Clutch problems

Squealing Clutch when pedal held down...

if you get squealing when pressure is on pedal: suspect defective clutch release bearing: SOLUTION: remove clutch housing bolts remove and replace bearing

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Clutch Arm Repairing

Peter Cooper's little tip to anyone who is suffering from insufficient clearance on their pre-verto clutch:

"The Old Rover 2000 (P6) model was blessed with an adjustable clutch slave cylinder push rod, that just happens to be an almost direct substitute for the standard fixed length job.

If you can lay your hands on one now, it may be the solution rather than going to the trouble of welding and reshaping the bottom ball on the clutch arm."

But, if you want to go through it, another contributor says:

"I found the ball on the clutch arm was badly worn. So much so I could not disengage the clutch fully.

As I did not have a spare arm I simply built it back up with weld and ground it back round with the angle grinder."

Bite point too low/high

The purpose of the clutch levers etc is to move and disengage the clutch from it's 'normally-engaged' state...therefore...

• A 'good' clutch will release near the top of the pedal travel (ie: only push down a little)
• A poor clutch will need lots of travel to disengage. This can be caused by a few things, here are some of the favourites:
  • Throw-out stop too close to housing. As the release bearing moves in, the throwout stop limits it's travel before the plates have disengaged
  • Return stop (pre-verto). This means the arm travels back to far and expels too much fluid from the slave. The arm then has to travel before it starts to disengage the clutch
  • Worn clutch arm (either worn pivot ball, or worn pivot pin) This will need more pedal travel to disengage
  • Weak diagragm centre spring fingers (Verto clutch) (needs more travel to pull pressure plate off friction plate)
  • Slave push rod worn or too short
• You can also have a 'poor' clutch that bites TOO high causing slipage. This is caused by:
  • Worn friction/pressure plate
  • Weak diaphragm outer (main) spring
  • Worn slave bore/seal. If fluid leaks here the master level will drop and the bite point will drop too

Verto-specific bite point and clutch change info

If the bite point drops it's problems with the arm/release/hydraulics/pressure plate and needs more pump to disengage.
If the bite point rises it's the friction plate wearing. This needs less pump to disengage.

Check that the throwout stop nuts are not being touched on the end housing.

It's not tricky to renew the clutch plate. Pull out ancillaries, Undo mount, jack end of engine up, cover off, pull flywheel (the trickier bit), renew clutch, reassemble.

Bleeding

IMO the clutch slave has always been a pig to bleed on Mini, even more than the old, single cylinder front brakes! After many years of trying various methods, including Easybleed etc. I find the best way for the clutch is to revert to the old two-man (or persons) system:

• Attach pipe to slave, with pipe end fully immersed in new fluid in suitable container
• Open bleed valve on slave, get partner to press pedal steadily to floor then hold. Shut off bleed valve immediately. Release pedal
• Repeat (1) & (2) three times, then check performance

This system is the only one that I can rely on. With all other methods, air always seems to get into system. In fact I suspect that 'Easybleed' introduces air into fluid whilst under pressure in the supply bottle. This last statement is open to argument because, on the Mini production line, pressure bleeding was always used, with the simultaneous operation of the brake pedal. I seem to recall, however, that the returned fluid was pumped through a vacuum chamber to remove any dissolved air.

Bleeding 2 - also in "fitting braided hose"

"To bleed the system, I recommend that you undo the engine tie-bar at the block and swing it out of the way. This way it'll be easier to get a spanner on the bleed screw. This needs to be a fairly thin spanner - 11mm or 7/16ths - to allow the bleed hose to be fixed.

The process of bleeding is then fairly straight forward. I would, however, suggest the following; it is fairly tricky to get all the air removed, so finally, close the bleed screw and depress the clutch pedal fully, and fix it in this position for several hours. (In my case I left it overnight) This will allow any remaining air to escape. (Don't ask me how - I don't know, but I would speculate it seeps out past seals etc. After all, the system is fluid-tight, but not necessarily gas-tight).!

Oiled up clutch assembly? Ed: get-you-home repair only!

"Firing a dry powder extinguisher into the clutch housing gets an oiled up one through a rally ;)"

How to free a siezed clutch

• Disconnect the ignition in case it starts up!
• Fully charge the battery
• Have plenty of space in front of the car
• Hold the clutch pedal to the floor (assuming the arm is still moving)
• Put the car in first gear
• Lurch the car on the starter until the rust on your flywheel gives
• All the starter torque goes across a clutch plate only held on with rust to
  the backplate and flywheel

Rebuilding the Clutch Master Cylinder

"The only trick with rebuilding master (or slave) cylinders is making sure the bore is clean before inserting the new components. Having dismantled the cylinder, look down the bore and check for scratches, grooves or pits and holes caused by corrosion or extraneous bits of left over rubber. Clean out the bores using a homemade honing tool.

• Cut a piece of fine (800/1000 grit) wet and dry about 12cm long and 2 to 3 wide, double it over lengthwise
• Get a piece of wooden dowel about 15 cm long and less than 1 cm diameter
• Split one end of the dowel and feed in the strip of wet&dry - like the feathers on the end of an arrow
• Twist the ends of the flap in the same direction (flat strip of wet&dry now takes on an "S" shape)
• Stick the other end of the dowel in your electric drill
• Run that up and down the bore a few times and the inside of the cylinder will be all shiny and clean and any bad news (pits and gouges) will be painfully obvious.

Buy yourself some rubber grease and a pair of circlip pliers and you're in business. If you go the whole hog and have the bores sleeved in stainless steel you may never have to buy a new cylinder again."

Verto Replacement Tip

I removed the old pressure plate and dumped it as it was U/S.

The problem was that when a new pressure plate was ordered it did not come with the inner spindle which is required to fit to the tapered spindle. This part must be removed from the old pressure plate and fitted to the new.

The part is NOT available separately other than from a broken engine.

Anyone replacing a verto pressure plate in the future DO NOT throw your old one out till you have removed all required parts from it. Lucky for me I have managed to get a replacement from a broken engine.

More Clutch Adjustment Tips

Either bending the arm or lengthening the rod are both bodges, and should not be necessary.

Are you sure that the clutch is assembled correctly with the thrust pad in place etc?

With the engine held securely, it should be possible to manually operate the clutch to the limit of the throwout stop and I always do this before re- fitting the engine.

Are the stops adjusted correctly?

updated 16 Dec 2002

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