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MG Midget and Sprite Technical - Concentric slave on 1098 with type9

I have a 1098 Mk3 Sprite with a type 9 Ford 'box, to which I recently fitted a roller release bearing. (See thread "Broken clutch").
Last night I was out in the car and noticed a rattle from the clutch, which I could get rid of by lightly resting my foot on the pedal.
On inspection today, I see that the whole of the outer race of the bearing is turning in the housing which is causing the rattle. Obviously it will eventually break up.
I'm going on a club run on Sunday with everything crossed that it will hold till after then.

I am now seriously thinking about going down the concentric slave route. I have a standard 1098 clutch and the guide tube of the gearbox has been cut off, so I would like to know if it's possible to fit a concentric slave to a standard 1098 clutch and will I have to replace the front seal/guide tube. Also, a rough estimate of how much it will cost.
Obviously, the cheaper and simpler solution would be to buy a NOS Borg & Beck carbon thrust and put that in, but I'm getting fed up of pulling the engine when I could be driving.
Thanks as always.

Bernie.
b higginson

You could try using Loctite or bearing lock 'n' seal between the bearing outer race and housing. Probably you'd need a long thin piece of pipe extended to the tube of Loctite/etc.

If you can run a roller release bearing on the clutch, and clearly you can, there is no physical reason why you can't use a concentric slave as all you are doing is applying a very similar bearing via a direct hydraulic link rather than indirectly via a lever.

However, while the later clutch hydraulics (seperate clutch master) can cope with the concentric clutch, albeit with a mod to prevent over travelling the clutch fingers via the bearing, if your car has the early combined clutch and brake master I'm not certain it will cope with it. However, no hydraulic problem is insurmountable.
Daniel Stapleton

We use the Burton concentric kit. Not cheap at about £280 but superb in action,light and smooth.

J L HEAP

JL. I assume that the Burton kit, in common with others, requires the removal of the pad on the clutch fingers. This is not possible on the 1098 as there are only three arms supporting the pad. Hence my question, is a concentric release possible on a 1098 standard clutch.

Bernie.
b higginson

Bernie the drawing attached is what I used to make my own fitment to use Burton's adapter (£5 on ebay I think it was)

As you see I had to make it quite thick because I didnt get the whole Burton doodah and needed to make it fit my Saab concentric

What I'm trying clumsily to show you is that there is lots of metal there and if you needed to I'm sure you could make one thinner to suit the extra thickness of the clutch pad.

"is it possible?"

Yes it must be, it's just a matter of engineering. I bet Daniel haa it covered in his book.

Burton themselves sell a series of adapter plates of various thicknesses just for that reason. Make it fit.

The 90mm figure is based on the outer diameter (and a bit) of the Saab concentric slave, the grooves should be adjusted to the unit you use.

have fun

bill l

Bill. That's fantasic! I knew that you had made your own and had a drawing, but I didn't like to ask you to put it up. I don't have a lathe, but I know a man who has. Steve Kiel is a MASC N.West member and is an excellent engineer.

I'vd just got this run to do on Sunday which I can't duck because it's my run and I'm the only one who knows the route. LOL. I just hope it holds together. Then I'll have time to do it without rushing.
Yep. I'm sure Daniel has it covered, but can I find a copy of his book? Nope.

Bernie.
b higginson

I hope it is some use to you Bernie

I think that Guy and I worked out that you need about 12mm fo 'push space' between the bearing and the ppressure plate

Measure up to give you that much and you will have the thickness you need

The devil is in the detail

I used Saab the first time and because I lost my bottle I used Ford the next rather than buy the Burton stuff.

If I'd properly threadlocked the screws first time around I'd still be happily Saabing along

Instead of nigh on bankrupting myself ;)

There IS LOADS of this, in Technical archives look for "Concentric Type 9 Guy" I usually find this lets the search function find all I need.

Hours of interesting reading, keep you tied to the 'pooter for days
bill l

Is it necessary to have a guide tube with a CSC? The reason I ask is I have a Ford Type 9 mated to a bell housing that has been drilled for a Saab 9000 CSC but th'ole through it is too small for the Type 9 guide tube.

Rob
Rob aka MG Moneypit

Rob the CSC has its own built in guide tube

The central tube is fixed to the body of the unit and the bearing slides along it attached to the carrier tube seen alongside the end

I dont have a guide tube on mine, it was removed when the Ford cover plate was replaced by the Burton one.

bill l

Ok, thanks Bill. I'm all set then, just need some time to do it.

Rob
Rob aka MG Moneypit

If you don't need to remove the pad on the clutch fingers to run your existing roller release bearing there is no reason to do so when using a concentric slave as all you are doing is applying a very similar bearing via a direct hydraulic link rather than indirectly via a lever.

Also as Bill states, the setup height can be varied and if using the Burton kit this is by thicker or thinner or no spacer at all.
Daniel Stapleton

I've just come off the phone from Burton Power and the guy said that there is only one release bearing that can be used, part number HD4941. This is a radius faced bearing as used on the 1275 diaphragm clutch and he said it may not work correctly with a pad on the clutch as on the 1098 clutch. He said that it would need a flat faced bearing.

So I ask again, has anyone done this conversion on a 1098 using the standard clutch, if so, what bearing was used?

Or do I now have to have my flywheel machined to take a 1275 clutch? this starting to spiral.

Bernie. (Getting desperate).
b higginson

Bernie, Burton Power should know what they are talking about, but I think that information is wrong. The "rule" is to use a radius faced bearing if it is to operate directly on fingers. This is because with a flat faced bearing the fingers would pivot on the outer edge of the flat section and eventually wear a groove resulting in weakening or fracture of the spring fingers. So in this respect he is right, but the converse is not true. i.e If you have a flat pad on the spring diaphragm then either a radiused faced or a flat faced bearing will work just as well.

Be aware also, when doing your sums, that the concentric bearing operates in constant light contact with the clutch. That is, the at rest position of the clutch has the bearing touching, and spinning with the clutch. In this position, the bearing needs to be "retracted" by about 12mm from its max extended (foot on the pedal) position. For some convenient reason, I found that the fluid displaced by my 1275 m/c was exactly the right amount to result in this 12mm movement of the slave.(I used a Ford slave) This may not be the case with the 1098 M/c, so this may be something else that you will need to check.
Guy Weller

Actually it is a radius faced release bearing against straight diaphragm fingers, like if you remove the standard pad, and a flat release bearing against diaphragm fingers formed with a radius on the inner ends. I think if you leave the pad in place then either will work fine as Guy says.
David Billington

And as Msieu Python would say

I agree with them

It won't matter if you use it on a flat face even if it does have a slight curve

I can't remember now but Im sure my old Peter May roller release bearing was slightly curved and I believe they can operate on any BMC clutch type. Need to check with Peter May, he has oodles of experience with Spridget boxes and would know if it can be used on both clutches

Now I see that Guy repeats my 12mm measurement, that should leave the slight contact you need
bill l

Thanks for everyone's input.
It was my thinking that it would be OK to use a radiused bearing with the pad, but as Burton are the experts, I took the salesman's answer to be correct.
The kit appears to come with all I need, including spacers and hydraulics, so although it's expensive, I may go for it. I'll decide once I get the engine out.
Should I remove just the engine, so that I can keep the hydraulics "live", or would it be better to get the whole assembly on the bench to do the measurements?

Bernie.
b higginson

This thread was discussed between 26/06/2014 and 30/06/2014

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