Adjusting gear box selector for easy neutral?

phil37 said:
No Paul - all left as standard - regards - Phil
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Hi Phil

now you have me thinking about drilling more holes...... ;)

so, it is common to drill holes in brake discs but not brake pads. Wouldn't the same principle apply to drilling a bunch of holes in steel clutch plates and leaving the fiber plates alone? I wonder if multiple holes in the steel clutch plates (similar to holes in brake discs) would do anything to improve clutch action? Might aid in preventing clutch plates from sticking together? I may have to give it a try, just for fun.

Paul LeClair



 
Reckon if holes in friction pads would be of benefit, it would be have been practised throughout the motorcycle industry by now... 

Reduces friction area but increases specific pressure, more danger of over-loading and possibly burning the friction material, making a couple of extra plates necessary. ::)

Holes in the plain steel plates would also be contra-productive, most of all through uneven heat dissipation leading to excessive warping.

There's more to lightening than just drilling a couple of holes, but do feel free to try it out for us Paul! :D

piet
 
sfcpiet said:
Greg,

At the inner end of the splines, deep inside the drum, you should find a groove in which solid residues can accumulate.  This is often full to the brim with muck, preventing further muck to drain off out of harms way.  Much like an over-filled oil slinger, a royal pita to clean out.  Reckon a couple of dozen radially drilled holes wouldn't hurt clutch plate movement or compromise the drums stability.  Just don't think the weight difference would justify the effort from a weight-saving point of view.

piet
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Thanks, I'll have a look at that. Any drainage from there would seem to be a good thing. Maybe not that many holes though as that portion of the drum has to be heavily stressed...
Greg
 
sfcpiet said:
Reckon if holes in friction pads would be of benefit, it would be have been practised throughout the motorcycle industry by now... 

Reduces friction area but increases specific pressure, more danger of over-loading and possibly burning the friction material, making a couple of extra plates necessary. ::)

Holes in the plain steel plates would also be contra-productive, most of all through uneven heat dissipation leading to excessive warping.

There's more to lightening than just drilling a couple of holes, but do feel free to try it out for us Paul! :D

piet
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Hi Piet

as much as I like "adding lightness" by drilling holes in things, based on your explanation I think I will refrain in this particular instance...... ;)

Paul LeClair
 
I always understood the holes in brake disks were there to improve wet braking, by improving water film displacement.
So, does it help to displace oil from a wet clutch?
Think Piet may have a point...

Steve
 
way I have always looked at the standard Laverda wet clutch is it is designed as a wet clutch but then due to the design the oil has a hell of a lot of difficulty actually getting in there so it sort of festers in its own sludge
that is why I drill the clutch baskets on every engine I rebuild, to promote a better flow of clean fresh oil passing through the wet clutch pack though even with the drillings doubt oil flow is greatly increased

has nothing to do with lightness from my point of view unless you do the "full suite of drillings" as Phil has posted which I do on the hot rod engines we build
plus we machine the outer shape of the clutch baskets as well to balance them better

never had a set of Kevlar coated clutch plates stick on us yet, no matter what oil is being run in the engine




 
Most motorcycle wet clutches could best be described as "semi wet". Have a look at an automatic transmission to see a real wet clutch setup. Packaging is easier if they're inside the cases, hence exposed to oil, Guzzis and BM's excepted...
Pretty much every fiber clutch plate I've ever seen has been slotted - incl I note, Red's kevlar ones - which has the effect of turning them into dry clutches once they're spinning. Always assuming the oil has somewhere to go - which i think we can agree is not well provided on the Laverda design.
I've dealt with a number of big HP late model Jap motors and one thing stands out - the clutch drums are very well drained indeed.
 
When I was rebuilding my RGS from the best parts from two bikes, I noticed that the outer clutch drum from the 'donor bike' had a row of small holes drilled at an angle all round the circumference of the drum, presumably to fling the oil away from the plates.
 
GregT said:
Most motorcycle wet clutches could best be described as "semi wet". Have a look at an automatic transmission to see a real wet clutch setup. Packaging is easier if they're inside the cases, hence exposed to oil, Guzzis and BM's excepted...
Pretty much every fiber clutch plate I've ever seen has been slotted - incl I note, Red's kevlar ones - which has the effect of turning them into dry clutches once they're spinning. Always assuming the oil has somewhere to go - which i think we can agree is not well provided on the Laverda design.
I've dealt with a number of big HP late model Jap motors and one thing stands out - the clutch drums are very well drained indeed.
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But these are of a complete different design.

