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- - - - - Clutch Master Cylinder Slave cylinder

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#1
ChrisA

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Yesterday, I was bleeding brakes after installing a pressure sensor and also did my annual clutch fluid flush. When doing the clutch,  I noticed the slave wasn't moving anymore after about the 3rd pedal stroke. The fluid also wasn't going down. Since there was no fluid coming out the slave boot I figured the Master cylinder must be shot. I got my pedal presser out of the car and gave it a try and there was NO resistance (it would have been nice if my helper said something  :rolleyes: . I did a little search on installing a new cylinder and read that getting the air out can be tricky. I had sucked the old fluid from the reservoir prior bleeding the brakes and refilled with fresh fluid before moving to the clutch. Thinking maybe it got some air in there I went down at midnight and pumped on the clutch a bit and the pedal seems to have returned. Yeah!  However, it now has me wondering if I should replace. These are the original 20-yr old Master & Slave cylinders and while they have been maintained with fresh fluid, I don't expect them to last forever. That said, I occasionally try to follow the rule of "don't fix what isn't broken". Any thoughts, recommendations?


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#2
Mark

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The slave is such a common failure point just replace it. While you are at it toss the stock curly-q clutch line and replace it with a one piece clutch line. It makes engine / tranny swaps so much easier.

 

Mark


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#3
lillyweld

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Easy peezy. Do what Mark said. It's more cheap insurance. Also, purging the clutch couldn't be easier: it's a straight shot from the master to the slave, so open the bleeder valve in the slave and pour in the fluid. Gravity will do the work. When fluid starts running out the bleeder valve, close it. I pushed few shots of fluid through it for good measure. (I replaced the curly clutch line with a straight one as well, so maybe that is where potential air problems may occur.)


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#4
OrangeCrush86

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+1 on buying the braided clutch line and replacing the slave.


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#5
ChrisA

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So, slave and master then? The rubber flex line was replaced some time ago with a short SS line, but it still has the looped hard line. Who is good for the longer line? Anyone close to the East Coast for a quick delivery?


Chris

 

Happiness is a dry martini and a good woman ... or a bad woman.
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#6
OrangeCrush86

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So, slave and master then? The rubber flex line was replaced some time ago with a short SS line, but it still has the looped hard line. Who is good for the longer line? Anyone close to the East Coast for a quick delivery?

 

I think the master is much less likely to fail, so replacing that is up to you. The slave is cheap and easy to change. I think Miata Cage has a 1 piece SS line. My only complaint about that product is that it uses SAE wrenches for the fittings (7/16 and 9/16). A small annoyance on a car that is entirely metric fasteners.


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#7
FTodaro

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If you replace the master there is a bench bleed process and as i recall they give you a few hoses to do the bench bleed. I replaced my master because it was leaking. Lastly while you are messing with your clutch, adjust it so the engagement/disengage  point is at the top of the pedal not the bottom. Improperly adjusted clutch pedals account for Transmission wear and tear do to shifting while the drive train is engaged partially.


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#8
Michael Novak

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always replace both ---to cheap to risk it..


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#9
OrangeCrush86

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 Improperly adjusted clutch pedals account for Transmission wear and tear do to shifting while the drive train is engaged partially.

 

This is good advice. I once had a problem where I thought the transmission was going out because midway through the race it was hard to shift.

 

 

Turned out my clutch wasn't adjusted well and when everything was cold it would push far enough to disengage, but once everything got heated up the clutch fingers got a little softer and now there wasn't enough throw to fully disengage.


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#10
ChrisA

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If you replace the master there is a bench bleed process and as i recall they give you a few hoses to do the bench bleed. I replaced my master because it was leaking. Lastly while you are messing with your clutch, adjust it so the engagement/disengage  point is at the top of the pedal not the bottom. Improperly adjusted clutch pedals account for Transmission wear and tear do to shifting while the drive train is engaged partially.

 

I ordered a master, slave cylinder and long flex line from Advanced. Should get here Fri to install this weekend. I wonder if the flex line would reach back to the reservoir to bench bleed it. Or whether that would just make a mess when routing it over to the slave? After I get that installed and bled, I'll know if I should adjust the pedal. Since installing the ACT clutch the pedal has required a full-throw, which I don't like. If the pedal does not improve with the new cylinders than I'll probably adjust it, although it's a PITA. Would likely require pulling my seat which is no fun to install... The thing has 6 mounting points and all but 1 are blind holes. 


Chris

 

Happiness is a dry martini and a good woman ... or a bad woman.
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#11
callumhay

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Yesterday, I was bleeding brakes after installing a pressure sensor and also did my annual clutch fluid flush. When doing the clutch,  I noticed the slave wasn't moving anymore after about the 3rd pedal stroke. The fluid also wasn't going down. Since there was no fluid coming out the slave boot I figured the Master cylinder must be shot. I got my pedal presser out of the car and gave it a try and there was NO resistance (it would have been nice if my helper said something  :rolleyes: . I did a little search on installing a new cylinder and read that getting the air out can be tricky. I had sucked the old fluid from the reservoir prior bleeding the brakes and refilled with fresh fluid before moving to the clutch. Thinking maybe it got some air in there I went down at midnight and pumped on the clutch a bit and the pedal seems to have returned. Yeah!  However, it now has me wondering if I should replace. These are the original 20-yr old Master & Slave cylinders and while they have been maintained with fresh fluid, I don't expect them to last forever. That said, I occasionally try to follow the rule of "don't fix what isn't broken". Any thoughts, recommendations?

I've used the motive pressure bleeder with the clutch master cap attachment. For sure easier than pumping by foot which takes a lot of time..but will work with persistence. There is a video on line I saw about "burping" the slave cylinder..to get the last bubble of air out. Have not tried that... If the master has been on there for 20 years good luck getting the nuts loosened on the brake lines... I hope you use the brake line wrenches as there is nothing worse than rounding those. I found that cleaning the threads (on the male side) with a nylon brush helped in putting it back together..the threads are so small and the fitment can be tight and they are easy to cross thread. 

 

 

 

Cal






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