Stuck Clutch.

[My Dads Car]

3 minutes ago, Z320 said:

What Stuart and I point on about the clutch slave (piston full in for bleeding)

I have not seen discussed at any TR forum, while it is IMO specilly for TR6 very interesting.

They have the most problems with the clutch (because of further construction problems too).

On this lovely slave master all air is easy to bleed out on top!

Sadly it is from a Mazda MX5 (Miata) and not from a TR 😂

The TR clutch master is 1" in diameter and the drilling for the nipples go in angular and end the half way to the center, 1/2" in distance.

All on top of the red line (slightly angled), 1/4" high, can not be bleeded with the slave installed in the bracket.

With the piston "in any position" (TR6, "self adjstabel clutch") more air remains in the slave,

with the pistion fully in (arrow)via the adjustable push rod less air remains in the slave.

Don't forget to adjust a free play of 0.1" after bleeding.

Ciao, Marco

Thank you very much, Marco.

I just tried it again after re-bleeding with the slave piston pushed in. Once the engine heated up enough to trigger the electric fan I shut it down, engaged the shift lever in second gear, depressed the both the clutch and brake pedals fully, and turned the key. After a slight "lurch" forward with the engine seeming to stall, the motor turned over and the car idled. When I slowly released the clutch the car began to move forward with no sliding noise. All good so far- right?

However, when I tried to push the clutch back in and get out of second gear the shifter wouldn't move at all. I shut the engine down and tried to move the shifter from second to neutral - no movement possible. I got out of the car and rocked it back and forth once and then I was able to move the shifter smoothly through all gear positions. This happened three times: each time the shifter was stuck even just a slight movement of the wheels freed things up.

I am trying to do the bleed by myself- I am beginning to see that's where the problem is... The clutch pedal just doesn't feel the way I remembered it. I will ask a neighbor for help soon!

Thank you- Jamie

[Charlie D]

Doesn't all this point to a problem in the gearbox or overdrive?

Something jamming up internally which can only be "un-jammed" by driving the gearbox through the back wheels (The rocking backwards and forwards.)

 

[tim hunt]

15 hours ago, Z320 said:

What Stuart and I point on about the clutch slave (piston full in for bleeding)

I have not seen explained in detail at any TR forum, while it is IMO specilly for TR6 very interesting.

They have the most problems with the clutch (because of further construction problems too).

On this lovely slave master (new/old) all air is easy to bleed out on top!

Sadly it is from a Mazda MX5 (Miata) and not from a TR 😂

The TR clutch master is 1" in diameter and the drilling for the nipples go in angular and end the half way to the center, 1/2" in distance.

The drilling for the bleeding nipple does NOT end on the top!

All space above the red line (slightly angled), 1/4" high, can not be bleeded with the slave installed in the bracket.

With the piston "in any position" (TR6, "self adjstabel clutch") more air remains in the slave,

with the pistion fully in (arrow)via the adjustable push rod less air remains in the slave.

Don't forget to adjust a free play of 0.1" after bleeding.

Ciao, Marco

I see your 0.1" Marco and raise you to 0.3" See attached Service Bulletin from Leyland Triumph Inc. dated 15th December 1966

Tim

[BlueTR3A-5EKT]

29 minutes ago, tim hunt said:

I see your 0.1" Marco and raise you to 0.3" See attached Service Bulletin from Leyland Triumph Inc. dated 15th December 1966

Tim

I don’t get that.  TR4 A has a solid non adjustable push rod.   Or am I missing something.

 

[tim hunt]

57 minutes ago, BlueTR3A-5EKT said:

I don’t get that.  TR4 A has a solid non adjustable push rod.   Or am I missing something.

 

Not so Pete - the slave cylinder push rod on my 4A is adjustable for length, as per p2.106 of the WM (attached) as referenced in the Bulletin.

Tim

TR4-4A Workshop Manual p 2-106.pdf

[Z320]

As I know there is no 4A workshop manual, there have been only some additional sheets.

My TR4A came with adjustable push rods on master and slave, and this is what I recommend everybody, also TR6s.

For 0.3" I have no explataion. If you know what you are doing and check it from time to time you can adjust zero gap.

A slightly preloaded release bearing (always spinning) IMO is better than one stopping and accelerate in a twinkle of an eye.

