Sticking Brakes....

[TheReaperWaits 6 1 Cars]

Howdy folks,

 

Straight to the point. The brakes have started to stick on my standard 1.9. When cold they are fine, but they slowly grip on more and more the warmer the car gets (coincidence?). The brake pedal slowly gets harder until there is very little movement and the brakes are on hard.

 

I took it to a garage for a free brake test and they found no problems. I have put in a brand new master cylinder and I still get the issue. I can't imagine a defective caliper would cause this? (then again I'm still learning). Only thing left would be the servo. I was thinking the air line that runs from it?

 

Looking for some experienced input as extra heads are always welcomed.

 

Cheers.

Edited April 6, 2013 by TheReaperWaits

[TooMany2cvs 65]

Front flexis could be dying internally and acting as a one-way valve. When they're locked on, undo the bleed nipple, and see if fluid comes out under pressure, freeing the brake off.

 

I dunno 1.9 front brakes, but if they're single piston sliding yoke calipers, make sure they're clean and copaslipped up so they can slide easily.

[Slo 283 1 Cars]

Its usually all the old crap and rust thats formed on the caliper pistons as its pushed out over time because the pads have worn down. when you put in shiny new pads you have to push the pistons back in along with all this crap still stuck to it. the crap gets trapped between the piston outer wall and the rubber seal and traps hence brakes stick on. solution take the calipers off one at a time and press the brake pedal slowly until the piston comes all the way out then clean it up, take out the caliper seal carefully and clean that and its guide that it sits in and a bit of brake fluid to make it slippy push it back in bleed brakes after

[TheReaperWaits 6 1 Cars]

I have braided hoses all round. Garage checked these and they were fine. Was the garages first guess.

 

Would this 'rust and stuff' leave the brakes running fine after I leave the car to cool down? Anything is worth a shot ATM.

[welshpug 1,646]

Find which brake is causing the problem, go for a drive and feel which wheel is warmest.

[Slo 283 1 Cars]

Yes as the car warms up or brakes are used and warm up rather the brake fluid/metal parts will expand pressing out the piston and bind the brake shoes, i've had glowing disks in the past due to this problem. If you can remove the pads and press the pedal to push the piston out you can check the condition of the piston walls without popping them completely out and a good dousing of brake cleaner could save a stripdown job but dont use wd40 and lubricate with brake fluid and nothing else. If theres crap contaminating the caliper seal the problem will return again in time

[glenwah 20]

Sounds to me like the master cylinder is the issue here not allowing expanded fluid to evacuate the system, if it was calipers they would be seized hot or cold.

[TheReaperWaits 6 1 Cars]

All the wheels feel like a lot of heat is coming from them. Certainly smells hot from both the front wheels. Definately feels like more than one is sticking (if not all).

 

Thanks for the replies.

[glenwah 20]

Master cylinder for sure. Sounds like the piston isn't returning to its original position and keeping the fluid under pressure then as it warms and expands it puts the brakes on even harder hence feeling free when cold and binding when hot.

Edited April 6, 2013 by glenwah

[welshpug 1,646]

Repeat the symptoms then loosen the 2 13mm nuts, if it frees up you need to adjust the servo pushrod

[TheReaperWaits 6 1 Cars]

Will give that a go tomorrow when work doesn't get in the way.

[TheReaperWaits 6 1 Cars]

Okay, got her warmed up... Switched her off as those nuts are closer than I want to be to the belt. Loosened the two nuts holding the master cylinder on. Heard a hiss of air then the car started to roll forward.

 

Is that the result you were expecting?

[welshpug 1,646]

Yup, you need to adjust the pushrod, the measurement and method is in the haynes manual, out at the mo so havent got it to hand!

[TheReaperWaits 6 1 Cars]

Got my copy on the car. Will have a flick through and try to find it. Cheers.

[TheReaperWaits 6 1 Cars]

Found a section about maintaining and replacing the servo with a diagram. Didn't find a method of adjusting it. The replacement servo I brought has arrived so I could get a closer look to how it works.

 

Adjusting would be done via the screw in the centre?

 

Does this screw move over time? Trying to figure out why this started in the first place.

[TheReaperWaits 6 1 Cars]

Finally got some time to myself and the car...

 

Upon removing the master cylinder I noticed it was dripping brake fluid from around the rubber washer... Is this normal?

 

I like pictures, so here.

 

[TheReaperWaits 6 1 Cars]

Got the old servo out. (What a pain.. No idea how I'm going to get the new one in). It had quite a bit of brake fluid inside, so I went ahead and ordered a new MC. Will get a refund on this one.

[TheReaperWaits 6 1 Cars]

More free time...

 

Got the pedals and the replacement servo back in. New master cylinder is in with brake lines connected.

 

Having a bit of trouble getting the reservoir in the MC is there a trick to getting those in? Or is it in far enough?

 

(Images attached).

[Slo 283 1 Cars]

No, lubricate it with a spot of brake fluid round the rubber then good old fashioned elbow grease wiggle it side to side with firm pressure on top should go in all the way with a bit of persuasion

[bondo 6]

You do need an alarming amount of pressure to reseat the reservoir.

[TheReaperWaits 6 1 Cars]

Bringing this back up as I have had more time to work on it.

 

Still cant get that res to go in. The plastic is flexing with amount of jiggling/force. There must be something I'm not getting. I took the rubber seals out to make sure they fit. I can only get it in half way like the photos...

[Slo 283 1 Cars]

Lubrication, lubrication, lubrication ............. is what ya need!

[TheReaperWaits 6 1 Cars]

Gave up with that MC. Put my old one back on and got the reservoir on with just a bit of jiggling.

 

Problem I'm having now is trying to bleed the system. Doesn't look like pumping The peddle is pushing the fluid through.

[Slo 283 1 Cars]

Get yourself an easy bleed kit much easier. Are you sure that new mc is exactly the same?

[TheReaperWaits 6 1 Cars]

Currently using an easy bleed with one way valve. The MC was the one I had on the vehicle during the sticking brakes troubleshooting.