Clutch slave cylinder- delay in retracting

[eddiecross]

Hi there ,
67 FHC (mid year)
I have some clutch slip but wanted to check the clutch release mechanism is working correctly first.
I had my son press the clutch pedal while I was under the car. No problem with it fully extending but when he takes his foot off the pedal it is taking a few seconds to release fully.

Clutch master cylinder and slave are new. I have the spacer between the master cylinder and the pedal box.

Does the slave cylinder and spring look correct?
Should I swap out the original old clutch hose in case it is restricting the return flow?
Worth re-bleeding- although no issues with clutch disengaging.
Bigger return spring?
I swapped the feed to below the cylinder so I could bleed it from the top- hopefully not caused any other issues.

All suggestions welcome and apologies as I got a bit lost with the clutch slave cylinder versions.

Thanks
Eddie Cross

[bitsobrits]

The return spring does not appear to have any tension on it when at rest with the slave piston fully retracted. You want a bit of tension present when everything is static, as evidenced by a small amount of visible separation of the spring coils. You can pivot the plate under the slave lower bolt to about a 45 degree angle to accomplish this.

Also, while you are 'here', ensure you have just a bit of freeplay (1/16" or so) when everything is at rest before the throwout bearing contacts the pressure plate. You can do this by feel (best done with the spring disconnected) or by looking up into the bell housing through the lower inspection hole.

[chrisfell]

BTDT.

If there is clutch slip there is only one solution. I blamed the master cylinder and the slave cylinder but that merely avoided the inevitable, and expensive solution.

And once I had replaced the clutch and release bearing, and ensured the released fork was true and working freely (a lazy clutch can indicate a bent or ill fitting release fork), I found the pedal return spring had broken.

[eddiecross]

Many thanks,
Will reset the return spring tension, check clutch free play

RE: Return spring in the pedal box.
Image from strip down....May have missed this. Looks like part of the return spring is broken?

Thanks
Eddie

[chrisfell]

That doesn't look broken. Easy to check, if the clutch pedal is floppy, the spring is fecked. If the pedal remains hard against the pedal box, the spring is doing its job.

[MSM]

You also need to trim the excess length from the split pin. That is just waiting to jam up on the casting.

[caveman]

Eddie,
Looks like you do have a spring issue:

[eddiecross]

Many thanks. I'll work through all the suggestions and let you know the outcome.

All the best
Eddie

[Zei220]

Hello,
I have had this very problem, I even changed the clutch, no fix. The problem turned out to be the rubber hose which connects the slave to the hard pipe from the master cylinder. The rubber hose swells and reduces the return flow.

[eddiecross]

Good point just ordered the hose as well as the spring.
Thx
Eddie

[eddiecross]

I have fitted the new hose and bled the system but cannot get the clutch pedal to hold pressure without pumping it. Not sure where the air is getting in as the hose connections are not leaking at either end and no sign of fluid around the slave rubber seal. Was fine with holding pressure before I swapped the hose over.

I'll keep trying. All suggestions are welcome.

Regards
Eddie

[MarekH]

All suggestions are welcome.

So you have plenty of air still in there.

1/ Disconnect the clutch slave pushrod from the fork linkage into the bellhousing
2/ Push the rod all of the way back into the slave
3/Attach a suitable hose onto the slave bleed nipple and terminate the other end of the hose into a bottle such that the end of the hose is immersed in clutch fluid
4/ Put some grease around the slave bleed nipple so air doesn't get in that way
5/ Open the clutch slave bleed nipple
6/ Slowly pour fresh fluid into the reservoir

It should simply drain through and into the bottle. Once there are no more air bubbles, you can close the bleed nipple and tease the pushrod back out slowly and reconnect it such that the correct amount of free play is set up. You probably had lots of air sitting in the slave if you tried to bleed it from scratch with the slave piston half way down the bore.

kind regards
Marek

[eddiecross]

Many thanks Marek. I'll try that 1st.
One of situations where it gets worse before it gets better. I tried poking a welding rod through the old hose and there was definately a blockage and the fluid is now flowing through the system much quicker.

I also found spare master and slave rebuild kits in my box of parts so can move to stripping them if I need to.

Cheers
Eddie

[eddiecross]

Quick update.
Yes thanks Marek. All the issues were around the slave cylinder. Disconnected link and pushed piston back and then bled the brakes. Plenty of air came out but 1st bleed was not successful.
Thought I would swap the rubber seals for the spare ones even though the aftermarket (cheap) slave was pretty new.
Old internals pulled out. Inserted new seal and piston.
Then realised replacement was the wrong type (without the hole in the seal to fit the rear of the piston
Fished out my replacement and swapped back in the original plus lots of brake grease.
Rebled. Seemed to be ok and holding pressure only when I removed the external return spring but maybe the sealing is marginal on the unit I have.
brake fluid flowing very freely everywhere and great on the hands. Wish I had converted to silicon.
Will order a new seal kit.
Thanks
Eddie