Really caught - trying to get the clutch to engage

[Ricrose]

Hi All
After going over the hydraulics 3x and pulling the gearbox out 2x I am finally coming for collective wisdom.

I am struggling to get the clutch to engage on a 65 series 2. It is the hydrostatic type clutch.I am pretty sure the problem is not the rod from the slave cylinder set up because even when the thrust bearing is fully out it does not touch the release fingers on the pressure plate. I have a new clutch plate (9"), but everything else is original. I have missed something obvious, but can't see it!
I wonder if someone who has their gearbox out could measure the following for me.
1. The distance from the edge of the bell housing to the fully extended release bush. Mine is 30mm. - photo attached
2. The distance from the front of the pressure plate to the top of one of the three fingers.- photo attached. Again mine is 30mm. I know this fluctuates with the condition of the clutch, my plate is new and about 6mm thick.

Also attached a photo of where I'm up to - not a natural but I'm really enjoying it!
Cheers. Richard

[Phil B]

Is the clutch friction plate in the right way round?

[Ricrose]

Is the clutch friction plate in the right way round?

Phil
I’m certain I have as it’s stamped gearbox side.

[JDNSW]

When you say you can't get it to engage,I think you mean you can't get it to disengage? In other words, the clutch release sleeve is not reaching the three release fingers.

As far as I can see, there are only three possibilities:-

1. Incorrect clutch driven plate - too thick

2. Incorrect clutch cover (pressure plate), or bolts on to flywheel loose

3. Clutch release shaft is not set on the right splines in the fork. (See manual for details how to set this)

In my view, (3) is the most likely.

[Ricrose]

When you say you can't get it to engage,I think you mean you can't get it to disengage? In other words, the clutch release sleeve is not reaching the three release fingers.

As far as I can see, there are only three possibilities:-

1. Incorrect clutch driven plate - too thick

2. Incorrect clutch cover (pressure plate), or bolts on to flywheel loose

3. Clutch release shaft is not set on the right splines in the fork. (See manual for details how to set this)

In my view, (3) is the most likely.

Thanks
I have only changed the clutch plate, everything else has been taken apart ( not the pressure plate) and cleaned with new bushes etc.
one of the reasons I was looking for the measurements was to start eliminating the possibilities.
When I swap the new clutch plate for the original the fingers only drop down to 22mm (from 30mm) - but the 8mm difference is easily explained when you look at the fulcrum of the fingers. I could easily see that a 1mm thicker plate could result in a 2 or even 2.5mm difference.

Also, I haven’t messed with the locked adjusters in the pressure plate, so it’s looking more and more like the release splines!

Let’s see where it goes.
Thanks again
Richard

[1950landy]

Is the clutch plate exactly the same diameter as the old one , why I am asking is I bought a new clutch plate once & it was slightly bigger than the original , like 1 to 2mm's & the outer edge was touching on the pressure plate housing . had the gearbox out about ten times until I worked out the problem . Probably not that but worth checking.[bighmmm]
You could also check that you do not have too much end float in the crank shaft causing the flywheel to move forward causing you to run out of travel on the throw out.

[Ricrose]

Is the clutch plate exactly the same diameter as the old one , why I am asking is I bought a new clutch plate once & it was slightly bigger than the original , like 1 to 2mm's & the outer edge was touching on the pressure plate housing . had the gearbox out about ten times until I worked out the problem . Probably not that but worth checking.[bighmmm]

Thanks, I’ll check that in the morning- I know it’s not 91/2” though.
I sympathise with 10x!

[1950landy]

Thanks, I’ll check that in the morning- I know it’s not 91/2” though.
I sympathise with 10x!
I also added to my original post for you to check the crank shaft end float.

[Blknight.aus]

as mentioned, release bearing thrust fork is on the wrong spline in the box, its easy to prove, simply drop theslave off and then rotate the shaft (by hand if the box is out) and by means of a long bar and a pair of vice grips on the connection tube if its in teh vehicle

from memory the throw from the face of the throw out to the casing should be nearer 50mm than 30 but I forget the exact number from last time I went through this.

its easy to id if the plate is a near enoughs good enough and just a fraction too big under the pressure plate, if you undo all the retaining bolts about 2 turns it will remain stiff to center up with an alignment tool

[whitehillbilly64]

Can you really put the plate the wrong way round.
It will only go one way, pressure plate wont tighten up if wrong, will it ????

whitehillbilly

[Ricrose]

https://uploads.tapatalk-cdn.com/20200213/99369551d0e3910bbfc3d985d2d37dd7.jpg
Cut a piece of timber to 11mm and checked the alignment of the splined shaft on the clutch release forks - it was correct. I will reinstall and continue eliminating as soon as the new gasket arrives.

