mk1-forum.net

Good afternoon ,

Wondering if anyone could advise.

The clutch on a 66 850 fully standard is not engaging. I can have the clutch fully depressed, in gear and there is constant drive.

I have replaced all linkages & slave rod (apart from the plunger coming out the wok), the system has been fully bled up on several occasions, there appears to be good travel on slave rod, and the adjustment for the free play is all as per the book. For the purpose of testing the overthrow nuts are fully backed off.

When I take the inspection cover off the side of the wok I can see there is movement on the clutch plate, so not seized etc.

Would anyone be able to advise on anything else before having to take the plunge to taking the WOK off and seeing if there is anything untoward happening? Thank you.

From where you are at, I'd suggest measuring how much movement of the backing plate you are getting. Turn the engine over until you have a backing plate bolt head in the inspection hole and measure from that. You need a minimum of 0.040" here. With all new parts, you'll get around 0.060".

I'd guess though, that the issue will be that the Plunger is worn.

Thank you for your response really appreciate it.

How would advice on the best way of getting that dimension? Dial gauge or rule on the head of the bolt whilst someone operators the clutch?

This is my suspicion also, just trying to eradicate absolutely everything before the wok coming off.

I'm thinking plunger or the perennial and always overlooked clutch problem of worn plunger as per Spider's answer or general wear in the axis pins and axis pin holes in the rods.

It'd also be interesting to know whether this has just come on or it's been getting 'heavy' (for want of a better word) for a while

This is what the inside of the clutch plunger looks like when it's knackered! check the 'ball' on the end of the arm as well.

Thank you,
Should have added my apologies, was all functioning and selecting gear before disassembly for complete nut and bolt rebuild.
Gearbox etc rebuilt by Guessworks, my fault as when I reassembled clutch etc completely overlooked a potential worn plunger so same one went back in as it wasn't giving any issue previously!

Austinmini1966 wrote: ↑Sun Mar 16, 2025 7:43 pm Thank you,
Should have added my apologies, was all functioning and selecting gear before disassembly for complete nut and bolt rebuild.
Gearbox etc rebuilt by Guessworks, my fault as when I reassembled clutch etc completely overlooked a potential worn plunger so same one went back in as it wasn't giving any issue previously!

All good responses....however, you say you can see the movement of the clutch when you look through the inspection/timing hole.
That would indicate that the diaphragm is being pushed in.....
Perhaps there is an issue with the clearance on the primary gear......it should stop spinning when you engage the clutch...which stops drive into the gearbox.
Maybe the primary gear thrust washer....C washer... If there was insufficient clearance,,,,the flywheel would be putting pressure on the C washer on the crank.
It would feel OK when it is just sitting on the crank prior to torquing the flywheel up.
This would prevent the primary gear from stopping.
Just a thought!

When you say you’ve got constant drive while in gear with the clutch depressed - are the front wheels off the ground or are they on the ground?

Wheels are on the ground……if I went to start it in gear with my foot on the clutch the car would “lurch” forwards ?
Thank you

Austinmini1966 wrote: ↑Sun Mar 16, 2025 6:37 pm Thank you for your response really appreciate it.

How would advice on the best way of getting that dimension? Dial gauge or rule on the head of the bolt whilst someone operators the clutch?

This is my suspicion also, just trying to eradicate absolutely everything before the wok coming off.

I find I can do it with a 6" ruler, but if you don't feel you have an eye for small measurements, then it might be best to set up a Dial Gauge.

Thank you,

I will try to get a measurement tomorrow evening and just check there is enough movement on the plate.

Now all rebuilt with a new plunger and still no change......all linkages, arms and pins are now all new.

Looking like it must be something internal?

I have had a good few clutch issues with new components, and in one care the push rod simply wasn't long enough to get the travel required. I took the advice of Dermot on here and put a sump plug washer behind the thrust bearing - on the plunger. That solved the problem I was having. An alternative to that is of course to have an adjustable push rod, which saves you having to dismantle again.

Primary gear drag can be caused as explained above, but I also recall an old engine that had the oil ways clogged up which meant it wasn't spinning freely either. Dod you check them when it was apart?