N/C Clutch

[lloydy1]

Hi everyone.

Has anyone come across this before?

I got hold of some new clutch plate for my N/C as every time I came to it after she had stood the clutch would not free up, so I started the strip down yesterday and 4 out of the 6 retaining bolts that hold the clutch plates are spinning and wont unthread from the female peg. Has anyone experianced this and if so would it be a case of drilling the head of the bolt or is there something that can be done which is no so drastic? Cheers, Dave

[DewCatTea-Bob]

Has anyone come across this before?

" as every time I came to it after she had stood the clutch would not free up, "

____ It's fairly common for a left-inactive set of clutch-plates to become stuck-together. _ Even new plates are apt-to (however somewhat less likely) become victim of such oil-induced setup-adhesion.
__ Try some different oils in you sump-oil mix.


" 4 out of the 6 retaining bolts that hold the clutch plates are spinning and wont unthread from the female peg. Has anyone experianced this "

____ Yes BUT not with more than just one or two of the six clutch-spring retaining-screws ! ...
What happens is that the screw's associated column-peg's press-fit into the clutch-hub becomes loosened-up, (and thus-then leaving only it's tip-end riveted-head to keep it within it's place), so-thus it can then turn along-with the screw.
__ I have no explanation as to why yours has so many as "4" all going-bad that way.


" and if so would it be a case of drilling the head of the bolt or is there something that can be done which is no so drastic? "

____ Attempting to drill-out the screw is usually a waste of time, as both screw & it's shaft-peg simply spin along-with the drill-bit.
__ Rather instead, ya most often have to grind-off the head of the stuck/too-tight screw (using a ball-stone or ball-headed rasp-file held nearly at a right-angle, with a hand-drill). _ Once a screw-head is ejected, the remaining threaded-shank of the screw can then rather easily be unscrewed-out while holding it's associated column-peg with needle-nose pliers.
But before doing that,, you might be able to grab the head of the screw with a drill-bit chuck, and with the chuck driven by a compressed-air tool, then HOPE that a QUICK-burst of compressed-air (to power the chuck) will then spin-loose the screw away-from it's grip within the column-peg.
____ Once all six screws have been removed, you'll then-next have to deal with the clutch-hub & it's four badly-held column-pegs, before ever expecting to retighten-down those four clutch-spring retaining-screw locations.
Unfortunately I have no advice as to whether welding is a feasible repair expectation, as I-myself had always had good spare hubs to replace those very-few which I had happened to come-across with any loose shaft-pegs.
__ So now that you realize that you may quite possibly do all this additional extra work without fully obtaining the original pay-off which you've expected to accomplish, you now really ought to consider skipping going-through with your intended job, and let it wait until some-time in the future when you may then have ANOTHER/more-important reason to tear-into your motor so deeply.


Hopeful-Cheers,
DCT-Bob

[machten]

Unfortunately I have no advice as to whether welding is a feasible repair expectation, as I-myself had always had good spare hubs to replace those very-few which I had happened to come-across with any loose shaft-pegs.

Recently came across the same problem on a friend's 450 desmo. A small tack weld on the back where the peg heads protrude does the job nicely. Only a tack weld was used to avoid pumping any serious amount of heat into the hub.

Kev

[lloydy1]

Has anyone come across this before?

" as every time I came to it after she had stood the clutch would not free up, "

____ It's fairly common for an inactive set of clutch-plates to become stuck-together. _ Even new plates are apt-to (but somewhat less likely) become victim of such setup-adhesion.
__ Try some different oils in you sump-oil mix.


" 4 out of the 6 retaining bolts that hold the clutch plates are spinning and wont unthread from the female peg. Has anyone experianced this "

____ Yes BUT not with more than just one or two of the six retaining-screws ! ...
What happens is that the peg-shaft's fit becomes loose within it's fitment to the clutch-hub, thus it then turns along with the screw.
I have no explanation as to why yours has so many as "4" all going-bad that way.


