Brake Pad Replacement, Please Help

[Fassi]

I'm in the process of replacing my rear brake pads and I've experiencing some problems. One of the pistons moved easily to the side to allow the installation of the new pad. However, with the other one, there is nothing doing. I can't get it to move far enough to slide the other side into place. I've tried wood and a channel lock, but it seems frozen at that spot. Also, I've destroyed the sensor when I forced it out, but I'm not sure if that's typical. Anyway, the car is jacked up right now and I would appreciate any suggestions how to get the new pads in. If it matters, they are metal master pads. Please help.

Thanks.

[kepperly]

sounds like you have the piston" cocked "in the bore.
try a small pice of sheet metal or a file to use when compressing with the channel locks. Compress each side until it goes in ortherwise pull the caliper and take it apart and rebuild that
corner.

keith-87 slant nose cabriolet wide body carrera

[Fassi]

Once side compresses with no problem. I finally gave up on the other end and put the old ones back in for now. Tomorrow I'm thinking of loosening the caliper a bit to give me enough clearance to insert the pad. I only need like 2mm. Is this advisable?

[avi8torny]

Originally posted by Fassi
Once side compresses with no problem. I finally gave up on the other end and put the old ones back in for now. Tomorrow I'm thinking of loosening the caliper a bit to give me enough clearance to insert the pad. I only need like 2mm. Is this advisable?

Not advisable if one if your pistons are stuck in the bore. What did the pad look like that come from that side? Not worn? You need to free up that piston some how and make it right. Or you are going to just ruin a set of pads.

[Fassi]

Hi,

Both sides look equally worn. The piston is not stuck in that position. It will move out towards the pad when you depress the brake pedal. I just can't get it to move back far enough to insert the pad. As I said I just need a little more room. In that case should I just loosen up the caliper a bit?

[RoninLB]

Originally posted by kepperly



sounds like you have the piston" cocked "in the bore.

[pwd72s]

Fassi, instead of channel locks, which might scratch the piston, bringing eventual corrosion, use your old pads to try to push the piston back...pry bar or large screwdriver tip between the old pad & the disc... this tip given to my by a long time mechanic, and it's always worked for me so far...just apply gradual force...you'll feel the piston begin to go back in...if it's not cocked, that is. Try to pry on the pad so the force is just above the piston.

[widebody911]

Did you open the bleeder valve?

[pwd72s]

Originally posted by widebody911
Did you open the bleeder valve?

[911pcars]

Shouldn't have to open the bleeder valve as fluid will back up into the reservoir and overflow into the trunk.

There's a chance the piston seal will tear as you push it back into the caliper bore. Might be time to rebuild the calipers. Parts cost is minor. Brakes are important.

Sherwood Lee
http://members.rennlist.org/911pcars

[widebody911]

A while back, I was putting in new pads the day before a track day (ie in a hurry). I had the pads out (yes, both), and was pushing one piston back. I didn't have the bleeder open, so when the piston moved back, both pistons on the opposite side popped all the way out of their bores and smacked up against the rotor! I tried to push them back in by wedging a screwdriver into the small notch in them. This is how I learned how soft and fragile 930 brake pistons are. I cocked one of them in the bore - and how! I ended up having to remove the rotor and caliper (always a treat with the 930 setup; I ended up inventing my own wrench for this job), removing the piston, filing down a ridge I'd created on it, and then polishing it back down. Installation is the reverse of these steps.

What I learned:

• don't remove both pads at the same time
• if you do have to remove both pads, put a block of wood or something in place of the pad
• open the bleeder valve
• don't force anything (I broke a screwdriver trying to push them back in
• one half of the handle of a small pair of pliers, with the end inserted into the hole in the piston, works great for pushing pads back, as it puts the force in the center of the piston, rather than the edge

Long story short, caution is the word of the day. ("Legs" is tomorrow's word - spread the word). Opening the bleeder will help the piston move back into the bore (as long as it's not cocked up already).

[Fassi]

Originally posted by pwd72s
Fassi, instead of channel locks, which might scratch the piston, bringing eventual corrosion, use your old pads to try to push the piston back...pry bar or large screwdriver tip between the old pad & the disc... this tip given to my by a long time mechanic, and it's always worked for me so far...just apply gradual force...you'll feel the piston begin to go back in...if it's not cocked, that is. Try to pry on the pad so the force is just above the piston.

Your mechanic friend's trick did the trick Thanks for the tip; and thanks to everyone that responded. My question now is what do I do about the broken sensor on the one side? Also, the front pads looked ok, so I didn't replace them. However, I'm not sure if they are of the same composition as the rears (metal masters). Could this pose some problems? Thanks.

[ZCAT3]

Fassi - I am not near the expert as some of those who have posted here, but on the sensors I would only worry about them if you rely on them to alert you of brake wear. If you are like most of us, you will know when your pads need to be replaced long before the sensors are triggered. If so, I would just leave them unplugged and disable them by putting a jumper wire in them to complete the circuit and keep your brake light off.

On the pads, if the fronts look fine then you should not need to replace them. My uinderstanding is that you always replace pads in pairs by axle. The fronts always wear faster than the rears, so you would be tossing a lot of good pads if you always did all four wheels.