The most common clutch types have only a small number of tangs on the drive plates that fit into large slots in the clutch drum.  Old brit bangers had maybe 6, the japs have steadily increased this to 10 or 12, but the main problem remains, the tangs create dimples in the drum that can cause slip and drag over time.  The modern alloy-based friction plates often have a thicker tang to spread the load a bit, this, and the selection of suitable materials, seems to have solved the majority of the problems.

The Laverda clutch was designed with a far greater load-bearing area from the start, the 70-odd splines do add up!  Unfortunately, this calls for an enclosed clutch drum, and imho the greatest problem there is getting the heat out.  I find many over-heated and warped plain plates, probably through abuse or incorrect assembly.  It should be noted that the majority of Laverda clutches have covered a far greater mileage than many other bikes don't even come close to, and the major components are often at the end of their service lives and really should be replaced.  But, as new parts are hard to come by, as well as being horrendously expensive, we put up with them and their idiosyncrasies.  As Paul has found out, simply replacing worn parts with new ones can transform clutch action.  I was lucky enough to buy a new drum and hub when they were still affordable, the clutch in my 3C has performed faultlessly for the past 20 years since fitting them.  This was slipping and dragging before, and I was truely fed up with it.

piet
 
sfcpiet said:
The Laverda clutch was designed with a far greater load-bearing area from the start, the 70-odd splines do add up!

piet
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You'd think it would be feasible (and reliable) to mill away some of those 70 tangs, effectively leaving gaps for oil to exit - without compromising the safe transmission of power through the clutch drum. Surely it could cope with less.

So, for ex, remove a number (how many??) of tangs so there remain an even number in equidistant sections around the drum. Or, maybe, remove every second one?

Maybe Paul could try ths and report back  :D

QF
 
sfcpiet said:
But these are of a complete different design.

The most common clutch types have only a small number of tangs on the drive plates that fit into large slots in the clutch drum.  Old brit bangers had maybe 6, the japs have steadily increased this to 10 or 12, but the main problem remains, the tangs create dimples in the drum that can cause slip and drag over time.  The modern alloy-based friction plates often have a thicker tang to spread the load a bit, this, and the selection of suitable materials, seems to have solved the majority of the problems.

The Laverda clutch was designed with a far greater load-bearing area from the start, the 70-odd splines do add up!  Unfortunately, this calls for an enclosed clutch drum, and imho the greatest problem there is getting the heat out.  I find many over-heated and warped plain plates, probably through abuse or incorrect assembly.  It should be noted that the majority of Laverda clutches have covered a far greater mileage than many other bikes don't even come close to, and the major components are often at the end of their service lives and really should be replaced.  But, as new parts are hard to come by, as well as being horrendously expensive, we put up with them and their idiosyncrasies.  As Paul has found out, simply replacing worn parts with new ones can transform clutch action.  I was lucky enough to buy a new drum and hub when they were still affordable, the clutch in my 3C has performed faultlessly for the past 20 years since fitting them.  This was slipping and dragging before, and I was truely fed up with it.

piet
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Well, no , I'd argue they're only different in detail design. It's still a steel/fiber plate sandwich, compressed by springs. The total torque transmitting capacity is limited by the friction generated between the plates not the design of the tangs IMO.
The difference in friction coefficient as between wet and dry is considerable, hence the current (modern) concern with getting oil out of the drum.. If the clutch can be made to emulate a dry one in operation and capacity, then it becomes cheaper to make and can be smaller for easier packaging.
PB2's suggestion of removing a few rows of splines would work IMO. If the current build on my bench makes enough power to embarrass it's clutch, I may have to look at that.....
 
If oil removal was my paramount concern, I'd drill a set of off-set holes radially through the drum.  Could be quite large holes, covering maybe 4-5 splines at once, should allow the oil to be flung out quicker than it can enter.

piet
 
When doing an oil change on my early 3C engine, I'm always draining the pimary drive housing, too. With the amounts of oil usually coming out there (guessed a half pint max.), IMHO there can't be that much oil inside the clutch basket that needs to be drained when the engine is running. Might be different on later engines, though...
 
