I was on a little stroll the other day, and passed a car park on my route that has a somewhat steep exit ramp. There was a car trying to leave the car park, but his exit was temporarily blocked. So he was sat there revving his engine, holding his position on the slope by slipping his clutch. The car was quite new, and it made me think, some poor schmuck will pay for that when he trades it in, because his clutch is probably badly worn if he often does that - but how could you tell when buying second hand? It will fail sooner rather than later and that can be expensive.
What is a clutch? Well, it has several parts, but fundamentally it is a way of connecting and disconnecting your engine from the gearbox, so that you can change gear and then get back on to engine power again. So, on the back of the engine is a flywheel, a big metal flat round plate. Bolted on to that is a clutch cover, also metal and round and has springy bits to it, we’ll come to that in a minute. And then in between the cover and the flywheel is a clutch plate, you guessed, it’s round, but it has a friction material on its outer surface. When you press your foot onto the clutch pedal, either by hydraulics or by a cable, this causes a clutch release bearing to press onto the clutch cover springy bits. The clutch plate has a splined hole in the middle, and a shaft from the gearbox slots into that. As you’re driving along, the flywheel is spinning, and the clutch cover is holding the clutch plate tight against it, so the turning of the engine turns the gearbox input shaft, happy days, the car moves. When you press in the clutch pedal, the release bearing presses on the springy bits and causes the cover to lift away from the clutch plate, so the engine is no longer turning the gearbox.
However… as your foot moves the clutch pedal up and down you can vary how much the plate is slipping, and that’s how you ‘feel’ the clutch and adjust how much power reaches the gearbox, and how my man in the car park was letting his car rest on the partially spinning clutch plate. So what was wrong? Well there’s a lot of friction involved in that, a lot of heat, a lot of wear on the plate. Clutch plates are designed to last a long time, but, like brake pads which use similar friction material, they don’t last forever. And the more slipping you do the less long they last, of course.
Holding your car on hills with the clutch is not advisable, and neither are very high revving screeching starts off the line, as again this generates heat and wear. There are other ways to damage the mechanism, if dirt gets into that area of the car it can play havoc, as can liquids, and you can get oil leaks that deposit oil onto the clutch faces which obviously is disastrous.
So, you detect an issue with the clutch. You may be able to hear it slipping, you may find hill starts become very tricky, it may pack up altogether. Could you replace your clutch?
Well, I think you could, but you’re going to need some tools, and a good friend to help probably, but it’s not too hard if you are of a mechanical bent. Spoiler alter, I have done it myself, a couple of times, and I blame this job on my bad back, because I foolishly once tried it on my own. Gearboxes are very heavy! Get a mate.
Cars vary of course. You will probably need a lift of some kind, you will need to get access to the gearbox housing, there are so many variations of front and rear and all-wheel drive, you probably need a Haynes manual, or finding a clip on YouTube that suits your car, to proceed.
In my own case, funnily enough, I did not need a lift because my gearbox came out of the car from the inside! Yes, it was a long time ago, and cars were not so well built back then, and simply removing a cover from over the gearbox exposed all the bits I needed to get at. Not so nowadays I suspect. But in essence, you unbolt and remove the gearbox, remove the clutch housing from the back of the engine, exposing the clutch mechanism. Unbolt the clutch cover, and there you have in your hand the clutch plate. Yes I know, it won’t be that simple, but it can be done.
Then… recall I said I had done it twice? Well, learn from my mistake, replace EVERYTHING to do with the clutch – I cut corners and discovered I’d misdiagnosed the fault and had to do the whole job again, properly this time. Buy all the clutch-kit you will need, in the end that will pay off.
If you do try it, good luck, but I can say that on the whole I enjoyed the job, as it uncovered all the interesting bits and bobs that go to make your car work, and an appreciation of the engineering involved in simply changing gear.
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