Grinding clutch

[Doherto]

As an extension to this thread i would like, if possible to requst some clarification please. My clutch is now "ok" but i am not happy with the adjustment. I have a post hydrostatic slave cylinder which is 95mm and i understand should have a return spring. I have fitted a new return spring and am struggelling with the final adjustment. I have read tons of stuff but am not sure which measurement is should be setting. The book says 95mm play for a hydrostatic but i believe 1/8th inch for a non hydrostatic. Neither of these settings are working for me. Can anyone tell me what clearance there should be between the thrust bearing and the pressure plate without any pressure on the pedal. Fortunately i have two access holes in the bell housing, one for a light under the flywhel and the other for feeler guages which can reach the thrust bearing, so i have a chance of setting the slave cylinder settings by this method, if this information exists. Help please.

[Doherto]

Sorry the book says 19mm

[XJR308]

You just need free play at the operating fork and the slave cylinder push rod, the amount of play is not that critical. Too much play makes 1st gear engagement difficult and too little or no play at all will result in premature clutch slip. When the adjustment is set at 1/8 what symptoms are you getting?
Bruce

[PPV]

The manual says that the hydrostatic clutch operating slave cylinder was fitted to engines later than the following numbers:
2.4 BJ.5110
3.4 KJ.7659
3.8 LE.2533
Before this the slave cylinder had a return spring fitted. The manual says for the hydrostatic slave cylinder then you should adjust the slave cylinder operating rod by as per the manual on page E10/E11. This basically is done by disconnecting the slave cylinder form the clutch lever, push the clutch operating lever away from the slave cylinder until resistance is felt and keep it there, then push the operaing rod into the slave cylinder to its limit and adjust the rod length so that the dimension of 19mm is obtained between the centre of the fork end hole and the centre of the clutch operating rod hole. Then reconnect and bleed as necessary.

However, as long as there is some free play there should not be a noise from the clutch.
What exactly caused the issue in the first place.
Regards,

[Doherto]

Hi again, thank you for your prompt replies and support. This is a complete car rebuild project with all new clutch parts and now having replaced the spigot bush, which has stopped the grinding, i am not too happy with the sound of the new parts. I set the paly at 19mm but felt that the thrust bearing is in slight contact with the pressure plate. I have now read, proberbly too much, but can now confirm that i have a 95mm slave, C29801 which i understand needs a C5120 spring which i also have. I am going to work on it today so will report back later on progress. I am going to rebleed the system before resetting the slave cylinder play although i am not sure if i should set first and bleed after as the book says. Anyway i should have some more information later, amd fingers crosse hopefully a solution.

[Doherto]

Ok, had a few hours of play with success of a kind. I tried all sorts with some success but eventually opted for adjusting he push rod length half a turn at a time and checking i still had clearance between the thrust bearing and the pressure plate. I now have a clutch that is not touching the thrust bearing but the pedal is very low. Perhaps this is standard for a mk2 i would not know never having driven one. There is about one and a half inches of movement on the pedal before i feel any resistance although the slave starts to move instantly, but the clutch works fine, however to get to this point the slave push rod is at the maximum length. On release the clutch releases about half way up the pedal. I cannot imagine that it was designed to operate on the limit so still believe ther is something potentially wrong. I measured the push rod length as i understand there are two, mine is 100mm or 4" in old money. Any thoughts appreciated.

[piman]

Hello Doherto,

there is a spring return (or should be) on the pedal and this should return it to it's designed position.
If I understand correctly, then it means the master cylinder is not getting a full stroke but that almost sounds wrong as you have a functioning clutch, i.e. it is fully releasing the clutch when the pedal is depressed?
The parts book lists three different slave cylinders, early cars, late cars and finally late 340 model. (No mention of the 2.4 but my book does not cover that model so it's not surprising.) It does not say what the difference is but should a smaller bore slave be fitted than specified it will need less stroke from the master cylinder to operate it for the required travel? I don't know, it's just a guess?

Alec

[Doherto]

Hi Alec, the foot pedal returns to full height after use so i assume the return spring is ok. I may need to add some info here. When i bought the car, not on the road, the slave was leaking and had a return spring bracket but no spring. I ordered a new cylinder and was advised that the part number quoted previously was correct and is a 95mm non hydrostatic. I have also recently purchased a new spring, part number above. I do not have the old slave cylinder unfortunately but have reused the push rod as a new one was not supplied with the new slave cylinder. The original may have been a shorter 85mm cylinder, i dont know and cannot remember. If so do the different cylinders have different stroke volumes which could effect my pedal? Unfortunately i cannot progress till Monday now so any and all comments welcome so hopefully i can rectify this on Monday.

[piman]

Hello Doherty,

I have had a look at my (Jaguar published) workshop manual and there is no reference to slave cylinder bore.

I'm guessing a little here but the hydrostatic cylinder is designed so that periodic adjustment of the clutch release to compensate for clutch wear is not necessary, hence the original 19mm setting which is the space that allows the piston to progressively sink lower and lower in the cylinder as the clutch wears, the clutch itself returning the piston back into the cylinder after operation. This is why no return spring is fitted.

When you say the pedal is low, do you mean that it is low when the clutch releases? My take on clutch bite points is that a new clutch has a low bite point and a worn one has a high one? That is with spring cover plates, not diaphragm cover plates.

Alec

[Doherto]

Hi Alec, and others. I am proberly overthinking this. This morning i have, after playing around again retrying the 19mm setting and 1/8" setting, settled on the 1/8" with the spring and the clutch works fine. It "feels" as though the drive is released about 3/4 of the way down the clutch pedal depression but it engages drive about half way up the travel. Perhaps this is close to normal and i have decided to leave it at that for now and allow the new parts to bed in, when i get her moving about, and see where we are then. Thank you everyone for your help and hopefully this may help someone else. As a note on another subject, has anyone orded anything from sng on line recently. I just did and their confirmation email has their terms and conditions of sale attached. A 20 PAGE DOCUMENT. The world has gone mad

[piman]

Hello Doherty,

the 19mm setting is only for the hydrostatic slave cylinder, and as you have a return spring it is not relevant. The 1/8" clearance between the thrust bearing and the clutch seems sensible.

Alec