" and if so would it be a case of drilling the head of the bolt or is there something that can be done which is no so drastic? "

____ Attempting to drill-out the screw is usually a waste of time, as both screw & it's shaft-peg simply spin along-with the drill-bit.
__ Rather instead, ya most often have to grind-off the head of the stuck/too-tight screw (with a ball-stone held-at near a right-angle). _ Once a screw-head is removed, the threaded-shank of the screw can easily be unscrewed-out while holding it's shaft-peg with needle-nose pliers.
But before doing that,, you might be able to grab the head of the screw with a drill-bit chuck, and with the chuck driven by a compressed-air tool, then HOPE that a QUICK-burst of compressed-air (to power the chuck) will then spin-loose the screw away-from it's grip within it's shaft-peg.
____ Once all six screws have been removed, you'll then-next have to deal with the clutch-hub & it's four badly-held shaft-pegs, before ever expecting to retighten-down those four clutch-spring retaining-screw locations.
Unfortunately I have no advice as to whether welding is a feasible repair expectation, as I-myself had always had good spare hubs to replace those very-few which I had happened to come-across with any loose shaft-pegs.
__ So now that you realize that you may quite possibly do all this additional extra work without fully obtaining the original pay-off which you've expected to accomplish, you now really ought to consider skipping going-through with your intended job, and let it wait until some-time in the future when you may then have ANOTHER/more-important reason to tear-into your motor so deeply.

Bob, Thanks for the advice. If as you say left until another day, are the pegs likely to come away from their seating while the clutch is in operation? Dave

[lloydy1]

Unfortunately I have no advice as to whether welding is a feasible repair expectation, as I-myself had always had good spare hubs to replace those very-few which I had happened to come-across with any loose shaft-pegs.

Recently came across the same problem on a friend's 450 desmo. A small tack weld on the back where the peg heads protrude does the job nicely. Only a tack weld was used to avoid pumping any serious amount of heat into the hub.

Kev

Thanks for the tip. Dave

[machten]

Dave,

I should point out that our 450 clutch peg experience was consistent with DCT-Bob's - there was only one loose peg. I only mention this as you may have a deeper underlying root cause.

Kev

[DewCatTea-Bob]

Bob, Thanks for the advice. If as you say left until another day, are the pegs likely to come away from their seating while the clutch is in operation? Dave

____ I'd doubt it, as I've never seen a loose shaft-peg actually pulled-through & out of it's fitment-location within the hub,, but then again, I've never seen any clutch-hub with more than two loose shaft-pegs.
I can't imagine some unordinary-functional cause for leading to the shaft-pegs becoming loose, but if some such effect also caused the shaft-pegs to actually pull-out (of their set-place from within the back-base of the hub) as well, then you'd notice a lighter spring-pull on the hand-lever, and it would then be possible for the screw-heads (along-with springs) to expel-outwards (from within the hub), far enough to come into contact with the inside of the primary-cover (& make an associated noise). _ But I'm not saying that that's any likely-hood of a possible occurrence, as not-only have I never heard of any such malfunction (of pulled-out pegs), it also seems fairly unlikely to ever actually occur.
Good-question though ! _ Perhaps someone-else (with good experience) will also have an opinion for you.


Hopeful-Cheers,
-Bob

[LaceyDucati]

Hi Dave and all

As has been said, It is unusual to have more than one or two pillars loose, but it all depends on what abuse it's been subjected to! It is also not unknown for pillars as result to be shot out the hub, more likely under racing conditions. It is also not only narrowcase bikes that can suffer from lose pillars, widecase bikes share the same hub.

Things that won't help are:

450 springs as they put more load on the pillars. Although necessary if you need them.

Worn pressure plate drive segments as this will put more twisting through the pillars (also doesn't do the cups much good either!).