[Ricrose]

Is the clutch plate exactly the same diameter as the old one , why I am asking is I bought a new clutch plate once & it was slightly bigger than the original , like 1 to 2mm's & the outer edge was touching on the pressure plate housing . had the gearbox out about ten times until I worked out the problem . Probably not that but worth checking.[bighmmm]
You could also check that you do not have too much end float in the crank shaft causing the flywheel to move forward causing you to run out of travel on the throw out.

Just checked the clutch plate - identical to the old one. The one I’d removed was 3.5mm thick and almost on its rivets and the new one 6.8mm. That was the only difference.

I’m starting to suspect the linkage to the slave cylinder and will check that out when I get it all together.
Thanks again.

[Ricrose]

Finally got the clutch to disengage this morning. The gearbox was only out 3 times so I guess it could have been worse.
I bought new linkage which removed all the play, made sure the slave was properly bled and then changed the splined cross shaft (I couldn’t get clutch on the 11mm in the manual) until it worked.
Now when the release bearing is not engaged there is about a 5mm gap before the fingers. I guess that’s OK?

[Blknight.aus]

Finally got the clutch to disengage this morning. The gearbox was only out 3 times so I guess it could have been worse.
I bought new linkage which removed all the play, made sure the slave was properly bled and then changed the splined cross shaft (I couldn’t get clutch on the 11mm in the manual) until it worked.
Now when the release bearing is not engaged there is about a 5mm gap before the fingers. I guess that’s OK?

untill the clutch is about 1/2 worn it'll be fine.

[Ricrose]

I figure that would be the case - I think I’ll have to adjust again - it really is a compromise!
I don’t fancy removing the gearbox once the resto is finished.

[Blknight.aus]

you dont need to remove the gearbox to adjust it.

theres a length adjustment on the push rod.

set it up so the push rod is fully extended with the forks at the 5mm distance and the bearing is face is extended from the rest position by say 20mm. then as the clutch wears you shorten the rod letting the push forks rotate backwards to accomodate the play.

the II/IIa clutch is a little bit of an artform but its key to remember that its still a hydraulic system that is largely self adjusting. once you've set it up mechanically with the throwout bearing clearance checked with the slave in the 1/2travel position you need to have enough mechanical adjustment/piston retraction to get the 11mm clearance from a new clutch.

once you have the mechanicals up and in postition 99% of your throwout bearing freeplay is going to vanish as they hydraulics do their bit.

I personally always aim to hit

rod at 3/4 max lenght
piston at 1/2 face travel
throwout bearing .5mm off of new clutch fingers.

Remember if your putting a SIII pressure plate onto a SII clutch throwout you need an adaptor that sits between the fingers and the throwout as the III's fingers sit in a different position to the levers on a II clutch

You wont get a good adjustment without the adaptor

if you find the piston is bottoming out on retraction then you can space the MC body up about 1/4 of an inch without too much hassle by adding a spacer plate or washers and slightly longer bolts.

[JDNSW]

Question for Dave - the Series 2a pressure plate is harder to find than the S3 one, because, as you say, it has the spacer attached to it. It occurs to me that it would be relatively easy to turn a spacer that attached instead to the thrust sleeve, probably by having a recess to fit it closely, and held in place ideally by a circlip, although I'm not sure there is room with the sleeve fully retracted, or a pair of grub scres. Balance would be a bit critical, and the face might need to be hardened - or would it?

Thoughts?

[Blknight.aus]

Question for Dave - the Series 2a pressure plate is harder to find than the S3 one, because, as you say, it has the spacer attached to it. It occurs to me that it would be relatively easy to turn a spacer that attached instead to the thrust sleeve, probably by having a recess to fit it closely, and held in place ideally by a circlip, although I'm not sure there is room with the sleeve fully retracted, or a pair of grub scres. Balance would be a bit critical, and the face might need to be hardened - or would it?

Thoughts?

nope,

158174
A proper series 2 plate, bit heavy on the leg
1581755
a modded SIII style plate for the SII/SIIA
158176
Seires III plate.

not hard to find at all, My usual goto's can get them and they're available from UK suppliers.

[JDNSW]

I didn't say they were hard to find, just harder, and if I needed to do one, I would probably get the proper one - I was just wondering whether my suggestion would work.

And on that subject, for my ex army 1970 2a, I am guessing it has the later 9.25" clutch with the pressure plate similar to the S3. Can I assume this (I know it hasn't been changed since it left the army), or do I have to look?

