MOT brake fluctuation

Discussion in 'Motoring' started by njdbaxter, Oct 1, 2017.

  1. njdbaxter

    njdbaxter
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    so had my MOT yesterday and passed

    the brake fluctuation on axel 1 was 80 and 90 %, axel 2 was 80 and 91%.

    It was done in Northern Ireland so is carried out by DVA test centres, not independent garages

    Here we drive the car in, sit in the drivers seat and follow instructions, go through light checks etc.

    He didnt check a lot of things, didnt check hazards lights or seatbelts, was not asked to open fuel cap and didnt open the hood for any off those checks.

    I then moved to passenger seat and he jumps in for the brake tests, when the car went forward on the rolling bars after the brake efficiency test, it just didnt sound right, sounded like something was wrong with the roll bars as i never heard the noise before during the test.

    tester didn't say anything, I just got out and he drove it onto the ramp to check tyres etc.

    he gives me the pass certificate and never even mentioned the fluctuation so not sure what the high numbers mean, or if the machine is faulty or if he messed it up, and as i said earlier, he left out a lot of checks too. Also the percentages almost identical on both axels

    I did have two new rear tyres fitted 7 days earlier, less than 50 miles on them at time of MOT and had the car washed the day before. I think the fitter overinflated the tyres too as they seen harder that normal and the guy said the pressure on my front tyres was slightly low so he increased them, However anytime I have checked previously they have been spot on.

    any advice appreciated
     
  2. 494930

    494930
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    I wouldn't worry about the fluctuation readings, for them to be calculated the tester needs to hold a constant brake force for about 5 seconds and as brake fluctuation is not a part of the MOT test this doesn't happen. If there was a problem he would have held the car on the roller for 10-20 seconds to allow the readings to balance themselves out (could be light surface corrosion on the discs due to washing etc)

    Out of curiosity, what centre was your test at?
     
  3. car-man

    car-man
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    Not sure what you mean by brake fluctuations.
    You will get a higher reading from the driver's side brake because there is weight on the driver's side...you.
    The reading don't look like the readings I'm used to from the brake testing machine...usually you will get readings up to or beyond 300 on a front brake or 100 to 200 on a rear. You are allowed a variation up to 20% if I remember, but it depends on the weight of the vehicle. The variation is called brake balance.

    The noise from the brake rollers is not unusual.
     
  4. njdbaxter

    njdbaxter
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    one at boucher road in belfast
     
  5. njdbaxter

    njdbaxter
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    the readings on MOT cert are brake fluctuation percentages N/S and O/S for both axels. when tester does the brake testing, the owner moves to the passenger side and tester sits on driver seat

    plus the noise from the brake rollers was not something i have heard in previous 8 MOT's so was just curious
     

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