Over tightening the screws will twist the riveting allowing the pillars to start moving. Using socket screws instead of the original slot screws, although great for spinning them undone does encourage some to then try out there new extended wrenches!! Socket caps are great but using a screw driver type driver will help restrict over zealous tightening.

Use of Loctite on the screws, why?

What to do if you have loose pillars

Don't ignore it as it may eventually spit out and it will make a mess of the inside of your cover on the way out. Not to mention chew up the cup and spring!

Best way I have found to remove a spinning screw is to drill off the head. Easier to do with a socket head but once centred it should work on a slot head. You probably may need to hold the head with some mini mole grips to stop the head from spinning. Failing that grinding the head as Bob suggested will be your only answer. Either way unless you are stripping the engine, you will need to degrease the pressure plate and cases and thoroughly mask off the engine internals as any swarf or grinding dust in the engine will give you more to worry about than a loose pillar! Also be warned you will be amazed how much pressure is behind that spring when the head pings off, WEAR EYE PROTECTION, avoid doing it in front of the patio doors and move the DOG! 95% of the time annoyingly the thread of the screw will spin out with your fingers once the head has gone.

If you are lucky you could rivet the pillar a bit and it may hold, but if it has been moving for a while the material could already be fatigued and belting it with a hammer probably won't improve things! Welding and brazing loose pillars in my experience usually ends up in degrading the material further and usually also ends in a nice brittle fracture of the 5mm diameter some time later.

The easiest fix is to replace the hub with a good used one or Nova transmissions have new aftermarket ones. The later Mototrans (also some late Italian) widecase engines had the pillars screwed in before riveting (M6 I think). These are recognised by a hexagon at the bottom of the pillar in the hub. These hubs seem much less prone to loose pillars, so worth looking out for.

Replacing the pillar/ pillars,

The original pillars are only 5mm diameter where they pass through the hub. you will need to remove the riveted over material and drive the pillar out with a pin punch. You can then either make an original type pillar and rivet it in or modify the hub with stronger pillars, which is what I prefer.

What I do is drill all the 5mm holes out to 8mm and make some flanged replacements which insert from the rear of the hub. There is enough room for a 2mm or so deep head. about 12mm diameter. Once in place you can either tack weld or silver solder the pillars in place (or get someone else to). I did have a batch of pillars made to do this and I may still have a few left if anyone can't make them or get someone else to. After this mod I can fairly well guarantee you won't have another loose pillar.

Hope this helps and if I can find some pictures to make things clearer I will post them later.

Best Wishes Nigel

[lloydy1]

Hi Nigel and All,

Thanks for the guidance, I think it is a case of drill out what I can and grind the rest and keep my eye open for a new or good condition used hub. I have been putting off getting down to sorting them, but now the nice weather is coming, I will have to bite the bullet and get them sorted. Thanks everyone, Dave.

[DewCatTea-Bob]

I think it is a case of drill out what I can and grind the rest and keep my eye open for a new or good condition used hub.
but now the nice weather is coming, I will have to bite the bullet and get them sorted

____ So-then it's-not such a good-time to have your motor torn-down (for no really important-reason)...
Since I'm pretty-sure that none of your clutch-hub's shaft-peg/pillar-columns are going to get pulled-out of place all on their own,, I'd suggest that you leave it as is (with motor put back together), and go-ahead & ride it until the season's-end and after you've got yourself another/replacement-hub.
__ And when you finally do get-around to tackling that dreaded work-job, perhaps then you'll have a heavy-duty needle-nose vice-grip hand-tool which you might try using to tightly grab-hold of the washer (behind the screw-heads), and-then use an impact-driver to hopefully help knock-loose the screws from their (loose)- column-pegs. - (The intended-hope being that the temp.impact-pressure [between the held-washer & hub-base] will momentarily squeeze-hold the column-peg stilly in-between, whilst simultaneously just the screw itself is shock-turned loose.)


Hopeful-Cheers,
-Bob