rear cup brakes

[Mack182]

i had my mot on Saturday and had a search on here but could only find people saying their rears were locking up,
but mine are the other way the work cause go a reading on 30 on both sides and a reading of 300 on both fronts.
was wondering if anyone had any ideas as to why the rears are pretty much non existent ?

recently had a full fluid change as well with ate super blue fluid so there is no air in the brake lines

cheers

 

[sbridgey]

It's correct

 

[MarkCup]

That's how they come from the factory, no ABS and a light twitchy rear end mean any more and you'd swap ends under hard braking.

Search on here for the VOSA article which explains to MOT testers why they shouldn't fail 172 Cups on low rear effort.

 

[Mack182]

i no it never failed mot and am aware about the rear brakes but thought maybe they were ment to be a bit more powerful than that but maybe not

 

[Cup_Phil]

I'd check that they know about the VOSA advisory first but mine failed on rear's being very low and I showed them the VOSA advisory and they said fair enough but still too low
Free'd the rear caliper sliders up, rebuilt them, loosened the bias adjuster under the car and then cable tied it in the UP position for maximum flow - took the car back and he said the braking force had more than doubled at the back. Drove a damn site better too

So yeah there is the VOSA advisory (but if they didn't know about that they'd of failed it on a missing bias valve link bar too) - but it's worth freeing the rear pistons and sliders too

 

[NorthloopCup]

The vosa advisories should come up on the testers list along with the info regarding the bonnet catches failing. There is no valid reason why all mot testers should not be aware of this particular issue now.

 

[sam JFM]

Just because of the VOSA advisory That’s not to say your brakes are working correctly, see if there is any movement in the bias valve - if its stuck solid in one position then it needs freeing off.

The valve should move on application of the rear brakes and then return when the brakes are released - sometimes its this that doesn’t happen even when the valve appears free, there is a small spring that should close the valve when you take your foot off the brakes (Its attached between the lever arm and the body of the compensator) and over time this gets weak so wont shut the valve up Thus you have no brakes to the rear.

To test this what you want to do is get the back end of the car off the ground, push the bias valve up toward the floor of the car as far as it will go and spin a rear wheel, at the same time get someone to apply the brakes and see what happens - it should stop the wheel . Then release the brakes and reapply them - this time it might not stop the wheel indicating that the spring is goosed!

To solve the problem I added another spring and small bracket (I will get some pics) and this solved the problem. I how have brakes as Renault intended.

 

[MarkCup]

There is no compensator valve on the 172 Cup. What model are you talking about?

 

[sam JFM]

Bias valve