Hello all,


after the replacement of breaking discs and pads, the car pulls to the right on hard breaking, any suggestions ?
Air bleeding complete, I wonder if the front right cylinder stacks, how can I "move" it free?


Thanks,
Panagiotis

 

It's more likely that the LEFT caliper is sticking - therefore the Right caliper applies more braking force and car pulls to right.

If you had no pull before replacing the discs/pads then it is likely that there was corrosion on the piston which is now causing the problem, I've attached a picture that explains what I mean.

You will need to remove the caliper and strip it down to fix the binding. You may need a new piston if there is significant corrosion or you may get away with cleaning up the old one (I've only had 50% success in cleaning up pistons). In any case you should replace the piston seal and rubber boot while the caliper is stripped.

 

Thank you b1mcp,

sounds logic, i'll check it.

Panagiotis

 

Brendan,
Neat diagrams.
On the few occasions I've had to replace caliper pistons, I've had them made in stainless steel. An easy job for a machine shop and a huge improvement on the OE chrome plated ones.

Graham

 

Hello All,

Are the pistons "thread" or just push in their housing?
I mean do i have to rotate (screw) the piston back, or just push it?

Thanks for any reply,
Panagiotis

 

Not threaded

Cheers
DD

 

You might also want to double check that you did indeed get all the air out of the front left line.

 

Thank you,


I'll do the job and enjoy the car, the more I get in the Forum (studying your answers) the most I love what I do and what I get from this car.


Wish you a great weekend,
Panagiotis

 

Also check the Caliper Guide Pins for corrosion as they can also cause your symptoms - in fact check them before any dismantling of the caliper. I should have mentioned that on my previous post.

 

Hi b1mcp/Allan/Doug/GGG,


The problem is solved !!


The LH front piston was corrode due a small hole on the rubber boot.
Exactly as you supposed !
I checked all of them, the rest pistons where brand new.


On a 19 years car with 145KKm this is quit strange to me..!
This was the very first pads change (and discs) on this car.


So removed again the wheel and the calliper assembly.
By pressing the pedal (s l o w l y) I moved out the piston carefully (since I don't know it's complete length), removed gently the rubber from its front housing-channel, sprayed the outer surface of the piston with brakes spray, supported the rubber boot open (with a gap) through a plastic screwdriver at its lowest point so to drain, put the rubber boot back when the piston was dry and several times pressing the pedal, piston out, push it in, pressing the pedal, piston out, pushing it in and so on and so on.


When the piston moved free, press the pedal-piston out-took out the rubber boot again and applied a small quantity of non salted pure animal fat (pig) on the piston's outer surface-push piston back-pads on and reassembly everything. (and the damaged rubber boot of course!, lack of new)


The car doesn't pull to the right any more.
Next step, order the sealing kit and remove completely the piston so to do a good cleaning on its outer surface.
For sure I'll measure the piston dimensions, so to be able in the future to ask a workshop to produce it in stainless steel.
The only thing I'm completely not sure about, is the tolerances of the outer diameter of this piston.


Any way, thank you all for your support on this issue!!!


Panagiotis


Pure animal fat is a product that I heard about it in different work shops, really suspicious I tried it on my front motorbike brake's piston, this fat lasts (is on) more than 10 years and three pairs pads exchanges, (disc next year)

 

That's good news Panagiotis, and thanks for updating on the conclusion. You are right to order the seals and fix the problem permanently as it will happen again for sure if there is a split in the boot.


Anyone in the UK know if Halfords stock pure Pig Fat?

 

Hi b1mcp,

I think that the correct procedure is to disassembly totaly the caliper from the braking system.
Disassembly the piston and clean the external piston's surface and the internal caliper's surface also.
Then reassembly everything, with the new sealings.

Forgot to mention: Pure Female Pig Fat, or PFPF..!!

Have a nice week,
Panagiotis