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Clutch Disengagement

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Lately I haven been noticing that it takes an increased amount of effort to shift from gear to gear--up or down--no crunching, no grinding, just resistance. During a drive today I tested the disengagement of the clutch and with the car in first unless I have the pedal hard down against the floor there seems to be a slight but perceptible bit of engagement and the car will creep very slightly ahead on level ground. This suggests to me that the clutch pedal is not being all it can be and while I have not yet been under the car I am wondering if this is more likely to be a hydraulic issue (primary or secondary cylinder) or one involving the linkage--wear on clevis pin, egging out of holes, etc.

What's the best way of diagnosing an issue such as this?
 
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pdplot

Yoda
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Re: clutch [I think] question

On the TR6, lay down on the floor, reach in and remove the cotter pin holding the clevis pin and examine the pin for wear. Mine was worn and will be replaced with a new one sourced from my local Ace Hardware store. For the egged-out hole, I Googled clevis pin and came up with a blog MGA With an Attitude setting forth with pictures how the owner repaired a worn hole by installing a bushing in the pedal. The Healey is probably similar. Mine will hopefully be repaired this week - but not by me.
 

Healey Nut

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Re: clutch [I think] question

Chances are the hole in the slave cylinder rod and the Clevis pin are worn out so you not getting the full benefit of the slave cylinder operation .
get the car up in the air or pull the tunnel and have a look see .
 
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Re: clutch [I think] question

When does the pedal start to engage? There should only be an inch or less of free play in the pedal; if more, it's likely a hydraulics issue.
 

roscoe

Jedi Knight
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If your clutch master cylinder is fastened to the welded on peg that was formerly the pivot point for one of the clutch linkages, be sure it hasn't managed to rotate on the peg. I don't know what the Smitty kit was like when you installed yours but I had to do some home engineering to make sure the one I just installed would remain solidly in position.
 

johnea

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Had exactly the same fenomenon on my MGB. Rebuilding the slave cylinder did the trick. Although clean and dry from the outside, the inside of the cylinder was really dirty.
 
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Michael Oritt
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I jacked up the car this morning and observed the clutch linkage operation while actuating the pedal from underneath. Beyond the initial 1/2" or so of free play at the top of the pedal there was an additional bit of slop caused by the pedal's rotating on the transverse shaft, indicating wear in either the bolt that passes through the shaft or the hole--or both. I did not have time today to do more than tighten down the nut, which eliminated the excess slop and appears to temporarily the problem, though a permanent fix will come from getting a new bolt through the hole. More tomorrow....
 
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Michael Oritt
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Bob--

No, it is hydraulic--actuation is via the clutch connecting lever to a short pushrod to the master cylinder.
 
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Presumably, you don't have the graphite 'donut release bearing, so it's gotta be air in the hydraulics or the slop you already mentioned, or a combination.
 
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Michael Oritt
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More shall be revealed when I drive out the bolt and replace it--hopefully tomorrow.

BTW if you look on p. 47 of the MM catalogue it is pn#25 that activates the pushrod of the clutch MC
 
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pan

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G'day Michael,
At first I ignored your question because I knew you had swapped the Austin transmission for a modern 5 speed, so assumed your clutch release was hydraulic and therefore outside my experience. But your recent comment about the cross-shaft prompted this reply. Many years ago I had similar problems and finally worked out that I was suffering from a loss of travel, that is, the first lever (attached to the inner end of the cross shaft) was not rotating by the same amount as the pedal. When I withdrew the shaft I found that it had split lengthwise and was twisting as the pedal was depressed. I thought this might be a common problem with BN1s & 2s, but I have never heard of another car having the same problem. But it's worth a look!
Cheers,
Alwyn
 
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Michael Oritt
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This morning I drove out the 5/16" bolt securing the clutch pedal to the transverse clutch operating shaft and found that the threaded portion of it ran up and past the hole in the shaft which no doubt contributed a bit of slop to the clutch pedal's effect. I replaced it with a grade 8 bolt whose shoulder comes clear of the pedal where it rides on the shaft and after tightening things down almost all free play in the clutch has disappeared. A test ride revealed that shifting was indeed easier and there was no creep when the car was in gear with the pedal depressed. I plan to rebuild or replace the master cylinder and when I do I will check the bolt that fastens the clutch connecting rod lever to the shaft for proper shank length as well and possibly gain a little more motion.

In answer to Bob's statement/question "So the Toyobox keeps all the wonky hardware of the 100 clutch?" the answer is no--all of rods, levers, etc beyond the clutch connecting rod lever are gone and that lever operates directly on the mc shaft. There are probably other ways to install an hydraulic clutch on a 100 but this is what Smitty came up with when we did the install at his shop in CA. After returning to MD I swapped in a BJ diaphragm clutch for the original spring clutch which made for much smoother and lighter operation.
 

njunear

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I followed this discussion with interest as I had a similar issue with out BT7-II many years back. Much worse, but similar. Shifting into gear after starting the car or from a stop - reverse or first, did not matter - was always accompanied with mild grinding of gears. Was bad enough that I would start the car in gear with the clutch depressed. When it got bad enough that I took the plunge and tore everything down, I pinned the issue mainly on the graphic donut throwout/release bearing. It was worn to the point that the clutch was never fully releasing. And I certainly was not making things any better by starting the car 'in gear.'

I bring this up to also point out how close I was to a catastrophic failure. There was still a tiny bit of material left on the clutch disc before the rivets would have dug in to the flywheel. But the heat from the slipping clutch that the flywheel had developed severe fire cracks - see pics attached.

Turns out all the linkage was fairly good although I did replace both clutch cylinders and clevis pins, the latter just to tighten things up.

Anyone need a good boat anchor?

IMG_6078 flywheel 01.jpg
IMG_6080 flywheel 02.jpg
 
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... In answer to Bob's statement/question "So the Toyobox keeps all the wonky hardware of the 100 clutch?" the answer is no--all of rods, levers, etc beyond the clutch connecting rod lever are gone and that lever operates directly on the mc shaft...

I felt I could disparage the original setup because I have it in my BN2/100M. I thought it would work like crap, but was pleasantly surprised; it actuates almost as smooth as the hydraulic system on my BJ8. I might spring for the DWM upgrade someday.

Michael, sounds like your clutch setup is now similar to the stock braking setup.
 
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