Recently repalced the clutch and cover and throw-out bearing etc. (clutch kit) And it works fine and all BUT... It requires decent rpm to drive to drive off without shuddering. Why does a clutch shudder? How can I fix it.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

A couple of causes could be the case here.
Lets start off with the worst and work backlwards.
a. You say the clutch was replaced a while back ! By Who ?? and was the flywheel torqued down correctly.
b. The clutch facings have begun to separate from the plate
c. The transfer case (clutch) oil seal was not replaced (or incorrectly fitted) when the and has start to seep oil onto the clutch plate (and flywheel).
d. The clutch throw out bearing has seized or is about to.
e. he clutch needs re-adjustment

From here on its hydraulic - and the most likely and the easiest of fixes

f. Master cylinder leaking or not giving full travel
g. Hose to slave is swollen and partially blocked.
h. Slave cylinder worn, rusted, leaking and not giving smooth retraction as the hydraulic activation is released.
i. Clevis pin on clutch pedal badly worn and giving eratic movement.

See if you can find a mini mate who can look at it and give a more accurate diagnosis. 80% of all problems are due to a simple cause. Dont be in a hurry to rip out the clutch just to find the rubber hydraulic hose is partially blocked.

Yeah I'm not in a hurry. You see it's not my car but my dad's clubby. He replaced it himself. I helped him along the way and realised just how much work it is. I'll get a mate to have a look. My dad mentioned oil on the flywheel as a probably cause, but I didn't see any leaking through. I'll check the slave cylinder and all hydraulic lines. Before removing flywheel and clutch assembly again.

Cheers for your help!

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

yeah - commonly that is the cause. It doesn't need much oil to do the damage. The clutch oil seals need to be replaced EVERY time the flywheel is taken off - its not a hard job while you are at it but a big job if it has to be done.

Mostly (although they just wear out) the seal works fine until it is disturbed. At the bottom of the transfer case is a hole with a split pin thingy. If the seal has gone sooner or later you will feel and see oil there but by then the clutch should be slipping because of the oil.

Now - the above is not a diagnosis - just a comment on the clutch oil seal. I personally bet its something hydraulic.

You also forgot to mension that it may be that the flywheel was not machined when the clutch was replaced. A poor face will cause shudder also.

Another point to check, and probably not well known, is the ridge around the flywheel hub. The diaphragm spring seats on this and the ridge can wear unevenly and cause the clutch cover and pressure plate to tilt slightly and/or be offcentre. Result is clutch shudder and it doesn't need much wear to cause the problem.

Hope this helps
RonR

i had a similar problem in Guvna... the flywheel had hotspots on it and needed to be machined...

Mentioned all of this to my dad, as we have a spare flywheel and everything, he said he feels like cutting his knucles in other clutch fix job. Hydraulics appear fine. The reason I rekcon it's clutch related is it didn't do it before the clutch was replaced, well I don't think it did, the clutch barely worked before anyway with the fully siezed throw-out bearing! Chucked that one into the shed somewhere!

But I'll do a double check on everything first as it is a big job.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Slinkey...
It will be very hard to detect a slight heat spot on your flywheel, it only needs a thou raise in one small area to throw out proper alignment with your clutch pads. This will never rectify itself over time as some people can assume. A flywheel to be machined will only set you back a few $$, and then you have peice of mind that it has been done corectly.
I know it is a pain in the arse changing it again, but when you have done it many times, you can get it all done in under 3 1/2 hrs removed and reinstalled. Less if you have a flip front

I bet a beer and fish and chips that it's the backplate strap mounting lugs (3 of them) are not flat. To check this, bolt it all togther and using a hydraulic press (yeah yeah I know) compress the diaphram down to see if all 3 sides are perfectly flat.

See this article: http://www.minimania.com/web/DisplayID/ ... ticleV.cfm

My backplate needed 3 whole mm taken off the face of 2 of the lugs to get it flat

Once machined flat, mark the backplate, diaphram and flywheel so that you assemble it back in the right way

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Lillee - 1969 Morris Mini K

It can also be the el-cheapo brand aftermarket asian clutch plate if fitted, they have facings with similar characteristics to a Kellogg's cornflakes packet.
I found this with Barney's old 1098 after we bought it.

I only use Borg & Beck plates, or failing that, a Quinton Hazell.

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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.

Oh don't worry, Borg and Beck's all the way! The flywheel shall come off again soon. But I'll get my spare one machined before hand so I can just swap over when it's dismantled.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Slinkey, PM me with your details or give me a call, I will get the flywheel machined for you very cheap, my brother works at SA Brake and Clutch in Sturt Street, I will do yours when I do mine. I gaurantee you it will be much cheaper than going anywhere else, it will be a Sat cash job...

Collins, That would be awesome, but it's not my car, it's my dad's and his Land Rover has, once again failed and will cost more money to fix. He's strapped for cash as for me...I just bought an SC-12 supercharger! Cheers for the offer but probably won't get machined for a while as the bank account doesn't permit it.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

hey slinkey Inc,
Have you been to regency yet? I'd be interested in hearing how it went. I'm aiming to take my 66 deluxe in next monday.