I went with a farmer friend of mine to have 4 BF Goodrich tyres fitted to his Landrover Defender.
I noticed that the rear offside brake pad had no lining at all, was scoring the disc and was seized up.
This Landrover passed it's MOT only 3 weeks ago.
How can this happen?
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The MoT man cannot remove anything. Therefore if visibility of the outboard pad is obscured by the wheel/covers then it'd be difficult to check it.
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It is possible to look at the disc from the inside while the vehicle is on a ramp. The disc was very rusty, with a small band of shiny in the middle.
As one brake was not working and it still passed an MOT, it makes you wonder if the test should be stricter.
The Landrover is booked in for new rear brakes at the garage which MOT'd it! They are going to use Delphi pads.
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If the inside of the disk was in poor condition and visible, it should have failed.
Depending on how the caliper siezes however, the disk can be rusty on the outside and nice and shiny on the inside. And just because the brake isn't working to full efficiency doesn't mean it'll fail - there's an imbalance tolerance which can be quite accomodating.
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>>- there's an imbalance tolerance which can be quiteaccomodating.
Not in my experience. I once had great difficulty getting a LandRover through an MOT because the brakes were very slightly unbalanced. Despite all new drums, shoes and cylinders the manufacturing tolerances still caused an imbalance that exceeded the MOT allowance. In the end I had to mess around swapping over drums until I found a combination that happened to be good enough.
They must have eased the standards since then.
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>>- there's an imbalance tolerance which can be quiteaccomodating.
Not in my experience either. The brakes can be fairly rubbish (remember a moggie 1000 can still pass), but only a small imbalance is permitted.
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>>I once had great difficulty getting a LandRover through an MOT...
Rear imbalance (or more pedantically, imbalance on non-steered axles) is not a reason for rejection, so, providing each side meets the minimum brake force requirements when tested, it will pass. On steered axles, 25% imbalance is allowed - a barn door of a tolerance!
It is possible to fail on disc condition, but, this is a subjective test aspect, and different testers would probably form differing opinions. As already stated, no dismantling is allowed - the tester can remove nothing to make his inspection.
The main thing to do is to make sure the vehicle's brakes get repaired ASAP.
Edited by Number_Cruncher on 24/08/2008 at 23:03
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Like I say, it depends on the mode of siezure. The Escort's N/S/F disk caliper was sticking with the inside having light surface rust, yet it passed at least 3 MoTs like that with a suspicious grinding noise.
Of course how do you know the other wheel isn't sticking as well yet isn't giving any symptons? Two sticking calipers = no imbalance.
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the big issue with testing landrovers as they are full time 4wd is that they cant always be tested on a rolling road and are often tested by the old method of the box on the floor and braking hard to read brake efficiancy ,as long as it met this it would pass
remember an mot only says that it worked when it was tested and 3 days is long enough to ruin a sticking pad /disc never mind 3 weeks
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My daughter's SEAT Ibiza (with rear drum beakes) failed its MOT on rear brake balance a couple of weeks ago.
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"My daughter's SEAT Ibiza (with rear drum beakes) failed its MOT on rear brake balance a couple of weeks ago."
There is no such fail criteria on the computerised system. (as Number Cruncher has already correctly pointed out)
What it can authentically fail on though, is rear brake efficiency which does not rise and fall at similar rates.
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What it can authentically fail on though is rear brake efficiency which does not rise and fall at similar rates.
It actually says on the notice "Nearside rear brake application uneven".
What I was told (by phone) is that the rear brakes were unbalanced, the solution being to strip down and clean the brakes both sides. Nice little hour long job for the dealer.
Edited by Bill Payer on 25/08/2008 at 22:46
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I looked up the reasons for failure, and it says:
c. The braking efforts at the roadwheels do not increase at about the same rate when the service brake is applied gradually
d. The braking efforts at the roadwheels do not reduce at about the same rate when the service brake is released gradually
- surely that's saying "imbalance"?
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>>- surely that's saying "imbalance"?
No, in MOT parlance, imbalance is a percentage obtained (in exactly the obvious way) by comparing the peak values of the brake force from each wheel.
The comparison during gradual application and release is a different failure item.
The first thing you would do in each case is exactly the same - strip, clean, lube and adjust the brakes on that axle, checking for the usual problems, namely wear, and siezed or leaking wheel cylinders.
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>>- surely that's saying "imbalance"? No in MOT parlance imbalance is a percentage obtained (in exactly the obvious way) by comparing the peak values of the brake force from each wheel.
OK, they don't call it imbalance, but that's what it is. Perhaps the peak value (when the wheels slip) could be called static imbalance and the other, dynamic imbalance. :-)
Edited by Bill Payer on 25/08/2008 at 23:14
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The brake discs were very rusty on the inside, I don't think the mechanic looked.
The MOT test station did not check the brakes, because the Defender is 4 wheel drive, it is difficult to do. You can't put them on the usual rollers.
My Defender was MOT'd at a different garage, they did not do a proper brake check either. The mechanic reversed it and said that they seemed OK!
My friend's Defender has had new rear brakes put on today at the same garage which passed it before.
When farmers take animals to market, the wheels are sprayed with disinfectant, which is acid, so this might cause brakes to seize. My friend's offside rear brake was very seized.
No-one wants their vehicle to fail an MOT, but if the brakes are seriously faulty they should fail.
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