Cup rear brakes

[SRIDENZ]

Today I changed the fluid as there was high moisture content according to Renault so added new fluid bled the callipers up to shift old stuff.

While up on the ramp we were looking at theload valve which isn't attached to the rear beam it was quite rusty and I thought no more of it.


The braking on this car has been sketchy since I bought it a few months back and today I realised that with the peddle pushed as hard as possible the rear wheels could still be turned by hand with ease. Is this normal??

We experimented with pushing the load valve/ switch further shut which seemed to make them better. My understanding was that, if the valve was attached to the rear beam, the more load applied the more closed the valve was and the less braking to the rear. Yet by pushing it shut the brakes got better.

Call it bodge but we cable tied it in place and I went for a drive, the braking was transformed. And for the first time ever the rear disks showed signs of getting hot and removing some of the rust and pitting.

Any suggestions? Is what we did sensible or safe ??

Sorry for the uber long post buti wanted to get the detail in. And sorry for not knowing the correct term for the brake bias/load valve thingy majiggy.

 

[SRIDENZ]

Any one?

 

[regi james]

im sure that is ment to be disconnected (i take it,its a 172 cup?) the rear brakes don't do alot one the 172 cup as they have no abs to stop the wheels locking up

 

[franx]

That load-valve; i think the 172Cup does'nt have this attached from factory . Mine was'nt either anyway. Maybe something to do with the car having no abs, being lightweight and backend-happy.
I think with this valve working (attached) they foresaw accidents happening do to rear-end breaking out/skidding because of blocking brakes ?

There is a thread somewhere about the rear brake power of the 172Cup being to low, therefore failing MOT. However there is a specification/description going round about this ; explaining the difference to the other RS models . (that valve, no abs, etc.)
With this description the MOT-inspector will have to "pass' the car.

Hope this helps, maybe more Cup owners who know will come along and fill us in further ?

 

[franx]

^^ ah, 182 Cup beat me to it

 

[MarkCup]

The Cup has its rear brake bias set at the factory, and the rear brake effort is very, very low.

My Cup has done 120k miles, and the original rear pads lasted for more than 90k, that shows how little they do.

As said above, the Cup has no ABS so with the forward weight balance, it is very, very easy to lock a rear wheel - which is why the brakes are set as they are with low effort.

I'd reverse what you've done back to standard straight away, as the second you have to brake hard/in an emergency you may well find the rear locking up and coming around to slap you.

 

[SRIDENZ]

Sorry I think I've confused ppl. I was aware they were not attched as standard and mine still is. However low brake effort should not be so low that u can turn the rear wheel by hand with ease (i wasnt hanging on it, i literally could turn it with one hand) when braking. I have not altered the the position of the valve, apart from holding it closed as it should be.

I was hoping some oneelse would have some experience of the valve failing. My rear disks are foooked, and that's all because they appear to have not been working, we ain't talking low effort, I mean a spirited 20mile drive on B roads and they are cold!

Maybe I'm looking for a prob thatsnot there but my car feels better than it didnow the rear appears to be working more.

 

[franx]

i think that a good clean of the calipers , (moving break parts?) of the rear is neccescary. Still easily moveable by hand while braking does'nt seem right.

Mine will be on a ramp/bridge soon and will also check this

 

[mark123]

You can turn mine but only just, not with ease.

I cable tie my valve up for the MoT to avoid the usual low rear effort problems and the hassle of explaining that's the way it's supposed to be...

With it cable tied up I once locked up the rears under braking so I wouldn't advise it long term...

 

[SRIDENZ]

You can turn mine but only just, not with ease.

I cable tie my valve up for the MoT to avoid the usual low rear effort problems and the hassle of explaining that's the way it's supposed to be...

With it cable tied up I once locked up the rears under braking so I wouldn't advise it long term...

When u say cable tied up do u mean so the arm is flush to themount or so it's wide open like this shape ... >

 

[Fred@BTM]

you mean you've pulled the arm down from the car and tied it "open"

 

[mark123]

I tied it shut, up towards the car.

The more it moves down the less effort to the rear.

 

[SRIDENZ]

you mean you've pulled the arm down from the car and tied it "open"

I did the opposite, as below and it made the "effort" increase. I realise this is not logical but I'm telling it as I found. My understanding was that the more closed it was (ie toward the floor pan of the car) the less effort.

I tied it shut, up towards the car.

The more it moves down the less effort to the rear.

 

[mark123]

That's correct behaviour, the more it moves down the less effort.

