Throwing clutches

[randylandrover]

G'Day guys! I bought a 92 Disco about three and a half years ago and thought it was the best thing on earth. About a year ago my clutch went. The clutch assembly, master and slave cylinder were all replaced. My clutch is now slipping again. Does anyone know if the 92 disco are prone to throwing clutches?

[Blknight.aus]

not usually, but if your still on your original clutch you might find that this time its actually slipping and not a hyds problem

[randylandrover]

The original clutch was also replaced. The mechanic told me that this clutch 'would outlive the life of the car'.

[Pedro_The_Swift]

yea,, what Daves saying is--

what did they actually replace last year?
clutch AND pressure plate?
and master and slave cylinders?

just trying to sort it out;)

[randylandrover]

Clutch, pressure plate, throw-out bearing and the flywheel was machined.

[LandyAndy]

Any oil driping from the bellhousing???
Andrew

[randylandrover]

There is only enough oil to coat the thread when I remove the bellhousing drain plug every 6500km's.

[Blknight.aus]

Urmmm have a really good look at your bellhousing and see if you can see any signs of spanner markings on the bolts that hold it together...

I've got some questions...

IS this going to be a DIY?
are you any good with the spanners?

Doing this leaves you with NO abiltiy to declutch so you want to be good at manipulating the other vehicle controls to compensate for the purpose of the test.

Find a slight downhill with a good run off and turning area.

grab a brake hose clamp and lock off the clutch slave at the flex hose, then unbolt the clutch slave, once its outwrap an elastic band around it to stop it coming apart and secure it somewhere.

in 1 high with the vehicle facing down hill start on the starter and bring it up to a bit of speed, keep your foot on the noisey pedal and using your left foot mash the brakes and try to stall out the engine. If it slips get off the brakes and the noise, then snap the main shifter into neutral, stop and replace the slave cylinder. Your up for at least a new friction plate at this point.

If it doesnt slip without the slave cylinder in repeat the test with the slave cylinder in after pressing the clutch pedal a few times. If its slips your up for a new (or rebuilt/rebuild it yourself) slave cylinder as its pitted and is jagging the piston and preventing it from returning all the way.

Heres hoping its just a fouled slave cylinder and your previous mechanic did the righty by you.

[BradM]

If the external clutch conponents are OK then it may be the following cause that is now giving you grief.

I have seen in some manufacturers fly wheel face designs when a flywheel has been machined where the clutch plate faces, the pressure plate face on the pressue plate unit where it bolts up needs to be machined the same amount. Otherwise this leaves the machined off surface on the fly wheel adding a wider difference to when the pressure plate contacts.

This is most often the case when the shop buys in the new clutch conponents and sends off the fly wheel to be machined. As the machine shop ususally does not have the new pressure plate unit as it is on order back at the shop or sitting on the bench.

This is OK for about 18 months to 2 years depending on how much has been machined off and your driving habits before the cluch friction plate wears down enough to start slipping again.

In some design cases the pressure plate mounting face should definitely have been machined down the same amount as came off the fly wheel for this not to happen. I suspect in your case this may possibly be the situation.

I must state however at this point in time it is only theory as I have never seen a Landrover clutch apart and do not know the finer points of it's design.

Fortuntely for me over the years age has bought me some wizdom coupled now with the lack of 300 hp+ upfront. I also switched to automatics to handle the hp.

BradM

[randylandrover]

Thankyou muchly for you help

[nobbydoldrums]

I have seen in some manufacturers fly wheel face designs when a flywheel has been machined where the clutch plate faces, the pressure plate face on the pressue plate unit where it bolts up needs to be machined the same amount. Otherwise this leaves the machined off surface on the fly wheel adding a wider difference to when the pressure plate contacts.

BradM

Do you mean machining a set amount off the entire face of the flywheel rather than just the area which contacts the friction plate? Are the friction plate thicknesses and clearances really that tight that they couldn't cope with a bit of machining?

Darren.

[awabbit6]

I have seen in some manufacturers fly wheel face designs when a flywheel has been machined where the clutch plate faces, the pressure plate face on the pressue plate unit where it bolts up needs to be machined the same amount. Otherwise this leaves the machined off surface on the fly wheel adding a wider difference to when the pressure plate contacts.


I don't think that anyone would really machine the flywheel this way would they?? I've never seen it done. It would actually be very difficult to do this way.

The only reason that I can think that only the clutch surface would be machined would be if the pressure plate spigots could not be removed.

[BradM]

I have seen it.

BradM

[BradM]

What makes a clutch slip? Hydrolics usually fail with the pedal going to the floor, ie, not being able to engage the clutch.

Slipping - caused by the throwout bearing not coming right back to where it should keeping the pressure plate partly engaged, the pressure plate being stuffed or the friction plate wearing down to a point where the pressure plate cannot hold the required amount of force on it.

The other answer may be that it is just a crappo friction or pressure plate or the rear engine seal is leaking spewing oil into the clutch.

The only real answer if it is not a hydrolic problem is to have a look. I suspect the machining.

BradM

[rick130]

I doubt if it would be the machining.
If they remove the cover plate dowels the whole face of the flywheel can be machined so there shouldn't be a problem.
Did this six months ago on a 300Tdi (basically the same) including balancing everything ('cause I'm a pedant)

Paul/Defender 200Tdi had a slippage problem a few years back with an AP plate/cover assy that had been installed by a previous owner about 70,000km prior, and for the life of me I can't remember what he found, but I think it may have been a weak diaphragm/crook fingers.

[BradM]

As I said I have not seen the Disco LR clutch setup. If they are done straight across the fly wheel, as some other makes can have a receess where the plate actually fits into, then as you say it should not be the problem.

If it's not the fluid system it will need to come out to see. As it is not that old, it is starting to sound like a crappy pressure or clutch plate.

BradM

[randylandrover]

Turned out it was a stuffed pressure plate. The mechanic said the one that was in it did not look like it was replaced a year ago and actually looked like it had been in it for a while. Mechanic said it was a small clutch for a torquey 200tdi. All is well now except every time I change gears it feel's like the clutch pedal friction point changes. He reckons its probably a stuffed master cylinder.
Cheers guys and thanks for the advice.