Grinder or Drill - Clutch hub

mik667

mik667

Senior member
Location
San Francisco, Ca
Hey all - so my 1200 has finally decided no matter what i try, i cannot free up the plates. sucks as apparently i can no longer source Reds Kevlar plates. anyway, i see in the manual / green book it says grind or preferably drill out the rivets in the cover - any one advise any tricks to it so i don't ham fist it will metal shaving from grinding all over - it hints that drill out may be preferable but also the cush post are susceptible to fracture ?

thanks as always
mik
 
You are talking about two different things. Clutch plate replacement requires removing the clutch drum and taking off the pressure plate by removing the springs.
Replacing the cush drive rubbers requires removing the thin outer cover plate that is riveted on. A search will explain the correct procedure for doing it.
Replacing cush drive rubbers will not fix sticking clutch plates.
 
thx Tippie - that is very helpful, i tried pulling on the clutch drum to remove it and it didn't seem to want to come off so i assumed the rivets were somehow holding the assembly on - sound like a little more fiddling is in order
 
Often the drum hangs on the teeth of the clutch plates and needs persuasion. Be very careful of the sprocket teeth, they are very easy to chip off. Having the primary chain on an levering carefully on it can work. Use a parts diagram (Laverdaparadies website), and/or a manual.
 
Thx Tippy yeah once i wiggled it with a bit more energy it came right off - sweet - plates looked like they came out of a 50 year old motorbike!
thx again
 
If the clutch drum still has it rivets that means the rubbers are definitely fucked so grind them off and drill and tap the posts for a m5 or m6 bolt. Make sure the bolt head doesn't foul with the webbing on the primary cover
 
motoddrob said:
If the clutch drum still has it rivets that means the rubbers are definitely fucked so grind them off and drill and tap the posts for a m5 or m6 bolt. Make sure the bolt head doesn't foul with the webbing on the primary cover
Click to expand...
It's been a while since I've replaced clutch rubber rivets with bolts, but I'm sure M5 isn't an option.

The drill size for a M6x1 tap is 5mm.

Once the rivets are removed, the holes are a bit larger than 5mm diameter (maybe 5.5 ish?). So tapping to M6 will end up with an incomplete thread profile, but there's enough metal there to be able to screw a bolt in. It just means the bolt torque will have to be reduced a bit from what you'd normally expect of a M6 bolt in an aluminium thread. There's plenty of thread depth though, so it won't matter too much. Also, there's practically no axial (pull-out) load on the bolts, so it doesn't really matter if the threads are a bit less than optimum.

If you really want a full-strength thread, you could drill the holes out to 6mm and tap for M7 bolts. But there's not a lot of metal in the little pegs that the clutch rubbers go on, so by increasing the centre hole size, you're reducing their wall thickness. Remember that the load on them is sideways, so they are in effect little cantilever beams.

I think a slightly loose thread (that has little load on it anyway) is less of an engineering compromise than a weakened clutch peg. Therefore, the preferred option in my opinion is to preserve the strength of the clutch pegs and put up with a sub-optimal thread. Tap for M6, then nip the bolts up gently with a bit of Loctite thread lock to stop them working loose.

On Series 1, 180° engines, there's not a lot of space for bolt heads on the clutch hub, so don't use washers under the bolt heads. Don't use socket head (Allen head) either because their heads stick up a bit higher than hex head bolts. Depending on the thickness of your primary cover gasket, you may find that even without washers, hex head bolts will still interfere with the inside of the primary cover. In that case you'll have to grind the bolt heads down a bit. Using a thicker primary cover gasket could mitigate this issue, if you can find one.

I don't recall having a clearance problem with the bolt heads on the RGS clutch that has a separate "spider" type bearing carrier, so I'm guessing it's only the series 1 engines that have clearance problems.

All of the above comes from delving into my memory, so if there are any stupid mistakes, someone please correct me.
 
Wasn't aware of the rivets hole size.
I suggested m5 to preserve the integrity of the post. I have never done it myself but Phil Todd did it for me on my 750 SFC when I didn't have the means to do it myself. After refitting I noticed the clunking sound of the bolt heads on the cover webs. So I relieved the webs to give them clearance. Button head socket bolts have a smaller head height than hexes so that's an option.
 
Not exactly sure of the rivet size but they are a tap out fit, so I'm guessing close to 5mm. I did my SF1 about 40 years ago and there was plenty of metal for an M6 tap. I put a minor countersink in the cover holes and bevelled the inside edge of cap head screws. No problem there, but the SF3 gearbox and clutch I'm using on the new bike came with 10mm hex heads from the Lav fabbrica - no contact with the primary cover.
 
6 mm screws in place of the rivets.
Grind off the head of the rivets and tap them out from outside in. This is where the operation is fraught with risk since you can split the posts. Take it easy and use heat.
If you're proficient with a pillar drill, drill the rivet down the middle making it easier to tap out.

Then tap to 6mm.

Paul
 
+1 - take notice of Paul's post and suggestions - drilling down the middle and heat are definitely your best friends.
 
isnt the original poster only trying to free a stuck clutch?
just undo the six clutch springs and remove the plates as a stuck lump, free then up on the bench, usinga very thin blade, they will easily part, give them a clean in petrol, and a very light sanding with say 600 git on a flat board/block, clean again and use airline to dry, soak them in new clean oil overnight and refit, it is usually the oil brand that will cause the sticking, so change the brand, but only do 100 or so miles before you drop the exhaust and drop the sump strainer, in order to check for fluff, if none, all is good refill with your changed brand and you are good to go, if you see any fluff, fit it all back together and do another 100 miles and repeat the strainer clean, you (hopefully) wont see any fluff and all is grand, this fluff only occurs when you change the oil brand, and usualy does not apear at all, it is rare and hugely random, plenty have got away with it as very little fluff builds up, but no one has worked out which oils have this effect, but it has caused camshaft seizure on two engines that I have seen and another poster from AUS that I didn not see, I cannot find the pictures that he posted.
CLEM
 
thx guys - yes i figured while i was in there i'd replace the cush rubbers (and new chain since again i'm in there) - so great advice. I was going to try and reuse the plates but since i need a few parts figured new plates too - i'll clean these plates as per Clem and use for backup should the RGS start sticking (more)
 
CLEMTOG said:
isnt the original poster only trying to free a stuck clutch?

