Micra rear brakes

Hi folks Just took the boys Micra down for MOT and all it failed on was the rear brakes low efficiency. The handbrake passed the test fine though so the guy reckons it's wouldn't be the shoes, possibly leaking cylinders? It's absolutely pissing it down out there today so I'm not gonna look at it till later in the week but any suggestions would be most grateful. I've not touched shoes and drums before although I've done front discs and pads on a Micra before and it was really easy, once the front wheels and calipers were off the discs just dropped off as they are held on by the wheel nuts. Are the rear drums gonna be as easy? As you can probably gather I'm a novice mechanic but I'll have a go! Many thanks Gareth

Reply to
Gareth Watkins
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The footbrake efficiency is totalled and then worked out as a percentage of the cars weight, so unless the rears do nothing they should still be able to pass, especially if the handbrake is ok, if the cylinders were leaking then the handbrake would have problems too.

Reply to
Mrcheerful

Or seized ones but yes that's most likely where the problem will be.

if the cylinders were leaking then

Why, seeing as the two systems are separate?

Reply to
Dave Baker

yes they are two seperate systems but linked by one commone component- the brake shoes. when you pull the handbrake on the shoes expand agaisnt the drum, but when they are covered in leaking brake fluid they wont "grip" the drum due to the fluid contamination.

reg

Reply to
kronenburgh

they are only partially separate. they use shared drums and shoes, if the cylinders have leaked enough to effect the footbrake efficiency by 'lubricating' the drum then the handbrake would show the same problem. seized cylinders could show a low braking effort, but generally would also show massive drag.

rear brakes on many small cars are very ineffective, metro rears for instance can still be turned by hand with the footbrake pressed hard, that small an amount of braking does not show up as a high amount on a brake test meter, an inexperienced tester or one just out for some easy money can claim the rears have low efficiency and fail it or 'fix' it for you.

My father had a similar problem years ago with something small and Japanese (I forget what, but I don't think it was a micra) I said to return it for a retest and show the tester the relevant pages of the testers manual (which I copied for him, and if they still would not pass it to ask for a vt17. They passed it.

Mrcheerful

Reply to
Mrcheerful

Or the rear compensator va;ves stuck.

Reply to
Duncan Wood

Partially seized cylinders are more likely than leaking ones on average with older Nissans over the years. New cylinders + shoes are the easiest fix, cheap enough for a DIY job.

Reply to
Steve B

Many thanks for the input guys. I took the drums off yesterday to have a look see. The cylinders are not showing any signs of leaking although they are very dirty. The shoes are fairly low with about 2 to 2.5mm so for starters I will put new shoes on and see what difference it makes. If that doesn't have enough improvement for the test then I will put new cyclinders in. I got the shoes today, 9 quid for both pairs, very impressed! The cyclinders will be about 13 quid each so I will see what the new shoes do for the little beast. Many thanks again.

Gareth

Reply to
Gareth Watkins

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