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Discussion Starter #1
Hi y'all, been frustrated by not having enough full disengagement of the clutch after replacing the clutch master cylinder last year. Only getting about 7mm travel of the new slave m/c. Pedal bottoms out on the floor. Tried bleeding the slave A Lot!. I read the threads about the pivot arm welds, and the 134mm distance between pivot arm pin hole and master cylinder. If I set it up at 134, my pedal is really low. So today I pulled off the m/c to re-check the pivot arm weld, and it strong. Is it possible the pedal had slipped on the pivot pin itself? I see there is a nut way up the pedal shaft on the pin. If I loosen that, reset the pedal height and tighten, do you think that will work?
 

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I'd first check the slave is not leaking (for this you need to pull back the rubber bellows)
then perhaps replace the flexible hose if you do not know how old it is....they can deteriorate inside and either close down on you or baloon out when you push the clutch.

Did you bench bleed the master when you put it in last year....? (Edit: sorry, ignore the bench bleed bit, that is necessary for the brake master, not clutch master...oops!)
 

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Bleeding the clutch system can be difficult - using the pedal you are trying to push air down - the opposite of what it wants to do and there are no check valves in the system. Also, make sure the slave cylinder's bleed screw is uppermost (the slave can rotate in the mounting on the bellhousing).

I reverse bleed clutch systems - pushing air/fluid up to the master cylinder. I use a 60 ml syringe (filled with brake fluid) and a short length of tubing to connect to the bleeder. Open the bleeder and push fluid in. Be sure there is room in the master cylinder's reservoir so it doesn't overflow (brake fluid is also a good paint remover). Sometimes it needs a final bleed using the pedal but it seems to work a lot better after filling the system by reverse bleeding. For very difficult to bleed systems you may need to disconnect the slave's pushrod from the clutch fork and push the slave's piston into the slave with the bleed screw open then close it when the piston is all the way in. This can help to force any entrapped air out of the slave.
 

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What is the normal clutch pedal travel? How far does the clutch pedal normally move?
The clutch pedal should sit equal to or slightly above the brake pedal when at rest. There should be a small amount of free play at the pedal to be certain the piston in the master cylinder is able to fully release.

More important is how far the slave pushrod moves.
 

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Is it possible the pedal had slipped on the pivot pin itself?
No, that isn't possible.

I see there is a nut way up the pedal shaft on the pin. If I loosen that, reset the pedal height and tighten, do you think that will work?
Nope. There is a groove machined into the pedal shaft (visible in the photo below) and a special bolt that fits into it - those parts lock the pedal to the shaft in only one position. The alignment between pedal and shaft isn't adjustable.

 

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Discussion Starter #7
Thanks everyone for the suggestions. The flex hose is new last year, and I'm very sure there is no leak in it. And slave is ok, from what I see. Glad I asked about slippage of the pedal on the pivot pin, as that would be a bear to get to that bolt without dismantling the whole thing. GHNL, I had read your previous threads about reverse bleeding, and I'll give it a try. I was using a vacuum pump method, with bleed screw at 12 o'clock. I do suspect it is either an air in the line issue, or a fault in my new master or slave cylinders....hopefully the air.. One puzzle though......with the clutch mc disconnected from the pedal, Even then the pedal is about 3/4" below the brake pedal at its highest. Weld looks good an original I think. Could a PO have welded the pivot pin in the wrong position? I doubt the brake pedal is too high, as the light switch bracket mates up well.
 

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One puzzle though......with the clutch mc disconnected from the pedal, Even then the pedal is about 3/4" below the brake pedal at its highest.....
have you tried pulling the pedal up to be in line with the brake pedal?
If its possible, I would suspect the pivot arm weld twisting.
 

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with the clutch mc disconnected from the pedal, Even then the pedal is about 3/4" below the brake pedal at its highest. Weld looks good an original I think. Could a PO have welded the pivot pin in the wrong position?
Regardless of whether a PO welded the pivot pin in the wrong position, or the factory weld failed, evidence points to a bad shaft-lever assembly (the part I pictured in post #6). Either way, the shaft-lever needs to come out.

You can try to salvage your old shaft-lever. But if it were me, I'd just order a new one, plus a new locking pin (in case you bugger the old one in the removal process).

would be a bear to get to that bolt without dismantling the whole thing
Yea, it is. Others have written about procedures for just loosening that big aluminum casting that holds the pedals & booster, removing the locking pin in situ, and then sliding out the damaged shaft. But then replacing the locking pin really requires some contortions. In my opinion, just disassembling everything - e.g., pulling the whole booster & pedal assembly - is the easier approach. I would much rather spend an hour working on something while standing, than 58 minutes on my back under the dash.
 

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Discussion Starter #12
Yes, Now the gears do crunch...they don't quite stop when the clutch is engaged. Prior to this latest attempt, the gear just barely stopped enough to switch if I pressed real hard down the floor board. But it was never right. The slave travel was about 8-9mm. Given the pedal height is low even at its highest with the pivot disconnected from the master cylinder, I think Alfajay is right: I'll replace the pivot arm....and the right way vs in situ. (I'll save the acrobatics for getting the gages out of the dash for refurbishing. Looks like I'll need to then).
 

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Discussion Starter #13
Thanks to all of you for your advice. The new clutch pivot arm solved the low pedal issue and insufficient clutch travel. Chalk this one up as another example of failed pivot arm. Tranny shifts smooth and quietly now. Brake and clutch are at the same height too. Surprisingly, the clevice pin went right in without issue. Thanks. THis community is a great resource!
 

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Discussion Starter #15
The clutch now moves about 11-12mm. Soooo much better! And the brake and clutch pedal are at the same height. Note: I made sure to adjust the clutch master cylinder rod to the required 134mm from the base to the back of the U-clip hole. It seems that by adjusting that a bit, you can can fine tune the pedal height slightly.
 

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I had to reverse bleed the clutch slave cylinder to remove all of the air from the system. I used a pressure bleeder that I purchased on the internet and it works great. The unit is made by Motive Products and you need to buy model 0100 which lists for $55.00.
 
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