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MG MGF Technical - Revs without equivalent motion?

Folks,

Before I diagnose a knackered clutch, does anyone have other ideas as to why I get less forward progress than I used to for the same revs from the engine? What else should I check?

By way of background in case it is relevant, I have been abroad since mid-November and the car was only used briefly over Christmas. I did not notice anything wrong in 2004 but am fairly sure now that revs are not translated into motion in the same way as previously. The engine also sounds as if it is more breath-y, if that makes any sense. A little like an asthmatic person.

I'm off to B&G for a service on Friday week, but wanted to check here first.

Thanks for you help.

Regards

Chaz
C Golvala

If you've got clutch slip, then either the friction material has worn out, or there is oil penetration. Either way, seems likely that the clutch will need replacing.

Only other thing I can think of, as I type, is the possibility that the clutch isn't being allowed to engage properly: is it possible for the clutch release bearing to stick in this fashion???
Rob Bell

if you have clutch failure then putting the car in 5th at 40 and flooring it will cause the engine to rev and then the car to start accelerating.

If this does not happen and the revs are propotrional to the speed, then you have memory failure :-)
Will Munns

Clutch lever in gearbox housing sticky due to rust, may be.
If it is, then the clutch doesn't engage complete.
Dieter K.

Thank you gentlemen. It looks as though I now have a test for whether there is a problem. Presumably, Will, there would be an appreciable time lag between flooring it and the car picking up speed. I fear that this is what I have observed in other gears and at other speeds, but I'll check.

As for other causes of the same symptoms, could lack of use and being in a barn over the winter cause the clutch release bearing or similar to seize?

Regards

Chaz
C Golvala

Yes it could.. and yes, it WILL be that..

-- well okay, maybe not.., but I bet my hat it is.

A load of wd40 to ease the release bearing whilst someone else pumps the clutch pedal, then slap some proper oil over it. Repeat for a few days and you're sorted!
(I use Scott Oil - the motorcycle chain stuff)

Good luck.
Neil H

There will be no lag on the revs climbing, but the speed will then catch up, the reason to use 5th is because in the other gears the car picks up speed too quickly to tell.
Will Munns

Thanks all. Absence of forward motion has decreased over this week as I've driven the car more, so stuck clutch release bearing seems most likely culprit. Will, your test doesn't produce much forward motion in any event, but neither does it cause the engine to rev without proportional acceleration (as far as I can tell).

Up to B&G this Friday, who have also suggested the WD40 approach, though they say that the bearing is hard to get the oil to.

Regards

Chaz
Chaz

>Up to B&G this Friday, who have also suggested the WD40 approach, though they say that the bearing is hard to get the oil to.

???'confused'???
I meaned the clutch lever bearing _ouside_ and I think Neil aswell. Not the release bearing on the drive shaft.
http://www.mgfcar.de/gearbox/dcp_3908org.jpg
Upright black part on the right. (Behind the gearbox, if you look down from above)

Dieter K.

There is a easy and simple way to test if the release lever is working or not or if it's sticking.

Remove the engine cover,
Remove the "R" clip from the clutch slave cylinder,
Remove the clevis pin,
Slowly push in the push rod and hold it in.

This will allow you to push and pull the lever as it is now disconnected from the slvae cyclinder push rod end.
You should be able to moving the lever back and forward and hear the release(thrust) bearing being moved and clunked on the shaft inside the bell housing. There should be about 3/4" travel of the lever.

cheers.
Branko.
Branko

Confused? So am I. Nice tip Branko, I'll try that when I have a chance, but B&G are going to get a go first thing tomorrow.

Regards

Chaz
Chaz

OK, no longer confused. I've now seen a clutch with the "lid" off and the offending lever/rod visible and immovable. I'm writing from home on a slow connection, so I'll see if I can find relevant pictures on Dieter's website when I'm at work on Tuesday.

I guess that Branko's description is of the same thing I saw with the gearbox and clutch out of a car. The lever on the outside connects to a 6 inch-ish rod that passes through one bush and across the centre of the clutch before being located in another bush (both nylon lined, I believe). The workshop manual calls this rod the clutch release shaft. There is no seal for where it passes through the casing and evidently moisture penetrates causing the rod to rust and seize. According to MGR and B&G it is difficult to lubricate because although the upper bush may be reached by any lubricat you spray through the casing, the lower bush can't be.

Certainly the release shaft on the MGF's clutch that I saw today was stuck solid. B&G were going to remove it, clean-off the rust, grease it (MGR said copper grease) and refit. But, that is a drop-the-subframe-gearbox-out job.

Now the $64 million dollar question (well about £600 actually)...do I need to have this done and if so how can I tell and how long can I wait (well, three questions, I suppose)? The car's pick-up has improved and I don't notice any lag or revs without motion now, but B&G say that the clutch is stiffer to operate than it should be and the problem will continue to worsen before it finally seizes up altogether.

I'll try to get some lubricant down the release shaft, as per Neil's advice, but in the meantime if anyone else who has experienced this problem could give me a prognosis, I'd be grateful.

Cheers

Chaz
C Golvala

I have had the sticking staft problem on and off for the last two years. But the car does not get regular use...

But keeping it lubricated has kept the gremlins at bay and saved me from a complete replacement.

SO don't worry just drive it, enjoy it and keep it lubricated every once in a while.

:-)
Steve Ratledge

Chaz,
That's a very good description you posted.

It's good that you actually saw how the clutch release lever works for yourself. From that you can see at what points the system can get stuck.
By all means play around with the WD40 treatments etc.

But,

If your clutch is slipping consistantly, I would advise you against letting that condition go for too long.
Clutch slip will create lots of heat. This heat is transfered to the flywheel, which (and I am talking from direct experience here) may cause the flywheel to distort, get surface cracks, get heat spots and your flywheel may not be able to be reused.
This equates to more money to spend.

cheers.
Branko
Branko

Thanks Branko, Steve R and all. I'll lubricate away, but keep it under close review.

Regards

Chaz
Chaz

This thread was discussed between 10/03/2005 and 22/03/2005

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