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MG Midget and Sprite Technical - Clutch slave cylinder worth saving?

I took the slave cylinder off today to replace the seals.
The large rubber out seal had a split in it and there was some nasty brown gritty stuff in the cylinder.
The cylinder is a little pitted in places, and sticky.

Is it worth trying to clean up the inside of the cylinder with some fine wet and dry paper or is it better to just bite the bullet and buy a new one? How smooth do they need to be to not leak ?

The picture makes it look worse than it really is.


I honed my clutch slave a few years ago, and it worked fine for a long time. Eventually I just replaced it - more for peace of mind than anything else. The price was pretty reasonable, and if I had it to do over, I think I'd have replaced it first.

That said, I'd recommend a brake cylinder hone over wet-and-dry if you do decide to refurb it.

Gryf Ketcherside

I've no idea about the slave cylinder but I would be concerned about the quality of new seals but I suppose the quality issue might be the same with a new slave cylinder.

Tricky one as you don't want to spend on a new replacement if you don't have to but then now or later you might want the peace of mind.

You could try the refurbishment and repair kit and keep trying the clutch once you've refitted the slave and see if the slave leaks and that the slave fully works during these continued tests before you get the car back on the road.

There a real decisive answer from me, or not so decisive but still from me, I'll look for a coin.
Nigel Atkins

Easy answer
Polish it out before you order anything for it--If it cleans up ok without pitting where the cup is going to work, get a repair kit--
If there is pitting where the cup runs ,throw it and get a new one
In your picture it appears that the piston is still in there, so you can't actually see the buiness part of the cyl.
William Revit

Replace it and keep the original!
I've found out to my cost that ditching original pieces is a bad idea as replacement parts vary considerably in quality - shock absorbers and flasher units spring to mind.
Should the new unit fail you can then do as Gryf suggests and refurbish the original. In fact you could do that at your leisure and then have a spare just in case :>
Jeremy MkIII

That cylinder is unlikely to be serviceable - new ones are not expensive.

You can also have the cylinder sleeved with stainless steel tube to restore it.
Chris at Octarine Services

Hi Chris (at),
I've just had a very quick look and they vary from #27.50 to #50, the last one I bought for my 1275 was #50 despite me remembering it being #20 previously.
(# is supposed to be a pound sign)

your photo also shows a lazy bit of house wiring apart from the unprotected wires there's not a grommet on the back box where the wires go through, next we'll look at the mortar courses. :)
Nigel Atkins

you made me laugh - again!
Well spotted though!
Jeremy MkIII

Well spotted Nigel :-D

A new one isnít going to break the bank.
Iíll have a look at the master and see what thatís like. If itís in a similar state iíll replace both.
I always keep the old parts, at some point they might come in useful.

master cylinder 100 l prefer to repair an old component as against simply buying new. But this for me would be the 99th case when l would replace the slave. They are so cheap, from around

Well spotted Jeremy but it does mean I missed the fun from those that miss it. ;)

the last (1275) slave and master cyiinders I bought were £50 a piece (which as I put surprised me as I thought the slaves were £20) so unless it's a typo £7.50 sounds wrong.

(I've no idea why the pound symbol is back to £ - aren't computers simply marvelous :) )
Nigel Atkins

Moss list the 1500 slave at £52
Dave O'Neill 2

Dave, when I had a quick look I saw that and MGB Hive at £27.50.

(IIRC MGOC Spares at £49.95 - sorry, just checked, I remembered wrong it's £41.95)
Nigel Atkins

Quite right Nigel, it was a typo. I missed the 1 off! Should have read "from £17.50". Still cheap enough though.

Here's one at £16.50 (plus the P&P of course)

Past Parts - refurbished and lined with SS £68.18

look under Triumph Spitfire for the 1500 cylinder
Chris at Octarine Services

Next question......
the piston is the standard sort from what I can see, but there is an extra bit thatís been chopped off another piston and put on the end of the existing piston.

Why? Iím thinking itís to give more travel at the clutch?

Thereís also some sort of threaded brass nut....?

