1975 350 MKIII clutch pillar problem

[themoudie]

So, having had a clutch pillar snap and come through the outer clutch casing on the 450 last year and replaced the pillars with flat headed 8mm pillars, silver soldered in place in the clutch hub, I thought that dismantling the 350's clutch would be relatively "easy"!

For a start none of the slotted screws would budge, when using a large flat bladed screwdriver, with a good fit in the slot. So, I resorted to an impact driver, with a good fitting blade and a 1lb hammer, having first given them a squirt of BDS. 5 out of six screws responded to the treatment and after initially budging, using the large screwdriver was sufficient to extract them. The final screw remained obstinate and so after more BDS and another blow from the impact driver there was a twitch. I applied the large screwdriver and was rewarded with a scraping noise as the screw and pillar rotated in the clutch hub!

So, I propose to jam the pillar and then having centre dotted the screw, use a left handed drill to remove the head from the screw, so that I can extract the faceplate and plates behind, before removing the clutch from the mainshaft/input shaft.

Does anybody have previous experience with this type of seizure or have other ideas for a solution?

As an aside, but on the subject of clutch hubs; how much lateral play can be allowed between the steel plate tangs and the hub? I may need to remove some grooves, so that the plates can slide in and out more easily, rather than catching on the wear ridges in the grooves in the hub.

Thank you for your time.

Good health, Bill

[Jordan]

Is there any evidence of use of Loctite on the removed screws?
If so, application of heat should help.

The amount of play between the clutch plates and housing is not critical, imho.

[themoudie]

Aye Jordan, thank you for your advice, but there was no Loctite evident.

I ended up using a Dremel, with the fine cutting disc fitted to cut the screw head into small vertical segments that I then cut out using a small, sharp cold chisel, standing well back as the spring, washer and screw bits were fired across the workshop, with the removal of the last part of the screw head. I had the two adjacent and the opposite screws well tightened before starting the job.

Needless to say, as expected, the riveting holding the pillar/post in place has let go and so I intend to remove all of the pillars, drill out the hub holes to 8mm and insert the headed pillars, silver soldering them in place, as I used on the 450 after it sheared one of the pillars.

At present the generator rotor is proving difficult, but that is for another thread, if necessary!

Good health, Bill

[blethermaskite]

Bill, the only Ducati single I have had this issue with was my 200cc race bike which spun two of the pillars due to me using loctite on the screws I'm afraid I didn't get too technical and just brazed all the posts to prevent it happening again, your repair is more elegant I really don't think it matters very much on the plate tang backlash on the drum.......but you certainly should clean away the wear grooves on the drum...it will just make the clutch action much sweeter.
Cheers,
George
PS Hopefully moving to East Dunbartonshire next year.......so maybe be able to call with you sometime

[themoudie]

Thank you George, I was hoping that clearances between the metal plate tangs and the clutch hub weren't too critical as I have already given the hub a clean up!!

As for the move to the Campsies, all the best, you'll have some back roads to play on. But, be warned, there are stretches in East Dunbartonshire and Stirlingshire that are in dire need of attention at present. Two weeks ago I took the road over from Lennoxtown towards Fintry then turned off right alongside the Carron Valley resevoir, before heading north via East Buckieburn to Stirling, then home via Sheriffmuir etc. The Dukes Pass is another gravel trap, squirty hole filling mess at present, but the steak and Stornaway black pudding pies in Aberfoyle are delicious!

Good health, Bill