Seized Brake Calipers/Pistons

Ceb

hey all, not sure if this would be the right section so if a mod feels it appropriate to move it then by all means do, heres my problem, the caliper on the right hand rear of my car seems to have siezed, grinding noise even at slow speeds, not just when the pedal is pressed but constantly, i think innitially it was just when pedals were pressed, the car is a 1994 renault 19 1.8 16v, just wondering does anyone know if this is just a matter of the brake pistons being siezed and if so how should i go about repairing this on a low budget sub intellegent scale (also do i need to get a kit of some type or is it tools all the way), any help is greatly appreciated, many thanks in advance
-ceb

itarumaa

I am not 100% sure because it is rear and not front brakes,

but for my Matiz, the front caliber was stuck and eventually me and my friend found a specially made tool to push that caliber´s piston back inside. Then some wd40 and lot and lot of force and caliber was fine.

I assume that you have discs as well in the rear axel? Then you can go and buy the tool at some parts shop (I got mine in Drumcondra) and if you are lucky you are able to get the piston free.

However I think you need that tool + 15mm spanner and 19mm spanner (or close) because otherwise you cannot get enough force to push the piston back inside.

This tool is precicely like mine:

http://www.lasertools.co.uk/item.aspx?item=356&cat=518&AspxAutoDetectCookieSupport=1

That tool was around 30 euros and new caliber 160e so some money was definitely saved:)

Mr.David

How long has it been happening for? If you have driven a fair bit on it you will need new pads as the pad wear will be uneven. Also it could distort the disc (by generating temperatures outside of normal operating ones) so you need to have a good look at it and make sure its ok. Pads are cheap anyway you are probably as well to replace them while your at it.

blackbox

Your symptoms of a grinding noise doesn't suggest a seized piston to me - I presume you haven't taken it off for inspection yet.

It could be due to a stone or other grit stuck in the brake pad.

Alternatively the wheel bearing could have failed.

Either way you're best to start by removing the brakes for inspection. Sometimes it can be quite difficult to get the pistons to push back to accept a new pad, even when they are not seized - this is especially true on the back where they are used by the handbrake. I 'm not sure about the Renault, but I used to have a Citroen and the rear cylinders had to be turned as they were being presed back.

Ferris

Just a question lads, are there not Drum brakes on the rear of a '94 Renault 19. Not sure myself because its a GT but the smaller engined models had drums.

itarumaa

oh yes, the easiest way to identify is brake caliber is stuck, is to drive nice and gently, then stop the car and try out the wheels. If you have three wheels that feels cold and one of that feels really hot, then you know where the problem is.

jaycen

Sounds more like you have a worn brake pad or something like a stone (mentioned above) caught between the disk an the caliper.

If caliper piston turns out to be stuck you don't need any special tools if you have a sturdy pair of water pump pliers or even a rubber mallet and block of wood (latter may be unhealthy for the ABS unit, if fitted) to push it back. Old Saabs needed a special tool to wind back the handbrake mechanism in front calipers but any other vehichle I have come across has been ok without.

If the piston is stuck, check the outer seal around it carefully for rips etc as this could be the cause for it getting stuck. If the seal if broken, the best option is to pump the piston out a "a fair bit" (until rust free surface is seen, be careful not to overdo it and allow the piston to pop out fully) and sand the rust with emery paper before pushing it back in. Coat with some grease and then renew the seal.

If the seal is ok and the piston feels very stiff, you can try pump/push the piston through the range a few time to see if it helps to loosen things up.

Ceb

hey all, many thanks for your advice there, i had thought a stone myself but this would give a scratch around the disc, there is nothing like that, its pretty much as if the pad is worn but constantly pressed in too, or so the noise would suggest...

(most 19's came with rear drums but the 16v convertible had discs all round which is my model)

again many many thanks to all