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81 SC clutch cable adjustment – first and reverse trouble

Long time reader with first post and first 911 (a very well maintained and documented 81 SC coupe) arrived less than a year ago after 30 years of dreaming about it. We have been enjoying it ever since… still pinching ourselves that this is our car. 88k miles now, we have added 4k since it arrived.

Went out for a drive and shifting into first was suddenly tough - started buzzing after we backed out of the garage. Not really crunching, but not shifting into the gear as it had since it arrived. Figured it might be me, so continued for a couple blocks, but no change, so drove back home. Sent a video to an experienced SC owner and he said the clutch cable needed adjusting – clutch not fully disengaging.

Pulled out the Bentley book and the 101 projects book to read up on it. Jacked the car up (for the first time), check the gap between the stop bolt and the large release arm – it was well past 1mm. Loosened the cable housing lock nuts and adjusted the gap between the stop bolt and the lever arm until it was 1.2mm and the feeler could be held in place, but also removed without to much effort. Then tightened the lock nut on clutch cable until the gap was 1mm. There was enough pressure to hold the feeler gauge, but could be removed with similar effort to when it was 1.2mm. Pressed the clutch in several times and re-checked the gap. It had changed several thou, so re-adjusted to get the 1mm gap back. Pressed the clutch a few times again, and re-checked. It was still a little off, not as much, and adjusted again, pressed the clutch several times, and it didn’t move. Put the car down, started it up, first was fine and backed out of the garage. Drove around the block a few times, then for a longer drive the next day. Used reverse twice (to back out of the garage).

Was thinking the problem was solved until we wanted to go for a drive today and reverse was buzzing. Put it into first, still fine, then slowly into reverse… still buzzing. Jacked the car back up and checked the gap. Still 1mm. pressed the clutch to the floor 3 times and re-checked – still 1mm.

Checked the clutch travel distance - 23.5mm. Adjusted the stop behind the clutch to 25mm. Now first and reverse are buzzing – clutch not fully disengaging.

Checked the coupler behind the seats, - set screw is tight as is the bolt. The bushings still have give (pressed in finger nail) so seem fine, no debris in the boot. Bowden tube seems secure - does not move. The roll pin that holds the clutch pedal looks good – front and back.

Starting to wonder about the clutch cable itself, or the clutch release fork as this seems to be a bit of a moving target, but am also recognizing I may have missed something or done something wrong. I am new to this type of work, but work with my hands for a living, so feel I am capable of learning and doing it. Hoping someone can pick up on something I have overlooked or offer a new approach to figuring this out.



here is a photo of what things look like.

Thanks in advance.

Old 06-24-2020, 06:22 AM
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i sometimes find a short video helps of the exact angle you are showing .
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Old 06-24-2020, 06:24 AM
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The first thing I would do is remove the 2 arms off the vertical shaft. The upper one tends to bind on the shaft and doesn’t permit necessary movement. Pull the upper arm and clean the parts with scouchbrite then anti seize lube. Put it back together, reload the cable and spring and set gap.
Now you know the adjustments will respond.
Bruce
Old 06-24-2020, 06:41 AM
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i do not do clutch adjustment like you do or others...one thing you did not mentioned -or is it mentioned in your Bentley -never seen the book-----how is your pedal cluster clutch arm stop?
If the stop is too low it would let you to compress(release) the clutch press plate with the TO bearing.
Ivan
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Old 06-24-2020, 06:42 AM
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the photo was just to show what things look like - as a point of reference for condition etc, not a specific area.
Old 06-24-2020, 06:42 AM
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At 88K miles, maybe you just need a new clutch.
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Old 06-24-2020, 06:54 AM
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well, let`s see you clutch arm with the adjusting screw...on picture above you can tell the clutch is fairly new but also the securing nut(13mm open wrench) is supposed to be on the other side of the arm.By the length of the adjusting screw you can tell how much material you have left on the clutch disc..The nut is later with km or mileage moved where you see it above...so you get extra room for adjustment..

let us see it

Ivan
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Old 06-24-2020, 07:13 AM
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here you can see where the nut should be originally .By the time your clutch disc gets thinner you will not have enough room for the adjustment.So the nut is being moved on the other side of the arm,now you will have about another cc.15K miles to go...
Ivan
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Old 06-24-2020, 07:33 AM
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Thanks Bruce - hadn't thought of that. I did have my son pressed the clutch to the rubber stop several times as I watched the movement from under the car. It seemed fluid and consistent, but maybe that wouldn't show the effects of binding as you mentioned.

