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Discussion Starter · #1 ·
Before I put my 1990 Coupe (SN95 conv.) away for the winter I was getting a sporadic mushy brake pedal as the weather hovered around zero Celcius, increasingly getting worse as the weather cooled. A few times it went to the floor so I decided to pull it off the road a little early in the season. I had assumed, and have been told that it is likely one of the diaphrams or seals gone bad in the master cylinder. Pedal has been mush all winter while away.

So today it was a beautiful warm day out so I decide to pull it out of the garage and assess what needs to be done prior to putting it back on the road and I got a consistently firm brake pedal all afternoon in the warmer weather. What gives?

Should I bleed and refresh the system, do the M/C, or both to be safe? What's the problem here? Inconsistency in brakes freaks me out and I want to know exactly what caused this to prevent it in the future.
 

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recheck the master cylinder.....check all the system for leaks....are the rear brakes adjusted up properly?
 

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whats brake woes?...lol
 

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maybe frozen water in the brake fluid????
 

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I would bleed the brakes again and make sure you have the Adj Prop Valve open all the way when you bleed the Rear Brakes.
 

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when it gets that cold it's possible it is freezing but more than likely there is moisture getting into the system somehow and that's just like having air in the system.
 

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Discussion Starter · #7 ·
Master cylinder is not that old and the brake fluid is looking a little suspect (read: brown) so I am thinking, yes the system needs a bleed.

I am going to try fluid with a higher boiling point this time around too, as the stuff that's in there isn't terribly old.
 

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Sounds like you need all new fluid. Zero Celcius is only 32 degrees so I doubt it was cold enough to freeze the fluid itself but if there's condensation/moisture in the system, you have a leak somewhere in the system. That means it isn't air tight and you have a breach somewhere. Another reason would be that the fluid is boiling but it isn't being driven so that isn't it.

I'd do a full flush, open the bleeds and do it until it's all out, and refill with fresh fluid.
 

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You can try a Pressure Bleeder when you bleed your Brakes again and dont forget to set the Adjustable Prop Valve to Full Open to the Rear Brakes when Bleeding them, then readjust after your done.
 

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Discussion Starter · #10 ·
Well, took my coupe to the local mechanics (also my neighbor) to get the car on the hoist and have a look around, see what could be the problem. Checked everything out and all appeared fine, calipers moved fine, lines under the car were good, fluid is still good and the master is only about a year old maximum motorsports unit so we focused elsewhere for the time being.

1) The connection at the intake port on the adjustable proportioning valve was not tight and was leaking a bit. That breach in the system certainly doesn't help, so we tightened it up, washed and dried it and will keep an eye on it.

2) Upon putting the cars wheels back on we noticed there was alot of camber movement in the front wheels. Mark had actually heard the clunking up front during his earlier test run. Turned out the bottom of both front struts were loose about a turn and a half so we fastened them up good and proper and there is no play any more. We played with the idea that the movement may have been occasionally pushing the caliper pistons back in, giving more pedal travel to initially engage the brakes but the jury's still out on this one as I'm positive it's one assembly and the rotor wouldn't have that type of play.

Anyhow, whatever the case, brakes are working fine at the moment (cross my fingers), so I'm going to monitor the situation and will need to bite the bullet and replace the M/C if it happens again.
 
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