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MG Midget and Sprite Technical - bleedin clutch

I would imagine that there are a number of midget / Sprite owners out there who have had issues in bleeding their clutches or indeed have experienced problems with their clutch associated with air in the clutch hydraulic circuit. Well, I have been fruatrated by difficulty in getting all of the air from the system and the performance in accessing the clutch slave bleed nipple.
So, I set about making life easier, by providing bleeding access beneath the car adjacent to the slave cylinder.
It worked for me, and I hope it will be of use to others:

Firstly I identified a suitable location for a remote bleed nipple: Picture 1
Then I cnstructed a link to the slave cylinder from the remote bleed nipple which I installed in a three way brake union, One of the ways was blanked and one has the bleed nipple, the third accomodates the pipe link to the slave cylinder. All of this positioned and fabricated off vehicle.


R C Skerritt

This picture shows the proposed location of the remote bleed nipple.


R C Skerritt

Conveniently, there was a suitable hole in the engine backplate right behind the slave cylinder:


R C Skerritt

This is the preassembled system


R C Skerritt

This shows the installation


R C Skerritt

As does this


R C Skerritt

and this!
Hope its of use to someone out there


R C Skerritt

Actually RC

A much better way we have found that follows your path is to run the hard copper tube up along the firewall to the top of the cowling with the remote bleed nipple at the top.... the advantage is you no longer have to crawl under the car plus you have a new HIGH place for the air bubble to rise to away from the hydrolics

personally what i do is ...

I get about 3 feet of clear vynial tubing and fit it to the bleed nipple and run the other end of the clear tubing into the clutch master cly and just pump the clutch peddle VERY SLOWLY once i no longer see any air bubbles in the clear tubing... i close the bleed nipple and remove the clear tubing and ... done, an air free clutch !!!

thanks for your contribution

prop
Prop and the Blackhole Midget

Or like this. The bellhousing is also equipped with a roller release bearing.
It is all for display on the Masc stand NEC in November.
Alan


Alan Anstead

Hello Prop
So nothing new under the sun!
One of my concerns though was to ensure that no metal hydraulic pipe crossed between th engine/transmission and the shell, since one moves in relation to the other.
However, i do like your clear poly tube bleeding idea, I may give it a try in the future.
Thanks
Bob
R C Skerritt

Hello Alan,
that overcomes the potential pipe fracture issue alright
Ive used a roller release in my Frog.
Bob
R C Skerritt

What sort do you have on your Frog. Peter May, homemade, concentric?

Alan
Alan Anstead

Bob

Your vehicle profile says that you have a 1380, so I presume you have the 1275 diaphragm clutch.

It would appear that you are using the earlier small-bore slave cylinder. Do you have any issues with the amount of travel this produces?
Dave O'Neill 2

Diaphagm clutch, 7/8 inch slave. Slightly longer stroke, firmer pedal. If you revisit the photos youll see that the engine backplate is solid and there is no provision for the hydraulic inlet for the 1.0 inch slave. the back plate is probably 1098.
The car has been "in build" for 11 years, it was originally a project for my son, but his university work, lack of time, workshop space and transport meant i inherited the wreckage in return for a useable means of transport. Having two other restos on the go at the same time extended time scales on all three!

The release bearing is concentric.


R C Skerritt

I intend to do this as part of the Frog resto. Do I simply use the old bleed nipple on the end of an "extension pipe"? And what parts do I need altogether? (Long time since I worked on a Sprite clutch).
Bill
Bill Bretherton

As you can see from the photos:
Its just a three way brake pipe union, coupled to the normal slave cylinder bleed orifice by a short preformed length of standard brake pipe. (pure copper is the easiest to form) The pipe is terminated with standard male brake pipe unions.
Youll need to form the pipe with the cylinder and 3 way union off car, fit it all together and tighten unions before fitting.
The extra outlet on the three way union is blanked off ( I used an extra bleed nipple) So, two bleed nipples were used.


R C Skerritt

Bob

Yes, the 1098 backplate is a different shape in that area. I think the hole you used is for the return spring on a Morris Minor mechanical clutch.
Dave O'Neill 2

Thanks Bob, I've got it. Obvious when one thinks about it I suppose! Lot of people on here seem to have done this.
Bill
Bill Bretherton

Bill. The easier way - as it involves less fabrication, - is to use a standard rear brake flexible pipe. One end fits directly into the slave cylinder bleed nipple orifice. It is long enough to go up the side of the bell housing and attach at the top with a home made strap. Then fit a female/female connector on the top end and the bleed nipple screws into that.
Because it rises continuously from the slave, air bubbles will rise up to the top and the nipple itself is easily reached under the bonnet with no grovelling under the car required!
GuyW

Bob,
beware of a slightly longer stroke, if you mean the travel at the slave cylinder end. Too much movement here can result in the clutch "overthrowing" which will eventually wreak the pressure plate fingers. Ask Bill (SDGPM) about that !
GuyW

Echo that Guy! I had the 'wrong' slave for a few years in my Frog and went through a couple of pressure plates before I spotted the problem. Swapped it over to the larger 1275 one and all good with a nicer (in my view) pedal.
Bob Beaumont

OK. Hear what you say, but, the car is built with a 1098 back plate which prevents me using a standard GSY113 1.0 inch slave. So, is anyone aware of a 1.0 inch slave with a similar hydraulic entry to the GSY110 7/8 version?
I calculated that in using a 3/4 inch mater with a 7/8 inch slave I would have around 3mm extra throw over the 1.0 inch slave. Also I calculated about a 20% increase in pedal force.
Comments please.
R C Skerritt

If you don't mind the heavier clutch, then you could just put a stop under the pedal arm. A bolt welded to a plate on the floor would work and could easily be a made adjustable.
GuyW

Thanks Guy, interesting option, ill certainly bear it in mind.
R C Skerritt

Thanks for the suggestion Guy - the simplest ideas are sometimes the best!
Bill
Bill Bretherton

Thats how the tri master peddle set up is done on the tilton tripple master cly set up

an adjustable bolt un the floor that the peddle hits into

RC.... dont reuse the clear tubing .... toss it when done thwt brake fluid eats it up in about 3 to 5 days pending what the tempature is

guy i like your idea of using a flex pipe instead of soft copper that would make it so much easier to twist and manipulate over a solid line

prop
Prop and the Blackhole Midget

OK Chaps
Next question...
How do you get a snail into a frog??
See new thread!
R C Skerritt

This thread was discussed between 13/09/2016 and 15/09/2016

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.