Gearbox noise - engine & box now removed

[mrbenn]

There is carbon on the face, but it doesn't look brill does it.

Looks like it has been rubbing constantly against the clutch -ie no free play, and hence the overheated 'blue' appearance of the pressure pad face.

Very interesting point. I reckon, preoccupied with trying to keep the hydraulic setup working, I may not have adjusted it correctly, as you point out.

Among the bits ordered I've actually paid for the kit to put the clutch back to rod operation. Hopefully this will be the last of the problems....

[kennatt]

as above looks like its been red hot, but you have hydraulic clutch which should be self adjusting ,I would be looking at sticking slave or master or collapsing flexi .Unless there is some other rod type adjustment, ..not familiar with the hydro system fitted to minors. Isn't it regarded as better to have the hydro system on the 1275 I think I would be having a look at the flexi etc before reverting to the rod linkage, .you may find its a lot heavier

[mrbenn]

There is an adjustable rod from the slave cylinder to the clutch fork which I thought was set ok, I even had an endoscope camera in the gearbox while operating the clutch and the movement looked fine.

The slave cylinder has just been replaced (again), the master was done not long ago along with the reservoir, pipe from reservoir to master and both pipes - flexi and copper i.e. the whole thing.

Therein lies the problem, the system seems to need pretty much constant attention and replacement parts.

My plan is to disconnect as little as possible from the hydraulics (clutch pedal connection and slave cylinder to clutch fork), install the rods as per original setup then give it a test. If it is too heavy then I'll have to look at think again.

[bmcecosse]

The hydraulic set up will always keep the carbon against the clutch - it should only be used with a roller bearing release assembly. The noise has probably been slight slipping at each gear change as the clutch released sluggishly.

[mrbenn]

That would explain a lot!

[kennatt]

Ahh yes didn't spot the carbon thrust ,simple answer fit the roller bearing thrust

[bmcecosse]

On the Mini/1100 hydraulic clutch there is a spring to pull the release bearing away from the pressure assembly - against a finely adjusted stop, so the bearing is 'only just' not touching the clutch. Do the Minor hydraulic conversions have such a system?

[mrbenn]

No, nothing like that on the Minor arrangement that I've seen.

[philthehill]

The hydraulic clutch system fitted to the 'A' series i.e. Midget/Sprite is fully self adjusting and there is no need for a return spring on the slave cylinder. The MG Midget/Sprite does not have a return spring and the release bearing is carbon. Though it would be an advantage to fit a roller bearing clutch thrust bearing.
See attached parts list link for MG Midget/Sprite clutch assy and associated parts.
http://www.moss-europe.co.uk/shop-by-mo ... 500cc.html

You say that the master cylinder has been replaced recently - did you inadvertently fit a brake master cylinder with its recuperation valve which will leave pressure in the line which will keep the carbon thrust pressing against the pressure plate bearing plate and which would lead to wear and overheating of the carbon thrust?

I suspect that the clutch release system fitted to your car is based on the Owen Burton set up as you are using the original Minor clutch release arm and the Owen Burton 'Marina to Minor' booklet has details regarding the use of the Minor release arm and a hydraulic slave cylinder.

[bmcecosse]

The Spridget system can only then be 'self adjusting' by holding the carbon against the pressure pad... I suppose it must rely on slight run-out to push the carbon a few thou away from the pad - same idea as disc brakes self adjust....

[mrbenn]

Thinking about it, the master cylinder replacement was probably around 3 years ago, and was replaced like for like with one of these:

http://www.burtonpower.com/girling-brak ... rk032.html

You're likely right on the basis of the system fitted here, Phil, very interesting. I'd have thought it would be a right mish mash of whatever the previous owner had to hand

Speaking of tools, I think I have introduced a new problem. I left the gearbox standing on its bell housing for 3 days.....

I drained the oil before doing so, but perhaps half an egg cup full has drained down. The gearbox oil had probably done around 1500 miles before I drained it last week and it looked clean.

Question: how likely is it that have I damaged the 'box, and is there anything I can do to sort it out? Remember you're clearly talking to an idiot here....

[kennatt]

Its an easy thing to do because it just looks right to stand it that way ,then any bits of grit end up in the first motion shaft bearing, might be all right after just three days ,but advisable to give it a good wash out with,something ,petrol,wd40 plus gas etc.

[bmcecosse]

I do suggest removing the front cover and washing out as above.

[mrbenn]

Thanks gents, I'll do that.

Is anything going to fly out never to be seen again when I remove the front cover?

[bmcecosse]

No - but take care with the gasket.

[mrbenn]

Thanks for the info.

[mrbenn]

Took the front cover off the 'box today to attempt to clean the front bearing.

Blew it through with lots of compressed air, followed by lots of paraffin. Fair bit of rubbish seemed to come out, fingers crossed it has survived the mistreatment

[bmcecosse]

Squirt some oil then spin the shaft -is it nice and smooth ?

[mrbenn]

It seems ok, about the same as it was before I think.

Guess the proof will be in the pudding!

[mrbenn]

Update time.

Spent a while in the garage over the weekend connecting everything back up. Engine and 'box slid back into place in a matter of minutes, its everything else that takes the time!

I'd decided not to change the clutch to rod operation at this point, but to get it back on the road with the existing hydraulic arrangement then change in the near future when I knew everything I'd done was sound. After all, it drove ok before so it'd be fine, right?

All wires/nut/bolts/parts refitted, engine started up, no gears Clutch had some pressure, but wouldn't select any of the gears. I immediately started going through all the things I'd done, wracking my brains as to what I'd messed up. Then realised the clutch slave cylinder wasn't being actuated, or rather only a tiny bit. Very odd, the car had driven into the garage fine before I'd removed the engine and gearbox and I hadn't touched the hydraulics except to unscrew the slave cylinder from the side of the gearbox.

A long period of adjusting, bleeding and some moderate swearing ensued. I just couldn't get the system to work. Again.

I was hot (it was 26 degrees last Saturday), tired and hungry by now. I decided to rip out the hydraulics and fit the rod linkage. This took about a quarter of the time that I'd wasted trying to get the system working. Result = clutch worked immediately.....

The clutch is a bit heavy and a little "sudden" (as expected) so I plan on getting one of the legs on the relay shaft lengthened but it selects gears perfectly and feels great. I'm almost tempted to leave it as it is! I probably need to get used to it a bit, only driven it a couple of times on the new setup.

Fortunately, the gearbox seems to have survived being stood on the bellhousing. The serious washing out of the bearing must have saved it. I won't do that again!

Many thanks to all that helped me out on this task, your advice has been invaluable and much appreciated

ETA - it is a Midget clutch in there hence the heaviness!