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MG Midget and Sprite Technical - 1978 Midget Clutch Change
|I'm a recently new midget Owner looking for a bit of advice. Ive been having problems with (I believe) the clutch. Whilst driving around Oxford last week I got stuck in second gear. No amount of effort moved the gear stick which was held solid. Turning off the engine I was able to get all gears, but nothing when the engine is running. I managed to get her home, and having left her sitting for a week, I tried again. Now, I can just about the forward gears, although not with ease, but have no reverse gear. Reverse crunches and rattles but wont go into gear. I have checked the hydraulics reservoir and it's full and I can't see any leaks anywhere. Anyone have any idea what might be causing this? The same happened a few months ago, but a specialist managed to get it working again, but doing some work, (he said) on the hydraulics. Is it worth just changing the old clutch instead of tinkering? Can you change the clutch without lifting the engine out?|
Any help or advice would be greatly appreciated
|There will be some real experts along soon to give you advice, I am sure but in the meantime to answer a question:|
Unfortunately the engine and gearbox must both be removed to get at the clutch so hopefully the problem will be with the hydraulics.
If there are no leaks and the reservoir is full then the only thing that would stop the clutch from working, apart from a damaged/displaced actuator rod, would be air in the system due to damaged seals.
Have you tried pumping the pedal a number of times to try to build up pressure and then trying to select a gear?
You might be able to have a friend look to see if the clutch slave cylinder is moving the pushrod when the pedal is pressed.If it doesn't move the problem is in the hydraulics.
If that works you just need to put new seals in the two cylinders and bleed the system.
If it doesn't help then it is probably an engine out job to fix the clutch and check the 'box.
|There is another slight possibility. On the 1500 the pivot bolt for the clutch arm can drop out. The clutch still works -in a fashion - but won't properly disengage. It could just be that. And it can be fixed without removing the engine/ gearbox. Check underneath and feel; if the pivot has dropped out the clutch arm will be free to move around. As a quick fix a 4" coach bolt with a large dome head can be dropped in to substitute for the pivot pin which should be an interference fit.|
Nice looking car!
|Thanks for reply. I feared it might be an engine out job. I noticed when the gears were stuck that the clutch pedal semed a little more stiff than usual, and possibly a slight grinding sound when pressing the clutch pedal.|
Also, Just before it happened I'm sure I heard a metallic clanking sound. At first I thought it might of been a stone hitting the underside, but with hindsight, it sounded like something pinging or breaking.
I have tried pumping the pedal, but no joy with that either. I don't know if it's relevant, but as I said, I haven't touched the car for a week, but after firing her up, and initially not being able to get any gears at all, after a minute or so of the engine ticking over, I was able to get forward gears although not smoothly.
|To me, that still sounds as if it could be the pivot pin dropping out. When this happens the clutch arm still works, pivoting against the edge of the bellhousing casing, but doesn't properly disengage the clutch so that the gears are very hard, or impossible to select, and at best would still grind horribly.|
|Thanks for comment Guy. I wouldn't know where to begin to feel for a clutch arm. I'm not a mechanic. My mechanical skills stretch to about changing spark plugs and air filters. What I wanted to know is as this aa happened before, whether it was worth just replacing the whole clutch, rather than tinkering and for it to happen again.|
She is a great looking car, a real head turner, although it does need a fair bit of work doing to it mechanically. Petrol tank as a slight leek, brakes pipes have a little errosion on them. A little play in the steering, i'm told it needs steering rack and king pins. It's also quite heavy on the petrol. Also, every bumpin the road I really feel. I'm told that is just Midgets, the suspension isn't that great, but I remember driving cars in the early 80s, and don't remember road bumps being an issue, although, the roads were a lot better back then.
|Definitely check for a problem with the clutch activation before removing everything.|
You would probably want to get a garage to do the work so they can have a look with it up on the ramps, with you standing by, to see if the clutch release mechanism is OK or not, and if it can be fixed in situ.
You could get them to give you a quote for fixing the steering, tank and brakes pipes and the clutch all at once.
Is there a MG or classic specialist near you?
You would be best to deal with an establishment who is familiar with the work.
|Guy, I to would be interested to know how you can check the pivot pin with the engine in situ. my 1500 grinds on downshifts and reverse, despite bleeding (with a pressure bleeder) and checking for leaks. |
I assume that you are referring to part no 65?
Pin 65 is an interference fit and they are known to drop out sometimes. (mine certainly did!) The pin is the fulcrum for lever part 64. One would think that if the fulcrum drops out the whole lever arrangement wouldn't work at all. Surprisingly is still does - in a fashion. Not clear from that drawing but the fulcrum point is sort of external to the main bellhousing shape. When the pin drops out the end of the lever 64 remains located in roughly the same position, and continues to pivot but against the edge of the bellhousing cut out. The effect is to reduce the clutch throw when you depress the pedal, making it hard to change gear, and certainly will make the gears crunch as the clutch doesn't fully disengage.
