Ok, here's the situation.
1989 911 with 135,913 miles. Sitting in a parking lot in Santa Fe Springs for the last 5+ hours, waiting for a third flatbed.
Dropped the car off at Perfect Lines in North Hollywood for a sunroof delete on June 7. Picked it up today, July 16, for the 117 mile drive home to Carlsbad / Encinitas.
47 miles into the drive, while doing 65 mph on I-5 Southbound, I applied the brakes and the pedal went to the floor, without the car slowing at all. I applied the pedal a few more times with the same result. I then pumped the brake pedal, no improvement.
The pedal felt exactly like it would were a brake bleeder screw open... straight to the floor with very little effort and ZERO braking action. The brake system warning light in the dash did not illuminate.
I was able to use the handbrake to slow the car down, move into the right lane and take the next exit. I pulled into a commercial complex parking lot, in Santa Fe Springs, and shut the vehicle off.
I popped the frunk, expecting to see an empty brake fluid reservoir.
It was at it's normal max level. I looked around the master cylinder and the brake calipers for leaks. None found.
I called my Porsche factory trained master mechanic uncle and described the problem to him. He said while he has never been able to figure out this particular failure mode, it did happen to his customers back in the day. They always just replaced the master cylinders.
As I was speaking to my uncle, about five minutes after pulling off the freeway and shutting the car down, I began to remove the driver's side floorboard (to inspect the pedal box) and brushed the brake pedal with my hand. It felt normal. I pushed the pedal with my foot, it felt firm / normal. Started the car and drive it around the parking lot a few times and it feels normal.
Not wanting to risk anything, I called my insurance company's, American Modern, roadside assistance line, only to have them claim the car isn't listed on my policy (even though I have a proof of insurance card showing it).
So, I call AAA at 2:30p to order a flatbed. It was supposed to arrive before 4p. I get a call from Hadley Towing at 5p claiming the truck that was slated to arrive broke down. So, I call AAA back for my third attempt at roadside assistance and here I sit, waiting for a response, posting on Pelican from my handheld.
So, I thought I'd post a "Name that brake failure mode!" thread here and get the collective group's thoughts. Any ideas?
I'm having a hard time reconciling M491 / turbo brakes that were working perfectly fine moments before, untaxed (it isn't like I was on the track), completely failing for at least 2-3 miles and then all pedal feel coming back less than 10 minutes after shutting down? No brake warning light, no easily discernable leaks. Both circuits failing concurrently? And now the pedal feels as firm as ever in less than ten minutes of sitting. I've started the car a few times and driven it around the parking lot and the brakes feel... Normal, which is to say firm / great.
So, whaddaya got? Any ideas, or is this the beginning of me losing my mind?
