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Anonymous Poster
simse7en@sympatico.ca
Mar 31, 2008, 7:20 AM
Post #1 of 4
(1733 views)
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brake problems
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I have a 1990 Mustang LX Coupe. It has been converted to newer SN95 5-lug four wheel discs with an SN95 master cylinder, 3-2 port conversion and a Ford Racing front/rear adjustable proportioning valve. Here is my problem:
The brakes worked fine and consistently up until last fall when the weather started getting cooler (around zero celcius) and in this cooler weather they were sporadically getting mushy. I mean, three stoplights and they'd be fine and one they would get soft. Occassionally pumping the pedal a couple of times would firm them back up, and then on a few occassions they went to the floor with very little braking action, so I decided to take it off the road early for the winter.
Yesterday, in the warm spring weather I decided to pull it out of the garage and assess what I need to get done on the car for summer. The brakes are now consistent and firm!!! It seems as though this may be weather related.
Anyhow, a few people had suspected the seals or diaphrams in the master cylinder are gone and I need to replace this. (M/C is about a year old). Others suggest it may be moisture or air in the system and are telling me to bleed/flush the system. The brake fluid does appear to be dingy and dark brown rather than clear as it should be.
What would you suggest? I want to make sure I have this licked so my pedal doesn't go soft on me again next fall!
Thanks in advance.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 31, 2008, 8:18 AM
Post #2 of 4
(1732 views)
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Re: brake problems
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Bleeding out brakes periodically is good maintenance and prevention for the moving hydraulic parts. That's a highly neglected area. Most brake fluids absorb moisture and need changing. Silcone high temp stuff doesn't but then any moisture just get to the bottom of things and isn't a cure for corrosion either.
I store cars and have for ions. Brakes always feel funny for a while when put back in service even with storage in controlled environments,
T
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Guest
Anonymous Poster
Mar 31, 2008, 9:05 AM
Post #3 of 4
(1727 views)
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Re: brake problems
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Thanks Tom. I will give it a try and am going to use fluid with a higher boiling point this time.
Any chance you can remove my email?
Thnx.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 31, 2008, 9:57 AM
Post #4 of 4
(1725 views)
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Re: brake problems
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It's not just boiling point! Dot 3 is probably what's called for. By about Dot 5 it's not hydroscopic (water absorbing) but does have the higher temp ratings. Ask or read labels. I would use what car calls for.
What seems to happen is the rubber to polished metal bores of master cylinder, other things (combination valves) wheel cylinders (N/A for this) and rubber ring to bore inside calipers can get a corroded area. When used daily they don't build up much crust. Master cylinder really shouldn't travel to end of bore as when you bleed brakes and many will tear up the seals by just bleeding. Yours was new so should be ok.
I need to do just what I'm sugessing to all of mine. All done before but should do it again - PITA but worth it.
Note on moisture: You want it to absorb so it can flush out but just a couple percent moisture lowers boiling points of brake fluid to close to plain water. They do need better than that or you would lose braking when real heated up - performance driving, mountainous driving, and trailer use especialy. I've never had a problem with the temp range of plain Dot 3 but I'm easy on things,
T
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