[Blknight.aus]

I didn't say they were hard to find, just harder, and if I needed to do one, I would probably get the proper one - I was just wondering whether my suggestion would work.

And on that subject, for my ex army 1970 2a, I am guessing it has the later 9.25" clutch with the pressure plate similar to the S3. Can I assume this (I know it hasn't been changed since it left the army), or do I have to look?

you could have almost anything in there although so far as I know if it had a clutch change late in life it got a modified plate not an OEM SII/a item.



if you were on task with the machining then yes machining up an insert will work, the face that mates to the IIa throwout could be normal mild steel only the part facing the fingers would need to be hardened. but then why bother? if you were going to that much effort just grab a throwout sleeve and replicate it with a wider section for the face.

[Ricrose]

you dont need to remove the gearbox to adjust it.

theres a length adjustment on the push rod.

set it up so the push rod is fully extended with the forks at the 5mm distance and the bearing is face is extended from the rest position by say 20mm. then as the clutch wears you shorten the rod letting the push forks rotate backwards to accomodate the play.

the II/IIa clutch is a little bit of an artform but its key to remember that its still a hydraulic system that is largely self adjusting. once you've set it up mechanically with the throwout bearing clearance checked with the slave in the 1/2travel position you need to have enough mechanical adjustment/piston retraction to get the 11mm clearance from a new clutch.

once you have the mechanicals up and in postition 99% of your throwout bearing freeplay is going to vanish as they hydraulics do their bit.

I personally always aim to hit

rod at 3/4 max lenght
piston at 1/2 face travel
throwout bearing .5mm off of new clutch fingers.

Remember if your putting a SIII pressure plate onto a SII clutch throwout you need an adaptor that sits between the fingers and the throwout as the III's fingers sit in a different position to the levers on a II clutch

You wont get a good adjustment without the adaptor

if you find the piston is bottoming out on retraction then you can space the MC body up about 1/4 of an inch without too much hassle by adding a spacer plate or washers and slightly longer bolts.

Thanks for the detailed reply. Exactly what I was hoping for. I have just set it up as described and will now go ahead and put it all back together again. Great fun!
Thanks everyone

[JDNSW]

The situation I could see when you would bother is if you need the vehicle tomorrow, and have an S3 pressure plate, but the mail only comes once a week.

[Blknight.aus]

The situation I could see when you would bother is if you need the vehicle tomorrow, and have an S3 pressure plate, but the mail only comes once a week.

wrong effort on the bother.

not bother as in why your would bother machining up just the spacer when you could just get the right clutch but why bother machining up a tight tolerance fitover component when you could just as easily machine up the spacer as part of a throw out sleeve.



IF it was me AND for some reason I couldnt make it as a one piece item I'd be drilling the face plate of the OEM thrust and screwing the adaptor to it with 3-5 m6 x .5 counter sunks and loctite 680.

the fitment adaptor in the pressure plate is fitted together as part of assembly of the pressure plate, not something I'd want to be getting wrong.

[mick88]

I didn't say they were hard to find, just harder, and if I needed to do one, I would probably get the proper one - I was just wondering whether my suggestion would work.

And on that subject, for my ex army 1970 2a, I am guessing it has the later 9.25" clutch with the pressure plate similar to the S3. Can I assume this (I know it hasn't been changed since it left the army), or do I have to look?

John,
I have a 1971 2A and it has the modded series 3 type pressure plate that Dave refers to (middle pic).

Cheers, Mick.

[JDNSW]

Thanks Mick, but I'm not sure how confident that makes me that mine has it. As far as I know they were optional until the end of 2a production, but I would not be surporised if all of the Australian ones had them well before then -- but I don't know! And when I do need to do the clutch, I would like to know what bits to order before I start pulling it apart!

I suspect I can see through the opening you get when you take off the gear lever assembly.

[Blknight.aus]

Thanks Mick, but I'm not sure how confident that makes me that mine has it. As far as I know they were optional until the end of 2a production, but I would not be surporised if all of the Australian ones had them well before then -- but I don't know! And when I do need to do the clutch, I would like to know what bits to order before I start pulling it apart!

I suspect I can see through the opening you get when you take off the gear lever assembly.

correct, you can also see it with a mirror on a stick by taking the rubber seal off of the clutch tube hole (if you're lucky you have a l/r version of the bellhousing the left one is really easy to get out.

[Tins]

John,
I have a 1971 2A and it has the modded series 3 type pressure plate that Dave refers to (middle pic).

Cheers, Mick.

My admittedly fuzzy memory from my RAEME days agrees with Mick.