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MG Midget and Sprite Technical - concentric hydraulic clutch release

I have an a series engine and box from a midget destined for another car I am building. I have very limited space for the midget clutch slave and release arm, so would like to use a concentric hydraulic set up.

Has anyone put one of these together- and can they advise what I will need. I have seen the ones on Peter Mays website, but money is a rather tight and I was hoping that I might be able to make one up from a load of parts- ford ones on ebay seem to go for about 30, has anyone used one of these?

Anyone got any ideas or suggestions?

many thanks

Ben
BC Maddison

Speak to Max T, he's got one.
Brad (Sprite IV 1380)

tilton engineering makes a universal one, at a reasonable price.

prop
Prop

Ben, Guy Weller and Bill Mohan can help you on this mather as both of them have a home made conversion.
Both are frequently on this BBS, they can drop in any moment now...
Arie de Best

I was waiting for Bill to!

Mine uses a Ford Puma/ Fiesta slave (£28 on e-bay) and a mounting carrier turned on my lathe from a solid billet of ally (£5). The rest was just bits and pieces I had around so I guess it cos about £40 in all.

Guy


Guy Weller

Mine like a few others uses a Saab 900 slave on a similar mounting carrier which you can see in the image, I've just had to replace it as the seals wore out, after some deliberation I opted for the easy approach and put another Saab one on, about £30.
Burton performance do a kit of bits (for the type 9 Ford box) but it looks like Guys Ford cylinder and all in costs three or four times as much. If you have no lathe their mounting kit and a cheaper slave might be an cost effective option.


Paul (MkI

Ford quoted me £76 for the slave unit that I used. Which is why I bought the same thing on e-bay for £28. But I guess Burton Power will be charging the (im)"proper" amount, plus the spacers and other parts that they produce, which would make it quite expensive.
Guy Weller

And to be honest I stayed out of this because I have no idea whether it would be easy or hard to do this inside an A series box's bell housing.

But as the front oil seal is inside that separate alloy casing it should not be too difficult to arrange to take it off and fit the CSC and allow for a seal in there too.

Just needs to decide where to source the CSC and procure a fitmentthat will be drill able to suit the pivot carrier now in use

mine in the picture


Bill

Thanks to all that have responded on this one it is a great help, cheers for the pics as well. Can I just ask guy and paul a couple of questions- are these operating a std midget clutch or is this an uprated one?

Also I assume that these are using the ford or Saab release bearing?

How deep are the mounting plates that you have made up to mount the cluch release on?

I am probably looking to buy the ford fiesta/puma one, as looks easiest to get hold of.

thanks guys

Ben
BC Maddison

Ben,
I am using a standard 1275 clutch, but with the pressure pad removed so that the Ford slave operates direct onto the "fingers" of the clutch cover.
Mine is also fitted to a type 9 gearbox. I see no reason why you shouldn't make up a unit for a rib-case box though. The actual Ford slave unit is quite small and neat (as is the Saab one) so I am sure there is room. You would need to work out what shape the back of the mounting block is to fit the front of the gearbox casing, plus how to attach it there.

One problem I did have was that the Ford unit uses a small non-standard size for the bleed connection. As Ford intend, this takes an elongated bleed nipple, but because of access in a Spridget this needs to be replaced with a pipe to a remote bleeder. I ended up using a banjo type fitting (see last photo) which wasn't ideal, but it works.

Attached is a shot of the remote bleeder. Incidentally, mine will now bleed automatically, by gravity without even having to press the clutch pedal. I just have to open the bleed valve and let it run fluid through into a jar to clear any air bubbles. Takes about 20 seconds which is something of an improvement on the standard clutch bleeding procedure for a Spridget!

Guy


Guy Weller

I have been having trouble finding the slave cylinder that Guy has used. It is one with green bellows around it, the chap I have been speaking to told me Ford have stopped making that particular model as the bellows were nipping together and leaking.

Beware buying from ebay or mail order, they often use a generic picture so what you see is not necessarily what you get.

Matt
Tarquin

That would be bad news! So far mine has been OK.
But I am not sure that the bellows actually contain the fluid though, do they? I would be surprised if they did as surely they would just swell up like a balloon rather than compressing a clutch spring? I cannot now remember how the thing is made!

That said, there are several listed on e-bay at the moment. e.g.:
http://tinyurl.com/6yfwdx

This is like the one I use.

Guy
Guy Weller

Yes it is the one you used, but like I said I bought one based on the picture, but I ended up with a different type (ebay item 170220490187). You can see in that auction that it fits many different models, so it probably supercedes the old model.

I agree Guy, I don't see how it could contain fluid but I didn't want to argue with the guy, he was trying to help me out after all. He did have one without the bellows (see pic) which maybe is also an updated version.


Tarquin

I see the problem! That e-bay item one (170220490187) wouldn't fit inside the bell housing!

Mine is similar to the green one in your photo, but not exactly the same as the hydraulic feed connection is positioned differently. The one behind looks like the same thing with the green bellows removed. Mine has a spring like that inside the bellows as they are designed to run in constant (light) contact with the clutch. I have an idea that Bill removed the equivalent light spring on his, but I forget what the logic of that was!

Guy
Guy Weller

Maybe just buy it of a proper Ford dealer to safe you the hassle of buying/paying for the wrong item? ;)
Arie de Best

Mine is operating a non standard plate and cover, it came from Tony Bolton just before he disappeared and I don't know what it is, some sort of Ford I assumed I will have to worry about this one day. Like Guy's it bleeds easily with gravity which is a treat after the standard set up.