When you press the brake a little piston pushes the compensator lever down. The spring if fitted resists this so the tighter the spring i.e. the lower the suspension due to weight, the more effort to the rear. With no spring you always get minimum effort to the rear. When you cable tie it to the chassis it can't move down when you press the brake so you get full effort to the rear.

 

[SRIDENZ]

FRED!?!?! come shed some light please

 

[ilovewilly]

Can someone who has cable tied it for the MOT, show a picture of which way they tied it for future reference?

My rears have the same stopping power as Tiger Woods' sexual temptation, so would like to see if this makes much difference or if I have issues eleswhere.

 

[SRIDENZ]

I love willy lol

Mine were the same and I'm sure the load valve should be closed as poss (flat to underside of car) as the bias is pre set at factory. Mine had sagged open and the brakes couldn't even take on my mighty biceps lol.

Awaiting Fred to come back and bless us with hisknowledge. Tried pm buthis box is full

 

[SRIDENZ]

Fred?!? COOOWEEEE lol

 

[Fred@BTM]

eh what? its meant to be UP against the car

 

[SRIDENZ]

I did try PM. Dint wanna waste your time on the fone for an answer. Thank you for replying

My issue was that the rear brakes were putting out MINIMAL effort as described above. But when cable tying the valve UP against the car the effort increased ...... should that not be the opposite??

Im still scratching my head about this and these things bug the crap out of me unless i can figure out a solution/answer. Any wise words?

 

[Fred@BTM]

yeah i'm pretty sure its the other way round LOL

 

[SRIDENZ]

FFS!! This is baffling me!

 

[mark123]

Up is more brakes and it is up at rest.

It moves down when you press the brake to take some of the pressure from the rears.

If you hold it up e.g. with cable ties. It can't move to take pressure from the rears so you get max effort.

 

[Fred@BTM]

there you go!

 

[Dangerous_dave]

any chance of a cable tied up pic? my cup just failed on this not entirely sure what/where i should cable tie...
my load sensing valve is pretty damn rusty. Could this be completely removed and joined together with a double female connector (or would this guarantee locking up) or removed and replaced with a bias valve?

cheers

 

[mark123]

I'll get a pic.

I have locked the rears with it cable tied up, so you would certainly be likely if you removed it altogether.

 

[Dangerous_dave]

manage to get a piccy mark?

cheers!

 

[mark123]

Here's some pics. I've drawn in where I put the cable tie.

 

[Dangerous_dave]

i did this quick fix on my cup and from when it failed the rear brakes were register 0.1 with 6 month old discs and pads done about 500miles! and after i pushed the bracket right up (bit in the piccy on the left , you literally push it right up it pivots where the brake lines go in and out etc.) cabled tied it all up as marks pics and got it retested and they registered 1.1!!!!

I would not leave it like this though as the rear brakes do lock up when cable tied up so i plan on slackening off the cable ties quite a lot, and test until i cant get them to lock up :-D but the rear brakes get a little bit more than 'next to no efficiency'

I hope this response will be useful for those who search this topic.
cheers all!

 

[Matt W]

I was just about to search for this as my cup has just failed on the rear brakes (and ball joint play )

Tester man didn't believe me that it had no ABS, he also asked if it was a 1.4 litre.

 

[mark123]

i did this quick fix on my cup and from when it failed the rear brakes were register 0.1 with 6 month old discs and pads done about 500miles! and after i pushed the bracket right up (bit in the piccy on the left , you literally push it right up it pivots where the brake lines go in and out etc.) cabled tied it all up as marks pics and got it retested and they registered 1.1!!!!

I would not leave it like this though as the rear brakes do lock up when cable tied up so i plan on slackening off the cable ties quite a lot, and test until i cant get them to lock up :-D but the rear brakes get a little bit more than 'next to no efficiency'

I hope this response will be useful for those who search this topic.
cheers all!

Glad it worked for you. Good luck with using them as a bias adjuster lol.

 

[Matt W]

Just had a re-test, and they're still telling me that it's dangerously low on rear braking performance. I've given them the print out from VOSA and everything

 

[franx]

^^ well that printout should have corrected them !?

This car is dangerous with any more braking power at the back btw

 

[Matt W]

It should have, but he didn't believe it. I'm going to write an e-mail.

 

[Dangerous_dave]

dont track my car really so has to be worth a try i could just rip it all out and fit a bias ... but like i said dont really track it.

 

[Cupman29]

Mine just failed it's mot for rear braking efficiency even with the vosa printout. Need to try this and see how they get on tomorrow.