Clutch problems

Last year amongst many other things the TF had a new AP clutch, the new greaseable clutch arm, a new slave cylinder, a new mounting bracket and a new hose/pipe from bulkhead to slave cylinder, I bled the system in about five minutes with no problems. Fast forward to the beginning of July   when due to hip revision surgery my wife was driving over Dartmoor when she became unable to select 1st, 3rd and 5th gears, after getting home I found that we had lost the horseshoe clip that holds the under the gearbox gearchange cable to it's bracket. Another clip was sourced and fitted last week, thinking that must be the end of the problems I was gutted to find the gear selection was not allowing and gear selection with the engine running but easy with it stopped. The problem is that the clutch is not fully disengaging with the pedal pushed fully to the bulkhead, so today I have fitted a new seal kit in the master cylinder and bled the system but it is still not fully disengaging. Today I have put nearly a litre of brake fluid through the system both with the easi bleed but also   with one person operating the cutch pedal and the other on the bleeder valve. There is virtually no wear on the master cylinder clevis pin, the one on the slave is virtually new. Other than the flex on the slave cylinder mounting bracket which is more than I expected, does anyone have any good ideas why the clutch is only just disengaging?

Possible worn release bearing? Was there any noise from the clutch? Sometimes you can hear a rumbling sound which goes when you depress the clutch pedal.

I hope not about 3,000 miles on a new clutch and release bearing would be almighty bad. There were no untoward noises, just a sudden inability to select all the gears where the gear-lever is pushed forward due to the loss of the horse shoe clip. It is possible that the inability to disengage the clutch put more force into the gear change cables which in turn caused the horse shoe clip to fail. However this doesn’t explain why I cannot get disengagement now. 

As I read this it seems to be a complex issue. Initially you could not select those gears that needed a forward motion of the gearstick, but the clutch was fine.
To investigate and resolve this you looked underneath and discovered a clip was missing (I am not familiar with that clip I have renewed the bell crank). You renewed the missing clip. But at that stage did not identify a reason to explain how that clip was lost. (Am I right so far?)

From what I read it sounds as though you then had a problem with selecting any gear and opted to re-bleed the hydraulics. Correct?
Executing further investigations it seems that you can select gears whilst stationary with engine off but not whilst the engine is running or when underway. Am I right in thinking that gear selection is inhibited for all forward and reverse gears when underway or just with the engine idling or both?
Please confirm that you can’t select any gear if you are stationary but with the engine running..
If that is the case it does appear to suggest that there is something wrong with clutch operation. Is it possible to see and monitor the clutch release shaft movement with and without the engine running.
Logically it would seem that something has failed within the release bearing arrangement. If the shaft is not responding to pedal movement then the bleeding action or one of the cylinder seals must be at fault.
What is still a puzzle is why the u clip was lost. Could that be down to a warn engine restraint acting in a way that put such a load on the cable that it forced the clip to fail?
After renewing the clip what was the consequence? Why if you could find 2,4 and presumably reverse what made you bleed the system as it must have been ok crossing Dartmoor if you could get 2&4. Renewing the clip alone surely can’t have changed that situation?

 

Thinking about this some more I’m still unclear why the u clip failed, why changing gear after renewing the clip didn’t improve.
it seems that something directed you to clutch operation and a seal was renewed.
So, can the movement of the clutch operating linkage be observed and if it less than expected or doesn’t continue to move as the pedal is pressed it points to seal efficiency perhaps. Asking the obvious : is the seal that you replaced the right one, fitted correctly and in the right way around. If all those answers are ok then the questions tend to cast doubt on the cylinder conditions of both master and slave. 
You mention the hose condition. If that is failing obviously that would explain the problem.
if the linkage movement is continuous then it does unfortunately point to release bearing or cover plate issues in my opinion.

There is still the question as to why the u clip became lost. I’m still puzzled by why gear change did not return to normal after renewing that clip.
Did you drive home using 2nd and 4th only after encountering difficulties in Dartmoor?

Delbourt, okay, we were driving across Dartmoor when my wife suddenly found it impossible to select , 1st, 3rd, and 5th gears but 2nd, 4th and rev not easy but doable whether the engine was running or not, due to the rain I did not investigate until we were at home. The following morning with my wife moving the gearlever I could see that the cable that runs underneath the gearbox was free to move in its support bracket due to the horse shoe clip being missing, You will have exactly the same arrangement even if like me you have the Mike Satur bell crank like I have. Having obtained and fitted another clip the gearchange was now perfect with the engine off but still baulking when the engine was running. Like a lot of other owners I has always needed the pedal pushing right down to get the clutch to disengage but now it wasn't disengaging at all. The next step was to bleed the clutch which just enabled me to change gear with the engine running. I decided to order and fit a master cylinder seal repair kit, this was fitted yesterday and there is still no change. You are quite correct that replacing the clip should have reinstated it to as before but when that failed to materialise the obvious next step was bleeding the clutch. Yes I can see the slave cylinder both the pushrod moving and the bracket flexing. 
Having thought about it overnight I am now inclined to think that like Pharg55 suggested the fault lies with the clutch/release bearing. I wonder if the release bearing did fail while driving then the increased pressure when changing gear caused the clip to break or fall off?

