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The clutch that won't disengage.


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I have just finished rebuilding the hydraulics on my 3A (new pistons and seals in the callipers and new seals in the master cylinders.)  Filled up with silicone fluid and bled everything through.  Brakes seem OK but clutch won't disengage.

 

This could be as a result of something I have done, but can't think what.  When I press the clutch pedal the slave cylinder pushrod moves back about 1/2" (and the bracket moves forward about 1/4") but clearly not enough for the clutch to disengage.

Given that it all worked when I took it apart a couple of months ago, I am beginning to suspect that the clutch has seized or frozen.  Is this likely?  The car has been outside all the time.

 

I have tried to free it by putting the rear wheels on stands, starting in gear and hitting the brakes whilst the clutch pedal is depressed.  All I achieved was some violent stalling! (like I said, the brakes seem OK)  I have even tried disconnecting the pushrod and pulling the clutch lever back with a pulley hoist hooked onto the chassis, but the clutch still doesn't seem to disengage.

 

 

In trying to get to the bottom of all this, I have discovered that:

1. My clutch master cylinder is smaller diameter than standard (5/8" as opposed to 3/4")

2. The slave cylinder bracket does not have a stay as shown in the manual which is probably why it moves forward.

3. The slave push rod is not adjustable.

 

Clearly none of these helps the situation, but it did all work before.  

 

Can anyone tell me how far the slave cylinder pushrod should travel, which would be a useful check?

 

What does the other end of the bracket stay fix to?  All of the manuals and parts catalogues only show the cylinder end.

 

Anyone got any other ideas....please!  

 

I would dearly like to get the **** thing going so that I can get it to a friend's garage where I can work on it inside.

 

 

Dave

 

:(

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Dave, the first thing to do is to fit the stay to the bracket, if not there is no way to continue. The bracket probably starts moving as soon as the clutch springs are loaded, in this case your 1/4 gain would be sufficient to release the clutch disk.

The stay is mounted under a bolt holding the oil sump, very simple.

The diameter of the main piston is bad news also, but I do not know if it's too small do release the clutch. Good luck

Jean

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Go with Jean's suggestions.  But there is a 1/8" thick flatwasher or spacer that goes between the stay circular end and the flange for the sump (oil pan) bolt.  This is to clear the rim surrounding the flange on the sump.

 

If you don't have any adjustment on the output rod for the slave cylinder, it may be from a TR6.  The adjustable ones with the threads for the early TR's and with the stop nut can be made up easily if you don't have one available.  The manual explains how to set the correct gap.  Do you have the end attached to the bottom or the center hole on the lever arm coming down ?  The manual says to use the center hole.  I have always used the bottom one.  More motion at the bottom means less travel for the throw-out bearing inside.

 

You don't say if you had your clutch apart.  Did you ?  Did you put the clutch lining back in the correct way - or did you by chance reverse it ?

 

The throw-out bearing may be jammed.  Or the pins (ears) on the yoke that moves out the throw-out bearing may have flats on them.  Rotate these or change them.  Is it possible that these pin-ears are not in the groove that moves the throw-out bearing forward ?

 

Let us know what you find.

 

Don Elliott, Original Owner, 1958 TR3A, Montreal, Canada

 

 

 

I think that the 5/8 dimeter master cylinder should be OK.

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Don and Jean

 

Thanks for the comments.

 

I will fit a stay this weekend and see if I get anywhere.  

 

I haven't had the clutch apart, only the hydraulics and what is really bugging me is that it all worked (albeit with the occasional "graunch") before!

 

The push rod clevis pin was in the lower hole of the operating lever.  I did try the middle one but with no obvious improvement.  In addition, the push rod didn't line up too well with the middle hole.

 

If anyone can bear to go out in the cold, I would love to know how far the pushrod needs to travel.

 

Will keep you posted.

 

Dave

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My TR3A is in my nice warm dry garage under the house, but it is under its cover for the winter and I can't move it or lift it because I need all the rest of the space for TS 81551 L that I'm restoring.

 

But I can guess that the slave cyl push-rod moves out about 1/2" to 1" when I put my foot on the clutch pedal.  If you disconnect the clevis or the rod from the lever and ask a friend to push on the clutch petal, check that the travel is all the way.  The stroke of the piston in the slave cylinder is about an inch and with no resistance, it should move about an inch.  Be careful if you really do have a TR6 clutch slave cylinder, the piston and push-rod may pop right out.

 

Don Elliott, 1958 TR3A, Montreal, Canada

TR Register member since 1987

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The distance the clutch slave should move is all to do with the volume of fluid you move when you press the clutch pedal. The Pi r squared calculation  multiplied by the stroke of the master cylinder and the the slave should tell you if you have any lost travel due to air.

 

The smaller diameter master cylinder will reduce the movement of the standard slave cylinder. I suggest that you move the push rod on the slave closer to the pivot on the gearbox.

