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MG Midget and Sprite Technical - Clutch in, revs drop
|On my midget, I have noticed that when I press the clutch pedal at tickover, the revs drop about 2-300 rpm (according to the inaccurate rev counter on the dashboard, but the engine note does change somewhat too)|
I haven't had the engine out to inspect, but was wondering what might be the possible reasons, and could anything be done or checked without engine removal?
There is a slight oil drip from the back of the engine, and I suspect the rear oil seal has seen better days as the PO has had the engine out at some point and seems to have been a bit of a butcher. Is there some kind of breathing of the clutch housing that I could inspect, or is this doomed to be pending mechanical catastrophe ? :/
|It's supposed to do this!!|
|lol - wow. Thanks for the quick reply, that's a far more positive response than I feared :)|
Is there a reason that someone can explain to me in words of one syallable? <:)
I'm now only worried that it's mentioned in the owner's handbook and I'm going to get lynched for not having read it :/
|I've no idea why it happens, I only know that it's normal.|
|Well not entirely|
It will be worn thrustbearings.
So it can be fixed and should be hardly noticable
With the thrusts worn you are pushing the complete crank fwd giving more friction slowing the idle down.
You can check if this is realy bad by having an assistent in the car press the clutch and look if the pulley moves
|Thanks, Onno, that job can be done from the bottom without the engine out by dropping the sump, am I right? |
Can anyone offer a "fool's guide" to changing them ?
Thanks again for all the help,
|should be doable|
but first check if you see the pully move if it does then you should think about replacing other wise just live with it.
In a 1275 it is not as critical as with the 1500's
Now if you do it is a case of
-removing the sump
-removing the oil pick up
-remove center main cap
-check what size thrust bearing was used (should be mentioned on the back)
-push the old top ones out with the new ones
-fit the botom ones in the main cap
-bolt the main cap down (same orientation as it came out)
-torque up the main cap
-check if it spins freely
-refit the rest
lube all new bearings (chainsaw oil is nice and sticky)
use new gaskets.
first get oil pressure before you start it up again.
But first check if it is needed
and if it does not fix the problem then ignore it as long as the engine has no other problems.
|Thanks Onno, I'll check if it moves and take it from there. Otherwise I'll just live with it, it was a real pain when the car didn't idle very well, as the clutch was enough to make it stall. Much better now the idle is sorted anyway.|
|I have also had the same symptoms when the carbon on the clutch release bearing has worn away and I had metal to metal between the bearing carrier and clutch cover. After a while it started to make a noise and the gears got difficult to engage.|
|The gears are easy enough to engage at the moment, and no strange noises that I've noticed. Is there any way of checking the release bearing without pulling everything out?|
|You could try it with a mirror and lamp through the top cover (rubber boot)|
but you should have noticed when it went out and the first while when the carrier was grinding the pressure table on the cover to size.....
But when the grinding is over it works fine drove on for about 2 months until i had time to fix it
|Well - that may have happened with the PO, but I've no way of knowing :/. I have had it for ages, but it has only just been road-worthy since the end of april.|
I'll see what I can see, and check the pulley movement first. I'll take it from there.
Thanks for all the advice,
|Assuming it's not a 1500.|
You've got 2 possibles as suggested. Either the thrusts, or the carbon release bearing.
I drove with worn thrusts for ages, and they do cause a slowing when the clutch peddle is pressed.
However, not as much as a shagged carbon bearing I found.
You can still change gears as long as the pressure plate center is depressed by the bearing which it will be (until you loose all the carbon, and most of the carrier), but because the carbon is knackered on the bearing carrier, it will be grinding away at the pressure plate, and causing serious drag through friction.
I think the quality of the replacement carbon releases deteriorated over the years, and they didn't seem to last as long as they used to. (I went ford 5 speed 10 years back, so don't know about now).
Anyway, you might not hear any noises for a while, but when you do you, and you will, it will be a kind of squeal, and you will probably feel it through your foot too, as the release bearing grinds the pressure plate pad away.
As I recall, without getting into my loft to look at my old 1275 box, there are also two rubber covers UNDER the g/box. One is the rubber boot over the clutch release fork, and the other is a dust cover, ---presumabely for for lh drive clutch release fork entrance?????????
If you can't get the angle with the mirror through the top rubber, get under and look through these with a pencil torch. You should be able to see the pressure plate and carbon release. If shagged, then as I am sure you know, it's engine out time.
|I believe (from memory) that you can see the release bearing through the top inspection hole.|
As Lawrence says, the lower LH hole is for LHD clutch operation, but only on mechanical clutch release - Minor and A35 - not hydraulic.
|Dave O'Neill 2|
|Ah didn't know that about the moggie and A35 being cable clutch.|
|Not cable, as such.|
The pedals go through the floor and there is a direct mechanical linkage.
|Dave O'Neill 2|
|I can imagine that when in good nick then, they must have been pretty reliable?? |
Certainly easier to sort out than a leaking slave or master.
Wonder why I never drove a moggie thou? Amazing, they were(still are) common enough.
|I have done the first part of the check, with my beautiful assistant operating the clutch while I examine the pully. If it moves it moves far less than my bleary eyes can pick out. I guess if I really try then I could just about make out that it moved, but I figure that's nowhere near enough to warrant me being concerned about it.|
I'll try and examine the clutch end of things too, but for the minute I suspect it's just going to move off my list of things to do something about and onto my list of things yo keep an eye on.
Thanks for the feedback folks.
This thread was discussed between 25/07/2011 and 30/07/2011
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.