fp944s2

Hi - anyone got any ideas on 'spongy' brake pedal on 86 951 ? Have put in new pads and SRF brake fluid - brakes now work and little or no fade on the track, but of all the 944s I've owned this one has a really soft pedal feel before anything happens - causes a slight lack of confidence on the track.

IceShark

How old are the flexible rubber hoses between the hard line and the caliper? They can cause that when they start to crap out. But if you are spending $70 US a liter for SRF and have owned other 944s that you are tracking, I assume you have that covered as well as any air hung up somewhere obscure.

I wasn't paying much attention, but I read a note from someone in the UK who was saying that a newer high end fluid, I think it was SRF, was more compressible than traditional stuff. He was having the soft pedal feel and when he went back to his prior fluid the problem went away. Let us know what happens if you try going back.

Ahmet

The 4-piston aluminum calipers on the turbo can really get out of shape, if old fluid is left in them, seals get brittle, pistons get scored, etc. -->spongy pedal.

The safest thing to do would be to replace the rubber lines with braided stainless steel, get good pads (that don't compress as much as stock, makes a huge differance in pedal feel), flush fluid, and you could go on to change the master cylinder.
Ahmet

belz

New Pads - New Fluid ... sounds to me like you have air in the lines. It doesn't take much to make the "pedal spongy". Have you checked your master cylinder?

Dave951M

I had a similar problem with mine. I could bleed it, but several days later, the spongy pedal was back. I wound up replacing the m/c and from there found a small leak in my proportioning valve, not enough to be obvious, just enough to intake air ever so slightly. Spongy pedal was returning about every two weeks. Replaced prop valve and now all is in order. My hoses were ok. I will replace them with braided steel when I do a full brake job. Right now there are other priorities.

A couple of points- the new brake hoses will help. I don't generally trust them on cars this old. Replace them as soon as possible. Change to Pagid Orange pads (my next step). Completely flush the lines and put in new fluid. 1.2G is spot on with his comment about that. When I started bleeding mine to diagnose the problem, it ran with the consistency and viscosity of cold molassas. I'm currently using Castrol LMA brake fluid. I know several people using this even in race cars with good results. Check out the specs. A dumb question- did you bleed both sides of each caliper and in what order? What order did you bleed the wheels? This could have a huge impact on bleeding brakes. There's no dark art to fixing brakes, just take a methodical approach.

Ahmet

Dave, I go by over1g, instead of 1.2gees now...

BTW, what do you think of the Castrol brake fluid? I've been using ATE Super blue racing, it fades ever so sligtly at the track, with pagid orange pads (mine's an NA though). And if you remember, how much for a bottle?
Ahmet

Ahmet

Also just realized, both of our ratings have gone down, since the post about the 928 vs. 911 vs. 944turbo. Actually, us among with a good # of other people... I don't see where you (or any others, including myself) have given bad advice, or weren't polite? Weird, what do you think?
Ahmet

keith

May want to check your booster? I have the same situation in my 951 and am trying to evaluate my booster's performance... I have what I consider to be excessive travel before the brakes engage (at the pedal) brakes work fine otherwise.

If you find a solution to your problem, please let me know! Thanks.

Dave951M

Thus far, I've had no fade problems with the LMA, but I haven't tracked it yet. I have driven with it in a "spirited" manner on some undisclosed mountain roads with heavy braking often and no fade that I've seen. The next brake work for me will be to switch to Pagid Orange pads in August. Like I said earlier, I based my change on advice from people I know who have it in race cars with no fading. Price is relatively cheap (oops, inexpensive) about $2 per pint I think. It is also supposed to be compatible with any other fluid although I wouldn't want to be the guinea pig on that experiment so I played it safe and flushed the system. I guess I am currently satisfied with it.

