Brake Feel

I have a 996.1 in which the brakes feel rather weak. The car does stop, but in order to do so you really need to press the brake pedal hard. I recently had the brake fluid flushed, and installed new pads and discs. I was hoping that would fix the issue but it has had almost no effect. I recently drove a 986.1 and the pedal feel and braking in that was significantly better. Any ideas on what could be causing it?

Quotes source post: 18983400

It could be the brake booster or the pads. If the booster isn�t helping apply braking pressure, it will take a lot more effort. Hard pads can have a similar effect.

If you glazed your pads then you would get problem. There is a procedure for bedding in new pads. Someone here might chime in.

Brake pads vary greatly in terms of required pedal pressure and gripping force. they are always a compromise with rotor wear as well as a consideration. I have Ferodo DS2500s. They have great pedal hardness and excellent stopping force and heat resistance, but at the likely expense of shorter rotor life. If you replaced with OEM pads and rotors, you should have the same feel as your previous pads. As suggested above, I would suggest that you have some pad glazing and/or disc break-in issues.

Out of curiosity, what rotors and pads did you use? You may need to bed in your new brakes. There is also an outside chance that you may have a caliper or two that needs to be rebuilt. With the cars and calipers being 20+ years old, it's not uncommon. Your indy can take a look and tell you. You Tube

In your case you can put the above hints about bedding in new pads on the back burner. With what you've done you would have felt a difference at the first braking you did with them. Since you don't, the cause lies in something you haven't changed (yet): the brake booster as mentioned before and/or the calipers. I bet the pistons on the outside of each front calipers are stuck and you only brake with the inner pad. Overhaul the front calipers and try again. Repeat at the rear.

Thank you everyone for sharing your thoughts. The pads are OEM, haven't used them much so far as I was conscious of not wanting to glaze them. Hoping that is the brake booster rather than having to overhaul the calipers too Thanks again

Quotes source post: 18984046

Since you haven't used them much, you may want to consider going thru the bedding process if you want to facilitate it quicker. Glazing typically comes from high speed braking on the track. In most cases, just driving around town with plenty of starts or stops will bed them. Especially since it looked like you replaced both pads and disc's at the same time. Bedding becomes more important if you are just replacing pads or just rotors because you have uneven ridges that develop and depending on what you replace will make it important to get the old part to wear into the new part. This is why when going to a dealer for a brake change, they replace both pads and rotors at the same time. It's easier for new pads and rotors to match up quicker than replacing just pads and keeping the old rotors. . As a side note, there hasn't been a time over the past 21 years when I replaced my rotors, or just pads, or both at the same time that it didn't take a little bit of braking to get the brakes "grippy" on my 996. Talk to your Porsche Indy and see what they say.

It's curious that the problem appears just after replacing the pads and rotors. Do I have that correct? It could be a booster, but I am inclined to asked what suddenly changed and having serviced the brakes and flushed fluid (replaced or simply bled?) at the same time would raise a flag for me.

OP, check this thread out https://rennlist.com/forums/996-foru...ormance-1.html

Sure, it could be alot of things. But to your question on new rotors and pads, as I write this, I just received a new set of rear Brembo rotors 345x28. Still waiting on fronts. Pulled them out of the box and they are smooth and slippery as you run your hand over them. All I need to do is put them on and have a little fun with braking to transform them. As the abrasion occurs, they get grippier. I'll take a picture and post. Used Brembo New Brembo with smooth finish. New Brembo with smooth finish.

... You Tube

Quotes source post: 18984244

Actually the brakes always felt weak. I had the brake fluid flushed and replaced the pads and rotors hoping for an improvement, but so far they don't feel any different. I would characterize it as the brakes just feeling dead, like there is no bite

I would watch the bedding in video and go find yourself a big parking lot that you can get some abrasion on your rotors from the brake pads. You will get more brake grip after going thru the process and it may help and or confirm its more than being new oem pads and rotors. Besides, it doesnt cost you anything. You can also eliminate boiled brake fluid since it was just changed. I would just look for leaking brake fluid as a step. Then the next step is talk to your indy to see what they suggest as next steps with other parts. One thing to consider, depending on what you drove before the 996 and it's braking feel, will influence your opinions on oem 996 braking feel. It may be as simple as getting some more aggressive brake pads which will give you more grip immediately. But will also give you more brake dust. It's a tradeoff.

Quotes source post: 18986487

Then it must be the booster. I have driven several different vehicles of the same exact year and model and sometimes the brakes feel different from car to car - one feels super grabby and the other requires a lot more force from your foot.

Thanks for the thoughts and suggestions. I'll chase up the brake booster as the most likely candidate

Don't forget to assure yourself that none of the pistons in the calipers are sticking as I mentioned earlier.

Quotes source post: 18989176

There�s probably an east vacuum test for the booster to determine if it�s working.

Quotes source post: 18989176

Does your car have traction control?

Rather than automatically assuming it�s the booster itself, might it not be worthwhile checking for obvious leaks in the vacuum lines and connections ?

The brake booster supplements your leg power to make pressing the brakes easier. If your booster is failing or has vacuum issues, the brake pedal will be harder to push as it requires more leg power and less "boosted" power. This can lead to longer stopping distances but only because it isn't getting the power assist. It's easy to test: With the engine off, pump the brakes — about five or six times is sufficient. This depletes the stored vacuum. Turn the engine on while pushing down lightly on the brake pedal. If your brake booster is working normally, the pedal will fall away a little, but then become firm. If your brake booster is not working correctly, nothing will happen, or the brake pedal will push back against your foot once the engine starts. This could be a sign of a brake booster problem or an issue with the vacuum hose. Non-OEM pads can give you more bite but often at the expense of more dust and noise. Many OEMs don't use better pads because the customers complain about some squealing. So they go with less grippy pads. If you want better bite, use better non-OEM pads. As noted by others, also verify the calipers are working correctly and don't need a rebuild. This is usually easily apparent when the old pads are removed at a brake change. They'll be uneven wear on the same side or opposite sides. Some uneven wear is normal but a piston that isn't retracting properly will cause a pad to wear much faster. Needed a caliper rebuild is rare in a daily driver. They don't generate the heat a track-driven car will so the seals are less likely to fail. My track driven car doesn't have seals on the pistons because they'd just melt anyway.

Good video from PCA on PMB and caliper rebuilds. It's inevitable as our cars get older. You Tube

Thanks everyone. I have some things to check to determine if it is the booster. Haven't driven the car in a few days so when I do I will run the test outlined above. Thanks again!