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Forum Index : Microcontroller and PC projects : Nice clutch....
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9553 |
Ouch....this is not good....      No problems, right? (rhetorical!) This was a NEW clutch plate, installed about two weeks ago. Car is an MG 1100, '64 vintage, but basically uses the exact same clutch arrangement as the classic Mini, Allegro, Metro, and all of the classic 1100/1300 cars. So, what went wrong here? The clutch plate was replaced, along with the primary-gear. Two weeks later, this was the result. When the car was examined a bit more in detail(after this failure), it was found that the crankshaft end-float was around 8mm or so. Ahhhhh......NOT good. This means that the crank can move laterally on the main-bearings, by up to 8mm in either direction. I don't expect there is much left of the center-main thrust washers... But this then allowed the crank to move drastically along the inner of the primary gear, destroying both the new clutch plate, new rear-main-seal, and the primary gear inner bearings. The primary gear itself, seems fine, but the bush bearings are chewed up inside. I still think we can re-bush the primary gear and save that, but..... This is not good. Will need a full engine rebuild to fix this. Smoke makes things work. When the smoke gets out, it stops! |
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phil99 Guru  Joined: 11/02/2018 Location: AustraliaPosts: 2535 |
Yes, the plate's flex-disc can only cope with a very small misalignment. |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7735 |
I don't think it would have been much worse if I'd got my wife to crochet one... :( Definitely rebuild time. :( Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| mozzie Senior Member  Joined: 15/06/2020 Location: AustraliaPosts: 131 |
G'day Grogster, Don't want to be the bearer of bad news, but last time I saw this it ended up with a two-piece crankshaft  The A series thrust bearings are only about 2.5mm thick so to get 8mm end float is really not good. A couple of odd things can cause this, and this is from experience: The rubber hose from the master to slave cylinder fails internally and acts as a none return valve. The brake and clutch master cylinders can be swapped but one has an internal valve (some models only) that restricts return flow. Have also been supplied the wrong one. The stop adjuster on the end of the release shaft comes loose / falls off. All the above mean the driver can pump the clutch faster than it can return oil and basically try and drive the crank out past no.1 cylinder, not good for the thrust bearings at all. This is all with Mini 998/1098 but basically the same I think. Hope your luck is better than mine  Regards, Lyle. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9553 |
Agreed. I have never seen a crank move that much in my life, and I have worked on lots of A-series engines in my time. The engine still runs, so I expect the crank must still be in one piece(perhaps it is cracked, but just hanging in there?), but when you start her up from COLD, you can hear all kinds of horrible big-end/main bearing noises. That does settled down quite a bit, once the oil pressure comes up, but I can imagine all kinds of bearing destruction going on - probably both crank and con-rod big-ends. At first, we just thought that the bearings were obviously stuffed, so we were planning a bearing job on it anyway, but then discovered it's ability to destroy brand new clutches, and we just grabbed the end of the crank and push-pulled it, and.....bloody hell!!! It's not my car, I'm just helping out a buddy, but now he's basically up for a block rebuild, which isn't going to be that cheap. Problem is, he bought the car sight-unseen, and did not ask me or my other mechanic chum to evaluate it first, so he has basically bought what they used to refer to as a "A Lemon". I think "Sponge" is a more accurate term, in that it is gonna suck your wallet dry!  Smoke makes things work. When the smoke gets out, it stops! |
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| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 562 |
On a lemon, MG means Mainly Gutted.. commiserations  |
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