Printable Version of Topic

Click here to view this topic in its original format

914World.com _ 914World Garage _ Brake issue

Posted by: Headrage Mar 20 2006, 11:17 AM

Yesterday after the fun run I went back to MikeD's place for a little while and when I left, after about the 3rd stop my pedal suddenly went to the floor and the brake light started flashing. Brakes pumped up okay and after about 25 miles on I-5 came bake completely but the light still flashes. Stopped the car when it first happened to see if I was leaking fluid from somewhere but couldn't find any.

Ideas?

Posted by: dlo914 Mar 20 2006, 11:19 AM

MC going bad?

Posted by: davep Mar 20 2006, 11:19 AM

The switch on the MC needs to be reset to stop the light from flashing. I'm more concerned about the pedal going to the floor. That sounds like really bad news. Was there any hint of softness before or after?

Posted by: Headrage Mar 20 2006, 11:21 AM

QUOTE (davep @ Mar 20 2006, 09:19 AM)
Was there any hint of softness before or after?

None. Brakes were solid all through the twisties...

Posted by: Cap'n Krusty Mar 20 2006, 11:23 AM

YOU NEED A NEW MASTER CYLINDER!!!!!!!!!!!!!!!!! Replace it NOW! Or maybe just up your liability insurance. The Cap'n

Posted by: brant Mar 20 2006, 11:27 AM

it does sound like MC issues.
pull the pedal board and then pull the rubber sleeve over the MC to check for fluid leakage...

If thats not it then my 2nd guess would be that one of your calipers is dragging.

(rear venting clearance too tight, or stuck front piston)

To check for this, put the car up on stands.. pull the wheels.. and pull each of the pads (yes all 8) compair thickness to see if one pair or even 1 pad shows increased wear.

my logic is that if you had a stuck piston, that caliper over heated.. Especially if it was a rear pad.. then due to over heating the fluid boiled and you lost the brakes until everything cooled down.

when you were parked did you have the parking brake on?

a track rule is to never set the parking brake when you come off the track... things are too hot and need to cool down. setting the parking brake allows for more heat transfer and boiled fluid.

2 cents
brant

Posted by: Headrage Mar 20 2006, 11:46 AM

I'll go over everything.

If it is in fact the master cylinder can I go to the 19mm with stock brakes since I'll be doing a 5 lug conversion pretty soon?

Posted by: Eric_Shea Mar 20 2006, 11:53 AM

MC. Check for a wet pedal assembly.

Go 19mm now if your intentions are to have M-Calipers etc. You don't want to replace a MC again anytime soon. You'll see what I mean.

Posted by: davep Mar 20 2006, 12:00 PM

Well, one guess may be a bit of crap in the MC got caught in a seal and prevented pressure buildup. Even if you replace the MC, be sure to thoroughly clean the reservoir first and flush like crazy. Thank goodness you just got a warning and not total failure. Keep us posted if you find any reason for the scare.

Posted by: Headrage Mar 20 2006, 05:24 PM

Didn't get a chance to put the car in the air but went home for lunch and saw a puddle of fluid under the right front suspension. Stuck my head under there and it looks like it's coming from the transition where the rubber and steel lines meet. The whole strut assembly looks like it's been sprayed.

I think it'll be an easy fix...

Posted by: brant Mar 20 2006, 05:27 PM

Daniel gets credit too...

but imagine that...
the captain was right
(for the 10,000 time in a row!)

thanks captain for all the help, advice, and direction you endlessly supply!

not said with sarcasm.

brant

Posted by: Headrage Mar 20 2006, 06:14 PM

QUOTE (brant @ Mar 20 2006, 03:27 PM)
Daniel gets credit too...

but imagine that...
the captain was right
(for the 10,000 time in a row!)

I don't thinks it's the m/c.

Just a line...

Posted by: Cap'n Krusty Mar 20 2006, 07:06 PM

Symptoms don't indicate a line. When a line fails, you lose braking and it rarely comes back until you do the repair. Master cylinders can fail by bypassing internally, and there will be no fluid loss when that happens. it may come back and work well for some time, only to fail again. Sooner or later, that can result in the use of a fixed object, or another moving one, for stopping your uncontrolled progress. The Cap'n

Posted by: Eric_Shea Mar 20 2006, 07:11 PM

QUOTE
Symptoms don't indicate a line.

with her...

Posted by: Headrage Mar 20 2006, 07:23 PM

QUOTE (Cap'n Krusty @ Mar 20 2006, 05:06 PM)
Symptoms don't indicate a line.

So why is the m/c dry and I have fluid all over the right front strut.

Posted by: Cap'n Krusty Mar 20 2006, 08:02 PM

THAT symptom, one you didn't mention at the start, does indicate a leak. However, the fact the brakes "came back", doesn't fit the facts. The Cap'n

Posted by: Dr. Roger Mar 20 2006, 08:26 PM

we'll i'll ask the stupid question...

where's the best place to get a 19mm master cylinder? (green-horn CSOB asking)

do we ask for a particular year 911/19mm MC?

Posted by: Headrage Mar 20 2006, 08:42 PM

Pelican sells them for $175.00.

Posted by: Aaron Cox Mar 20 2006, 08:52 PM

so tighten up the line, and bleed and report back....

at your disposal if you need my help to swap anything....

Posted by: Headrage Mar 21 2006, 05:26 PM

Okay, I got the front wheel off and took a look around at the caliper and lines. The only thing I could see is the fluid looks like it is coming from the fitting where the flex line meets the steel line to the caliper. Fitting was tight.

Is it possible that the failure is where the rubber line is crimped to the fitting?

Posted by: Porsche Rescue Mar 21 2006, 07:04 PM

I hope I misunderstand: Pedal went to the floor and you drove 25 miles on the freeway waiting for it to firm up?

Anyway, it is possible the rubber line has failed at the connection. Also possible that the metal line has cracked at the fitting from being stressed sometime in the past. However, as others have said, a line failure would not fix itself. An MC failure will (for a while). If it were my car, what with a nice new strong go-fast six and all, I would be replacing all four flex lines AND the master cylinder pronto.

Posted by: Headrage Mar 21 2006, 07:09 PM

QUOTE (Porsche Rescue @ Mar 21 2006, 05:04 PM)
I hope I misunderstand: Pedal went to the floor and you drove 25 miles on the freeway waiting for it to firm up?

If it were my car, what with a nice new strong go-fast six and all, I would be replacing all four flex lines AND the master cylinder pronto.

#1: No. I pulled over as soon as it happened. Jeez, ya think I'm nuts?

#2: Just ordered parts today and rescheduled the trailer down to the mechanic for the oil leak cuz I don't wanna even drive it out of the garage...

Posted by: Eric_Shea Mar 21 2006, 08:50 PM

QUOTE
If it were my car, what with a nice new strong go-fast six and all, I would be replacing all four flex lines AND the master cylinder pronto.

Ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding, ding. We have a winner folks!

Piece of mind beats piece of guard rail any day (not really certain if it beats piece of ass though... that's kind of a rock, paper, scissors thing ).

QUOTE
Jeez, ya think I'm nuts?

Let's see... You have a 914 and you've been known to... HANG OUT HERE!

I'd say that qualifies.

Let us know what you find out...