 

I agree that the stay is important, Triumph did not fit bits for fun. The TR6 bracket is different and is far thicker.

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My clutch wouldn't disengage, but that was after a long period stood in the garage..... had to do some hair raising things like jacking up the back end and running the car... then repeatadly engaging and disengaging the clutch... thank god it didnt fall off the axle stands... eventually there was a loud bamng, and the clutch worked normally...

 

:blues:

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Thanks Jean.

 

where else could I have found that out so quickly!

 

I am hoping that a second bleeding and the installation of a stay will sort out my problem.  However, I still have a nagging suspicion that the clutch has somehow seized or frozen.  We shall see!

 

Dave

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Thanks Jean.

 

where else could I have found that out so quickly!

 

I am hoping that a second bleeding and the installation of a stay will sort out my problem.  However, I still have a nagging suspicion that the clutch has somehow seized or frozen.  We shall see!

 

Dave

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  • 2 years later...

Just picking up a post from 2003 .... does anyone have a solution to a clutch that doesn't actually engage at all?

 

It did 3 months ago when I drove it into the garage ... now nothing at all. It just grinds! I've tried everything I can think of aside from taking the thing apart.... but does anyone have any ideas?

 

Many thanks

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<font color='#000000'>

I am hoping that a second bleeding and the installation of a stay will sort out my problem.

However, I still have a nagging suspicion that the clutch has somehow seized or frozen.

</font>

 

If the pushrod moves back by ½", surely that means that the clutch is moving and not seized?

(Yes, it could be stuck on, but that's not "seized")

 

Not suggesting for a moment that you're dumb enough to fall for such obvious oversights,

but I am speaking from experience!

 

Make sure the bleed nipple is at the top! (bottom would be much more convenient, wouldn't it!)

Make sure the slave cylinder is fitted to the correct side of the bracket.

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One way to free a seized clutch is to put the rear of the car securely up on a pair of stands and then wind up the rear brake adjusters until they are solid and locked on then warm up the engine for a good half an hour run time until temperature is up to normal , then switch off and allow the heat to soak through everything for about ten minutes. then put your foot hard down on the clutch and put the car into second gear and then start the engine. It may take a couple of attempts but this method has worked for me most times even on clutches that have been frozen up for years. Obviously you will need to make sure that you do have movement on the slave clylinder push rod first although as little as 5mm will give enough to disengage the clutch.

Stuart.

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Could it be that the pin securing the release fork to the operating shaft has sheared?

 

Hence outside bits moving but clutch mechanism inside bell housing does not.

 

Good shout Captain.

Dave

The little access panel at the front of the Bell Housing may allow you to see if the shaft is moving but the clutch fork not!

Unc

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Thanks for the replies, but I solved this three years ago. As far as I remember, it turned out that the clutch plate was so worn that the rivets were locked into the recess in the flywheel! DPO strikes again. I changed the clutch and have had no problems for the last 18,000 odd miles. The reason that the thread has reappeared, is that Ale Pie is having the opposite problem.

 

I'm afraid that I can't think of an answer to his problem unless the clutch plate has seized on its splines.

 

Dave

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Could it be that the pin securing the release fork to the operating shaft has sheared?

Hence outside bits moving but clutch mechanism inside bell housing does not.

In a previous post, on depressing the clutch, it seems the lever moved ½" and the bracket moved ¼".

 

I think if the pin had sheared, there would be no resistance and the bracket wouldn't move.

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One way to free a seized clutch is to put the rear of the car securely up on a pair of stands and then wind up the rear brake adjusters until they are solid and locked on then warm up the engine for a good half an hour run time until temperature is up to normal , then switch off and allow the heat to soak through everything for about ten minutes. then put your foot hard down on the clutch and put the car into second gear and then start the engine. It may take a couple of attempts but this method has worked for me most times even on clutches that have been frozen up for years. Obviously you will need to make sure that you do have movement on the slave clylinder push rod first although as little as 5mm will give enough to disengage the clutch.

Stuart.

Methinks this is a little too vicious. I usually jack up the rear wheels, start in gear, then rev up and brake, many many times.

 

If that doesn't do the trick (after ½ hour) then HEAT is the most important factor.

 

Last time I had this problem, I actually drove my car round and round with the clutch siezed, accelerating

and slamming the brakes on. Even 1 hour of that didn't do the trick. I had to remove the battery to

re-charge it, when I put it back in 2 hours later, the clutch freed like it hadn't been stuck.

 

HEAT, patience and MORE heat. Next time I have this problem, I'll run the engine 'til it's almost boiling,

wait 1 hour, do it again, then once more, THEN I'll try the clutch.

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i know its a different car but i had a fiesta with a siezed on clutch, i just drove it around late one light untill it pinged free, you can change gear without using the clutch if you get the revs just right, sounds agresive but its the easiest and cheapest thing to try first

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