Here is a better shot of the clutch arm showing the gap

Old 06-24-2020, 07:35 AM
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Thanks Bruce - hadn't thought of that. I did have my son helping me and pressed the clutch to the rubber stop several times as I watched the movement from under the car. It seemed fluid and consistent, but maybe that wouldn't show the effects of binding as you mentioned.

Thanks for the pic Ivan - that makes sense. Here is a better shot of what mine looks like;
Old 06-24-2020, 07:39 AM
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Quote:
Originally Posted by Flat6pac View Post
The first thing I would do is remove the 2 arms off the vertical shaft. The upper one tends to bind on the shaft and doesn’t permit necessary movement. Pull the upper arm and clean the parts with scouchbrite then anti seize lube. Put it back together, reload the cable and spring and set gap.
Now you know the adjustments will respond.
Bruce
i agree with this .. but be warned .... getting the helper arm off can be a bear.. this was the problem with mine as it became seized on the shaft and made the clutch impossible to adjust .
it is held in place with a roll pin to stop it dropping down ( which i personally feel is unnecessary ) . I had to drill that bastard out to get it out.. then reinstalled with two seals, one below and one above after putting spline grease on it.

no problems since.
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Old 06-24-2020, 07:43 AM
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Thanks Bruce - hadn't thought of that. I did have my son helping me and pressed the clutch to the rubber stop several times as I watched the movement from under the car. It seemed fluid and consistent, but maybe that wouldn't show the effects of binding as you mentioned.

Thanks for the pic Ivan - that makes sense.

thanks for the warning about the helper arm being a bear.
Old 06-24-2020, 07:46 AM
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Mods, can you help my friend Konrad get his replies through? He's a good friend of mine and really trying to share some info here to fix his problem.
Old 06-24-2020, 07:36 PM
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Could be the clutch release fork on its death throes.

The tranny has openings on the side you can look thru to see if the bearing is releasing.
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Old 06-24-2020, 07:44 PM
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When you say"buzzing" do you mean grinding?
Old 06-25-2020, 05:42 AM
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Originally Posted by gomezoneill View Post
When you say"buzzing" do you mean grinding?
It is not really grinding (I have done that before too, but more a buzz... sounds like the clutch is not disengaging as opposed to grinding, where it is sloppy shifting (if that makes sense).
Old 06-25-2020, 06:44 AM
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clutch issues: the long way around.

I have found that an out of adjustment shift coupler (in the tunnel) is often the culprit in the car not behaving properly. When you get in there, have all your plastic pieces on hand for the shift rod and ball cup bushing, these small sleeves are critical. You tube has videos on shift coupler adjustment.
Old 06-25-2020, 10:44 AM
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I, too, am confused with "buzzing." Grinding happens when there are issues with getting the car into a gear. Most noticeable when starting from a stop, because while moving at least all the parts are rotating, even if not at the desired speeds. And clutch maladjustment can, indeed, lead to grinding.

Good catch, Iceman. I thought the threaded bolt part looked too long, but that must be because of where the nut is.

If the vertical splined shaft in the transmission is stuck/binding, you have to remove the transmission (or at least the engine) to deal with it, don't you? The roll pin holding the throwout fork to the shaft vertically isn't accessible from outside of the transmission housing.

There is a second spec for setting the clutch (3d spec, including up at the pedal stop): The distance between the hook end of the cable and the threaded Bowden housing or somewhere in that area - that's why the end of the housing is adjustable in its holder with the two nuts. I assume you found and followed that also? I once had this all screwed up, and was chasing my tail with other adjustments until someone looked and said that looked wrong. Though your picture of that part doesn't look unusual.

Borescopes these days are cheap, all you need is the mini camera on the end of a cable which you can plug into a laptop (or maybe phone) and you can look inside the clutch bell housing through various holes (you can make a large one by removing the starter, but there are others0 to see if anything looks amiss there. One thing which can go wrong over time is the throwout fork - parts of it can bend. Don't know if you could recognize this with a borescope, but handy to have and if it precludes R&Ring the drive train, worth it.
Old 06-26-2020, 05:02 PM
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^^^ Usng the borescope to inspect the fork while someone operates the clutch is a great idea.
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Old 06-26-2020, 05:26 PM
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Konrad.as the boys said inspect if you can the TO bearing..but..your Omega spring is dry ..while you have to remove the little finger and the clutch arm lubricate the shaft too.Do you have the 2 rubber seal-o rings on the shaft?.On your pic it seams to me that the play space is too big.....

Ivan
looks like your clutch is fairly new..

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Old 06-27-2020, 01:16 AM
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