how did it pass the MOT

[joderest]

My daughters Aygo would not hold on the handbrake, it took a good pull to hold on a hill. It had MOT in December and passed.
Stripped rear brakes yesterday, thought it would need new shoes, first thing that i noticed was the hand brake lever attached to one of the shoes was seized solid operating the handbrake on drivers side. Replaced shoes and rebuilt, but for life of me could not get drum back on, even with adjustment slackened right off.
The culprit was the brake slave cylinder, totally seized solid, so foot brakes on that side not working either. Of course, it was a Sunday, nothing open to buy replacement, so used a clamp and worked the pistons in and out, they freed up in the end, very rusty.
Rebuilt and brakes are fine.
Ordered new cylinder to fit later. I suppose they could have seized up in two months, but the rust on pistons looked long term.
Just goes to go show that sometimes a reduced braking can get through an MOT.

 

[Blobcat]

It's a difficult one, on the day it will have given enough to pass. Having an MOT is only an indication that on that day it was good enough to pass, it doesn't make up for a lack of maintenance. In most cases an MOT will show up a lack of maintenance but as you've found the brakes in a poor condition 3 months after an MOT. There's been a fair bit of salt spread around this winter and that can rust things very fast.

 

[ioweddie]

mot is only really valid at time of testing

 

[d215yq]

Anyone know how these MOT rollers work and whether they simulate real braking anyway? I ask because I don't know how mine pass, in Spain it's a computer readout and they punch in the weight of the car and the roller checks the newtons of all 4 wheels and sees they are good by a formula. Mine gets 60% every year (the limit is 50%) when I'm told to stop braking as it's passed (so it has more to go). I questioned the guy last time as in the real world the brakes are rubbish and always have been (stamp as hard as you can on the brakes at 60mph and despite no ABS they will not lock/skid the wheels and feel spongy) and he just said a 4 yr old sports car gets 80% and 60% is good for an old car and more than safe...may be he's right as a change of brake fluid didn't help matters and not had a crash in 85k miles. Maybe they just feel bad and they aren't actually bad?

I remember my UK W124 coupe always having great feeling brakes and passing the UK MOT yet once there was ice and despite me having my foot on the brake and the front wheel stopped, the rears brakes weren't even poweful enough to stop the rear wheels turning in drive, thus the car would slow to a crawl and then continue to slwoly slide forward until put in neutral (found this out from observers shouting at me)! Yet it passed the UK MOT before and after that winter...

It does puzzle me as even the family's 20 yr old yaris (original brakes and second brake fluid) brakes very very sharply in comparison and I've locked the rear wheel accidentally by pressing the pedal too hard before, mainly when I've driven it after mine as the differenc is night and day...