Type_LT

The more I drive my car the less impressed I am with the brakes. I'm starting to think my booster is bad or master cylinder. I bled by brakes about 3 months ago and did the best job I could. I'm not sure if I should say the pedal feels "Mushy" because I don't know if it's the normal feel or not. Making a comparison to a brand new car, say a lincoln ls, within the first few mm of pedal travel your getting some decent braking, push a little harder and abs starts kicking in. In the 951 theres a good inch of travel before you start to do any braking and after that it seems like there is an exponential increase in required pedal force to get some hard braking out. I'm just thinking that my 951 should stop with even less pedal force given that it's lighter and has larger diameter discs than the 4,000lb lincoln, perhaps i'm expecting too much? Hopefully someone out there has had a similar experience.

Z-man

Comparing brakes between such different cars is not the best way to determine if your brakes are good. The Lincoln probably has more power assist than the 951 does, due to the average customer the car is marketted for. Don't know if your 951 has ABS or not, but comparing an ABS equipped car with a non-ABS car is also a huge difference.

My suggestion would be to try to compare your brakes with another 951 to determine if there is something wrong with your brakes.

You can always re-bleed the lines, and check your pads for wear. If you still have the wear indicators, that can help determine if there's still enough life in the pads.

You can always upgrade to track pads: that's what I've got on my S2, and there's no problems with braking power for me! (I can practically make my car stand on it's nose!) hehe....

Hope this helps,
-Zoltan.

Type_LT

Z-man: your definately right about the boost level's, hopefully i'll get a change to drive another 951 sometime. I do not have ABS and by pads looked good last time I checked (4,000 mi ago). I'm gonna re-bleed the system this weekend. I had a thought let me know if it's a concern: I bled the brakes when it was about 40F outside, is that an issue?

930 under Restoration

You have definitely got something wrong. My 951's brakes are freakin awesome! The braking pressure starts after only 1/4-3/8ths inch of pedal travel and then the pedal becomes rock hard. I can almost lockup the brakes using my big toe. Your master cylinder might be bad which will tend to keep sucking in air and making the pedal spongy, check the booster and it's vacuum supply as well. If you can, try to reach the bottom of the master where it meets the booster and feel around for leaking fluid.

Just my 2 cents, Dave

mmmbeer

If there is a lot of travel before the brakes start working it is easily fixed with the adjustment on the brake pedal. Just screw on the rod that is connected between the pedal and the master cylinder too adjust the travel of the pedal.

Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>

Type_LT

Thanks 951_in_resto, thats exactly the response I was looking for. I'll check those items and see if I can play with the pedal a bit like mmmbeer suggested.

Danno

Also the type of pads makes a big difference in braking force and feel as well. I usually run $15 AutoZone/PepBoys/Kragen's specials on my 951 for street driving and MetalMaster/Pagid/Hawk pads on the track. With typical street-type driving, there's not much of a difference between these pads, except for the noise of the track pads. But when you try to do maximum-effort multiple-stop braking the street pads simply take a lot more effort and feel 'softer'. I made the mistake of leaving my street pads on at Laguna Seca one time and ended up with leg-cramps from the excessive pedal-effort necessary. I later measured with a bathroom-scale laid-up against a wall that I was exerting around 250lbs of pedal force!

Adam Richman

Type_LT, the first thing you might want to do is turn on the car, pump up the brakes a few times gently and then hold your foot on the brake pedal with constant pressure. If the pedal falls away from you (i.e. goes toward the floor) then I'd look at the master cylinder. If it doesn't, pull the pads off the front and look at the surface. Look for a glazing on the pad - if you see what appears to be glaze, take a sanding block with some emory cloth and LIGHTLY scuff the pad surface. Also, inspect the pads and make sure that there isn't any taper to them as taper can cause longer pedal travel from my experience - no one recommends it but I swap inner to outer after each race (equivalent to couple thousand steet miles??) because they indeed wear and taper differently. If you reassemble and you still see the problem, get a friend to pump the brake while you are on the bleed bottle and look for air in the lines (I'm betting this isn't your issue as you'd have to pump the brakes constantly to get pedal pressure) and make sure they don't go to the floor (put your other foot or board under the brake pedal so you don't go to the floor). I'd check this at all four corners if it came to it btw. If the problem only seems to occur under vibrating circumstances as in, you can pump them up and they work fine now and ten minutes later but if you drive around the block they don't, check for slop in the caliper (slide pins are the only thing I can think of on the 944 N/A brakes, don't know the Turbo calipers). Also, if the pads are worn to roughly the thickness of the backing plate (this would apply to all four corners as well), they will force the caliper piston to over-extend to brake (meaning pump to brake and you'll have them til they back themselves off due to vibration).