Or you fit the return spring the wrong direction, have a gap anyway and let the release bearing spin (Joachim Gunst system).

BUT this is what I can't recommend everybody, because not everybody knows what he is doinig (sorry, this is true).

Ciao, Marco

 

[My Dads Car]

Ok - I tried bleeding the clutch hydraulics again. The car has no interior so I feel I have some room for creativity regarding doing the process alone.

I attached a hose from the bleed nipple to a container with fluid in it. I cracked open the nipple about 1-2 flats and, using a piece of lumber I cut to size, pushed the pedal to the floor and wedged the other end of the lumber against the back "seats." I made sure the master cylinder reservoir was full then moved to the slave. I was able to get the piston all the way back - and I did see some air come through - then I closed the bleed nipple, took off the lumber of the pedal and topped the master reservoir again. I pumped the clutch pedal about 20 times, it felt pretty good and no air bubbles rose to the surface. 

I then pushed the car out of the garage and let it run for about 5 minutes so it was decently warmed up. Of course, the car was in neutral on startup. When I tried to engage any gear... no luck. Something is preventing the shift lever from moving when the engine is running even when the clutch pedal is pushed down. Of potential interest is the fact that when I had the pedal pushed down I recognized the "whirring" sound that came from the clutch/transmission (only with the clutch depressed, not in normal driving position) that I used to hear when the car was operational..

The attached video shows the subsequent attempt: the raised two fingers in my right hand represent the shifter in second gear while the downward pointer finger on my left hand represents the clutch pedal being depressed. You can see the result. When I pointed my finger up on the left hand was when I released the clutch. As the car started to move I tried to re-engage the clutch with no effect... As the back wall of my garage loomed ever closer I turned off the engine and came to a stop... Thankful I didn't run into anything....

Apologies for the long-winded explanation... I truly appreciate everyone's comments and observations!

Here's a link to YouTube so you don't have to download the video:

https://youtu.be/E1Bl9X_Yq1s

-Jamie

IMG_3174.mov

Edited August 13 by My Dads Car

[Z320]

Hi Jamie,

you had the gearbox in pieces and the selector shafts out?

 

[My Dads Car]

Just now, Z320 said:

Hi Jamie,

you had the gearbox in pieces and the selector shafts out?

 

Hi Marco,

Yes, the transmission was rebuilt by someone else. The same person who rebuilt the engine. I lack both the tools and mechanical expertise to do those jobs myself!

[Z320]

Sorry,

now I‘m with Charlie, but never had bad experience with that.

[RobH]

To summarise from your posts Jamie ,   this is my take on it:

1/ With the engine off, you can select and de-select all gears.

2/ With the gears in neutral you can start the engine but cannot then engage any gear.  You can hear the release bearing turning ( the whirring).  

3/ You can select a gear and start the car provided the clutch pedal is down, but you cannot then get it out of gear unless you stop the engine. 

4/ With the engine running and the car in gear, with the clutch down the car does not move (as long as the brakes are on ?) . 

5/ if you then let the clutch up the car will move but you cannot disengage the clutch again.   

(I'm not clear in 4 what would happen if you let the brakes off while still holding the clutch down - does the car creep forward ?). 

If this is all correct, it would seem to confirm that  the fault is not in the gearbox; it is something to do with the clutch operation.  I say this because the difference happens when the engine is running If it was just a gearbox problem that could not happen. 

The clutch is not stuck but you are getting severe clutch 'drag' even with the pedal down, which is loading the input shaft and 'winds up' the gearbox internals because the wheels are not moving. When you stop the engine the load persists, and can only be released by 'rocking' the car to move the wheels, which allows the gearbox internals to relax.  

As Marco keeps saying,  air in the hydraulics is the number one suspect for reducing the push-rod stroke but your video of that suggests the stroke available might actually be enough.  

If further bleeding does not help, one thing you could try is to temporarily move the pushrod clevis to the upper hole in the lever.  It will make the pedal feel very heavy but If it cures the problem then there definitely is not enough stroke.  However if it makes no difference there has to be something else going on in the clutch mechanism.  

 

 

 

Edited August 13 by RobH

[Z320]

2/, the whirring, I expect is the gearbox ingoing bearing spinning

[tim hunt]

2 hours ago, Z320 said:

As I know there is no 4A workshop manual, there have been only some additional sheets.

