you put the new cylinder on.
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  6. Newbie Joined: Sep 2012 Posts: 10
    #6
    Drum brakes on the rear and they are free. Handbrake efficiency passed with no problems. It is the disparity between the left and right brake effort that it is failing on. I am sure it was bled properly but there must be something stopping the right brake applying properly. Hmmm!!
  7. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #7
    Quote:
    Originally Posted by f13sta View Post
    you don't have abrake bias valve on a drum axel. are the shoes free or even saying that are they adjusted correctly on that side.

    also is it the foot brake where it's failing or on handbrake efficiency could need a cable that side if it's the handbrake.
    or saying that is it bled up correctly after you put the new cylinder on.
    Do on mine mate,mine failed the MOT 2yrs ago with it srs.(drum axle)
  8. Regular Poster Joined: Aug 2010 Posts: 330
    #8
    i always take the clicks up as much as i can with the drum off so i can just get it on,them auto adjusting ratchets are shit
  9. Established Member Joined: Mar 2009 derby Posts: 1276 Black 03 vtr, Yamaha R1 @185 bhp
    #9
    I'm not too clued up on the rear brake system but my 2001 vtr failed on the rear brake load sensing valve, it became seized, I don't know if this would be the same on a drum set up as mine Is disc, hope this can shed any light
  10. Newbie Joined: Sep 2012 Posts: 10
    #10
    OK. Thanks for the suggestions. The problem persists and there is no sign of a brake load sensing valve anywhere in the vicinity. It is a 2002 S1, 1124cc, 44Kw model. The braking system is Bosch. The original wheel cylinder has been stripped, cleaned and refitted. There are no leaks. The auto adjust is working freely. If you work the foot brake the brake shoes are moving but, when it is all assembled again, you can turn the wheel with the brake applied!!

    The wheel cylinders are unusual as the brake fluid passes through holes in the piston itself. There was some suggestion that these wheel cylinders acted as load sensors and that there might be a valve inside the piston but it is not something that I have ever heard of. It is driving me mad.

    I will try and upload a link to some photos of the wheel cylinder.
  11. Newbie Joined: Sep 2012 Posts: 10
    #11
    Some photos here:

    http://www.flickr.com/photos/kinsarv...7631629171972/
  12. Newbie Joined: Sep 2012 Posts: 10
    #12
    Just to update. These are self regulating wheel cylinders on the rear, there is no brake compensation valve. Went to remove the wheel again today and could hardly turn it against the brake this time. Totally baffled but submitted it for a re-test and the car passed this afternoon. The braking efficiency on the right rear was up slightly and the left was done forcing the balance figure into the green and a pass. Still confused but I have a new 2 year ticket and the brakes work well. Result!!
  13. Newbie Joined: Nov 2012 Posts: 3
    #13
    Hi,

    I need to replace the cylinder on my drum brakes as its leaking.

    Can you advise me on the part number that I should be buying, my system is also borch.

    thank you