Personally, I would not run a "race" pad on the car for the street. All race pads I know of Panther XP 1107, Panther XP 1108, Panther XP 1109, Hawk Blue and I'm thinking the Pagid [give me the color here] and Porterfield R4 as well have operating ranges far in excess of street temperatures. I know from driving home from the track with Blues in the past they suck for a street pad and are far less stop-able as an HP+ or OE pad.

My experience is:
Pumping all the time to get ANY pedal pressure = boiled fluid; change fluid.
Pumping after driving for a while but seems to hold pressure for some intervals = pads too thin or substantial taper (caused by wear for #1 and in my case by caliper slop for #2); change pads or rebuild calipers depending on which case.
At a stoplight for instance, the pedal seems to fall to the floor with constant pressure = bad master cylinder; replace MC.
Braking distance seems comprimized but still have good pedal pressure = glazed pads; scuff pads.
Never had any booster issues but I would assume that foot force should increase as booster fails but pedal distance should yeild the same amount of braking pressure.

Thats just my take on it. Good luck and obviously YMMV.

Type_LT

Thanks Adam, that some great info. I've held the pedal down hard, with engine running, to see if they pedal went to the floor, it stays steady. Immediately after I let off the brake pedal I can hear a slight pop, as if a fluid check valve had instantly reversed direction. I can repeat this pop every time I press and release the pedal. I'll have to check the pads for glazing, I do know there is plenty of pad surface remaining.

bpp944

For what it's worth, my brother had similar issues with his 944S. The solution was to replace the rear calipers (the original ones were frozen) and replace the flexible brake lines with stainless steel ones for good measure.

Adam Richman

[quote]Originally posted by bpp944:
<strong>For what it's worth, my brother had similar issues with his 944S. The solution was to replace the rear calipers (the original ones were frozen) and replace the flexible brake lines with stainless steel ones for good measure.</strong><hr></blockquote>

I am not sure if a sticking caliper would yield the same behavior. When my right rear stuck, the only way I could tell was that one of the pads (cannot recall if it was inner or outer) wore at an alarming rate (especially for a rear pad). The other sign was that I was running a high perf street pad that dusted and squeaked, which I could see the dust and hear the squeak constantly. I do not recall any type of pedal softness associated with this (I guess if you wore down the pad enough, it would however). I would think in the case you describe, the act of flushing the lines might have given back a lot of pedal firmness (as most people don't often change fluid) which would have probably occurred when swapping brake lines. I am not of the mindset that stainless steel braided brake lines are necessary or even useful on a *street car*. Replacement with good OE rubber lines however is a very good idea if they are original IMHO.

Per usual, just my thoughts.

Greg Hammond

FWIW I used to think my 951 had horrible braking, especially in comparison with an earlier 944 NA that I owned of the same year with the same wheels/tires. My problem turned out to be a combination of pad glazing and worn brake rotors. I flattened/scuffed the pads flat, then replaced the rotors all the way around with Sebro cross-drilled (ok, cast-holed) rotors from Vertex, and voila - superior braking!

The car will EASILY lock up all four wheels if I whack on the pedal suddenly at speed. Before, it would require inordinate amounts of pressure on the pedal to stop at speed, and locking up the brakes was virtually impossible.

Greg

Dave

LT, You mentioned that you bled the brakes a few months ago, but didn't say when the brake fluid was last changed. Moisture in the fluid could make the brakes feel a bit "off".

adrial

[quote]Originally posted by Greg Hammond:
<strong>FWIW I used to think my 951 had horrible braking, especially in comparison with an earlier 944 NA that I owned of the same year with the same wheels/tires. My problem turned out to be a combination of pad glazing and worn brake rotors. I flattened/scuffed the pads flat, then replaced the rotors all the way around with Sebro cross-drilled (ok, cast-holed) rotors from Vertex, and voila - superior braking!

The car will EASILY lock up all four wheels if I whack on the pedal suddenly at speed. Before, it would require inordinate amounts of pressure on the pedal to stop at speed, and locking up the brakes was virtually impossible.

Greg</strong><hr></blockquote>

Did your car have a soft pedal/went down too far before engaging before sanding the pads and changing the rotors? Maybe this is my issue...I know my front rotors are worn (I can feel a definite lip on the fronts..and the rears were replaced not long ago)..