Andial951

Recently had a clutch replacement and afterward the brakes barely worked. Informed the mechanic and he said he found the master cycliner hose had a bad connection (thus vacuum leak I think).....he fixed it and went on his way.

BUT...the brakes were still really bad so he recommended I bleed them. Did the first bleed and the lines were full of old fluid with all kinds of crude in it. I did clean out the reservoir (got a bunch of grit and crap out) and thoroughly bled the lines until I could see clear blue fluid coming out. Took the car for a drive but the brakes were still bad. Mechanic recommended I do another bleed so I finally got to it today and a little debris and some bubbles did come out. Took the car for a drive and really worked the brakes making sudden stops.....pumping them....etc. The brakes are much better now but they just dont feel right.....not confidence inspiring.

Any suggestions on how to improve them or what might be the problem?

EdC

What is the problem? They feel spongy, squeak, soft, fade, pull, long stop, etc. I think you will need to better describe what concerns you about the brakes.

Ski

Check the little venturi tube under the intake. Jim was hearing something the other day and his brakes was spongy, his front pc popped out. He wiggled it back in, sound was gone and the brakes were back - then ordered the venturi delete kit from Lindsey.

Gator_86_951

<---- Also happened to this jerk

Andial951

I can describe the brakes pedal feel as been hard but having to push much harder than I shoudl to get good stopping power. There is no spongyness, fading or squeking. Takes longer to stop than usual. Veryhard to lock the brakes.....I have to stomp on them with all my weight.

autox951

I have the exact problem with mine, it stops but hard pedal prevents full lock up. I was thinking my power brake booster maybe bad.

Ski

Are you using a power bleeder?

ebs

I'm having similar issues, my brakes are a bit spongy, and the pedal effort before they bite seems to be further down than when I bought car 4 years ago. All the hoses are on, the brakes have just been bled, and the calipers, rotors, pads etc are all in good condition. I think the master cylinder may be getting old (20 years) and tired (approaching 65000 miles). My mechanic thinks its all normal, but my '84 928 stops better, and the brakes on my '77 Mazda 323 are more confidence inspiring. Any thoughts???

35thSLP

When I had this problem it was a vacuum leak in the brake line circuit. if your car is a 951 check the plastic "T" on the firewall in the brake booster vacuum hose. also check the make sure the check valve going to the climate control is not leaking. Check the check valve at the master cylinder and the grommet on the master cylinder. If the only problem is a really hard pedal sounds like no power assist and that is most likely a vacuum leak.

Andial951

35thSLP,

I checked the "T" on the firewall and that seems ok. Where is the check valve going to the climate control? Is the grommet you mentioned the small round connection on the wall of the master cyclinder where the tubing come out. This grommet moves around...is it supposed to?....but it doesnt come off. Is the tube going into the grommet supposed to be secure with no movement?

Andial951

yes I used the Power Bleeder........work great.

Andial951

I only have 72,000 miles on my 951.....do the master cyclinders go bad after such low mileage? Is there a way to test the Master Cyclinder?

Ian Carr

I have the same problem. I purchased a new master cylinder and installed it. It still seems like it does not brake as good as it should. I am going to try a caliper rebuild next and see whats up. I even have SS brake lines and it still feels like theres brake fluid or some thing on the rotor so when im trying to slow down its either a crappy slow down or the wheels lock up. I hope some one finds out what this problem is cause i want my real porsche brakes back

TheRealLefty

951 brakes should never feel anything but great, right

The vacuum rigging for the KLR valve venturi and the blue/black check valve to the HVAC vacuum canister are indeed likely culprits. I've had to seperate the issue of pedal feel from stopping power in my thinking. My NA racer has super linear pedal and very reassuring hard bottom with carbon kevlar pads and regular flushes with ATE Blue/Gold. My 951S has eye buldging stopping grip with the 33/5 bias but the pedal has never had the reassuring "buttom of the pedal" feel that my NA delivers.

Dilberto

My booster's pedal adjustment nut got frozen, and I have a wooden feeling real stiff. I wish I knew what a 951 really stops like.

Zach
"Dedicated to the Porsche that saved the Marque"