The Many Clutches

Nov 20, 2021

This week's puzzler is one from the past. So this is an oldie.

It was a fellow that came into the garage with a pickup truck. It was a big Ford pickup, an old one.

And he had put a clutch in his pickup truck. He personally had put a clutch in his pickup, and it was good for a few months. And lo and behold it stopped working. He was unable to disengage. He'd the step on the pedal and it would go 'RhyeaRhyeaRhyea", and then gee, what's the matter? Nobody knew. So he put a new clutch in, again by himself.

And then he was all right for a while and then he hears the worst possible sound, and he can't shift it.

So finally he puts another one in and of course this one doesn't even work for a minute. He just can't shift it and he assumes that there's something else wrong with it other than the clutch. And by this point, he has replaced everything, the clutch,  disc, the pressure plate, the release bearing, the pilot bearing. (Now we had this puzzle once before and we said it was the pilot bearing. So don't send that answer in because that isn't it!)

He finally gave up and he took the car to us. We gave up too! No, we didn't give up; we found we found the answer. There was nothing wrong with any of the clutches he had put in all nor was there anything wrong with his transmission, nor was there anything wrong with his shifter. The problem was somewhere else. And it was kind of interesting.

There are a lot of cars this can happen to, but you would not see this happen to a vehicle with a hydraulic clutch.



So what was actually wrong was that he had bad motor mounts.

And when he was stepping on the clutch, what he was actually doing instead of disengaging the clutch (and he didn't notice this until the mounts got really really bad, which was coincident with the last clutch being replaced), he was actually pushing the motor towards the front of the vehicle, and the clutch wasn't disengaging at all.

So the reason a new clutch would work for a while in its early stages, is that a new clutch is always easier to disengage than an old one. As a clutch begins to wear out, it gets harder and harder to depress the fingers on the pressure plate, until finally, you can't shift. You say, "Aha, I need a new clutch!" You put a new one in and it works for a month and then all of a sudden it doesn't work. Anyway, back to square one. And I said that this wouldn't happen on a vehicle that had a hydraulic clutch because, on hydraulic clutches, that whole mechanism is mounted right on the bell housing. So there's no net force on the motor. There's nothing to push the motor forward.

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