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  #1  
Old 01-14-2010, 07:32 PM
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Bad Master Cylinder?

I have to push the clutch petal in about two inches before it stops having free play. I just recently replaced the slave cylinder and bled out the system incorrectly by doing just a gravity bleed. However, today I tried to reverse bleed it by using the right from brake caliper; however, it did not improve the amount of free play needed. The clutch almost fully engages when the petal is lifted about an inch from the floor. Is this a bad master cylinder is is there some way to adjust the amount of free play?

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  #2  
Old 01-14-2010, 07:40 PM
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I don't know, but I've been having the same problem with my original master cylinder and a used spare that I installed after installing a new hose.
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Old 01-14-2010, 07:44 PM
aaa aaa is offline
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There's an adjustment up there, some sort of sleeve thingy where the bolt that connects to the master cylinder pushrod. You rotate it after loosening the bolt and it moves the bolt around by a few millimeters, which I suppose translates to a bit more at the other end of the pedal. Probably not enough for you though.

Define free play, anyways. Sounds like air in the system.
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Old 01-14-2010, 09:40 PM
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Quote:
Originally Posted by Squiggle Dog View Post
I don't know, but I've been having the same problem with my original master cylinder and a used spare that I installed after installing a new hose.
Did that fix the issue?
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  #5  
Old 01-14-2010, 09:49 PM
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After installing the new hose I had this problem. The bleeder screw broke off in the master cylinder so I installed a spare master cylinder and still had the same problem. I hope when I install the new clutch master and slave cylinders that this problem doesn't persist.
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  #6  
Old 01-14-2010, 10:47 PM
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I find that the clutch release point gets nearer to the floor when you turn a flywheel and don't shim it afterwards....I thought there is no adjustment on a 617 cylinder.
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  #7  
Old 01-15-2010, 02:14 AM
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Quote:
Originally Posted by t walgamuth View Post
I find that the clutch release point gets nearer to the floor when you turn a flywheel and don't shim it afterwards....I thought there is no adjustment on a 617 cylinder.
Where/how do you shim the flywheel?

I understand turning the FW would mount the disc and pressure plate deeper into the FW. then the travel would be greater for the throwout bearing, and the slave cylinder is extended farther out. there is only so much travel for it. where does the shim go, and where do we get one?

Charlie
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  #8  
Old 01-15-2010, 02:19 AM
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Quote:
Originally Posted by t walgamuth View Post
I find that the clutch release point gets nearer to the floor when you turn a flywheel and don't shim it afterwards....I thought there is no adjustment on a 617 cylinder.
It didn't have this problem earlier, I replaced the slave cylinder because the PO installed a type for an older transmission and it leaked.
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  #9  
Old 01-15-2010, 03:30 AM
aaa aaa is offline
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The older one is longer. That's probably the cause.
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  #10  
Old 01-15-2010, 02:10 PM
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Originally Posted by aaa View Post
The older one is longer. That's probably the cause.
I should of clarified more. It was working fine with the clutch disengaging at a normal point after I replaced the slave cylinder, then over the course of about a week, it would develop more free play and I'd have to bleed it out and it'd be OK. I stopped driving the car recently (my GF was just taking it back and forth from work) so I didn't notice how long it took for the free play to develop this most recent time.

I define free play as the motion required before the petal starts to have the resistance it's supposed to. The inch or so of free play here just makes it feel like a very loose cluch cable. However, the petal fully returns to it's resting point after it's released and I'm unable to pull it up higher.
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  #11  
Old 01-16-2010, 03:53 PM
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Quote:
Originally Posted by Squiggle Dog View Post
After installing the new hose I had this problem. The bleeder screw broke off in the master cylinder so I installed a spare master cylinder and still had the same problem. I hope when I install the new clutch master and slave cylinders that this problem doesn't persist.
The master cylinder has a bleed screw?
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  #12  
Old 01-16-2010, 04:14 PM
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I have had worn master cylinders start to pick up air, giving the effect of free play, but of course the piston is moving. If bleeding it properly fixes it for a day or so, a worn master cylinder is almost certainly the problem. I've also had a worn slave cylinder cause the same trouble once, but a few times with master cylinders.

I've fixed a few of them by polishing the interior of the cylinder with 400 grade emery cloth to make a cross-hatch pattern (wrapped the cloth around a rag around a screwdriver tip, twisting while pushing in and out, lubricated by brake fluid) and replacing the rubber seals.

I would not do this for a brake master cylinder, but the few times that I did this for clutch master cylinders, they outlasted the rest of the car.
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  #13  
Old 01-16-2010, 11:39 PM
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Quote:
Originally Posted by stupidsongs2 View Post
The master cylinder has a bleed screw?
Mine does, but my car is a 1968 W110 200D.

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