Better way to rebuild calipers

[Jubbie]

So,

As I resurrect my 74 911 that has sat dormant since 1987, I got into the standard caliper rebuild. In past, my Father and I have used the air pressure method to pop the pistons out. But, if the calipers are really stuck, the term pop is an extreme understatement. My Dad has used ear muffs from his gun cabinet and always enjoyed the spray of brake fluid when the pistons came out with a BANG.

We have seen where folks have used grease guns (which is great to find a use for an old tool) but, we were not looking forward to cleaning the grease out of the caliper when you get the pistons out.

So, I took an old grease gun and cleaned it out. I took the grease fitting off of the end of the hose and the threaded fitting screws right into the calipers. I mounted the gun in the vice and poured brake fluid in the tube. Then I pumped on the grease gun and waited for the pistons to move. To keep both pistons even, I alternated using a clamp on each side. Then when I couldn't get the clamp in there anymore, I just pumped until one piston got pushed out (notice lack of the word pop). The other piston was far enough out to be tapped or wrenched out. I was able to do all four calipers in about 30 minutes.

Next is the true test when my Father rebuilds the brake system on his 64' 356SC which has been down since 85'.



Photo is actually a posed shot. It was not that clean when I actually did it.

[cvfncrew]

Cool.
Thanks for the info.

[Neilk]

I just use the car's hydraulic system with C-clamps. Once you have one caliper done, you can close the brake line with a S caliper brake bleed valve. They seal the system perfectly.

[buster73]

I use the pressure side of my Mityvac vacuum bleeder and some metal spacers to make sure both pistons come out at the same time. Works great most of the time and without risk of damaging the calipers or pistons.

If the pistons are stuck, you might use a can of computer duster (pressurized air with some blowing agent). In this case you have to be very careful and make sure the pistons come out slow and in a controlled manner (using spacers or clamps) and to reduce the pressure before they come out completely. If you just let them pop out, they can be damaged and you can also hurt yourself. Not to mention the brake flluid flying around in the garage. Certainly not the best method (I confess), but works even with minimal workshop equipment (or for emergency repairs on the race track). Just be very careful and wear safety glasses.