In truth I have more experience with MGB clutch systems than the MGTF but the concepts are similar. After a lot of research (and hitting lucky when I came across someone with access to OEM drawings) it became clear that the whole system was designed to work "as one". In other words you needed maximum pedal travel, fully functioning master and slave cylinders, no excess freedom of movement in the slave push rod, and good pivot bush tolerances in the fork arm before the release bearing would push the cover plate the "designed amount".
I suspect the same is true for the MGTF system.
When testing hoses in a previous life at periodic intervals for safety compliance (not as a manufacturer but as a user) the theory was that under pressure the hose would extend in length. If it reduced in length it was indicative that the braid was failing or failed based on simple science. So if it looks like your hose is shrinking in length and bulging then that could be an explanation as to why the release bearing is not depressing the cover plate (the displaced volume is bulging the hose rather than pushing the cover plate).
If there are odd audible noises other than the "baulk rings protesting" when you press the clutch pedal but not attempting to change gear I would try and establish if the action of pressing the clutch pedal is delivering the correct movement of the actuating rod that goes into the bell housing. I have no idea what that should be. Perhaps someone on here might know that. If when you press the clutch pedal (without changing gear) and there are odd noises that would tend to suggest the release bearing.
If you are an MGOC member there was an article earlier in the year describing how someone renewed the bushes in a stabiliser bar that apparently ties onto the sump and connects to the sub frame ~ I have not looked at this on mine. If that is worn out on yours it might be a reason for the engine to move a bit leading to a situation that over tensions the gearchange link cables and breaks the u clip. I don't know if that is possible but I think it would be good to understand why that clip became lost. 
Surely if the clutch failed whilst trying to change gear it would damage the gearbox components and not the gear linkage.
To my way of thinking the reluctance to explore renewing the release bearing etc is understandable. I think i would be more inclined to explore renewing master and slave cylinders simply because damage to the bores of those can't be ruled out and loss of efficiency will translate into less movement of the release bearing. But it is only a suggestion. If there is unusual noise when stationary with engine running and just pressing the clutch pedal I'd say the problem is in the bell housing.
FYI ~ I too have a Satur bell crank.
 

Other than having to change the gear cables, which still haunts me at night, cold sweats etc, I’ve never had any concerns with gear changing. I have fitted a spacer between pedal rubber & pedal to lift it to the brake pedal hight but other than that & dribbling machine oil onto the clutch release shaft, when “I’m in that vicinity”,all has been well.
However there are two upgrades, one being the Satur bell crank, the second is the slave cylinder brace.
Can anyone explain what the advantages are of these modifications, the brace is to reduce lost motion, which is fine but how do the advantages of these modifications manifest themselves?
M

I have had another look at it today and have decided to get the slave cylinder brace before I do anything else. It is now just driveable but due to a bit of clutch drag it isn't perfect. I am still astonished as to how much the slave cylinder bracket moves backwards when the clutch is depressed, If the bracket stops all rearward movement the I am sure that I will get good disengagement.. The downside is that MG Mania are not answering there phone and as yet have had no reply to an email sent five hours ago. Mike Satur's bell crank only improves the gearchange by having metal ball joints instead of plastic ones. Although others might disagree I wouldn't do it unless I was replacing the original plastic ones, £42 against £24 isn't quite as bad then.

When I got my TF the gear change was "diabolical". I started with the bell crank and that made some improvement. Not long after I had some other work done by a garage. In doing that they also inspected the gear change and replaced a missing part under the gear stick that had been "botched" in the past when under different ownership. Fitting that made a huge difference.

I can understand that it might be desirable to add extra bracing. But on the other hand why is that necessary now? What has changed since before the Dartmoor trip?
As the slave is visible under the engine cover I'm not about to rush out and look at that situation. I presume you are suggesting that there is loss of potential thrust bearing travel as some of the mechanical advantage is taken up by the movement of the slave cylinder itself. If so it does make sense to brace it. But why now is still a mystery as is the loss of U clip.
It will be interesting to hear what you experience once the restraint is fitted. Please keep us informed.
 

Thank you gentlemen I am clearer now on both counts. On the bell crank, you say the difference is in the plastic snap in joints, rose joints are substituted. A little bit of engineering would resolve that. The brace situation is harder to pin down as I can’t operate the pedal & look as what’s going on in the depths.
There was a YouTube video on the brake servo brace which adequately illuminated what I had overcome after I’d made & fitted one, my guess is YouTube will furnish me with one for the clutch.
Again thanks & much as you will no doubt keep us informed, I too will throw my twopeneth in, as & when.
M

While I have been googling to find answers I came across a thread on another forum where someone had  one of these clips break, someone else said that they rust and eventually become brittle, nobody knows if mine became thin with rust and snapped or whether it failed for another reason.  The gearchange has always been a bit odd, you needed to be firm and decisive with the gear lever, if you were like that it was good but if you dithered it would always tend to baulk. To be fair I have only driven it once or twice since the beginning of February, since then we spent nine weeks in NZ and Oz followed almost immediately by my hip revision surgery which prevented me from driving until last Wednesday. In the meantime my wife has been using it almost daily until we lost or broke the clip. She has never complained about the gearchange other than it was "stiffer" than she would like. I am going to pursue the support bracket in the hope that will solve the problem. I have found the following this afternoon on the MGOC website;
"The poor design of the MGF & MGTF clutch slave cylinder mounting bracket allows for flexing of the slave cylinder body when depressing the clutch pedal, reducing the throw of the clutch arm and making gear changes less smooth. Over time the original mild steel locating bracket can fail preventing disengagement of the clutch. MGOC Spares is pleased to offer a Clutch Slave Cylinder Support Bracket, manufactured in the UK from stainless steel and designed to reinforce the slave cylinder location by securing the slave cylinder to the gear box bell housing. Supplied complete with stainless fixings and instructions".
And this on the Elise parts website; https://www.eliseparts.com/shop/gearbox-drivetrain/clutch-slave-cylinder-support-k-series/  It is interesting that they insinuate that 40% of the travel is lost.
The problem is that it doesn't fit cars with a PRT so I may have to make one up myself.