As for the rating thing, that seems like a popularity thing since there are die hards in each camp. Take the 928 vs. 911 vs. 944turbo thread for example. The response from the 928 guy was borderline bbs rage for the first few posts. In his first post it seemed like he was on set, go from the beginning. I felt it was a rather vehement response, totally ignoring the initial question. Note that no one impunged the reputation of the 928 or the 911, just stated known public information. If some folks can't live with it, well.. too bad, in God we trust, all others bring data. I hold no malice nor disregard for owners of these models and each model discussed is a fine piece of German engineering, just different. I hope they feel the same about me for having a 951 pocket rocket. There are objective realities to owning each model. No, I didn't see that either you or I was either unfactual or impolite to anyone. I think what whacked me was recommending the kid get a truck. Some on this board would consider that smacking of heresy, but I still maintain the truck is the best objective choice, all factors considered in a non-emotional manner. In addition, some of the people doing the rating of other members on this board have never turned a wrench, puked an engine, thrown a rod, bent a valve, considered the finer points of volumetric efficiency, the effect of port and polish, the effects of cylinder hone patterns, the hp effects of lift/duration, and probably don't even know what align boring is. Why should I be concerned about their rating me? In searches I've done in the archives, I've run across some less than accurate information. There are a number of people I consider to be sound sources, you are one as is Keith and Garrity. There are a number of others as well. The converse is also true but in the interest of peace and tranquility, I won't go there but I think you may well know what I mean. These ratings are anonymous, therefore suspect. Don't lose any sleep over it. Your knowledge of these cars is nearly encylopeadic and your autox experience more valuable than any "book learnin". So, is it weird? Nope, irrelevant. Some don't like the PCA and think they're a bunch of old fogies. When you press these guys, they either haven't been to an event, only went to one and didn't like that one, or have taken the judgment of someone else at face value. From that limited contact, they judge the whole organization. I maintain you get out what you put in. Tying in to the idea at hand, again, why should I be concerned with what someone thinks about me (or you) who hasn't been there, done that, or is so married to one idea they can't see the ocean for the waves. As for me, I'll continue on, learning and passing on what I know to be true from experience to others who want to benefit. That's why I like these boards.

Peace to all, couldn't care less about popularity when I know I'm right. Don't let it bother you Ahmet.

Ahmet

I've been happy with ATE for over two years now, but I'd like to try others just to know first hand how they compare. If you happen to track the car, after the pagids, please let me know how you feel about them.

You do have a good point about who's rating who, but it's too bad that now I appear to be giving wrong advice, or being impolite.

I won't change though, some things need to be told the way they are, undilluted...
Ahmet

Dave951M

Once I get all of the mechanical issues under control to my satisfaction and get stone cold familiar with the noises and motions of this car, it'll be track time. At this rate, that would be early next year. In the meantime, some autox will be in order to reveal any other hidden problem areas. Not that my 951 is a problem child, I just would be uncomfortable tracking it at the moment. Pagids will be on it when I do.

From most of the comments I see on this and other bbs' there are a lot of enthusiasts out there, sadly, not many are taking the time to really learn the limits and capabilities of their cars. I mean by this that it would appear that while many cars are maintained to the point of being safe on the street, the owners don't have the experience or knowledge to know when it has become unsafe at the 8-9/10s part of the envelope. Case in point, a friend of mine's son can recite detailed stats about the stereo in his car, but doesn't have a clue about torque steer and timing belts. IMHO a sad state of affairs from one who claims to be an enthusiast. So forget even mentioning hp/wt ratios and gearing. Enough rambling on this point. I might lose more stars

Ahmet

I couldn't agree more with your comment there.

I think most new cars don't let (inexperienced) the driver know just how close the car is to it's limits. People get used to driving 9/10ths or so, and when they step over 10/10ths, it's a big shock... I've been a wuss about riding in other people's cars now, since I was involved in a pretty serious accident recently (as a passanger).

That reminds me, I think I'll be in the market for a new car, in the 15k to 20k bracket soon, but I should probably start another tread for that somewhere else, look for it!

I can see your approach, and I think it's a good idea to track/auto-x something that's relatively close to stock, but having done it the only thing I can tell you is, I'd drive anything that will not fall apart, on track. Anything halfway decent, it's probably the most fun I've ever had.

PS: Check your rating, it just might've gone up
Ahmet