r911

$30 thru Pelican.

Any way to get smaller tubes for DIYers?

vytenisb

Update: Shop replaced master cylinder. Brakes fine now.

PS How does Porsche sell new cars with "stiff" seals on the calipers? I don't think customers would buy "the brake pedal will stiffen up in a week."

rnln

Again, Mr. Pete Zim. know the weird problem. An access of 911 technical online.
Peter, anything you don't know?

I had similar problem before, not the same, but similar. When I repalced my brake switches. I asked my wife to do the slowly stepping when I take the switch off.
The pedals of our car are way too hard for her, and I have no one to help at all. After several days of deciding, I asked her for this task anyway. She praticed for longer than I can wait. After all, when the switch is off, she push the pedal quicker than the speed of light. Fluid spread out faster than my... I was frustrated but finally we found that when the switch was off, the pedal got lighter. And I drove the car with very light mooshy brake pedal for several days. After several days, the problem was gone and the pedal was back to normal, hard and solid.
Well, this seem to have nothing to do with the original topic but if you think about it. The act she did is the same as when we use the '2 men' fluid flush method AND if you step too hard and quick on the pedal (Porsche), you might have the same problem as the original topic above.

pjc

I had this problem after a complete refurb of the rear calipers - thought it was the master so replaced that as well (nearly 30 years old so had done good service) but still had a soft pedal - problem was that the caliper pistons were pushed too far into the bore, every time I applied pressure the pistons moved forward onto the pad but on releasing the pedal they were being 'sucked' right back to where they started because the seal was not seated in the correct position. Solution was to pump up pedal and block between the pedal and seat frame and leave for a few days - this enabled the seals to settle into the correct position.

PJC

Peter Zimmermann

rnln: LOL! There is a lot that I don't know! One thing that I do know is that if any of you out there are going to replace your master cylinder switches DO NOT have someone push the pedal down. Be quick, do one switch at a time start to finish, and you'll only lose a small amount of fluid and your brakes won't be affected (no bleeding necessary).

vy: The calipers designated for a new car are assembled by the manufacturer (Brembo, etc.). They are packed in boxes and sent to the factory. The piston seals are settling in this entire time. The factory installs them on a new car, along with new pads and rotors, and bleeds the system. The combination of new parts minimizes the piston movement necessary to press the pads tight against the rotors. Then the car is tested over a pre-determined course of (approx.) 30 miles. Then the car is transported to the dock, loaded on a boat and shipped to a distant port of entry. The car then receives a PDI, and is shipped to a destination dealership, all the while those piston o-rings (which have a square, not round, cross-section, by the way) are getting happy.
Pete

redtdi96

put a 2x4 under pedal so you don't go too low in the bleed process or use a miti-vac vacuum and maybe / or a dangerous pressure bleeder.