Brake failed on freeway
07-03-2011, 09:00 PM
#1
Burning Brakes
Thread Starter
Brake failed on freeway
Today, the temperature in the San Francisco bay Area was really warm. I had to pick up my kid in Berkeley. On the way back to SF on the Bay Bridge, I( noticed the brake was a lot more sensitive with the brake pedal travel unusually short. I thought there was also a slight drag on the brake. The traffic on the bridge was heavy so I was traveling about 35 to 40 mph. At some point I had to brake and the brake pedal went to the floor but did come back up when I released. There was very low braking power. I was on the left lane. I immediately turned on the hazard and down shifted all the way. There was luckily a left lane exit Harrison/Embarcadero just 1/2 mile down and I was able to get the car off freeway and parked. To help to get on the tow truck, the car was still drivable with some braking power. There was no smell of burning brake or any fluid on the ground as far as I could tell. There was however ALMOST some fluid/solid in my pants.
By the time the car got towed back home. The brakes seemed to be working fine again as I was backing it into the garage.
Master cylinder?
Steve
By the time the car got towed back home. The brakes seemed to be working fine again as I was backing it into the garage. Master cylinder?
Steve
07-03-2011, 09:18 PM
#2
Rennlist Member
Sounds like a frozen piston that didn't retract all the way, that's what gave you the sensitive pedal, the caliper was already squeezing the disc. That friction caused the heat whcih caused your brake fluid to boil and no brakes.
07-03-2011, 09:28 PM
#3
Team Owner
I also vote for a bad MC
it might be time to consider a brake system refurbish to include,
4 new stainless flex lines
a new MC and
a new rear proportioning valve.( screws into the ABS unit)
after this, then inspect the calipers for dragging pads in the calipers,
this requires pad removal and cleaning of the pad ends road test using minimal braking ,
using the IR gun check for hotter rotors this would indicate a dragging caliper .
i suggest to use ATE super blue racing fluid.
it might be time to consider a brake system refurbish to include,
4 new stainless flex lines
a new MC and
a new rear proportioning valve.( screws into the ABS unit)
after this, then inspect the calipers for dragging pads in the calipers,
this requires pad removal and cleaning of the pad ends road test using minimal braking ,
using the IR gun check for hotter rotors this would indicate a dragging caliper .
i suggest to use ATE super blue racing fluid.
07-03-2011, 10:22 PM
#6
Drifting
Pull the check valve out of the booster. Stick something long and somewhat flexible into the hole and down to the bottom. See if it has brake fluid on it. If so, change the master cylinder.
07-03-2011, 10:24 PM
#7
Drifting
What Adam said first. Those symptoms describe water contiminated brake fluid and a stuck caliper. Water in the brake fluid lowers its boiling temperature and contibutes to caliper cylinder corrosion.
The master cylinder can be ruled out because your brakes felt normal again once the car was able to rest. The rest gave time for the stuck caliper to cool off.
When did you last flush the brake fluid? Was this part of a normal 24 month flush? Remember, not every flush removes all the old fluid, so periodic is necessary to replenish most of the water bearing fluid.
The master cylinder can be ruled out because your brakes felt normal again once the car was able to rest. The rest gave time for the stuck caliper to cool off.
When did you last flush the brake fluid? Was this part of a normal 24 month flush? Remember, not every flush removes all the old fluid, so periodic is necessary to replenish most of the water bearing fluid.
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07-03-2011, 11:21 PM
#9
Nordschleife Master
Steve, glad you got it slowed down and no one and nothing was injured/damaged.
Good luck. While it might not be an inexpensive fix, it probably won't be terrible.
Good luck. While it might not be an inexpensive fix, it probably won't be terrible.
Glad your ok
07-04-2011, 01:27 AM
#11
Burning Brakes
Thread Starter
07-04-2011, 03:21 AM
#13
Burning Brakes
Thread Starter
07-04-2011, 05:04 PM
#14
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
More likely is the booster was boosting and applied the brakes. When it happens again pull the vacuum line out of the booster and see if the car rolls freely. Also you MIGHT adjust the brake pedal for a bit more freeplay that sometimes is enough to stop the booster from boosting. The 85 I bought did the same thing on my way home so I pulled the vacuum line and drove it home.....brakes were very poor until they cooled down then it would stop reasonably well with no power assist. I adjusted the pedal and drove it around with booster operative and thus far no lock-up. You can also learn a lot by feeling the wheels (they do not mind) to see if one, both or all are HOT when you experience the dragging of the brakes. If only one is hot then it is a problem with that caliper or brake line.
07-04-2011, 05:43 PM
#15
Burning Brakes
Thread Starter
I also vote for a bad MC
it might be time to consider a brake system refurbish to include,
4 new stainless flex lines
a new MC and
a new rear proportioning valve.( screws into the ABS unit)
after this, then inspect the calipers for dragging pads in the calipers,
this requires pad removal and cleaning of the pad ends road test using minimal braking ,
using the IR gun check for hotter rotors this would indicate a dragging caliper .
i suggest to use ATE super blue racing fluid.
it might be time to consider a brake system refurbish to include,
4 new stainless flex lines
a new MC and
a new rear proportioning valve.( screws into the ABS unit)
after this, then inspect the calipers for dragging pads in the calipers,
this requires pad removal and cleaning of the pad ends road test using minimal braking ,
using the IR gun check for hotter rotors this would indicate a dragging caliper .
i suggest to use ATE super blue racing fluid.
Would you recommend the brand of SS brake lines and place to buy?
Thanks.
Steve