It is easy to check if this has happened. From under the car reach up and get a hold on the clutch lever near the pushrod end and feel to see how much it moves around. It should be fairly well located if the fulcrum pin is still in situ. If it has dropped out the clutch lever arm will flap about, essentially only retained by the thrust bearing around the gearbox input shaft.
If the pin has dropped out the "official" repair would be to remove the engine and gearbox complete and to drift in a new fulcrum pin. Being essentially lazy. I found that I could reach up over the edge of the bellhosing from under the car and drop a 4" coach bolt in as a replacement. As I recall, I didn't even put a nut on the bottom to retain it. It survived and did its job perfectly for the next several years and many thousands of miles of enthusiastic driving!
|Just wanted to note that the lever and pushrod are internal on the 1500, and you can't see or examine them from outside, unlike the A-series design. |
|Not familiar with 1500 but had similar problem with 1275. It turned out to be cummulative wear on the activation rods on master and slave cylinders plus clevis pins and clevises themselves. Had wife push clutch pedal down while watching movement of release arm. once all replaced clutch was smooth. While waiting for parts put small nut on end of rod on slave cylinder to take up slack and that worked quite well.|
I said that the pivot point "is sort of external to the bellhoiusing shape" What I was trying to explain is that the main bellhousing shape is conical, with the pivot pin being fastened through a sort of ledge that extends outside this basic conical shape. The effect is that a replacement pin can be dropped down through the top of this ledge from outside the bellhousing. And with some jiggling around of the parts this can effectively re-locate the pivot point for the clutch arm.
And although you cannot see the lever from outside, you can certainly got enough of a hold of the end of it to determine if it is overly loose. To me this was sufficient of an examination to tell whether the pin had dropped out. This is what I did any way, and I very much doubt that I am the only one to do this!
|Guy has it exactly, seen plenty of these "fixed". You can use a tapered punch from the bottom to align the arm, while you drop the new "pin" into place. The pin is actually (sort of) retained by a corrugated tin sleeve, which is supposed to be an interference fit between the pin and arm. These break or squash = no interference = no pin.|
GB's observation re clevis wear also applies.
|It looks like mine has already been 'fixed', There is a large bolt in place of the pin. However when I removed the slave cylinder outer seal clutch fluid poured out so will probably need honing & seals.|
|Well at least you have managed to pin-point the problem as hydraulics! I suspect that the same applies to the original post by (Mr/Mrs/Ms/Miss?)R Jones.|
Reverting to that first message, crunching gears is almost always caused by a clutch not disengaging properly. Other less common causes are damaged gearbox syncromesh or low gearbox oil level. And if it is that the clutch is not disengaging, then I would suggest that removing the engine /gearbox probably is not the way to go and may not really help. At least not just yet - a bit more diagnosis is needed first! (see below)
The reason I say this is that as a clutch wears it will usually slip - i.e. disengage too much, rather than not disengage. If the thrust bearing wears out or disintegrates then it will not disengage, but this is less common a fault on the 1500 which has a fairly robust thrust release bearing. Also, the information that it was previously fixed by the garage would suggest against the problem being with either the clutch internals or with the release bearing. The possible mechanical noise is a worry though.
That leaves a hydraulics problem, and probably the slave cylinder. This would be consistent with a problem that develops progressively; one that can be fixed by a garage but then deteriorate again. It is also easiest to check. Do what BH Harvey (who?) has done. Lift the edge of the slave cylinder rubber dust cover and see if brake fluid comes out. It should be pretty dry under the dust cover. If it is, then the seals are good. On the 1500 the slave cylinder is attached to the left side, near trhe front of the gearbox. Lifting the edge of the rubber dust seal with a small screwdriver will do it no harm and will show if it has been leaking.
Finally - (sorry for long message), 1500 also do have problems with the crank shaft thrust bearings. If these wear badly the whole crank/ flywheel/ clutch can move forward from the force of pressing the clutch. This is not good for the engine(!) and also effectively reduces the disengagement of the clutch and would result in crunching gears. You can check this by looking at the crank shaft pulley at the front of the engine whilst someone presses the clutch. There should be no forward movement of the pulley in relation to the front of the engine (timing chain cover) However, I suspect this is not the problem as it doesn't really fit with your comment that it had been fixed but has gone wrong again.
My money is on a hydraulic problem that will NOT be helped by having a garage remove the engine/ gearbox unit.
This thread was discussed between 11/09/2011 and 14/09/2011
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