Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Clutch Notchy Noise - diagnosis help please

This was the problem with my 2013, low mileage (3000 miles). New clutch needed was the solution. Done by a terrific and conscientious dealer. Morgan Mid-Atlantic Clevis pin and other cheaper solutions did not work. Good luck.

"The release (throw-out) bearing was failing. The bearing surface rides on the pressure plate, so it rotates. There were a couple of bad spots, in the 360 degrees of operation, where the piston would get caught – not springing back freely. This was one likely cause of the clunking."

the stock connection between the push rod and the clevis is 5/16 UNF.
For me I modified at the same time as I transformed the crankset to put in it a universal clutch master cylinder which is easily found.

http://www.talkmorgan.com/ubbthreads.php/ubb/showflat/Number/496823/Searchpage/3/Main/32254/Words/%2Bclutch+%2Bmaster+%2Bcylinder/Search/true/re-clutch-master-cylinder#Post496823

Hi James Moss, yes that is what I was concerned about. However, having sprayed some lube on the pedal joints the feeling has noticeably improved so I'm pretty sure that's the problem.

SOLVED ! (we hope)


Further to the above posts and helpful tips from other forum members I decided to further investigate the clutch sticking issue. For newcomers there is a video of the noise in my earlier post. The problem manifested itself as a distinct "notchy feeling" through the pedal during the release of the clutch - no noise during the application of the clutch. It felt almost like something was binding and then releasing, causing the noise and the feeling through the pedal.

My concern from the outset was that this might be a slave cylinder/clutch issue and require a lot of dismantling.

Reaching into the footwell and "wriggling" the clutch pedal by hand does shown an alarming amount of slack in the system. One theory was that it could be caused by wear in the clevis pin and/or holes in the clevis and clutch pedal. To eliminate this as a cause I removed the pin from the pedal - easy to do as only retained by an R pin - and then fabricated a new lever arm from two pieces of wood. This allowed me to activate the master cylinder input shaft by pushing on the end of the clevis with no involvement of the pedal mechanism. It made no difference - the noise and "notchiness" were still evident.

To try to pinpoint the source a little further I tried listening to the noise with my ear on the end of a long screwdriver, while my brother Chris operated the pedal. When touching the master cylinder the noise was very distinct. When touching the metal hydraulic junction on top of the bell housing (leading to the slave cylinder) there was nothing. This clearly pointed to the master cylinder.

A new theory was that the master cylinder piston and/or bore could have worn and introduced a lip of some sort. To test this we undid the bleed nipple on top of the bell housing to allow fluid to bleed out so that we could operate the input shaft by hand and feel for any issues. Surprisingly the action felt completely smooth. This was getting frustrating and starting to defy logical explanation. However, I did notice that the fluid being pumped out of the bleed nipple was very black which was unexpected - the fluid in the reservoir was clear of course.

The next step was to remove the master cylinder which is actually not too difficult and can be done through the inspection hatch. The pedal box has to be unbolted and moved forwards to allow access and the removal of the master cylinder. The fluid connections were not undone until the master cylinder was through the hatch which minimised leakage.

We then took the master cylinder apart - one internal circlip and were able to remove the piston and spring.

What this revealed came as a bit of a shock as this should be a clean hydraulic environment, but was actually a large amount of black debris (non metallic), together with contaminated hydraulic oil. Some particles of debris were tiny others were like flakes, but all black. Where did they come from ?
1. Inside of the feed pipe from the reservoir ? - no sign of that
2. Break up of the oil seals on the piston ? - the high pressure seal looked fine but the low pressure seal showed some signs of wear. The low pressure end of the master cylinder bore did have some rust with some also on the end of the piston. It is possible that the seal could have been wearing on the rust - but not enough to create the amount of debris. There was some polishing on the bore and on one side of the piston on one location, but nothing to explain the notchy feeling.
3. A coating (paint?) on the piston when originally fitted that had broken down in the clutch fluid over time ? This seems to be the only possible explanation.

Despite all the above we still had no evidence of what could be causing the notchy feeling or "binding on release" sensation.

- maybe the debris causing the piston to get stuck in the bore ? But it wouldn't do that repeatedly and the debris felt very soft.
- maybe the debris getting trapped in the small bore outlet of the high pressure side and acting like a valve ?

Everything was carefully cleaned and re-assembled and is now working perfectly, so who knows ?

Subjectively the clutch pedal does seem smoother and lighter than before and there is no notchy feeling at all.

TIP for anyone else with clutch issues - try bleeding the master cylinder and see what comes out...

Colin, the later 4 wheelers use the same (almost) master cylinder and I've changed a few over the years, some have mucky fluid as I assume never been bled or flushed since build-up

My main suspicion is the internal bore of the short feed pipe gradually breaking down, I swabbed one inside once and the black gunk that rubbed off was a surprise, I've replaced mine with specific flexi tubing that's safe with hydro fluid because I can't find any ID markings on the original & suspect it's a bit low grade

Hi Jon,

Thanks for the input and you make a good point.

The feed pipes on my M3W do have markings on them and I think they are probably correctly specified for handling hydaulic fluid, but will have a look to check next time I have the bonnet off.