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MG Midget and Sprite Technical - Why won't the clutch work!?

I am at the last stage of a long restoration of a 1971 Midget with a 1275 engine. Engine is running fine, but no mater what I have tried, I have been unable to get the clutch to operate correctly. You name it, I've done it from bleeding time and time again to replacing the master cylinder and so on!
The clutch was new when I did the engine.
In exasperation, I managed to get it to my local, very trustworthy, garage and they have tried seemingly everything, even replaced the clutch, but the inability to disengage the flywheel enough to engage the gears still happens!
Anyone come across this before, anyone got any ideas? We are at a total loss as to where to go now!! HELP
R Clayton

Worn clutch arm bolt?
Onno K

Even (or perhaps especially) with all new clutch components I had to make a variable length pushrod to get the pedal movement to exactly match what was required. Combination of tolerances for new clutch covers, release bearing, bent or ovalled forks, push rods, slaves etc can all mean the movement is spot on.
Dean Smith ('73 RWA)

Thanks, that was new when we put the new clutch in.
R Clayton

Are you sure you bled it all out? They're notoriously hard to bleed and even a little air in there will ruin the whole affair.
Also, what Dean says, did you check every component for wear?
Are you sure you have the correct components. I don't just mean they came in a box or bag saying they were right, I mean are they actually right!

There could be a lot wrong here, or almost nothing at all. What does the clutch pedal feel like?
Roadwarrior

Not so hard to bleed. Just make sure you push and hold the rod, fully into the slave cylinder before starting, to prevent any air being trapped behind the piston. Then apart from access to the bleed nipple it's very easy.
Lawrence Slater

Thanks for your suggestions, everyone. With regards bleeding, I used conventional method carefully, used Eezibleed method, had neighbour, who is experienced with this type of engine, to bleed it "his way". The clutch pedal felt reasonably stiff, but when depressed would not effectively disengage from the flywheel. There was a significant drop in revs, or even stalling when the clutch was depressed with the engine running.
I got all the bits from MGB Hive, as has the garage with the latest replacements.

I will pass on the suggestions regarding tolerances etc.

Thanks everyone.
R Clayton

"There was a significant drop in revs, or even stalling when the clutch was depressed with the engine running."

Then you don't have a bleed issue.

Your push rod may be too long, causing overthrow, and forcing the cover thrust against the driven plate.
Lawrence Slater

what are the symptoms of driven plate in wrong way round?
David Smith

1st motion shaft binding in pilot bearing?
Bernie Higginson

I had the same problem, try bleeding it at the master cylinder by undoing the union on the clutch pipe where it connects to the master cylinder, sounds like it wont work but it did with mine, quick and easy so must be worth a go. Dan
d a hadaway

I still prefer the 'Australian method' from Colin Dodds Sprite Parts :-

http://www.spriteparts.com.au/tech/bleeding.html

O.K access is slightly more difficult for RHD cars but works for me.

R.
richard boobier

The first thing to do is check under the car to see how much (if any) movement there is on the arm when pressing the pedal.

Another thing to check is whether you can push the car, in gear, with the engine NOT running.
Press the clutch pedal all the way down and see if you (or an assistant) can push the car. If not, lift the pedal up slowly and see if there is a point where it disengages.
Dave O'Neill 2

Ive seen this before on the BBS

3 possiable problems...

1. the flywheel was "over resurfaced " and the pushrod is now to short

2. The clutch plate is installed backwards..

3. The rubber boot that supports the fork is missing or worn out.

My money is on option number 2...its easy to do

Do you hav the correct slave ... the bleeder is at the bottom of the slave ?

Probably illrealavent but did you bench bleed the master before installing.

Prop

Prop and the Blackhole Midget

Has it got the correct thrust release bearing. The 1098cc looks like the 1275 one but is shallower ie the 'arms' which go into the clutch fork are slightly shorter and will mean the slave piston bottoms out before the clutch disengages. You can try a temporary fix by lengthening the pushrod. try putting a small nut on the end of the slave piston then put the pushrod back in. I experienced this and eventually replace the thrust bearing and all was well.

Bob Beaumont

But this is a key statement.

"There was a significant drop in revs, or even stalling when the clutch was depressed with the engine running."
Lawrence Slater

I had a similar issue last year when I had to replace the old tincan master with a newer plastic one. After buggering about for quite some time, I found that the new master cylinder pushrod was 1/4 inch shorter than the original so could never push enough fluid into the slave.
worth taking a look.
p.s. my new master was from sussex but I bet they all use the same supplier.
graeme jackson

Again.
"There was a significant drop in revs, or even stalling when the clutch was depressed with the engine running."

If the slave wasn't engaging, the above wouldn't be happening.

It's more likely that the rod is too long, or there is some other fault. I can't see how it's a fluid problem.
Lawrence Slater

It could be engaging just enough for the release bearing to contact the clutch cover but not enough to actually release. that would cause the engine to slow down.
graeme jackson

After seeing the revs drop stuff, i'm with Lawrence. It's bled fine and somewhere there's an issue with parts dimensions and clearances.

Worth trying what Dave mentioned above with the pushing the car and seeing if the actuation is too far and is jamming the clutch into the flywheel and if not, try the nut trick mentioned by Bob with some pushing and see if that points to under-travelling.

Once you know if it's too much or not enough, you still have to find out why though...
Roadwarrior

Was there any work done to the engine during the restore?

Engine revs dropping when the clutch is engaged is not a common problem with the 1275 engine but to eliminate it from the equation... check there is no forward movement of the crank pulley when the clutch is engaged. You might need and dial gauge to be sure.

Best of...
MGmike
M McAndrew

Left out the crank thrust bearings? You'd know it if you did I reckon. ;).
Lawrence Slater

Thanks to everyone who had responded. Really grateful! I will be passing on your comments/suggestions to the garage and hopefully things will be resolved.
Bob
R Clayton

This thread was discussed between 15/03/2015 and 16/03/2015

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