The rubber cap is removed from the proportioning valve. It is not leaking there, or anywhere.
All calipers are leak free and work perfectly. They clamp hard when the pedal is pumped (we cannot turn any of the wheels using a crowbar across the studs), and they release immediately when the pedal is released. Unlike the earlier cars, where the proportioning valve is in line with the rear circuit, on the Milano it is in parallel with the MC. I've now been told by a couple of seasoned veterans that a failed proportioning valve on a Milano can show the same exact symptoms as a failed MC, as it's presumably behaving like a MC that is allowing fluid to pass by it's rubber seals. Anyhow, we'll know better tomorrow after we swap it. I'll post the results to the list. bs -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Joe Elliott Sent: Wednesday, June 02, 2010 11:24 PM To: [email protected] Cc: [email protected] Subject: [alfa] Re: Strange braking problem Odd. Now you've got me scratching my head when I should be sleeping. I imagine any weird booster failure mode that might occur would not be improved by pumping the pedal so it's got to be in the hydraulics. Which is to say that it's got to be a leak or trapped air. Is it possible that a flex hose is trapping air in a weird way? You're sure it's not leaking out the back of the bias block, under the rubber cap? Does each caliper clamp down its respective disc when you apply the brakes? -Joe At 3:21 PM +0000 6/2/10, alfa-digest wrote: >Date: Wed, 2 Jun 2010 08:21:15 -0700 (PDT) >From: Brian Shorey <[email protected]> >Subject: [alfa] Strange braking problem > >Hey All, > >We're having a strange braking problem with our LeMons car that has >me scratching my head. Here's the history and symptoms: > >The car is a Verde, however we've removed the ABS and replaced it >with a stock non-ABS Milano system. Ran the car for three races, >the brakes have always worked fine, but felt a little mushy. >Noticed that the fluid in the reservoir had drained out over the >winter, put 2 and 2 together and made the blind (and apparently >wrong) assumption that the MC was bad, so replaced it with a new >one, but didn't test. > >Later, observed a leaking rear caliper, so did away with the rear >calipers and replace them with Spider rear calipers. > >Bled the system a zillion times, including at every possible >junction coming out of the MC and bias block, we're confident that >there is no air in it, anywhere. > >Now, we have decent brakes if we pump the pedal, however if we let >it sit, then press the pedal, it goes to the floor with some, but >very little, resistance. > >With the car running and vacuum to the booster, everything is the >same except the pedal feels mushy.. > >Replaced the MC with a used one I had lying around (we'd already >tossed the original), and the symptoms are the exact same. > >There are no hydraulic leaks in the system anywhere, we're quite >confident of that, and we're also confident we've got all the air >out of the system. > >Tried vacuum testing the booster, vacuum goes to 0 as soon as we >press the brake pedal (MityVac manual says it should drop about 6"). >However, we tried another booster I've got lying around and it did >the same thing. > >My question is this - is there anything internal to the booster that >could cause the problems we're observing? Every bit of experience >I've got tells me that if there is no air in the system, and no >leaks, then a sinking pedal is the MC. But we're on MC #3 now, and >one of them was new. > >Changing the booster is not fun in these cars, especially with a >cage and seat in there, so we'd rather not go that route unless >we're sure. > >Any input or advice will be greatly appreciated. > >Thanks, > >bs -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected] -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