My TR4A came with adjustable push rods on master and slave, and this is what I recommend everybody, also TR6s.

For 0.3" I have no explataion. If you know what you are doing and check it from time to time you can adjust zero gap.

A slightly preloaded release bearing (always spinning) IMO is better than one stopping and accelerate in a twinkle of an eye.

Or you fit the return spring the wrong direction, have a gap anyway and let the release bearing spin (Joachim Gunst system).

BUT this is what I can't recommend everybody, because not everybody knows what he is doinig (sorry, this is true).

Ciao, Marco

 

Quite right Marco, my WM was gifted to me by a customer many years ago and is entitled TR4 on the cover. It contains several supplementary pages dated August 1965 to cover detail changes on the 4A as attached.

Tim

WM TR4A supplementary pages.pdf

[Lebro]

Agree with Rob H above, it does not sound like a gearbox problem.

One other thing to consider - the spigot bush in the flywheel, could it be siezing on the input shaft.
If not then there is something wrong with the clutch, or release system.
When pressing the pedal does it feel right ? the pressure required to push it down should increase slightly to start, then get easier as the diaphram flexes.

Bob

[My Dads Car]

2 hours ago, RobH said:

As Marco keeps saying,  air in the hydraulics is the number one suspect for reducing the push-rod stroke but your video of that suggests the stroke available might actually be enough.  

 

Thank you, RobH, for the spot-on summary of my situation! With regard to your questionnabout the brakes being applied in your point four: the video I shot was without any involvement of the brakes as that technique was more from a "frozen clutch" diagnostic than a hydraulic issue.

59 minutes ago, Lebro said:

When pressing the pedal does it feel right ? the pressure required to push it down should increase slightly to start, then get easier as the diaphram flexes.

 

I honestly don't think it feels right, but the car has been off the road since February 2022 so I am not sure I fully remember how it's supposed to feel. I wonder if the optimist in me is saying "Yea, that's how I remember it feeling" after I bleed the brakes, when, in actuality, I should be a bit skeptical... Honestly, I seem to recall the pedal traveling further than it currently does, and is lacking that initial resistance, then easing you describe above

I'm wondering if the "home-brew/solo" method of bleeding the brakes is at the root of the problem? While I, on the surface, get the desired results (in theory) I am wondering if in order to push the pedal down with the lumber using my arms I am opening the bleed valve on the slave cylinder so much that it allows some air back in through the threads? I have tried opening the bleed valve less, but then the force required to push the pedal all the way down with my arms is too much. It's usually a two-person job, perhaps for a reason?

I should be able to recruit some help over the weekend to do a proper bleed... Continuing what I am currently doing seems an exercise in futility.

Thanks for all comments- Jamie

 

[RobH]

1 minute ago, My Dads Car said:

With regard to your question about the brakes being applied in your point four: the video I shot was without any involvement of the brakes

That may be an important symptom.

If the clutch was not disengaging properly initially , the car would creep forward when you start the engine even with the pedal held down.   It means the clutch has got sufficient travel to operate properly to start with, with the engine off.  It also means the spigot cannot be seized on the input shaft.    It would seem the drag starts only after you have released the clutch pedal when the engine is turning, so that effectively you cannot de-clutch again.  

[My Dads Car]

24 minutes ago, RobH said:

That may be an important symptom.

If the clutch was not disengaging properly initially , the car would creep forward when you start the engine even with the pedal held down.   It means the clutch has got sufficient travel to operate properly to start with, with the engine off.  It also means the spigot cannot be seized on the input shaft.    It would seem the drag starts only after you have released the clutch pedal when the engine is turning, so that effectively you cannot de-clutch again.  

So, does this point to a hydraulic issue even more directly?

[RobH]

8 minutes ago, My Dads Car said:

So, does this point to a hydraulic issue even more directly?

On the contrary - it tends to suggest the hydraulics are OK at least to start with.  I suppose there could be  air trapped which then limits travel on subsequent operations  but hydraulics usually work the other way, getting better if you pump the pedal.

It might be worth trying the trick where you push the pedal down and hold it down overnight with a wooden brace.  that sometimes works with soft brakes. 

