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MG Midget and Sprite Technical - Self bleeding clutch. Guy?

Having fitted a new engine/type 9 combo with a concentric slave cylinder, I intend checking the operation before I refit any of the other ancillaries. (Just in case it all has to come out)
I'm sure I remember somebody, possibly Guy, describing their set up as "self bleeding". If so, where and how high up was the remote bleed nipple fitted?
The pic seems to be inverted. I have the bleed at 12 o'clock, and the feed at 8 o'clock.

Ta, Mark


M Crossley

Yes, mine Mike.

On the Ford one that I use, both the feed and the bleed are adjacent to each other, at the top.
The bleed line then goes out of the bell housing and up to a bleed nipple mounted to a bracket fitted to a bell housing bolt on the o/s. See picture.

Once the system was first filled (using an easibleed) I then found that whenever I subsequently crack open the bleed nipple, I get a gentle, steady flow of fluid out of it. It self bleeds.

I am not sure exactly why this should be. Obviously there is a "head" of fluid through the system from m/c reservoir through to the outlet. The outlet is higher than the slave so any air bubbles would rise up to the bleed nipple. The only other factor is that on my arrangement the release bearing is constantly held against the clutch by a light internal spring in the slave which maybe has the additional effect of slightly pressurising the slave "cylinder" and bleed pipe. That would happen if there is some sort of shuttle valve built into the design.


Guy W

I think it works that way on all of them with the nipple above the slave and below the master. As you say Guy, it's the head. Like water flowing from a tap fed from a header tank. Mine's the same. My bleed nipple is also near the top side of the g/box. As soon as I open it, out flows the fluid. Wish I'd done it to the 1275 before I converted to a 5-speed.

Here's an earlier thread discussing it.

http://www.mg-cars.net/mg-midget-sprite-technical-bbs/how-do-i-bleed-the-clutch-on-my-mk3-midget-201109032104176702.htm
Lawrence Slater

Lawrence,
I just wondered if the internal spring had an impact on it.
If not, then why doesn't a standard 1275 system self bleed when the nipple is cracked open in the same way? Gravity should draw the fluid through in much the same way, setting up a syphon to lift the fluid through the short uphill bit above the m/c.
Guy W

Hi Guy.
My concentric doesn't have an internal spring, but it definitely self bleeds.

As for the 1275, what I wrote was a bit misleading. I really meant that I wish I'd extended the bleed nipple up the side of the g/box for ease of access.

You may be right, the 1275 won't self bleed. But I wonder. I never tried just opening the bleed and letting it flow on my 1275 slave when I had one. I only ever opened the nipple when the pedal was held down. But in principle, what would stop the fluid flowing out of an open 1275 nipple? With the master so far above it, there must be sufficient head. Maybe the internal construction of the 1275 slave prevents it. Does the piston seal off the free flow of fluid to the nipple outlet? Whereas in the concentric the chamber behind the piston is connected to the master I think.
Lawrence Slater

Whatever.
I'm not that concerned. Mine self bleeds which is what matters, and I was just replying to Mark's specific question.
Guy W

Whatever? LOL. American are you now Guy? ;).

http://www.youtube.com/user/whatever
Lawrence Slater

Mine is Burton too and is also positioned upwards.
Now you guys mention it I should refresh the oil again, could be 3 years ago??


A de Best

Are you sure you really need an oil change Arie? These boxes didn't have a drain plug originally. The oil was supposed to be in there for the life of the box.
Lawrence Slater

No Lawrence,
not American. Much better than that!
https://www.youtube.com/watch?v=zV1zK8zRCPo

Arie, did you mean the gearbox oil? - or the hydraulic oil?
Guy W

Yes, I mean the hydraulic oil.

Eventhough Ford says the oil can stay in there for the life of the box I think it wont harm or even extend the life expectancy of the box.
As it is very likely (nock n wood) that I outlive the gearbox I would like to buy as less as possible in my lifelong midget-carreer.

Plan to take the engine out this winter and before putting it all back I will flush the gearbox and refill it again.
A de Best

Yup, that's funny Guy. LOL.
Lawrence Slater

This thread was discussed between 04/05/2014 and 08/05/2014

MG Midget and Sprite Technical index

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