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Thread: 3000Gt VR4 Clutch Pedal Issue

  1. #11
    Thermal Engineer- Mmbr Since:8/2005 verified Feedback Score 0 Alex3000gt's Avatar
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    Silly question. If you look under the dash at the pedal assembly, is the pin & cotter still in place linking your pedal to the clutch master rod?

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    Then there wouldn't be many master mechanics!

  3. #13
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    Quote Originally Posted by Alex3000gt View Post
    Silly question. If you look under the dash at the pedal assembly, is the pin & cotter still in place linking your pedal to the clutch master rod?
    Yeah, it was all there. In fact, i just pulled it out.

    So here's what was happening... you push the clutch pedal and it pushes the rod that goes into the booster. But after about 1 1/2" of movement, the pedal won't push any further. You can see the rod going into the booster move but then it acts as if it bottoms against a solid object internally. And no reasonable amount of force will budge it (I'm over 200 lbs and was afraid I was going to bend something if I pushed the pedal any harder).

    Looking inside the clutch master cylinder, there's no fluid movement with the pedal movement. And this is with the slave cylinder dangling loose from the transmission. I would have expected the booster, even with no vacuum, to activate the clutch master cylinder. It doesn't seem to be doing that.

    So, it appears as if the clutch booster is internally jamming up and not pushing on the clutch master cylinder. But the rod does move that 1 1/2". Now, if whatever connects the booster to the cylinder got jammed solid, that would create similar symptoms. But I have no clue what's inside there or in between the two. Also, it seems as if the engineers would have designed this so that couldn't happen. At least that's how they design brake systems and boosters.

    I just removed the clevis from the rod going into the clutch booster. Now the pedal goes to the floor and (obviously) allows the starter to engage. The car won't run because everything is removed to remove the slave cylinder.

    There's this LITTLE part of my brain that wonders what happens when there's no vacuum to the booster... One would think it would still transfer movement, just not boost anything.

    Well, time to go back out in the Texas heat and work on it again...

  4. #14
    Forum User Not Verified Feedback Score 2 (100%) RealMcCoy's Avatar
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    May you should stay out of that Texas sun for a while... You just stopped making any kind of sense....

    Quote Originally Posted by extremeRacer View Post

    So here's what was happening... you push the clutch pedal and it pushes the rod that goes into the booster. But after about 1 1/2" of movement, the pedal won't push any further. You can see the rod going into the booster move but then it acts as if it bottoms against a solid object internally. And no reasonable amount of force will budge it (I'm over 200 lbs and was afraid I was going to bend something if I pushed the pedal any harder).

    Looking inside the clutch master cylinder, there's no fluid movement with the pedal movement. And this is with the slave cylinder dangling loose from the transmission. I would have expected the booster, even with no vacuum, to activate the clutch master cylinder. It doesn't seem to be doing that.

    So, it appears as if the clutch booster is internally jamming up and not pushing on the clutch master cylinder. But the rod does move that 1 1/2". Now, if whatever connects the booster to the cylinder got jammed solid, that would create similar symptoms. But I have no clue what's inside there or in between the two. Also, it seems as if the engineers would have designed this so that couldn't happen. At least that's how they design brake systems and boosters.
    You don't know what's really happening, because you haven't tested anything... I already told you how to diagnose the problem. There is nothing an engineer could do differently to prevent a part from failing from old age, neglect, contamination, and corrosion... The clutch hydraulic system is designed EXACTLY like the brake system, and there is nothing magical about the design of a brake system that prevents the same thing from happening. It can and does happen to brake systems... I just last week replaced the master cylinder in a Corvette for the exact same symptoms. it sat for ten years, and the master seized... You could have put a jack on the pedal and probably just damaged the firewall, because that cylinder was not going to move.


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  5. #15
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    You are correct... I don't know what's happening because I haven't gotten it all apart yet. I was merely restating what I DO know and the history while I was taking a break from working out in the heat and looking for the online diagram of the entire assembly.

    Thank you for letting me know that the clutch booster works EXACTLY like a brake booster. I suspected as much but wasn't sure. A brake booster would NEVER be designed to "lock up" in the case of catastrophic failure because to do so would cause the driver to lose all braking ability and crash. But, since the clutch wouldn't necessarily lead to a crash, I wasn't positive.

    I intuitively found it unlikely that the clutch master suddenly seized up since it worked just fine a week ago. It just seems strange to go from "working great" to "completely seized up" in a less than a day. My expectation would have been that it would have gotten progressively more difficult, not a black and white thing. But, that's not to say that isn't the issue. I'm down to removing two nuts, one on the brake booster and one on the clutch pedal assembly. I don't have my tool set here and I need at least a universal joint and a deep socket to get either of those last two nuts off.

    I have an appointment with a local shop in about an hour. I've reached my limit of alloted time for this project. I have an entire fleet of project cars and I just need to sell this one. I figure it will bring more money running and driving but there's a tradeoff of time/money/selling price there. I can always sell it was "running but clutch doesn't work" if I have to. A friend of mine keeps telling me "Just sell the stupid thing 'as is' and get it over with!".
    Last edited by extremeRacer; 08-07-2019 at 01:37 PM.

  6. #16
    Forum User Feedback Score 0 B-Line's Avatar
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    How did this turn out? I recall another user having a similar issue where the clutch would go straight to the floor. They finally traced the issue back to a the slave cylinder flex line. It had severed at the end and allowed air into the system. Bought a new line and was back on the road.

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