Clutch Problems....
Submitted: Wednesday, Nov 09, 2005 at 15:40
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Kero
Hi all,
First time user of this post and hope that I can find the answer I am looking for.
I own a GQ 4.2 Diesel Patrol, with about 350,000 kays on the clock. A good rig, and has served me
well on and off road since I have brought it with less than 200,000 kays. This vehicle is set up with a vacuum assisted hydraulic clutch system from factory (similar to a brake set up of any normal car/4x4)
I have been experiencing recently, problems with the clutch mechanism, and cant work out if, A, the clutch is failing, or B, (which I suspect) the clutch boosted is failing. The clutch does not seem to be slipping, but I am finding that the clutch petal range from “normal” to “extremely heavy” when pressing to change gears, (engine running, of course).
I have asked a number of mechanics and have been told that it could be the pressure plate failing and hence why it can be hard to use, the clutch plate is worn out, or the clutch booster or hose has failed.
Master and Slave on the clutch system have been replaced recently after the old master spewed it contents all over my firewall.
Anybody got any ideas or experienced anything similar?
Thanks in advanced for you help.
Kero.
Reply By: Bilbo - Wednesday, Nov 09, 2005 at 23:01
Wednesday, Nov 09, 2005 at 23:01
Kero,
All the above suugestions have merit. Another one to consider is that the vehicle has done a high mileage and this is starting to show in clutch performance.
Modern clutches consist of the back face of the flywheel, the spinner plate also known as the centre plate) and the pressure plate. The pressure plate applies pressure to the spinner plate by a conical shaped diaphrgam made of spring steel. It's a very shallow cone but a cone nevertheless. When you put your foot on the clutch pedal, you apply pressure to this diaphragm "spring", the initial reaction on your foot is one of pressure from the resistance of the spring diaphragm, then as the diaphragm "goes over centre" i.e collapses the diaphragm or turns it inside out, the spring actually helps the clutch to release and the release pressure at your foot becaomes less. I can't think of a suitable anaolgy to describe this.
When a pressure has a load of
miles on it and it has experienced a lot of heat, this spring starts to lose it's temper (i.e tension), and the consequent flip flop, inside out collapsing of the diaphragm becomes almost non-existent. It then becomes difficult to press the clutch down (and hold it down) because this "self servo assistance" is no longer there.
I would suggest a new pressure plate at least. I renewed my GQ clutch at 200,00 kms when it was getting a bit hard to press. When the clutch was inspected the rivets holding the clutch friction linings on the were just about to touch the rear face of the flywheel. So it was time anyway. When it was all rebult with a new pressure plate & thrust bearing it was a completely different truck to drive. A pleasure. You don't realise how bad it was until you put a new one in 'cos you get used to it over time. Same applies to brakes.
Bilbo
AnswerID:
138735