engine revs when depressing the clutch pedal

[dalgrae]

Any ideas please when I depress the clutch pedal on my 1953 series 2 whether the engine is hot/cold the engine revs drop by a considerable amount the engine never stalls but I would like to know what the possible causes could be.The car changes/engages all gears easily with no g/box crunching noise at all

[mike.perry]

The engine will lose revs when depressing the clutch, particularly on a low powered engine such as the 803. This is because you are pressing against the clutch springs and effectively applying a brake to the engine. If the engine timing is correct and the tickover speed is not too slow then the drop in revs will be less noticeable.

[bmcecosse]

The graphite release bearing may be worn out, and the pedal may be going down too far - putting excessive force into the engine thrust bearings! You must minimise use of the clutch - never ever sit with your foot on the clutch.

[robedney]

Also make sure that the clutch is properly adjusted. I can't remember what the manual says, but somewhere around 3/4" of free play at the stop of the stroke is probably OK. Before doing that, make sure the the clutch return spring is still there and attached. If you've got no free-play what BMC is suggesting may be the culprit. A graphite throw-out (release) bearing acts much like a disk brake with excessive pressure.

[dalgrae]

Thanks for all the suggestions I will check them out

[katy]

On the subject of release (throw out) bearings, is the mechanical, ball bearing, type, release bearing available for the Minor, in place of the carbon (graphite?) type?

[bmcecosse]

There are such things - but - the operating arm moves in an arc so the bearing would be moving across the pressure pad. Not so important with the graphite sliding bearing. The graphite bearing lasts well enough IF you make sure you don't ever sit with foot on clutch - at traffic lights etc. Always - clutch down - into gear and move off immediately. Never sit in gear with the clutch down.

[robedney]

I once ordered a clutch set for an old Peugeot. It came with a "live" release bearing (ball bearing sort), and what came out of the car was graphite. I put in the live bearing, and two weeks later took it out and put in a new graphite bearing. For a live bearing to work it has to center on the pressure plate fairly precisely, whereas a graphite bearing has some room for the arc BMC talks about as well as some slop in the alignment. In other words -- I wouldn't sub a live bearing for graphite again. They are cheap enough, and I've never seen one not outlast the clutch disk itself.

[Chris Edgar]

I fitted a new clutch about a month ago, replacing the one which came with the car. It was worn down almost to the rivets & was beginning to slip.

The springs on the new one are so much stronger, the engine revs drop when the pedal is depressed. No doubt after considerable time, as the clutch wears the pressure needed will be less.

[bmcecosse]

Make sure the pedal is not going down too far!

[mike.perry]

Roller bearing clutch release bearings are available for the 1098 engine, the smaller engines have a different thrust bearing.
I would recommend fitting a roller bearing if using the 1275 MG engine with a diaphram clutch as the extra load required will destroy a carbon thrust bearing in a short time

[Neil MG]

My 1275 Midget had a carbon thrust bearing...

[mike.perry]

My 1275 MG engine chewed up the carbon thrust before I modified the manual linkage and fitted a roller thrust bearing

[riley 1489]

Hi all,

I have had my 1275cc MG Midget since 1980 and have never worn out a carbon release bearing, I think I have changed the whole clutch once in 32 years / 120k plus miles. BUT when I build up my 'new' MG Midget I will probably convert to roller bearing due to my positive experience of installing one in my Riley 1.5. I converted my Riley to diaphragm pressure plate, using MGB parts (so much better) so while it was all apart I also did the MGB roller release bearing conversion. The key feature is that the face which bears on the pressure plate is coated with something which mimics the carbon- maybe it's Teflon or similar- so it does accommodate the arc of the bearing as it is brought to bear against the pressure plate. Result is no slowing down of the engine when I operate the clutch, which had been quite pronounced previously.

Regards
Chris

[riley 1489]

Carbon bearing:[frame][/frame]

Roller bearing:[frame][/frame]

[bmcecosse]

Yes - as several have mentioned - the Spridgets came with graphite release bearings and they seemed to last ok! So I can't see it's anything to worry about. It must of course be installed/adjusted so it's NOT rubbing all the time - and drivers must NEVER sit with foot on clutch for any time at all. Thanks for the pics of the roller bearing 'riley'.

[katy]

Thanks for all the different info. I'll have to have a look-see and find out what type of clutch is in our '61 Minor 1000.
There's a 1275 in there, but I don't have a clue as to it's ancestry as it was in there when we bought the car and the PO didn't know either. It did have twin carbs and a broken exhaust manifold on it when we got it, but we've changed that to a single carb and unbroken exhaust manifold.