MOT failure

[Dan1503]

My car went in today for its MOT. The guy from the garage called me to say that it has failed as the rear brakes are not working, not even a little! I asked is that a case of needing new pads and disks but he says he is unsure why there is nothing on the back.

To me the car has always braked well and iv never had a problem, the brakes will be amazing when it is fixed if im used to only having front brakes on it!

Anyone have any idea what may be causing this? He said something about a load valve?

Thanks

 

[R20 CWH]

dvla website visit

 

[Gaz_]

http://www.dft.gov.uk/vosa/repository/MoT Issue 31 - Apr 2006.pdf

 

[Bucko]

How does the DVLA website help him diagnose a brake problem? Am i missing out on a valuable source of information here?

 

[Dan1503]

was looking more for a reply on what may be causing this like someone maybe having the same problem before

 

[Da]

There isn't actually a problem, the test centre obviously aren't aware of the advisory issued by VOSA regarding 172 Cup rear brake bias.

See here.

 

[ChrisR]

How does the DVLA website help him diagnose a brake problem? Am i missing out on a valuable source of information here?

As said, it's a known issue/feature on the cups to do with the bias stuff. If an MOT tester doesn't know about it they may well fail the car for it appearing to not work correctly.

 

[Dan1503]

Thanks for the information no doubt you guys have just saved me some money!

 

[Bucko]

You learn something new everyday

 

[mark_182_54]

indeed you do very interesting

 

[scotty2hotty81]

the tester is not doing the test right, as soon as you put in the vehicle details it comes up with a warning about rear brakes on cup models

 

[Mark One]

There isn't actually a problem, the test centre obviously aren't aware of the advisory issued by VOSA regarding 172 rear brake bias.

See here.

172 CUP

It's specifically the CUP

 

[Da]

Indeed Mark, I've added the Cup in for the avoidance of doubt

 

[Dan1503]

well i took page 8 down to the garage and they have still failed the car apparently the brake effiency needs to be at least 50% and mine is coming up at 49%!! past failed MOTs of the car show the brake effienceny at 46% i dont know what to do with it and neither does the mechanic???

Any ideas im so annoyed with constant car problems im seriously tempted to sell it and get something that doesnt have special requirements for MOTs

 

[caister]

I would either take it to a MOT centre that knows what they are doing, and get a refund off the original place once its passed or get him to phone VOSA while you are there.

 

[_WILL_]

It does sound a bit dodge to me, if the car feels like it has good brakes then I can't see it failing on brake efficiency, although I'm not 100% sure what it is or how its calculated! I would be tempted to take it somewhere else! I use the local council run one personally, they have no reason to f**k you over!

 

[scotty2hotty81]

second opinion. tester is a tw@t :rasp:

 

[Dave..]

So even after showing him the advisory, they've still failed it?

Maybe you should ring it in big red pen, and sit there while he reads it?

 

[Dan1503]

The tester has phoned VOSA and they have apparently said it has to be at least 50% now am i right in saying that the pressure is pre set by renault to be lower then normal?

So no matter what they try to do to fix the problem of brake effiency they are never going to achieve it? I have to take the car back on wednesday but im not sure what he will try with it, or even if there is anything he can do.

Has anyone else had this problem before, or do you have a brake effiency percentage that the test station has passed?

Thanks any help is much appreciated!!

 

[Jimbo_924]

I took the same page in for my MOT and they said they passed it under the special advisory, so I assume you must have a mechanic and possibly VOSA phone chap who aren't very well informed. Assuming that the rear brakes look sound upon inspection and therefore are working as they should.

What I would do is a quick fix similar to something I have done to my car. There is a 10mm hole through a chassis stiffening member just above the rear brake bias valve as you look up at it from under the car. If you put a bit of wire or even a zip tie between this hole and the end of the bias valve lever then the valve won't be able to move down and reduce rear brake effort. Providing your MOT man either doesn't spot it or have a problem with it then this should do the job!

I've done a similar thing but with a spring, to get a little more rear braking but still ensure the rears don't lock first 99% of the time.

 

[Jimbo_924]

Forgot to answer your first question, which is Yes Renault have reduced the rear brake effort over the 1*2's with ABS to ensure that the rears never lock first as this is considered unsafe on road cars, which it is. The other cars use the ABS system to avoid this, so they don't suffer from the same low rear brake efforts, only the Cup.

 

[Dan1503]

Might have to try that but before i do i found something else that apparently works. I phoned basingstoke MOT station (last place of MOT) and they said to get it to pass they struggled as the back end is so light and barely gives a reading so they sat a cppl of mechanics in the back whilst testing to put weight on the back which made it pass!

Wish the tester seen the advisory and passed it, tbh i thought thats what the advisory was all about!