Brake Question

I noticed something weird with my brakes that I thought was the result of a recent rear-end collision, but may not be (as nothing that was damaged has anything to do with the brakes). Every morning on a cold start, when I'm backing out of my garage and go to apply the brakes, the pedal has a "hard" feel to it; it doesn't seem to want to go down all the way, and the brakes don't grip tightly to stop the car. If I go either backwards or forwards for about 20-30 feet, this just goes away and the brakes grip tightly. Any ideas what's going on here? I'm about to take it to the shop to have them keep it overnight and experience this for themselves. When it recently was brought in following the accident, they checked the brakes and said everything was fine. But, then they only saw the car after it had been run for a bit that day. Thanks.

sounds ****ty, something on the brake pads, or a mis-adjusted self adjuster for the p-brake?

Update: Took the car into my dealer and left it overnight so they could experience what the brakes feel like on start-up. The mechanic said that he experienced what I described about the pedal feel and the brakes not "grabbing" initially, but said that in his view this didn't feel any different than any other 996 on a cold start. They sent a technical inquiry to PCNA for further advice. Anyone have similar experiences to validate what he says? That is, when you first start your car in the morning and are backing out of the garage or driveway, when you apply the brakes for the first few times, does the pedal feel "hard" and like the brakes aren't grabbing, only to go away when you drive a short distance more?? Any help appreciated!

Yup, I have experienced this, goes away after the first application of brake pedal though, and I have only ever noticed it when backing up...... I never gave it much thought...........and my brakes are just fine.......... edit addition. It is an infrequent event and only happens when I am backing up. My driveway is steep, up hill, so I remember that this happens cause it catches me by surprise............... I still do not consider it a problem though....

I have not had this experience. I would notice if I did, 'cause I park in a tight spot with another car behind me. Any lack of brake response would scare the s__t out of me. Anyhow, I'll try to pay attention tomorrow to see if I'm missing something, but I really don't think this happens on my car.

Never had that problem. To me it sounds like a problem with the brake booster. It maybe a computer error with the abs. What your experiencing is a brake booster that is not apply force to the master cylinder. It might just be a delay in the abs computer, I have seen this in old mercedes with abs.

Further update: Dealer replaced a brake line, bled the system, checked for computer faults on the ABS system and otherwise and everything checked out fine. Yet, on a cold start, it still does what I describe. It feels like no power to the brakes on the first couple of applications, then everything's fine. Is it possibly something wrong with the booster? Also, is there any way any of this could have been caused by a rear end collision? I never had this problem until I was hit. The dealer thinks the two are unrelated, but this problem showed up the very next day. Thanks, again!

Something does not sound right. I never noticed any lack of braking ability when first started. Is the brake booster not vacume assisted? Perhaps there is a bad vacume line that is not as apparant when the engine is warmed?

Thanks, Sloth. I think that's the avenue the dealer is pursuing. There is a valve that is on back order from Germany, but the service rep whom I just spoke with said that Porsche is proceeding on the assumption that there is a lag in the system's building of vacuum pressure on start-up.

Further update: Per Porsche US recommendation, the dealer replaced a vacuum valve and the "venturi tube". Still, same basic problem, though. Cold start after sitting overnight, first couple applications of peddle, the brakes seem like the booster isn't kicking in; goes away after I drive about 25-30 feet. I asked whether the booster could be bad, but the service rep said if it was, the problem wouldn't be there only on a cold start. He says they checked out a couple of new cars on the lot and mine is "within spec." They're going to have a regional rep look at my car the next time he's in the area. Any further thoughts about what the problem might be, or whether this is even really a problem?? Thanks, again, for your input!

Like I said, I don't think you have a real problem. This dynamic would be substantially less noticable if you had a stick instead of a Tip. With the tip, the engine pushes the car, especially when you first start it up, even with light brake application. However if you find you have some equipment not working correctly, that will prove educational.... The dealer makes a profit from "warranty work". good luck.

Gretch (and others) - Sorry if this gets double-posted. I thought I replied earlier, but it hasn't shown up. Anyway, thanks again for your thoughts. This whole "issue" might have existed from day one, and the only thing that prompted me to really laser in on it was that I only really noticed it following my rear-ender and. I really don't know. But, I plan to lighten up and just enjoy the ride-- that is, after I take it back in to find out what caused the "Check Engine" light to come on today!!

Do you step on the brake pedal before starting the engine? If so, this will release the vacuum from the booster. Try this with another car with vacuum boosted brakes. Step on the pedal a couple of times with the engine off. You usually get only one or two pumps of the pedal before the vacuum in the booster goes away and the pedal feels exactly as you describe. Then when you start the engine cold, the engine goes to high idle and doesn't create a lot of vacuum initially. You might try blipping the throttle a couple of times before you back to insure you have built up some vacuum in the reservoir. Just a thought...

Hi Roger - The first time I step on the brake is after I've started the engine when I'm putting the car in gear to back out of the garage. When I back out and apply the brakes the very first time, no problem. If I back further, and/or put it in drive and go several feet and brake again, that's when I get the "hard" pedal as if the booster is not kicking in.