Clutch Travel.

[Don2138]

2.5 P.I. Engine and Gearbox. I have a noise coming from the bell housing area, it can sometimes be intermittent. I am as certain as I can be that it is due to the clutch release bearing staying in contact with the pressure plate. If I remove the pushrod from the slave cylinder the arm that goes into the bell housing I can feel that there is contact with the release bearing to pressure plate in the position that the hydraulics is when no clutch pedal pressed, move the arm slightly the bearing moves away from the pressure plate. I have done a search but cannot find a definitive answer. I have replaced the Clutch Master and Slave Cylinder ( Correct bore sizes ) and replaced the pipe between the two with stainless braided. I have just competed work on the engine and the end float is now correct ( 0.006” ). Is there a solution for this as my only ideas are to make an adjustable pushrod and move it to the top hole position on the arm that goes into the bellhousing. Any ideas or comments welcome.

Many thanks,  Don Kennedy.

[mikew]

I thought that the release bearing always had some permament contact with the pressure plate. As the clutch plate wears, the fingers of the pressure plate move out, pushing the bearing back, and the adjustment is taken up by the altering amount of fluid in the slave cylinder.

There is no return spring to pull back the release bearing, so it must be the pressure from the fingers that push it back when the actuating pressure is reduced, and they cannot push it out of contact.

There were some articles on a USA triumph site that advocated a spring to hold the bearing into better contact with the pressure plate, the idea being that if the contact was light, and the bearing had some resistance, the fingers of the plate could slip on the bearing, and wear away - also making noise. This may be what is happening if the noise goes when you press on the clutch pedal - you are adding enough pressure to stop the release bearing sliding over the release fingers and making it rotate correctly.

At the end of the day I suspect you have simply got a worn or noisy bearing - there have been batches of bad bearings about which is why there is this fuss over Uprated release bearings.

I'd would suggest dropping the gearbox and inspecting, and replace the bearing and any other worn parts. Its just a pity its such a pig of a job.

Its one of the reasons I replaced my 5 release mechanism with a tilton release, and are about to do my Stag in a similar fashion. These tilton releases are also left with the release bearing in permament contact with the pressure plate

mike

[piman]

Hello Don,

you don't say if the noise is loud or worrying, but there is normally some light contact between the clutch pressure plate and the release bearing. The slave cylinder is supposed to have an internal return spring to return the piston so yours may be weak or missing. Also the thrust bearing carrier may be tighter than it should be on the gearbox.

An adjustable push rod does nothing with these clutches as they are designed to be self adjusting by the fact that the slave cylinder is deeper than it's stoke so the piston gradually sinks further into the cylinder as the clutch wears away.

Alec

[Don2138]

Hi Mike & Alec,

Many thanks for the replies. I had assumed ( wrongly ) that the release bearing moved away from the pressure plate. Seems as if the release bearing has a hard life being in contact all of the time. The noise is not great just annoying for a picky sod like me. Looks like I will have to turn up the volume of the radio for a while as I am not going attempt removing gearbox etc until next year, hopefully nothing serious will happen to it until then. I may have a try with a modification. If I use some threaded rod, bolt it via the bottom bolt hole that holds on the slave cylinder, adjust it so that when the lever that goes into the bell housing just moves the bearing away from the pressure plate (  is pulled back with a spring ) and makes contact with the threaded rod. This would mean when the clutch pedal is not pressed the spring will pull the release bearing away from contact but the threaded rod will stop the spring pulling it too far. I realise this has to be a VERY fine adjustment but will only take about half an hour to try.

Once again very many thanks for your time with the replies.

Don Kennedy

[mikew]

Good luck with this mod - let us know if it works.

The other option (assuming the noise goes when you depress the clutch pedal) is to increase the preload with a spring - i.e. your mod in reverse.

mike

[Richard B]

piman wrote:

The slave cylinder is supposed to have an internal return spring to return the piston so yours may be weak or missing. Also the thrust bearing carrier may be tighter than it should be on the gearbox.

Willing to be proved wrong, but the pedal has a return spring, to help protect the Master Cylinder internal return spring.

An internal spring on the Slave Cylinder will push the piston out, not assist it to retract.  :-/

[piman]

Hello Richard,

"An internal spring on the Slave Cylinder will push the piston out, not assist it to retract."

Yes of course it does, not thinking clearly.
So that would seem to be there to keep a consistent and minimal clearance between the thrust bearing and the clutch, presumably to make sure there is a consistent clutch operation.

Alec

[Don2138]

mikew wrote:

Good luck with this mod - let us know if it works.

The other option (assuming the noise goes when you depress the clutch pedal) is to increase the preload with a spring - i.e. your mod in reverse.

mike

Hi All,

Once again many thanks for all the replies and comments.

I will try various "mods" and let you know what happens.

Don Kennedy