Hi all, hope this finds you well.
I'm looking for a bit of help regarding a dual clutch on a Massey 35 4 cylinder. The tractor actually belongs to my brother and I recently sourced a replacement engine for it. I planned to fit this engine engine early in the new year and as the clutch was well worn on the tractor I thought I'd treat my big brother to a new clutch for Christmas.
The engine swap went well. I had rebuilt the spare engine at my leisure thus allowing him to have the use of the tractor in the interim. The rebuilt engine had glow plugs fitted and now starts after 10 seconds of heat. Amazing for a Standard 23c!
Unfortunately the clutch change out didn't go so well. The original clutch was of bevel spring design. I had wanted to order a kit to change springs, pins and so on since the original clutch had seen a lot of use over the years. However, these parts don't seem to be available. I noted that Agriline offered a complete clutch for the tractor so I decided to push the boat out and buy it.
when the new clutch arrived I discovered it was a coil spring type as fitted to the Perkins engined tractors. I was slightly concerned, but couldn't see a reason why it wouldn't work. I fitted it to the flywheel, aligned the two plates to a newly fitted pilot bearing and set the pto release bolts to service manual spec. I set the height of the release fingers to that specified for the 23c clutch, as opposed to the Perkins engine clutch. I assume the flywheels of Standard and Perkins engines must be of different thicknesses.
Once reassembled the main drive clutch worked without issue. However, the second stage clutch wasn't disengaging the pto shaft. I reduced the clearance on the pto release bolts by about 0.5mm and tried again. This improved things slightly as the pto would disengage when heavily loaded, but would still drag with light load. I reduced the clearance by a further 0.3mm and noted something very strange . With the clutch pedal fully depressed the pto seemed fully engaged, but with the pedal raised some 20mm the clutch seems to hit a sweet spot and release beautifully. I can not understand what is going on there. By a process of trial and error I'm trying to strike a balance between pedal free play and pto clutch release bolt clearance so this elusive sweet spot converges with the bottom of the pedal travel, but something must surely be wrong.
I'd be most grateful if someone could shed a bit of light on this for me.