Once you have clocked the selector wheel put a dent in the casing to where it will point too when you have to resemble it.

Actually I believe the Breganzie Factory did put a very fine line scribe on the face of the casing for this purpose.
 
When I was rebuilding my RGS from the best parts from two bikes, I noticed that the outer clutch drum from the 'donor bike' had a row of small holes drilled at an angle all round the circumference of the drum, presumably to fling the oil away from the plates.
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As stated! Don't know the provenance of the 'donor' bike but by the holes drilled all over the place, I suspect it was raced. The clutch drum on my my RGS didn't have the holes but the donor does. Possibly somebody years ago was confronted by a clutch problem and came up with the solution.
 
Piet, Red, and Phil, since drilling the holes appears to be a good idea can you do them if sent in, or is it so simple a caveman could do it?

Pauls problem is very similar to the problem I have with my 80 1200 with the exception that when hot and with my clutch pulled in going into gear it grabs nearly full force (like the cable is not disengaging the clutch). It does not happen all the time, but in traffic it is pretty scary. A couple of times I have had it happen after ridding in traffic and then parking the bike for a couple of hours and the engine has pretty much cooled down. I figured it could be either sticking plates, or something binding.

Since I have to pull it all apart anyway it seems like the best time for getting all of this done and install new plates, discs, and springs. Just want to make sure that the springs are not going to be an issue. I will need to order up the parts so they can be home when I get back into the country and then see how it all shakes out.

Clay
 
Clay,

Reckon a caveman with a keen eye could do it if his cavewoman spins his drill press fast enough, but a rotary table on a milling machine does a much tidier job. :D  Holes should be as equidistant as possible in order not to disrupt balance too much.

piet
 
'71 SF said:
Piet, Red, and Phil, since drilling the holes appears to be a good idea can you do them if sent in, or is it so simple a caveman could do it?

Pauls problem is very similar to the problem I have with my 80 1200 with the exception that when hot and with my clutch pulled in going into gear it grabs nearly full force (like the cable is not disengaging the clutch). It does not happen all the time, but in traffic it is pretty scary. A couple of times I have had it happen after ridding in traffic and then parking the bike for a couple of hours and the engine has pretty much cooled down. I figured it could be either sticking plates, or something binding.

Since I have to pull it all apart anyway it seems like the best time for getting all of this done and install new plates, discs, and springs. Just want to make sure that the springs are not going to be an issue. I will need to order up the parts so they can be home when I get back into the country and then see how it all shakes out.

Clay
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Hi Clay

I don't have access to a rotary table or a mill. I measured carefully, scribed, center punched, then used an electric drill. I did use a "chamfer" bit to finish each hole. So, it is not as neat or precise as what Red or Piet or Phil etc would do, but it is functional for me.

while you have the clutch apart, or when you are ordering parts, order new ball bearings for the two piece push rod, and order a new hardened steel actuating bar, the bar that the clutch actuation rod pushes against to lift the clutch basket, I have had a couple of them bent or worn to the point where they were an issue in various triples. I have been using a piece of tool steel to replace them. In my 79 1200 the little steel actuating bar was bent like a banana when I first got the bike way back when.

as noted earlier in this thread, check the free spring length of any new clutch springs you may buy, and check the free spring length of the springs you take out, depending on the supplier the original springs may be better than new ones.......

also note that you DO NOT have to remove the crank nut (the so called "Jesus" nut) or the crank sprocket to get the primary chain off to then remove the clutch. Just take the bolts out of the clutch hub, and wiggle the clutch hub sprocket off the rubber isolators, the chain will come off with it, and it goes back together the same way. Will save you a ton of grief if you just leave the crank nut and crank sprocket alone. You can also usually just leave the primary chain tensioner nut alone, the primary case will come off and go back on with it still tensioned if you are careful in how you present the primary case back on.

Paul LeClair


 
Thanks Piet and Paul for the words of encouragement, and more importantly the added instructions that hopefully will make the task a breeze  :o. I still have the clutch cable setup but I am seriously looking at changing it to hydraulic (hands just don't grip like they used to) when I have it apart. I also plan on doing like you did Paul with all the new plates and discs along with the other things mentioned which hopefully will end up giving me similar results.

Clay
 
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