No rear braking one side on cup

[ilovewilly]

Took my cup for its MOT on Sat, and it failed on the rear braking. 0 one side, 10kg of braking force on the other.

I went home and read up on the VOSA newsletter thing to see whether that was to be expected and had a mate take a look at it as he is also an MOT tester. He took the brakes apart and did what he thought improved the rear braking. My handbrake is also much better as that was also an advisory.

Took it back yesterday to the MOT station, and they stated I am now getting 80kg from one side, and still 0 on the other.

Now I am aware that something must be wrong, I can appreciate that a reading of 0 is obviously a problem and not just a characteristic.

I have noticed no braking issues, it still stops like it always has and doesnt pull to the side or anything unusual.

Anyone have an idea of what braking force the rear is supposed to have in kg?

I am tempted to chuck a load of weight in the back and try again as because there is no spare or anything I am wondering if its making a noticeable difference.

 

[Riley!]

are they testing it on the handbrake? If so could be a snapped cable

if there testing on foot brake I'd say seized caliper, but try bleeding it before you write it off

 

[ilovewilly]

They are testing it on the footbrake.

The caliper was sticky, but was wound out and seemed alright after. Suprised me that the reading is showing as absoloute zero.

I will be bleeding it and checking the lines throughout at the weekend.

I put it down to lack of use and short journeys.

 

[Riley!]

If there defo testing it on foot brake get them bled up and then to test spin the wheel whilst its jacked up and get someone to press brake and see if it stops, then see how well it holds by trying to turn it with pedal applied

 

[Mike_182]

Yah, bleed them. Possibly got air in that line. Also check for what order you should do them in as you should do it in the right order!

 

[W111ALG]

I had same at MOT and ended up needing a replacement caliper, was about £50/60 for a recon one.

 

[ilovewilly]

If there defo testing it on foot brake get them bled up and then to test spin the wheel whilst its jacked up and get someone to press brake and see if it stops, then see how well it holds by trying to turn it with pedal applied

Held the disc while the pedal was applied and it gripped, but didnt think about putting the wheel back on and trying it

Yah, bleed them. Possibly got air in that line. Also check for what order you should do them in as you should do it in the right order!

I wasn't aware there was an order, so cheers for that!

I had same at MOT and ended up needing a replacement caliper, was about £50/60 for a recon one.

Looking a possibility.

Will get it up on a ramp and check every avenue.

The mate that can have a look at it for me properly is an MOT tester anyway, so will get him to MOT it after while its there. Lose out on the fee I already paid elsewhere but never mind. Should have gone to him in the first place really.

Just had to tax and insure the beemer, the tax is due on the clio this month, the beemer needs a full service, the subaru needs some work on the suspension. This month is a dear one for cars! To top it off I have been walking to work due to the snow and illustrated the point I don't really even need one car.

 

[Munson]

Have you tried jacking that corner up and seeing if you can spin the wheel when the brake is on? Might sound silly but it's the first thing I'd do. If there was air in the line you'd feel it through the pedal.

 

[Mike_182]

I'd normally agree Mr. Munson but i may hazard a guess that as the brake pedal does sweet nothing to the back end, there's very little feel comes back?

 

[Munson]

I can't see it somehow but I'm no expert. Zero effort at the wheel and not feeling any air in the pedal? It can't hurt to bleed them anyway.

 

[ilovewilly]

Right,

Had a free dry day so had another look at the car, I took the brake pipe off the caliper to see if there was any fluid coming from this as there wasnt anything coming from the nipple. The pipe slightly dripped, where there should obviously be alot of pressure.

Tried the other rear side, and it got wet at the first turn undoing so that side is fine. Bled them all. Again, not a sausage from the left when bleeding that one.

So the caliper doesnt seem to be at fault as I first thought. Now I need to check the rear compensator thing. Which to be fair, I dont even know where it is! On my 306 GTi6 it was obvious to see when looking underneath, but on the cup I have followed the two lines on the nearside but cant see anything without getting it on a ramp. I hope it is that at fault

 

[renaultsport1981]

sounds like a collapsed brake hose to me. look fine from the outside but deteriorate and block up. try taking the hose off completely at both ends and see if the fluid flows freely from where its disconnected.
good excuse for braided hoses methinks.

 

[Munson]

172Cup does not have a load compensator.

 

[Riley!]

yes it does, its just set to a pre-set value and not connected

 

[Munson]

Ah I see. Well technically it's not a load compensator then

 

[ilovewilly]

sounds like a collapsed brake hose to me. look fine from the outside but deteriorate and block up. try taking the hose off completely at both ends and see if the fluid flows freely from where its disconnected.
good excuse for braided hoses methinks.

Thats something I didnt think about. I checked the end and it looked clear but could be fluffed inside. I agree!

 

[ilovewilly]

yes it does, its just set to a pre-set value and not connected

Where is it?

 

[Jay Payne]

above rear axle, passenger side

 

[Riley!]

Where is it?

sat on the rear axle beam fella

 

[ilovewilly]

Excellent, Thanks!

 

[russ_0016]

I had same issue last year but 0 effort on both sides. i had fluid etc and braided lines. So changed the comp valve and was better but not perfect so strpped and cleaned the calipers, so take the rear caliper slide pins out clean and lubricate ensure they slide freely and move the piston about to free it up, should sort you out fella! i got around 100kgs at mot just gone

 

[ilovewilly]

I had same issue last year but 0 effort on both sides. i had fluid etc and braided lines. So changed the comp valve and was better but not perfect so strpped and cleaned the calipers, so take the rear caliper slide pins out clean and lubricate ensure they slide freely and move the piston about to free it up, should sort you out fella! i got around 100kgs at mot just gone

Taking the calipers apart is going to be my last plan. The handbrake operates it fine, and no fluid is coming from the pipe to the caliper so its going to be something before then.

At some point I will take them apart and clean them up anyway, but hopefully the fault will lie with the brake line or compensator. I don't even want to know how much they cost if its fubared!