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MG MGB Technical - Clutch slave cylinder

Hi all,
For some time now I have had a small leak in the slave cylinder or possibly on the flexi hose that goes to it. Or both. Eventually plucked up the courage to tackle the job, and have acquired a new cylinder and flex tube. I drained the system and set about taking it apart but simply cannot move the pipe nut that holds the metal pipe onto the flexi. Have tried penetrating oil, and am using a flare nut spanner, but it jusy will not budge.
Any usegul tips before I get the hacksaw out and just accept that I will need a new pipe too?
Car is a 1981 reg GT, but I believe the clurch hudraulics didnt vary much over the years.
Thanks in advance,
Steve Elster
SJ Elster

If you cut the hose off from the bottom of the bracket and grind away the fitting that side you should be able to lift the pipe out of the top of the bracket. With the other end removed from the master you may be able to work on the nut on the bench and save the pipe. OTOH the nut may be beyond further use after all that, meaning a new flare and nut at least. Not done it mind, just thought about what I would try having read the problems of others in this area.
paulh4

Thanks, Paul, that sounds like a workable approach. I can get the nut off ok from the master so will give this a go in the morning. Have used up my daily quota of "spanner energy" for today.
SJ Elster

I would try TIGHTENING the flare nut first and then work it back and forth to loosen it.
Chris at Octarine Services

If the flexi is being replaced and the flare nut is seized I usually get the whole thing out on the bench and support the side of the end fitting of the flexi on something hard like an anvil or the block on the vice and go round tapping the flexi pipe fitting where the flare nut screws in and that will expand it a tiddle and make it easy to screw the nut out---If that doesn't do it the nut splitter comes out or grind the side out of the fitting on oposite sides and it will loosen up
Steve
A bit of caution--sometimes when a new cylinder is packaged they fit the bleeder in the wrong hole so as it will fit in the box
Make sure that when you fit your new cylinder that the bleeder then goes in the top position otherwise air gets trapped in there and it will be a pain to bleed
William Revit

William - the hose fitting goes through the chassis bracket so unless you cut something off either the bracket, hose or pipe you can't get anything on the bench.

Grinding off below the bracket may well generate enough heat to free the flare nut so try holding the stub in grips and undoing the flare nut before disconnecting at the master.

The bleed nipple and hose definitely do need to go the right way round, but I have found reverse bleeding i.e. bottom up which in theory should leave air in the cylinder has been far easier when bleeding the clutch than conventionally i.e. top-down. The thing that seems guaranteed to work if all else fails is to wedge the clutch pedal fully down over night then release slowly i.e. don't just knock the wedge out, next morning.
paulh4

Paul - yes you can, as long as you can remove the large nut holding the top end hose end fitting into the bracket you can undo the cylinder flare nut and remove the whole assembly down through the chassis bracket.
Chris at Octarine Services

So it does. Hadn't realised the flare nut was smaller than the large nut until I looked just now.
paulh4

Used the grinder to remove the nut and bit of hose fitting from the bottom of the bracket. This is indeed possible but not a pleasant job. Using angle grinders under the car and very close to brake pipes etc no fun but anyway it is off now. Top pipe nut at m/c came away easily enough but surprisingly difficult to wiggle the pipe out of the car.
On the bench, I tried to get the flare nut out of the remains of the hose fitting but damaged it in the process.
I have a local motor factor that can make up pipes, so off there now to get one done.
Putting it all back together with new parts should be straight forward, and I note the comments about putting the bleed screw into the correct hole.
Then we will come to bleeding. I note your various comments and have read the info on Paul's website, and intend to try filling from the bottom using an eezibleed. This seems to be a problem for nearly everyone, so wish me luck.
SJ Elster

Duly wished.
paulh4

Well, everything went back together ok, and filling from the slave seemed to have worked quite well. However the pedal was very soft so I tried a bit of top down bleeding, using the eezibleed connected to the master cylinder. This pushed a bit of air out immediately that must have been in the slave. With the gunsons still connected and pressuurised, I pushed the pushrod into the cylinder and that pushed out a few more bubbles. Closed the bleed valve, and disconnected the eezibleed, tried the pedal again and it felt much more like it should.
Got the car back on its wheels and on the ground, started it up and gingerly tried to select reverse. It went in fine, and I was able to back out of the garage. A short test drive showed no problems, and the level in the master was constant.
I will keep a close eye on it over the next few days in case there are any leaks, but I think it be ok.
Thanks to everyone that offered advice, it's great to have backup from this forum especially when doing simething you havent done before.
SJ Elster

Well done.

After a couple of good drives to shake any bubbles up you could try checking again with another straight forward bleed.
Nigel Atkins

If it isn't grinding in reverse and you have a good biting point I wouldn't open it up again. As any bubbles are likely to have been shaken to the top of the pipe by the master what you could do as wedge the pedal down overnight. They should float back to the top, then be flushed into the reservoir when the fluid flows back from the slave next morning.
paulh4

I have always found that there is no need to bleed the clutch in the conventional way.

Fill the master reservoir and pump pedal vigorously for ten secs - hold pedal down for 10 secs and repeat, after a few repetitions you will have a firm pedal and full clutch throw.
Chris at Octarine Services

Yay - good stuff
Don't go looking for trouble though, if it's working ok ,
Chris's method is good for getting the air out of the system, I'd drive it for a day or so then do that as a final step to what you have done already, just pump the pedal several times reasonably quickly, no need to go mad and froth it all up, then hold it down for half a min. or so, and let any remaining air bubbles to float up then release and any unwanted little bubble friends will find their way back to the reservoir (Chris)

willy
William Revit

"pump pedal vigorously"

Only tried that once and all it did was turn the fluid milky with tiny air bubbles so I had to drain it out and start again.
paulh4

Took it for a medium length drive today, about 20 miles, and no problems at all so will leave well enough alone.
On to the next job soon, replacing the rear bump pedestals. I will probably need some advice on that too one too but will create a new topic when I get started or stuck.
Stephen Elster
SJ Elster

You might like to have a look at http://www.mgb-stuff.org.uk/suspensiontext.htm#rbpedestals
paulh4

Thanks Paul, that is an extremely useful resource. I have new pedestals, u bolts and nuts, but I will check the rebound straps before starting.
SJ Elster

This thread was discussed between 06/06/2019 and 11/06/2019

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