How to change brake pads and delete wear sensor

AVI_8 · Jul 9, 2010

My wear sensors have been illuminating intermitently, though the pads need changed, they were doing it long before that, seemingly it's a common fault, I'm going to do away with them altogether.

My plan is to upgrade the brakes on my car next year, it's a Carrera 2, which has the smaller 2 piston rear calipers, hopefully I'll be able to source a pair of larger front calipers, then use the current 4 piston front ones on the rear after a small modification.

I'll replace the disks then with uprated ones.

For now though I'm just going to replace the pads all round, back ones first, firstly remove the locking pins, one from each of the pad mounting bars.

Next use a punch to gently tap the 2 securing pins inwards.

My punch tapered out, so I sacrificed a small diamiter screwdriver to push them far enough back until they were loose enough to pull out.

Once both of the pins are removed, use a large screwdriver to gently lever out the pads, give the area, a good clean with brake cleaner, then you need to push in the pistons, I use 2 large flat blade screwdrivers to do this, use the disc to lever against (it should only require a small amount of pressure (take the lid off the brake fluid reservoir first) push the piston right back in using even pressure at opposite ends of the piston, I use a small piece of wood, to stop the other piston from being squeezed out whilst doing this, or you could use the old pad.

put some copper grease on the sides of the new pads where they seat, and on the back face where the piston will have contact.

It looks like I've used loads on the above pic, the flash has exagerated it, there was only a small smear

Clean the pins with some sandpaper or something abrasive, then smear some copper grease on them.

Before and after here

Insert the new pads, fit the metal bracket unter the pin, slide in the pins with the hole for the locking pins pointing outwards, tap them home gently, and dont forget to fit the small locking pins. Job done

AVI_8 · Jul 9, 2010

I'll get round to doing the fronts, if it ever stops raining, my garage is too narrow to work on the car so it's outside when I work on it.

Meanwhile, I'll show you how I bypassed the wear sensor, The sensor consists of 2 small diameter wires running through a sensor on the pads, when the pads wear down the sensor wire is broken, cutting the electrical circuit and activating the warning lamp on your dash.

Follow the wire from your pads (no not the ABS sensor!!) You'll see that it goes to a small plastic cylinder, where it's plugged into, the ABS sensor is plugged into the same area, open the catch on the cylinder, remove the plug and cut the wire around 5 inches from the plug, the wires are surrounded by a plastic tubing, pull that off for now. you'll be left with this:

Cut another 4 or 5 centimetres off the wires (you'll be sliding them back into the plastic shield that you pulled off and want the shield longer as it will provide the weather protection and keep the bridged area dry.

Once thats done carefully expose around an inch of the wires, I used a stanley knife, watch the fingers!

Twist the 2 wires together, solder (if you have a soldering iron) it's not really necessary as long as the connection is good and it will be protected from the elements, fold the connection back over the wires

Tape up the bridged connection tightly with electrical tape, and push the wires back into the black plastic sleeve that you took off earlier, it'll be a few inches longer than the wire.

Fold it up, and tightly secure with a cable tie, plug in and repeat for the other sensors

That should keep the connection dry, If you have a heat gun and shrinking tubing, (whatever it's called) you might want to do that instead

Plug the sensor back in and forget about it now, no more false warnings.

It obviously goes without saying that you'll have to check your pads from time to time now!!!

Steve Brookes · Jul 9, 2010

Hi Logan, regarding your intentions on upgrading the brakes, many have the idea of putting the fronts on the back. However, even with turbo size brakes on the front the pistons in the 964 fronts are too big for the rear which will result in too much rear bias.

The tried and tested route is to put big reds or blacks on the front along with the appropriate rotors and caliper adapters and to put 993 C2 rear calipers on the rear. The latter fit straight on standard 964 rear rotors but it's advisable to change the pressure proportioning valve and to also upgrade the master cylinder (993 one I think). I haven't done this myself but you'll find write ups from others on here if you do a search on brakes.

What I have done is upgrade my rear 2 pots to the 4 pots found on C4s and later C2s. I've found this a major improvement (especially with Pagid pads fitted for trackdays). It can be difficult to find used C4 or late C2 four pot rears however the same rear caliper is also found on the 928 S4, 944 turbo, 968 and 993 C4. You just have to swap the bleeds with the feeds on the non 911 calipers to suit the different mounting (i.e. ours go on the leading edge of the rotor rather than the trailing edge). You also need to upgrade the proportioning valve to the 55 bar version to get the best out of the 4 pot rears. You'll find a write up on my upgrade at the link below:

http://964uk.com/html/How-tos%20-%20Brakes.htm

iangray100 · Jul 10, 2010

I've also upgrade from 2 pot rears to 4 pot rears ..its a major inprovement and also the rear pads last longer as the rear with 2 pots would only do 2:1 to the front pads. As Steve says make sure you upgrade the proportioning valve in the front boot when you go to 4 pot rears. Also to be honest upgrading the front from the STD 4 pot in my eyes isn't worth it as even on track days I haven't seen any fading.
The only front upgrade I did was to fit two new calipers ( new off ebay USA a while ago..bargain!!) as the old ones were sticking and I fitted a full set of Stainless covered flex pipes was the only other update . I run the Textar pads all round . If you go too far in brake upgrade your insurance wont like you.....been there done that with a Impreza and fitting a huge Brembo upgrade ..insurance hated it !!!!

AVI_8 · Jul 10, 2010

Hi Guys, thanks for your reply, I was under the impression that the 4 pot rears on the C4 were the same as the fronts......obviously not, yes it's the big reds I'll be looking out for, along with the calipers you mentioned for the rear, I knew about the proportioning valve, will keep an eye on the breakers nearer the time and get a pair which will be reconditioned before fitting.

Steve Brookes · Jul 12, 2010

I think you'll find the link below useful when deciding on your brake upgrade:

Porsche brake caliper chart

You'll see that the 964s that came with big brakes as standard (turbo and RS) use 34/30 pistons at the rear while our standard fronts have 40/36 pistons...hence why they would be too big on the back even with big reds on the front.