Problem bleeding near side rear calliper - no fluid!

[Deek1182]

As title says I'm having problem trying to bleed near side rear calliper. No fluid was coming out bleed nipple so I took main brake line out calliper and no fluid there either!

I Had to replace this calliper and brake fluid was present when old calliper removed so not sure what could have changed / happened. Any ideas?

thanks in advance for any help

 

[Owen92]

How long did you persevere with bleeding for? Is there a leak further up the system?

 

[Deek1182]

The brake pedal felt like normal when bleeding. I tried bleeding o/s/r calliper and that worked fine with brake pedal goin right to floor. Engine is meant to be off and does it matter if cap is on brake fluid reservoir when bleeding?

 

[pastieman]

Bias valve at fault ???

 

[Deek1182]

Well I have thought of that but doesn't make sense how offside working ok and fact that there was fluid present when I removed old calliper. I used a brake pipe clamp on the flexi pipe when I was taking calliper off - could that be issue ie its crimped shut? Doesn't look like it tho

 

[pastieman]

Doubt it mate.... I would take off pipe from bias valve for the side you are not getting any fluid from and with it removed see if any fluid comes out the valve !!!

 

[Deek1182]

I'll give it a go

 

[Dan519]

Remove the spring from the bias valve and work the arm back and forth. May need lubrication

 

[Deek1182]

Eventaually got this sorted - bias valve was at fault! No fluid getting through n/s circuit in valve but after alot of brake cleaner and air to try free it up it eventually freed up a bit.

Now i have a new problem! Car eventually passed MOT but the tester has mentioned to me that there is a big imbalance of rear brake efficency - n/s recording 114 kgf, o/s recording 23 kgf!

Can anyone tell me what reading i should be getting on rear brakes so i can determine if bias valve goosed or not?

There is also an imbalance on front brakes - n/s recording 212 kgf, o/s recording 171 kgf. Not sure how concerned i should be here but i would expect these should pretty identical? I have just fitted Brembo HC (painted ones), DS2500 pads and flush out with new ATE super blue so not sure if its just a bedding in thing - anyone any ideas?

 

[pastieman]

I would say you need a new valve matey.... That's low on the o/s rear effort for the service break... The front prob need bedding Abit more ( did you re lube the sliders on the callipers each side

 

[Deek1182]

Do u know what force / effort I should b getting on rears?

 

[pastieman]

The n/s might want to be slightly higher but the o/s is near no effort at all !!!

 

[ben lee]

rears should be 100-150. front inballence needs to be less than 25% looking at the readings thats what the fronts locked at. did you watch the readings as it was tested? as they probably was the same untill they locked out so will be fine.

o/f/r is defiantly low and should really of never passed the mot.

 

[Deek1182]

Wasn't there when it was getting tested but asked for a copy of the brake test report. The f/n/s value did have a note next to it saying lock up.

Reading up about cup rear brake issues i've seen a few that mention values around 20-30 kgf which made me think this was the normal level and that reading of 100 kgf etc would be due to the bias valve arm position being manipulated?

As i mentioned earlier i cleaned out / freed up the n/s circuit of bias valve and now its recording the higher value but to be honest it doesnt feel like the arm is doing much when its moved i.e. it feels very loose - i would've expected this to require a decent pressure applied to move?

Wanting to go on trackday next month so really want brakes 100% - last thing i want is too much rear brakes!

 

[ben lee]

front sound fine. does sound like you have a problem with the rear thought cups had the bias valve preset and the arm removed?