How wet should a wet clutch be?

[Andy Flexney]

this is not a Triumph related issue and I am hoping there are some people on here that have experience with clutches that run in oil?

The clutch has only done about 150 miles since I rebuilt the engine. It was relined by a specialist, not with cork but with a material I was told was a replacement in a wet clutch environment.

On our drive out yesterday I noticed it was slipping, especially in 3rd and 4th gears and particularly when driving up hills.

I spent this afternoon taking out the gearbox as I have decided I will replace the pressure plate springs with new ones and also to see if anything else was amiss.

The clutch plate looks as though it has survived quite well as has the pressure plate and the flywheel. When I “cracked” the gearbox from the engine oil did come out as I was expecting but the inside of the clutch i.e. plate and pressure plate look rather dry.

So back to the title of my post “how wet should it be inside the clutch?”

Looking forward to your answers
AndyF

[esxefi]

I think you have answered the question already.

the clutch was dry when taken apart and you experienced clutch slip so I would say it needs to be almost completely immersed to work properly unless something else is the cause.
although it seems to go against logical engineering thinking,get oil on a car clutch and it is more or less toast.

[JohnD]

Andy,
Is this a bike clutch?  Wet clutches unknown (on purpose) in Triumphs, common on bikes.
So yoiu will find more help on those sites.
A quick look shows me that adjustment needs to be just right, as several offer detailed instruction for your specific machine.

John

[RobPearce]

Just to be really picky... wet clutches are certainly not "unknown in Triumphs" as the overdrive cone is one.

From the very little I know of motorbikes, the clutch is normally compressed sufficiently to exclude nearly all the oil from the working surfaces. If you dismantle it with the clutch engaged, the free oil will all drain away before you open the clutch, and the friction plates will appear "rather dry".

[yorkshire_spam]

The clutch on the old rover 16/50 was a wet clutch (late 1920s) - and the answer to how wet...? VERY, it took ages for the clutch housing to drain back into the sump after switching the engine off.

[junkuser]

I wonder if the new inserts hold oil to a different extent to cork and so, different pressure settings are required.
Sounds as though there was oil being held on the faces as you could see no damage after the slipping. May be the different inserts are better at retaining oil.
Possibly there is a different oil specification for the application the new type inserts are designed for.

When corks were commonly used in bottles, these were used to make replacement inserts and worked well.
Times change.

[nang]

Try and find info on late '30's Morris 12's or I think 14's. I remember as a kid, family had one of these with a cork clutch. End of memory. (huh)
Tony.

[Jonny-Jimbo]

I think I actually have a workshop manual for one of those! Certainly some old Morris. I'll check at the weekend when I'm back home.

[roger.england]

We had a similar problem with a 1937 Railton at the Shuttleworth Collection (a cork clutch running in oil). I know that the wrong oil was used and when replaced with another oil it worked just fine. I'm at Shuttleworth again on Thursday so will ask what oil was used.

Roger

[JohnD]

Good point, Rob!  Bottom of the class for me!

What vehi leis it, Andy?
John

[Andy Flexney]

It is a Morris Twenty from 1935 with freewheel and Bendix clutch control.

I now know there was perhaps not enough oil getting to the clutch plate although enough was in the bellhousing, I will need to look at that. I have also presumed that the oil will be pressed out of cork easier than out of the new material which could mean I need stronger springs. BTW if you are replacing with corks do not put in used corks as they are usually damaged from teh cork screw.

The bendix clutch control is inactivated but it could be the freewheel clutch that is causing the problem but as I do not yet have a workshop manual for it I do not want to take it apart.

Thanks for all your input it has ben really helpful.

AndyF

[sparky_spit]

From my experience of bike clutches (Honda, Yamaha, Suzuki and older British bikes) the clutch runs directly in oil, from either the gearbox or chain-case, and is completely wet.  Oil choice is important and the correct oil for the type of friction material needs to be used.  Is it possible you are using oil that was suitable for cork originally and is not suitable for the new fibre material?

On a bike (for both cork and fibre clutch plates) if you run with too little oil you tend to get clutch drag rather than slip. And then, ultimately, with no oil the cooling effect of the oil will be lost and the clutch will overheat and burn out.

[junkuser]

I was assuming bike also.
The experience I was calling upon was from 40s British bikes, early post war production of pre-war design.
The smaller corks, used by chemists, were the ones to use and readily available new from most local pharmacies.
Some of the clutches used round inserts, just push the cork in and trim, my BSA used key-stone shaped ones so the cork was forced in sideways after a little trimming.

[JohnD]

And my experience of a cork clutch was a completely dry one, that took ordinary corks from a home brew shop.
It was on an Atco lawn mower, now in the National Lawnmower Museum .
John

[esxefi]

^^now there's somewhere to hide when the missus next wants me to mow the lawn