750 twin sprag clutch removal advice

S

smlav

Senior member
Location
Shropshire UK
I'm about to fit new springs etc to the starter clutch, I have the puller and crank locker from ILOC library. Have tried tapping the nut (I know it's reverse thread), but it's not budging. It seems a bit of a faff to remove the primary case in order to lock the crank. I have the green book and have searched the forum, but couldn't find enough detail.

Is there a tip to attempt for removing the reverse nut (I don't have a rattle gun).
If I have to remove the primary cover, are there tips for that, anything to watch out for? Don't think it's ever been off before.

thanks
Sean
 
When removing the primary chain the green book says the crank nut may come loose by putting in fifth gear and holding the rear brake on to lock things up. Can I not try the same method for spray clutch?
Sean
 
Hi Sean,
I wouldn't follow the recommendation to loosen crankshaft bolts by blocking the rear wheel! The crankshaft is a pressed together construction. Therefore, I would block the crankshaft at the point where the torque is applied to open the nut.
 
Unless it is stripped or Loctited on it should loosen with the crank just rotated backwards against compression and giving a good few whacks with a hammer onto a socket bar instead of applying torque. It is not a big thread on that side of the crank and should not be overtightened. If you see any sign of Loctite you can weaken it with heat. Also it is not generally recommended to loosen things on one side of pressed up cranks with a stopper on the opposite side if they are super tight.
 
Does the ILOC library not have the appropriate C/peg-spannner for the sprag clutch housing? That's what the hole at TDC is for...

piet
 
sfcpiet said:
Does the ILOC library not have the appropriate C/peg-spannner for the sprag clutch housing? That's what the hole at TDC is for...

piet
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Excellent thanks Piet, that's the info I needed. I have the C spanner but mistakenly thought it needed to go on the primary side, I see now it is much ore simple and logs locks into the hole as you say. Here goes...
 
As Tippie mentions, on compression the nut will almost invariably come loose if you give the socket bar a few whacks with a hammer. But having access to the C-spanner you're all set. Never had a factory toolkit when removing the starter clutch on the side of the road out in BFN!
 
natm said:
You can buy electric rattle guns quite cheaply. They're perfect for that type of job.
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Personally I'd be worried about using a rattle gun to do the nut up - a Jeezus nut it ain't. I've seen the thread stripped and repair would not be straightforward.

I made a custom tool to hold the starter clutch while I do the nut up manually (ie no rattle gun) - it's basically a plate that bolts into the top two M6 sidecover holes and a rod that fits into the hole in the clutch. I'd never needed to tighten it with a holding tool until the SFQ put more stress and strain on it - eliminating the tendency to kick back on starting has also helped avoid the issue. I had had three broken keys and even a snapped starter chain - a heavy repurposed used triple cam chain!). The taper interface was always in good nick ... before anyone mentions it.
 
Just give me a bell Sean if you need to.

I did a little fine tuning on the plungers to reduce the chance of the springs/plungers snagging where the ‘sharp’ edged opening is in the plunger. For me it’s experimental but thought I’d do it while in there. KN did it on my RGS plungers a few years ago 👍 and all seem fine.

David
 
Tree Hugger said:
Just give me a bell Sean if you need to.

I did a little fine tuning on the plungers to reduce the chance of the springs/plungers snagging where the ‘sharp’ edged opening is in the plunger. For me it’s experimental but thought I’d do it while in there. KN did it on my RGS plungers a few years ago 👍 and all seem fine.

David
Click to expand...
Thanks David,
The nut came off quite easily once I used the C spanner. But then I hit an issue with the threads where the library puller screws into were a bit squashed and the puller couldn't be screwed in. So I used a 3 jaw puller which did the trick, again fairly easily (thanks to whoever it was who advised putting the nut on the end of the crank to prevent everything flying all over). The rollers, plungers and springs are all in good condition, probably protected by the excessive amount of old grease all over the place which was the plungers to stick. So now it's just a case of getting all the old grease out of the nooks and crannies. I'll fit the new plungers etc, but the ones which came out are all intact in good nick so can be spares.

Sean
 
If the plungers look fine I would re-use them as there has been experience with late replacement ones breaking. Whenever I service mine only the springs are much the worse for wear. I also have tried to smooth the plungers to avoid them snagging the springs.
 
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