Pic shows cylinder at top, spring, piston, extra bit of piston, and nut


Or would it just reduce the clutch pedal movement?

Hereís a pic the the piston with the extra bit that sits in it to make a slightly longer piston


Those extra pieces would not give more travel! Travel is determined by the amount of fluid pumped by the mastercylinder and cannot effectively be altered.

They would change the portion of the slave cylinder that the piston moved along (it doesn't need or use the full length of the bore) so may have been done to compensate for worn linkeages or pivot points in the train of components downstream of the slave cylinder. At best its been a dubious bodge!

(my comment relates to the addition of the brass bit. The extra bit on the piston may not be a bodge, but I have never seen one like it on an A series slave cylinder before)

Or is this a 1500 slave?

it's a 1500 cylinder, hence my surprise at your bargain find prices (still a very good price on the A slave).

The extra bit(s) smack of a bodge to me and a bit of effort to do the bodge too or just whatever bits were to hand. A bodge to get you home is fair enough but on the inside of the slave sounds more like an at home bodge to me, I could be wrong of course as I've never seen the insides of a slave cylinder.
Nigel Atkins

Yep, I was a bit slow on that one! Not acceptable either, since I owned a 1500 for many years ! Dohh!

Until I looked up the prices I thought the 1500 and A-series slaves looked (more or less) the same.
Nigel Atkins

£34 at the Welsh MG Centre.
Jeremy MkIII

Doesn't state for which model though. The asking price of a few of their second hand parts that I've seen can be high especially considering the presentation condition.
Nigel Atkins

I'm in the camp of replace it, just because a new replacement is so cheap and inexpensive and easy to install
1 Paper

Slave cyl for 1500 from Sussex under £25
Graeme Williams

The photo is very small for that but it *looks* like some of the rougher looking casting ones I've seen photos of, but who knows they might be better finished internally, operate better and last longer than the prettier finished ones.
Nigel Atkins

My guess is that the cylinder started leaking in the past and the PO or a mechanic decided to move the operating position of the seal further back in the cylinder where the bore was not pitted/worn.

Chris at Octarine Services


in my experience if the Welsh MG states a price that's what you pay, irrespective of the model.
His ebay prices are pretty steep but folk must buy otherwise he wouldn't be selling.
You get a better deal in person or over the phone I've found.
I bought a new flasher unit and asked if he had any old ones in his yard - he sent me 3 buckshee, one of which has outlasted the new one...
Jeremy MkIII

Good to know Jeremy. They certainly didn't dress up the s/h parts for the price I saw on ebay.

I'm surprised you bought a new flasher unit after the info on piss-poor quality new parts on here, the old ones generally seem to go on forever.

I've got an old spare one I've offered on here before (for free) and holder you could have had them.

I went over to an electronic (oh the shame) a good few years back after experiencing piss-poor quality new ones over 11 years ago.
Nigel Atkins

I was just looking at the Welsh MG website for something unrelated, when I noticed this:-

"Note: all prices subject to market fluctuation, please call for current pricing"
Dave O'Neill 2

It was a while ago Nigel, measuring it in years rather than months - when I was a mere slip of a lad and knew no better :) LOL.
Have you changed to LEDs as well as an electronic flasher?
Jeremy MkIII

Not if it's illegal to do so.

Although I do believe that the previous electronic relay type flasher unit I had fitted that works well with ordinary bulbs would cause LED bulbs to flash annoyingly fast so if that was the case you'd want a different type of electronic flasher unit to slow the rate of flashing down.

For off-road use and where it's legal to do so you'd also want amber LEDs for amber lenses and if you were to fit LEDs to the rear lights you'd want red behind the red lenses.

There appear to be different quality LEDs being sold with some red rear bulbs not differentiating enough between rear and braking but others give excellent light for both.

I believe for off-road use and where it's legal to do so you can also get some warm white LED bulbs for the front side lights, rather than the very white/blue ones that look too modern for classics.
Nigel Atkins

This thread was discussed between 20/12/2017 and 28/12/2017

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