Brake pedal stops normally then slowly fades to floor. Master cylinder? Booster?

[Rotmilky]

Well, I replaced the ABS with a used one from a wrecked 2001 base. It had the same part number as mine (it's a 2001 S), so I figured it'd work. Installed it this morning, bled the brakes (and bled and bled and bled...there's a lot of air in the ABS to get out). Took her for a test drive and the brake pedal is back to normal. Woohoo! Nice to have normal brakes again.

Lucky thing there are a lot of used ABS units out there at a reasonable price (I paid $70). A new one from Porsche is about $3000.

So, if anyone happens across this thread in the future and has a similar issue. If a replacement master cylinder doesn't fix the brake fade, take a look at the ABS.

[lskolnick]

👍👍👍👍👍👍👍👍👍👍👍👍🙌

[chriscpm]

Originally Posted by Rotmilky

Well, I replaced the ABS with a used one from a wrecked 2001 base. It had the same part number as mine (it's a 2001 S), so I figured it'd work. Installed it this morning, bled the brakes (and bled and bled and bled...there's a lot of air in the ABS to get out). Took her for a test drive and the brake pedal is back to normal. Woohoo! Nice to have normal brakes again.

Lucky thing there are a lot of used ABS units out there at a reasonable price (I paid $70). A new one from Porsche is about $3000.

So, if anyone happens across this thread in the future and has a similar issue. If a replacement master cylinder doesn't fix the brake fade, take a look at the ABS.

I know this is an old post. But I'm going down this same path. A new master cylinder didn't fix it I'm going to do the ABS pump next. Another symptom is the rear pads wore faster than the fronts after some track use.