Series 3 clutch

Introduce yourself and find help on using our Forum.

Topic author
clarky
Posts: 3
Joined: Wed Jan 12, 2022 1:31 pm
Great Britain

#1 Series 3 clutch

Post by clarky » Mon May 09, 2022 1:45 pm

Hello everybody

I find myself looking after a rather nice low mileage series 3 that has been giving me an irritating little issue with the clutch. It needs pumping before you first select gear as if it was full of air then behaves perfectly well all the time its being driven. Stop for 5 minutes and it will need pumping again then its fine. This is ok if I remember to do it but end up looking a bit of a pillock in the petrol station in a nice shiny Primrose Yellow Jag and stalling it!

I've replaced the seals in the master cylinder and changed the slave for a new one but even if I just do a bleed there doesn't seem to be any air in it anyway.

The clutch itself feels fine, nice biting point and no slipping but I have been thinking that maybe the release bearing is sticking on the shaft. Could this be the case and does anybody else have a similar issue?

Thanks

Clarky

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

DWW
Posts: 893
Joined: Sat Mar 12, 2022 1:14 am
Great Britain

#2 Re: Series 3 clutch

Post by DWW » Mon May 09, 2022 4:05 pm

Not an expert though I had my share of clutch problems....First check the clutch lever operated by the slave is moving all the way from cold with the help of another person. If it does then the problem is elsewhere in the clutch mechanics like a sticking release bearing or a problem with the pressure plate.
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR
"Experience is something you don't get until just after you need it."

Link:
BBcode:
HTML:
Hide post links
Show post links


christopher storey
Posts: 5698
Joined: Sun Mar 09, 2008 3:07 pm
Location: cheshire , england
Great Britain

#3 Re: Series 3 clutch

Post by christopher storey » Mon May 09, 2022 5:16 pm

This is commonly caused by the pushrod on the slave not being long enough, the result of which is that the slave piston is only pushed part way back into the cylinder when the pedal is released , and bleeding is only partially effective . If it is the adjustable type, then I should try progressively lengthening it . If is is non-adjustable , then you need to see , when the pedal is released , how much further the slave piston can be pushed back into the cylinder, and then lengthen the rod ( welding is easiest ) by about 1/4 inch less than the free play . Best of all is to convert the rod to an adjustable type

Link:
BBcode:
HTML:
Hide post links
Show post links


Topic author
clarky
Posts: 3
Joined: Wed Jan 12, 2022 1:31 pm
Great Britain

#4 Re: Series 3 clutch

Post by clarky » Tue May 10, 2022 7:43 am

Your comments regarding the slave cylinder and push rod are very interesting. I've looked at this previously and have adjusted it as much as I think I can but I was a bit suspicious as to whether it was long enough. I think I will have to buy some rod and experiment with a bit of welding.

Thanks for the help folks

Clarky

Link:
BBcode:
HTML:
Hide post links
Show post links


MarekH
Posts: 1565
Joined: Wed Jul 21, 2010 8:30 pm
Location: Surrey
Great Britain

#5 Re: Series 3 clutch

Post by MarekH » Tue May 10, 2022 4:03 pm

Freeplay should be 1/8" for a standard v12 s3 setup (it is 1/16" on a standard 6cylinder setup).

I wouldn't have thought there is a bleeding issue here, as I don't see how it is solved so easily and reappears when left standing.

What the evidence suggests is that there is more freeplay if left standing. That can only happen if the external return spring is set too strong and a too short pushrod was used on the slave, i.e. the slave cylinder piston does not normally sit/return all of the way equally all of the time. That also suggests there is friction in the bore somewhere.

viewtopic.php?f=3&t=9381 explains how it works. Aside from the mechanical advantage ratio being related to pi x radius squared, which Hugo spotted, the explanation ought to be good.

I think you either have the external spring on the slave set slightly too strong or that you have friction between the seal and bore, either in the master or in the slave, or both. I'd check the freeplay length just after a drive and then again after it has been left standing to decide whether this is at the master or slave end.

kind regards
Marek

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

mgcjag
Moderator
Posts: 8071
Joined: Fri Jul 09, 2010 6:15 pm
Location: Ludlow Shropshire
Great Britain

#6 Re: Series 3 clutch

Post by mgcjag » Tue May 10, 2022 5:06 pm

Hi Clarky.......sounds typical of air in the system.....ensure that when you bleed the system the nbeed nipple is only open on the downstroke......so open nipple press pedal down and hold it down...close the nipple...release the pedal. then repeat.........ensure that on your last stroke befor closeing the nipple that you push the pushrod fully into the cylinder...invariably a bit more air comes out ......Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

Link:
BBcode:
HTML:
Hide post links
Show post links


Topic author
clarky
Posts: 3
Joined: Wed Jan 12, 2022 1:31 pm
Great Britain

#7 Re: Series 3 clutch

Post by clarky » Wed May 11, 2022 7:35 pm

I can't remember exactly how much freeplay I have but I'm sure it's more than 1/8" so I will look closely at it as well as the length of the rod. Also the rod sticking in the bore makes sense as it would explain why it happens after it's been standing.
I've tried various ways of bleeding including pressure bleeding but never seemed to be able to much, if any air from it unless there is some air trapped that just moves back and forth as the pedal is pumped but pressure bleeding usually would solve this, I will have another go.

Thanks for your input.

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

mgcjag
Moderator
Posts: 8071
Joined: Fri Jul 09, 2010 6:15 pm
Location: Ludlow Shropshire
Great Britain

#8 Re: Series 3 clutch

Post by mgcjag » Wed May 11, 2022 8:11 pm

Hi Clarky.....pumping the pedal when bleeding just moves air back and forth....you must never release the pedal with the nipple open.......and you wont get rid of all the air unless the pushrod/piston goes right to the bottom of the cylinder....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

Link:
BBcode:
HTML:
Hide post links
Show post links


MarekH
Posts: 1565
Joined: Wed Jul 21, 2010 8:30 pm
Location: Surrey
Great Britain

#9 Re: Series 3 clutch

Post by MarekH » Wed May 11, 2022 8:49 pm

You should simply be able to gravity bleed the clutch, as the system is just an open and unobstructed pipe if the pedal is not being used.

1/ disconnect the pushrod from the fork
2/ push the pushrod back into the slave all of the way (that shouldn't be very far if you only had 1/8" freeplay)
3/ stick a hose on the bleed nipple and put the other end into a bottle half full of brake fluid such that the other end sits "underwater", i.e. in the brake fluid so there will be an air seal
4/ open the slave bleed nipple
5/ watch the fluid drain out of the reservoir and into the bottle
6/ top up the reservoir slowly so you don't put lots of micro-bubbles into your new brake fluid

It should simply flush through without needing to play with the pedal or bleed nipple at all.

When you are running out of fluid, close the bleed nipple, top up the reservoir, reattach and adjust the pushrod length so only 1/8" freeplay exists. Refit external spring so it has almost no tension.

Test it hot and cold. Recheck freeplay.

You might also want to check whether the pistons move freely in and out without sticking anywhere before you bleed it. You haven't mentioned whether this is a factory supplied manual gearbox car, whether it is an auto to manual conversion or whether there are any non-standard components fitted. These things matter.

kind regards
Marek

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic