Hi all,

I've been having a problem with clutch judder on and off over the last few weeks. Normally it's fine, but occasionally it will get quite bad, then fix itself.

I looked around a little, and found that clutch judder can be caused by the drive straps not being parallel to the flywheel. My theory is that the clutch (which was replaced before I bought the mini) did not have it's backing plate machined and the straps not parallel. The pedal is quite firm.

But since I really don't know much about clutches, I was wondering if there was anything else I should look for. I was going to take the wok off and just have a look. I believe an oil leak can also cause judder (as unlikely as that is in an a-series engine :).

The judder normally occurs when changing down gear, but sometimes when changing up too - that's why I'm not sure about the straps being the problem.

I would look at oil first. Is there any oil leaking out the drain hole in the bottom of the clutch housing? (The hole with the split pin poking out)

Some of the causes for clutch shudder (judder);-

Worn Primary Gear bushes,
Oil on Clutch Plate,
Worn Clutch Plate,
Bent Clutch Plate,
Drive Straps stretched, loose or incorrectly assembled (usually with the wrong bolts),
Flywheel and / or Backing Plate running off and in need of machining,
Broken spring in the Diaphram,
Worn Crank Tail,
Excessive end float of the Primary Gear,
Broken / Damaged / Very Worn Idler Gear Bearing,
Flywheel loose on the Tail of the Crank,
Worn Splines on the Clutch Plate and / or Primary Gear

The most common causes that I have found would be the top three on that list, so I'd suggest starting there. In one case (which drove me mad ) I could find no reason, however I replaced the Clutch plate and it came good. The plate was more thoroughly examined and no defect found. It was fitted in another car and was OK so ???

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If you change down then let the clutch up quickly (without bringing engine revs up), the drive straps are all in compression and tend to buckle and you get a shudder.
This is more likely IF the diaphragm spring has not been set to flat on assembly (ie, with the 3 backplate lugs machined to suit).

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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've had the same problem for a few years, well since I had the gearbox overhauled
by a very well respected mini workshop.
I had the clutch replaced 2 or 3 times and different flywheels fitted but no better.
It does it mainly in first when starting off but also when changing down.

So it could be the drive straps fault
what does this mean Dr 'diaphragm spring has not been set to flat on assembly'

Sounds like we have the same problem.

Sorry to hi jack your thread

Read here- and ask me what you don't understand.
After 40 years of flywheel and backplate wear, and their remachining without checking assembled height spring flatness, it can needs up to .070" off the 3 backplate lugs to rectify this.
http://www.minimania.com/web/DisplayID/ ... ticleV.cfm

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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.

probly a broken engine mount

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.