[Val101]

hi all

i was changing the brake pads on my saab 9-3 aero (2005). i managed to change the fronts with no problems.

however the backs were more tricky since i had no manual to look at. from what i have read on the net, the rear brake calipers have a 4mm hex nut that retracts the piston, thus enabling you to fit the new "thicker" pads. the front calipers need to have their pistons compressed.

but unfortunatly i have unscrewed the rear pistons way too much, the piston has actually fallan out of the caliper and its rubber housing.

what i need to know is firstly how do i get the damn thing back into the rubber housing, its almost impossible.

second of all when the piston fell out a liquid was behind the caliper, is this liquid some sort of oil used as a lubricant or is it brake fluid, i am asking this because most of this has ended up on the garage floor! so i need to know what it is beause i need to replace it, how do i do that??

many thanks

val

 

[michaLcoughliN]

READ!

http://www.saabcentral.com/forums/showthread.php?p=1024514#post1024514

 

[Val101]

that link still doesnt explain how to refit the piston now that it has been completely removed from the caliper, it only explains how to change pads and disc.


i need to know if its possible to refit the piston into the caliper now that it has been removed, i have tried to refit it but therubber gaiter curls under the piston and stops it from seating properly.

 

[JBob]

The fluid will be brake fluid as the piston has come out. I'm not sure what the hex nut you refer to is - these pistons have two small holes in them that a suitably-sized brake retraction tool inserts into.

It should be possible to refit the piston and screw it back in, but as the piston seal has come out it is going to be very difficult. The piston will also require some pressure on it whilst is is being rotated for it to retract back into the caliper. Ideally a piston retraction tool would do the job (although few have found ones that fit the locating holes in the piston).

I suspect though that the rubber seal will be damaged, or will get damaged whilst trying to re-install the piston.

I would probably take the caliper off the car by removing the flexible hose & handbrake cable and stick it on a bench. Then lubricate around the outside of the piston/seal with brake fluid to ease some of the friction on the seal.

The piston will require a fair bit of rotating to get it back in, and you'll have to check that the seal isn't being damaged.

If you are successful you'll need to check that the seal isn't weaping once all re-installed (keep a regular check on the brake fluid level). If not it's a new (or have the old one reconditioned) caliper I'm afraid.

Either way, you'll have to bleed all the brakes once all re-installed.

Good luck!

 

[dc99]

In all honesty, since the piston is completley out I would replace it. By the time you put in back in without damaging the seal, you still looking at maybe it won't leak then to take it back apart, it's more aggrevation that's it's worth. My 2 cents.

 

[Val101]

thanks guys for all ur advice, will try and give it a go today, will kep u informed.

 

[Val101]

just to update everyone, i have managed to re-fit the piston into the caliper, however there is a tiny pin hole in the rubber gaiter, would this mean that ideally i need to replace the gaiter, or would i need to replace the whole caliper?

many thanks

 

[epsilon93]

The gaiter is just for keeping dust out so you should be ok for now. I think you can buy replacement for these parts but I am not sure where you can get them from. Maybe try an ATE brake parts supplier?

 

[Val101]

hi guys

i rang several saab dealers and asked about buying a rebuild kit for the caliper, but they told me that no such item exists! they dont supply the rubber gaiter seperate so it would have to be a whole new caliper costing from £160-£220!!

i'm just a little confused, when you guys refer to the seal, are you talking about an internal seal or are you talking about the rubber gaiter that covers the piston. its the rubber gaiter that has a tiny hole in it, epsilon93 says its only to keep the dust out, which makes sense, so are we talking about two different parts, i.e an internal seal and the outer rubber gaiter?

cheers

 

[Val101]

quick update -


after bleeding the system there were no leaks, phew! but i need to re-bleed the system the old fashioned way, 1 person on the pedal and one at the wheels, i tried one of those "one man easy bleed" systems from halfords, going to take it back for a refund tomorrow, it was absolute rubbish, so my adivce save ur money and bleed your system the way mechanics do it.

 

[JBob]

I suspected the dealers wouldn't have an overhaul kit for these calipers yet. And that replacement caliper is rather expensive!

Glad it didn't leak once the system was bled through - strange the one-man bleeding kit didn't work as I've always had great success with them, especially when the old 'pump the pedal' method didn't work (rear calipers on Peugeot's seemed particularly difficult to do this way!) but the Saab braking system is a bit complex.

 

[SoFChef]

Bleeding brakes

I'm curious about bleeding the brakes and the ABS system. Did you do the two man method? Did you do anything special before/during/after? IOW did you disengage unplug the ABS pump or control wiring? Did you start at the rear right brakes and work around clockwise?

BTW - I almost had that piston come out on me when I changed my rotors and I was scared [email protected]#7less! Glad you got yours back in.