if the clutch is leaking however, it won't allow the clutch to disengage, but also won't cause over extension as has happened here.

Was the bearing pushed up hard against the carrier shoulder when it was put in?

Apart from the clutch arm wear, other items to look at are the top and bottom clevis pins, or damage to the clutch spring plate where the bearing contacts the plate. I haven't heard of the clutch arm bending under load...but it might also be worth a look?

Definitely time to remove the wok for a look see however...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Well thats what I thought but I'm seeing good movement of the slave, no visible leaks, pumping made no difference.

I could see that the plunger was hitting the circlip. As soon as I removed the circlip and gave a bit more adjustment it felt normal all the way home.

When I first posted I replaced most links. I'm expecting to see massive wear in the plunger. I guess the ball could be cracked but as I say it is one of the new thick arms.

Yes the bearing would have been fully home, it was all operating perfectly when new plunger etc. was installed.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

I tested an original, it was over 50HRC.
I tested 2 KC ones a month ago, they were about 1 and 2 HRC... They were told the material was EN24 but apparently it was not the case.
These appear to be made from Ledbrite free machining steel then plated, not hardened. Can't heat treat this stuff...
Kc has some real `EN24' (hopefully) ones coming from UK in the next shipment.

I have since saved 2 soft ones by drilling the hole to 9/16" diameter then press fitting hardened silver steel bushes I made.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

How new/old is your engine? About 3 months ago I decided it was time to rebuild my engine (at this time the clutch was almost non exsistant), upon dismantling the engine I discovered the end float was nearly 3 times spec and as I put my foot on the clutch it was pushing the crank towards the radiator, stopping the clutch from disengaging.

I think you will find the plate that the bearing presses against will have a groove worn in it.
Any way hurry up and remove the wok as we are all eagerly waiting for the answer..

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

That is another recent problem.
2 AP orange dot diaphragms I bought in the last 18 months had soft thrust plates. They need to be hard. Try a file on the corner, if you can file it, swap the plate with an old one.

it's about time some of the UK parts suppliers exercised a bit of Quality Control instead of shipping us rubbish.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Mspares supply (or used to) a heavy duty shuttle that had a slot rather than a cylindrical drilling ..and a matching clutch arm with a wide cam like end rather than a ball. = massive increase in contact area between arm and shuttle bore.... = equivalent reduction in point load between the faces.

Cheers, Ian

They also list 2 standard design plungers- an EN24 one, and a cheap minispares one which is rubbish, as mentioned in this thread- basically it's a zinc plated turd.
WHY do people continue to sell parts that are clearly inadequate and unsuited to purpose..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I was got caught out with a gearbox layshaft from the UK that wasn't hardened properly.
Only lasted 2000km before it went and put metal throughout the engine and gearbox.

Sourced from the UK, but made in one of those SE Asian sweatshops, I'm betting...............

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

because they shipped in a container load from china and still want to make a quid out of it

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

I think I know why I lost my clutch. Although I suspect the soft thrust bearing carrier has worn so much and had been adjusted so far it jammed and snapped. I'll hopefully get the wok off over the weekend.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Oooohhh....

Now we all know!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Ok wok off. The thrust plate on the pressure plate is fine. Thrust bearing fine. removed the carrier and removed the broken ball.

The wear on the thrust bearing carrier is incredible. In the pictures you can see there is a second mark, this is where the broken off the arm was pushing against the bearing carrier after the ball broke. Maybe the arm was bent or broken for a while and it left a second mark, although I suspect it broke when I broke down and couldn't get any clutch. When I over adjusted it in an attempt to get home the broken end was pushing on the side of the opening. I'm amazed I got home with it like that.

In the last picture I have pushed an Allen key into the divet from behind to show how deep it is.







I have a new "soft" bearing carrier into which the good Dr. Mini has inserted a hard steel bush. Just waiting on a new bearing and should be all good.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Pieces of crap!

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.