chrisp

I'm an air cooled guy but I remember from somewhere that part of the 944 bleed sequence includes the clutch (shared fluid).

mhm993

Replace the fluid. Check for worn out pads--long pedal feels feels similar to soft brake. Then suspect master cylinder.

chrisp

One way to tell a bad master is push on the brake pedal (with the car running). If it slowly moves to the floor it's a bad master.

OriginalSterm

Can a master cylinder be bad without leaking?

cviles

Define "leaking". You'll most likely not see fluid seeping from the cylinder itself. What fails is a diaphragm inside the cylinder which then allows fluid to pass around the pistons inside and back into the reservoirs within the cylinder.

If the pedal isn't sinking under vacuum assist (engine running) and multiple attempts to bleed the brakes haven't helped, my first suspicion is air in the master cylinder. If the pedal sinks under constant pressure with the vacuum assist available, I'd suspect a bad master cylinder.

Professor Helmüt Tester

Yes.

OriginalSterm

pedal does not sink to the floor when the car is running. still have not bled the brakes, waiting for an assistant on that part.

pulled the pads off to measure for taper. found about 3mm max wear on the front pads, 1.5mm max on the rears. did happen to find almost 0.5mm taper on the fronts (only outer pads on both r/l) and about 0.2mm taper on the rears (again, outers only). is this excessive taper? i replaced the pads with a new set, but the taper worries me. i did happen to feel a slight chuck on the fronts, which would indicate i probably need to replace the bearings for the 3rd time in year. I put about 1/8 turn adjustment on the collar in the meantime.

SundayDriver

Here are a couple of more ideas - more obscure than what has been offered but if the conventional ideas do not get it taken care of then you can consider these...

I have had bleeder seats leak. When you bleed a lot, the needle/seat will get deformed and leak. Usually when this happens to me, it sucks in air but there is no visible fluid leak. You would have air when you bleed (but see next idea, below).

How do you bleed the brakes? It is quite possible for air to stick inside the caliper and not bleed out. Tap the calipers with a dead blow hammer or soft faced mallet before you bleed to knock loose any trapped air.

OriginalSterm

I do not use a mallet to bleed my brakes, but it's worth a shot to see if that helps. I have noticed a slight drop in the fluid level between sessions, I have attributed this to overfilling the reservoir since I have not found a signs of a leak even under pressure.

chrisp

did we ever answer the clutch/brake relationship question?

OriginalSterm

not yet, i'm waiting for someone to give me a hand with bleeding the brakes/clutch.

shiners780

Greg, if you need a helping hand let me know. I've got a Motive power bleeder I can bring along. PM me if interested, I'm free some evenings this week.

OriginalSterm

UPDATE

Bleeding the clutch tonight and have not found any signs of air. However, the pedal is now digital. It's either up, or all the way down. It'll stay on the floor too, seems like it might be a bad slave cylinder. Would this have caused my issues on the track?

2nd UPDATE

Bled the clutch even more, this time with the rear of the car even higher. Lots more pumping and I finally got a ton of air out of the slave. Hopefully this in addition to new brake pads will fix the soft pedal and poor braking. DE this weekend!

3rd and final UPDATE

Brakes felt great with proper bleeding and new pads!