Replacing Rear Brake Pads-Need Advice

Use the proper brake pad-spreader clamp or
crack the bleed screw to relieve pressure, then bleed the brakes.

 

Remove aluminum plugs on back of calipers using an allen wrench. Use a smaller allen wrench on inner screw to retract pistons. Helps to have a pry bar help the pistons back in. Install pads. Pump brakes until pads touch then bleed brakes. Done. Don't have to loosen bleed screws to retract pistons. Somebody posted details and how to make new aluminum plugs after you have stripped the original hex. Best bet is to just use a hacksaw and put a screwdriver slot in them. Don't leave them off even though they are only dust covers.

John

 

Here's a figure (246 is the same as 308 for this) showing the threaded dust cover that must be removed in order to access the female hex driven pinion gear that does the actual mechanical retraction of the inner pad as John mentioned (you can't just push the piston back in even if you open the line to let fluid out).

IIRC, the material of the stock 308 dust cover plug is magnetic so it's not Aluminum (unless 246 are different), but it's not any stronger than Aluminum, so John's comments still apply well (high likelyhood it could already be damaged or be tough to get out without damaging/modifying). If you need new ones, try a Porsche aftermarket supplier (914 use the same type of rear caliper), and they have developed stainless steel ones with a 10mm external hex head drive to solve this problem (at reasonable cost ) -- 2nd jpeg is the aftermarket version from Performance Parts IIRC.
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Bill - now that you have banged on the Allen screw on the inboard side of the caliper, you really did not have to do it.

In theory (say no more) you should be able to remove the old pads without difficulty by pulling on the open end towards the rear, or tapping with a drift from the forward aspect. They should slide out with only minimal difficulty introduced by dust and rust.

Gently but firmly spreading the pistons with a large screw driver or small curved-end bar should induce the pistons to retract to their pre-set position, which should allow room for the new pads to slide in (after cleaning the caliper shelves on which the new pads sit).

What is being referred to as the "plug" provides access to the handbrake adjustment, which, if you have turned the inner Allen screw, will need to be readjusted. This adjustment simply moves the piston towards the rotor and acts as a stop, preventing the piston from retracting too much. There is only an adjustment on the inboard side. There is no adjustment on the outboard side. Once you get the new pads in, reconnect your handbrake. Engage the handle up and down a few times to seat the cable and mechanism. Dis-engage (release) the handbrake. Turn the wheel. It should not drag. Now turn the adjustment screw until the wheel no longer turns freely. Back out 1/4 or 1/2 turn. Retry the handbrake. Simply repeat this procedure until you feel that you have the wheel turning freely without the handbrake engaged, and that the handbrake lever does not have to be pulled to high to completely engage the brake.

Have fun.

Jim S.

 

Would anyone know how to do the same thing on a 328 ?

Thanks,
Rui

 

Sorry Jim. the above is not correct for my '72 GT and I don't think it is correct for any Ferrari or Porsche that uses the same calipers. There is no connection between the auto adjuster screw and the handbrake other than than they both control movement of the pads. You can not retract the pads more than about 0.01" without turning the inner screw. That will allow the pistons to move 1/4" if necesary. As soon as you put hydraulic pressure on the caliper the auto adjuster moves in and will not move back out. Same on both inner and outer halves of caliper. Hand brake is not affected when new pads are installed.

John