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MG Midget and Sprite Technical - 5 Speed clutch probs, So Heavy

Just cannot seem to get to the bottom of this problem so posting up again.

The clutch on my 1275 Ford T9 conversion is just so heavy and just cannot fathom out why.

So a couple of questions . Is it correct to remove the thrust pad from the clutch diaphragm fingers when doing this conversion?
Has anybody found it beneficial to space the clutch fork pivot point nearer the engine. My thoughts are that the clutch fork angle is wrong and so it upsets the mechanical advantage.
I have the thrust bearing sleeve on the T9 box intact and the correct roller release and the clutch fork carrier is slotted and everything was free to move before fitting. Also correct 1275 slave fitted. I had a previous sprite 1275 and T9 conversion and clutch weight was fine
The clutch bite point is correct and no clutch slip the only fault is its so HEAVY.
Any thoughts
R Mcknight

Check that the slave that you have is correctly matched to the master cylinder. There are 2 sizes of each and if you get the wrong pairing it will effect the mechanical advantage.
Guy W

Hi Guy

Master is 3/4 and slave is 1 inch so it should be Ok.
R Mcknight

Check to make sure the diaphragm fingers aren't fouling the release bearing guide tube.

Which conversion is it?
David Billington

Its parts from MMC Birmingham. Don't think the fingers are fouling as there are no untoward noises and clutch fully works just heavy.
R Mcknight

Diameter of the hydraulic tube from master to slave too small. I had that on my midget, changed to the correct dia, slightly bigger than brake pipe.
Alex G Matla

Good point alex

I like your thinking
Prop and the Blackhole Midget

You know Alex I have had that thought myself and you the only person to mention it. Maybe I need to get a new hose made up.
R Mcknight

If the hose is presenting a restriction then I would expect a noticeable difference in the pedal weight between a fast depression and a slow one, is there any?
David Billington

Again David I had been thinking about that but as it stands at the moment I will try anything. Resolve all the easy options before I take the gearbox out. And I don't want to do that!
R Mcknight

I'd blame the MMC pivot thingmy

when I fitted mine the bracket device didnt give me a decent angle of pivotting, no matter how I fitted it (with and without packing pieces to move the pivot point deeper into the bell housing)

In a slight case of desperation I fitted the later car's wider clutch pipe and adapter to my dual master cylinder (1966 car) and the later type slave cylinder

It didnt help and I kept getting shdderingjuddering pedal which was also very heavy

After getting two broken diaphragms because the release bearing ran off center I gave up and fitted the first of my concentric systems



Which had a heavy pedal until I fitted a later type single master system for brakes and clutch (I used a 1500 pedal box)

Now I run a Ford concentric with a long bleed screw that protrudes out beside the bell housing for very easy bleeding
Bill sdgpM

To me it's got to be something to do with the hydraulic ratio, flow or leverage. Surely if it were some kind of fouling of any of the components then not only would it be heavy to operate but it wouldn't return properly either.

Mine is the same set up (though by Frontline) and has always worked perfectly, it's as light as the original one. I've been following your woes from the start, hopefully you'll get it sorted soon.
john payne

Was I right to take off the Clutch thrust pad off the clutch fingers?
And yes I spent a lot of time making sure the clutch thrust was inline with the clutch fingers, this in turn caused problems as the slave cylinder did not line up with the fork very well at first causing problems. Had to file out the holes in the slave cylinder to resolve that.
R Mcknight

Yes the pad is removed from the fingers on mine. It came like that from Frontline.

I also remember having to file the holes in the slave but I seem to think that was more to do with clearance from the chassis.

The thrust should always be in line with the fingers as it should be a nice sliding fit on the input shaft sleeve. The relation between the thrust and slotted pivot was the only thing that seemed to need some work setting up.

I used to have a car with a conversion by MMC and to be honest the clutch operation was pretty poor. It was their original set up and still used the carbon release. I ended up binning it and buying the Frontline parts to convert it. I think MMC have changed their conversion to one similar to Frontline now.

Here's a photo of the parts you get with the Fronline kit, you can see if the cover and release bearing are similar to yours. The kit from Frontline is 1800 plus vat!!
john payne

Sorry, here's the pic:



john payne

Have a look at

http://www.biker-lofty.co.uk/hobbies/boltonmods/5%20speed%20to%201275%20midget.htm

where he points out that the release bearing is not central due to a hole drilled slightly out of place.

Also, I thought if you used the carbon release bearing you needed the pad. Running carbon on the fingers alone leads to a very short life for the release bearing.

Rob
Rob aka MG Moneypit

Yes, the original MMC kit I had used the carbon release with the pad on the cover still fitted. I had to remove the pad when I changed to the Frontline release.

Also the MMC set up had the input shaft sleeve cut down which allowed the release bearing to just flop about all over the place. I ended up buying a gearbox to get an unmodified sleeve - back in the day when type 9's were cheap!
john payne

I think I also slotted the hole slightly on the pivot as shown in Rob's link. I remember it because filing it revealed that the pivot is made from hardened steel, presumably to prevent wear of the slotted pivot point.
john payne

This thread was discussed between 13/08/2015 and 14/08/2015

MG Midget and Sprite Technical index

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