 This fault is a real puzzle.

[stuart]

Unfortunately the cheap steel bleed nipples are a very slack fit in the cylinders an so unless you can employ a second person and do the “Down up down up” rhythm where you can shut and open the nipple every stroke it’s really difficult on your own to get rid of all the air, I use the brass bleed nipples to get over just this problem 

Stuart

[Charlie D]

16 hours ago, RobH said:

...which is loading the input shaft and 'winds up' the gearbox internals because the wheels are not moving...

 

Is it worth trying it with the back wheels jacked up (using axle stands) and seeing what happens?

Rob,

When you say " 'winds up' the gearbox internals", surely that points to a gearbox problem. Would that not point to some excess play somewhere in the gearbox/overdrive (does the car have overdrive?)

[RobH]

1 hour ago, Charlie D said:

When you say " 'winds up' the gearbox internals", surely that points to a gearbox problem

No Charlie.   I meant gears in mesh which have a load on the output ( the brakes or the weight of the car)  but which have a  torque load on their input comong from the clutch. The gears are then held together by that torque and are more  difficult to slide out of mesh because of friction. That isn't a fault.  Normally,  de-clutching removes the torque so they become easier to move.

 

 

 

 

Edited August 14 by RobH
multiple typos

[Charlie D]

Ah... OK.

[Ralph Whitaker]

I am concerned about your method of bleeding the clutch. You say you opened the bleed nipple first, then pushed the pedal down and wedged it with a piece of wood. You then moved to the slave cylinder and pushed the piston fully in before closing the bleed nipple. I have used the following method sometimes with success.

First adjust the pushrod on the slave cylinder so it is pushed fully in to the cylinder at rest and take all the free play out of the system,

Then push the clutch pedal fully down and wedge with timber.

Next, at the slave cylinder, attach pipe and place into a jar , and carefully slacken the bleed nipple a little and allow the clutch pressure plate to push the piston back into the slave cylinder, hopefully expelling any air, and lock off the bleed nipple.

Back in the car after making sure the reservoir is full slowly allow the clutch pedal back up.

See if that makes a difference.

If not repeat a couple of times.

Ralph

Edited August 14 by Ralph Whitaker

[My Dads Car]

17 hours ago, RobH said:

It might be worth trying the trick where you push the pedal down and hold it down overnight with a wooden brace.  that sometimes works with soft brakes. 

 

I tried this, no improvement.

Then, after putting the car on 4 axel stands I began to try this method from Ralph Whitaker:

3 hours ago, Ralph Whitaker said:

First adjust the pushrod on the slave cylinder so it is pushed fully in to the cylinder at rest and take all the free play out of the system,

Then push the clutch pedal fully down and wedge with timber.

Next, at the slave cylinder, attach pipe and place into a jar , and carefully slacken the bleed nipple a little and allow the clutch pressure plate to push the piston back into the slave cylinder, hopefully expelling any air, and lock off the bleed nipple.

Back in the car after making sure the reservoir is full slowly allow the clutch pedal back up.

 That pushrod won't budge without the bleed nipple cracked open, at least a little bit... As I was trying to move this I noticed something that may be germane to this situation. After every bleed attempt I am very mindful of the .1" amount of free travel (.3"now?) After every failed attempt at resolving this problem i test the slave pushrod for adjustment. Every time I have done so the piston is now hard against the pushrod, all free play is gone.

I began to wonder if I am using a wrong slave cylinder or rebuild kit, so I removed the slave. Here is a video of what I have:

https://youtube.com/shorts/TvWm0MmaqTQ?feature=share

I measured the bore- it is 1"

Thoughts? Anything I am missing? It looks good to me...

Now that the system is open should I use Ralph's method of bleeding? No resistance now!

-Jamie

Edited August 14 by My Dads Car

[My Dads Car]

Another item regarding the transmission itself.

While I did not do the transmission overhaul myself I did perform one mechanical task. As I was attaching the transmission flange to the driveshaft I noticed a castle nut with no split pin... some quick internet research told me this was very, very bad so I ordered the pin from Moss -was a very tight fit- torqued the nut to what the factory manual indicated and attached the driveshaft.

Could it be I have over-tightened this nut, leading to my shifting problems?

-Jamie