CLEM
Click to expand...
Yes, Clem, he was, but then it was pointed out that if the rivets are still in place then it is almost ceratin that the rubbers are donald-ducked - and so starts the rivetectomy. :)
 
  • Haha
Reactions: Rob
Dellortoman said:
It's been a while since I've replaced clutch rubber rivets with bolts, but I'm sure M5 isn't an option.

The drill size for a M6x1 tap is 5mm.

Once the rivets are removed, the holes are a bit larger than 5mm diameter (maybe 5.5 ish?). So tapping to M6 will end up with an incomplete thread profile, but there's enough metal there to be able to screw a bolt in. It just means the bolt torque will have to be reduced a bit from what you'd normally expect of a M6 bolt in an aluminium thread. There's plenty of thread depth though, so it won't matter too much. Also, there's practically no axial (pull-out) load on the bolts, so it doesn't really matter if the threads are a bit less than optimum.

If you really want a full-strength thread, you could drill the holes out to 6mm and tap for M7 bolts. But there's not a lot of metal in the little pegs that the clutch rubbers go on, so by increasing the centre hole size, you're reducing their wall thickness. Remember that the load on them is sideways, so they are in effect little cantilever beams.

I think a slightly loose thread (that has little load on it anyway) is less of an engineering compromise than a weakened clutch peg. Therefore, the preferred option in my opinion is to preserve the strength of the clutch pegs and put up with a sub-optimal thread. Tap for M6, then nip the bolts up gently with a bit of Loctite thread lock to stop them working loose.

On Series 1, 180° engines, there's not a lot of space for bolt heads on the clutch hub, so don't use washers under the bolt heads. Don't use socket head (Allen head) either because their heads stick up a bit higher than hex head bolts. Depending on the thickness of your primary cover gasket, you may find that even without washers, hex head bolts will still interfere with the inside of the primary cover. In that case you'll have to grind the bolt heads down a bit. Using a thicker primary cover gasket could mitigate this issue, if you can find one.

I don't recall having a clearance problem with the bolt heads on the RGS clutch that has a separate "spider" type bearing carrier, so I'm guessing it's only the series 1 engines that have clearance problems.

All of the above comes from delving into my memory, so if there are any stupid mistakes, someone please correct me.
Click to expand...
Drill size for a 1/4" UNF thread is 5.5mm diameter - if you wanted to mix and match
Dellortoman said:
It's been a while since I've replaced clutch rubber rivets with bolts, but I'm sure M5 isn't an option.

The drill size for a M6x1 tap is 5mm.

Once the rivets are removed, the holes are a bit larger than 5mm diameter (maybe 5.5 ish?). So tapping to M6 will end up with an incomplete thread profile, but there's enough metal there to be able to screw a bolt in. It just means the bolt torque will have to be reduced a bit from what you'd normally expect of a M6 bolt in an aluminium thread. There's plenty of thread depth though, so it won't matter too much. Also, there's practically no axial (pull-out) load on the bolts, so it doesn't really matter if the threads are a bit less than optimum.

If you really want a full-strength thread, you could drill the holes out to 6mm and tap for M7 bolts. But there's not a lot of metal in the little pegs that the clutch rubbers go on, so by increasing the centre hole size, you're reducing their wall thickness. Remember that the load on them is sideways, so they are in effect little cantilever beams.

I think a slightly loose thread (that has little load on it anyway) is less of an engineering compromise than a weakened clutch peg. Therefore, the preferred option in my opinion is to preserve the strength of the clutch pegs and put up with a sub-optimal thread. Tap for M6, then nip the bolts up gently with a bit of Loctite thread lock to stop them working loose.

On Series 1, 180° engines, there's not a lot of space for bolt heads on the clutch hub, so don't use washers under the bolt heads. Don't use socket head (Allen head) either because their heads stick up a bit higher than hex head bolts. Depending on the thickness of your primary cover gasket, you may find that even without washers, hex head bolts will still interfere with the inside of the primary cover. In that case you'll have to grind the bolt heads down a bit. Using a thicker primary cover gasket could mitigate this issue, if you can find one.

I don't recall having a clearance problem with the bolt heads on the RGS clutch that has a separate "spider" type bearing carrier, so I'm guessing it's only the series 1 engines that have clearance problems.

All of the above comes from delving into my memory, so if there are any stupid mistakes, someone please correct me.
Click to expand...
Drill size for a 1/4" UNF thread is 5.5mm - if you wanted to mix & match
 
to remove the face plate, knock the rivets through it, using a suitable sized pin punch, be carefull the cast alloy post will break if not supported, use some heat to expand them a bit, poersonally I have found that the holes in the castings are too large for a full thread on 6mm, (as others have noted) so what I have done in the past is use 7mm taps and bolts ot Timcerted to get back to 6mm, not much soare metal tough so again care must be taken and referably the drilling, countersinking and then tapping expanding of the timecert should be done on a mill or drill press. If you wish to retain the triplex chain, if you still have three row sprockets, buy a Norton Commando item (Regina or Reynolds) are shorten it. very much cheaper than stock from most Laverda outlets.
CLEM
 
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