I looked at a few Ford cylinders recently when mine bust, most had a longish arm on them unlike the one Guy uses and would not have fitted in the bell housing. On the Saab cylinder the bellows merely surround the spring which applies light pressure to keep the release bearing running on the clutch cover, I just assumed the green bellows on the Ford item did the same.
Paul MkIMkIV

Paul, I thought ive picked up some rumour about Tony using a Ford Focus cylinder????
Arie de Best

I havent even got the spring fitted inside my bellows

which is why my pedal is very fierce I think

next time the engine and box are apart it will get the spring for its assistance benefits

The bellows shouldnt have the fluid in if it does the CSC is buggered anyway

But you would need the bellows to protect the inner seal face, I wouldnt run mine without one.
Bill

Image: The kit supplied to me with saab cylinder.
Because of other reasons it didnt work on mine... :(
Spacer block is for ford type 9 to Rover K series hence the size difference to the 1275 conversions.

As Bill already explained there isnt suppose to be much fluid in there.
By Bellow you guys mean rubber ciylinder-thingy?
Thats just to keep dirt/dust out.


Arie de Best

Arie I still believe we can get that to work on your car properly you know

It has to be a matter of how far it is set from the clutch cover fingers that is stopping it
Bill

Arie, buying direct from Ford = ebay prices x 2 ....

I'll get a pic of my Sierra cover on tonight Paul, see if it's the same as yours.
Tarquin

I think that the point with these slaves is that the thrust bearing should be already in contact with the clutch fingers. Then when you depress the pedal it needs to move immediately forward somewhere about 8mm to release the clutch. At least that is what I found. I am sure there should be a specified dimension for this.

The distance that it moves will be dependant only on the ratio of the slave to the master cylinder, for a full stroke of the clutch pedal. There are no other variables or adjustments. But you do need to make sure that the "at rest" position of the slave piston is sufficiently compressed to allow for the full 8mm of movement. And then add a bit to allow for clutch plate wear. I set mine at 12mm "throw". Perhaps I should have allowed a little more.
Guy Weller

Arie, definately a Saab cylinder - perhaps he used both.

Bill, before I replaced it it had no spring, I did run it for a while with the pedal spring reversed to apply light pressure to the release bearing that way, also ran without as you do, non of the above made the slightest difference to the feel of the pedal.

Paul
Paul MkIMkIV

Ah thanks Paul

saves me making rash "split the units" decisions

was/is yours like using a switch on switch off pedal

Mine took quite some getting used to and Gwyn will just not drive it acos of the harshness

And it took the guys who drove it at the track day a few goes to get used to its suddenness

(Me? I like it as it is)
Bill

Bill, no mine's fairly light and progressive, very similar to my Frogeye which is on a standard hydraulic system and A series clutch cover, possibly better. What clutch and cover have you? Could that make the difference?
Paul
Paul MkIMkIV

There is no way that the small bellows spring could influence the peddle feel. If it acted in any way as an "assistance" then it would simply be fighting against the clutch spring and liable to cause clutch slip. The "fierceness" of the clutch must be either to do with how strong the springs are in the clutch cover, or something to do with the ratio of fluid moved by the master to the volume at the slave and the required movement there.
Guy Weller

If I understand well from the research ive done sofar on this mather is that the bore of the mastercylinder decides how much fluid is being moved and therefore give the "stifnes" on the pedal.
The biger the bore, the heavier the pedall.

I do think Guy also has a point with the stifnes of the springs of the clutch cover.

Bill, i returned the kit to the supplier who promised to look into it why it didnt work, ofcourse 3 months later still no sign of life from the supplier...
Hence why i still havent payed anything.
Ill probably go Burton.

Matt, twice the Ebay price, sowhat?
Atleast then you have the right part and can go on with the project.
Dont be such a typical thight-*rse Yorkshiremen!!! ;)
Arie de Best

Bill, as yours is a early car, do you know what bore master you have?
Tarquin

err not really

never measured it but it's the half a housebrick master available from most places about ten years ago, bought mine at Leaceys

(aint I helpful? ish)

same bore clutch and brake though

has to be fine with the disc brake front end, 'cos it is.

I ought to wrestle the bonnet off and see if I can check it out, but I'm used to it and it's only a problem 'cos I would like Gwyn to take her out sometimes
Bill

Ah yes

Further to this

it has always been a hard pedal whatever clutch system has been in use

(one of those things people snigger about when yer back is turned you know)
Bill

Didnt i say it straight in your face after having a go with Lara at Gaydon? :)
Arie de Best

Bill, actually when I say My Frog is on a standard system it's actually on a standard MkIV 1275 system, If my memory is working the early clutch covers had very weedy springs (??) so perhaps your clutch cover spring/cylinder bore mismatch is the issue.
Paul MkIMkIV

No Paul I'm on about the 4th clutch cover by now

All been difficult to work

In fact even Arie once told me that

as have a few others...
Bill

It is the ratio of master cylinder to slave cylinder capacity that controls how fierce the clutch is. Either the Saab unit needs less fluid displaced than the Ford one to operate through the necessary 8mm or so, or the early brick master cylinder is a larger bore and is moving too much fluid.
Guy Weller

This thread was discussed between 04/11/2008 and 06/11/2008

MG Midget and Sprite Technical index

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