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Discussion Starter #1
Just when I started enjoying the car again after a head job...the clutch MC quit on me! Swapped the slave MC, bled it, it works for a while then just sticks, same problem. (no dampener) The pedal just goes right to the floor, but strangely no leaking fluid. The brake MC is leaking a bit, but I haven't noticed until now, could this be causing my clutch problem due to them using the same resivor? Also could a leaking brake MC cause dragging rear calipers?

After searching the forums, changing the clutch MC looks very fun! wish me luck
 

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It's one of those jobs that isn't so gruesome the second time as the first. Like a lot of the 164 maintenance tasks. Getting the supply hose disconnected from the MC was a pain. Getting the pedal pin out and back in were a contortionist's dream. But all do-able.

Same reservoir issues would only cause problems when contaminated fluid is the source of difficulty, as far as I see it. The MC is said to potentially cause dragging left rear brake, but I don't see how. I think Jason Minos helped John Harrill dealing with an experience like this recently. Vague recollections and might be wrong.

Michael
 

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Massimo, Sounds like you had better go ahead and replace your brake MC while you are at it, it does cause dragging rear brakes when it goes bad, especially noticable in the hot summer months. I wished I had replaced my MC sooner, the new one has made for a huge improvement in my car. BTW, The MC reservoir has a separate little chamber for the clutch, so that if the brakes lose all fluid, there will be a little in the reservoir for the clutch to still work, so really not related. You may just have them both going bad at the same time.
Charles
 

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It's one of those jobs that isn't so gruesome the second time as the first. Like a lot of the 164 maintenance tasks. Getting the supply hose disconnected from the MC was a pain. Getting the pedal pin out and back in were a contortionist's dream. But all do-able.

Same reservoir issues would only cause problems when contaminated fluid is the source of difficulty, as far as I see it. The MC is said to potentially cause dragging left rear brake, but I don't see how. I think Jason Minos helped John Harrill dealing with an experience like this recently. Vague recollections and might be wrong.

Michael
I had the "Dragging rear brake" syndrome, which made the car exhibit bizarre behavior (Car slows down by itself on hot days; rear wheel becomes hot enough to fry the proverbial egg). All of which was solved by replacing the brake MC (Kudos, Jason).

I did the clutch MC a couple of years ago when I did the clutch itself. It's tight quarters under the dash and it easy to cut your hands on the steering column supports. Re-attaching the supply hose is a challenge; I used a longer hose from the reservoir and turned the inlet fitting on the MC to the slightly to the side. This made attachment easier.

Oh...The brake MC is not a difficult job. You just have to remove a few items first.
 

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Discussion Starter #5
Going to order both the clutch/brake MC tonight as I also have the "dragging rear brake syndrome", I rebuilt both rear calipers and new lines, but problem still there. Didn't know it was related to the MC. The brake MC does look much better than the clutch MC to replace.

What type of hose do you guys recommend for the supply lines, how much will I need?

Thanks guys, wish me luck
 

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As I understand it, when the internal seal in the MC degrade, the material mixes with the brake fluid and the result is a substance that, when heated by the engine, expands. This is consistent with what I was experiencing. The left-rear caliper would drag only after I had been driving for a while and the mixture would heat up. The new (to me) master cylinder cured it.
 

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If it were only and exactly what you said, John, then flushing the brake fluid would cure it. I suspect it is a bit more complicated, being that it is reported to occur preferentially in the LR brake. I'd be more suspicious of a plugged return duct in the MC (vague suggestion). The brake line should NOT be valved off from the supply reservoir, as I understand it, and it MUST be in order for heating to allow pressure to build up in the caliper instead of being relieved through the MC back into the reservoir. Or that's how _I_ see it, anyway. A restriction of the dual circuit MC could easily be circuit dependent. But basically, something is wrong that isn't just fluid.

addition: One candidate would be a failure to return the MC piston fully, which might leave one of the circuit returns blocked. Certainly when applying brakes, the return line to the reservoir must be blocked, else the pressure would go there instead of to the caliper. But it must be open when the brake pedal is fully released in order for the fairly common air purging technique of backfilling from the caliper with a pressure bleeder to work.

Michael
 

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In my case, replacement of the brake MC and renewing the brake fluid cured the problem.
Of note is that the seals in the old unit were soft and mushy.
 
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