Help! Crankcase breakage.

[Gimlet]

Nightmare yesterday. The chain snapped on my 1190. The joining link let go. It was fitted by a local independent mechanic, he just says it was a shit chain - which I supplied. When I flattened the tang on the locking washer to remove the front sprocket the nut was finger tight. Was that down to a shit chain as well...?

Anyway, that side of things is a whole other thread.
The problem is that on its way off the chain snapped off one of the lugs from the face of the crankcase that the clutch slave fixes to.

I assumed at first that this was disaster. New crank case etc. Cleaned it up today and now I'm wondering if I can repair it in situ.
Here's the damage. The clutch pushrod is in the centre of the picture. Below left at 7 o' clock is the bottom spigot for the clutch slave and what the top one should look like. Above left at 11 o' clock is the snapped off top spigot - end of pencil. The scuff on the casing above the pencil luckily is just a scuff so that shouldn't be a problem. It's just this snapped spigot/lug thing

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Luckily the sheared piece was held in place by the slave screw so I was able to retrieve it:

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My question is, would it be possible to chemically bond this piece back into place in situ and if so what with. I can get some 5 tonne epoxy. It only takes a sheer load from the actuation of the clutch slave. There's no lateral pressure and no big torque to deal with.

It's aluminium obviously but the mating surfaces are rough and grainy where the casting has snapped. Can't smooth them because then it won't fit. I do have some acetone to clean them. Any ideas?
If it's a new engine casing that's the end of the bike unless the insurance will cover it but I doubt it.

[Big Red]

I dont know if epoxy will be strong enough to hold, but I would probably look to make a bridge between the bottom left and top bolt with a threaded bush mounted to the bridge in the right position to take the mounting bolt for the top of the slave cylinder.
That way you will be supporting the top of the cylinder through two proper bolts and a metal bracket for fixing to.

[Gimlet]

It's a possibility. My only concern would be that the slave is then only attached directly to the crankcase by one screw and the pressure when the slave was actuated would therefore put a leverage load on that screw.

Unless you mean bridge not from the bottom slave spigot but from that torx screw on the outer engine case below left of the broken spigot. That might work and then there'd be two screws for the slave to push against. Forgive my misunderstanding of that's what you meant.

I need to make sure there's room for the chain catcher and the plastic sprocket cover to fit back on but you could be onto something there.

[Big Red]

Yes, thats what i meant. You would be supporting the slave with two bolts holding on the new bracket with the threaded bushing welded onto the bracket in the proper position. Therefore bracket supported with 2 bolts and then slave supported with original bottom bolt and new top mounting bolt position on bracket. You may have to mess about getting everything to fit, but I am pretty sure this will be a strong permanent fix.

[Dodgy69]

JB Weld any good.???

[GuzziPaul]

Is there a bit of bolt still in the crankcase? If so is the snapped of bit just more of a spacer with any pressure taken by the bolt?

[Gimlet]

Is there a bit of bolt still in the crankcase? If so is the snapped of bit just more of a spacer with any pressure taken by the bolt?

No unfortunately. All the available thread is in the snapped bit. All that's left on the engine case is the stub end of the drill hole.

[Druid]

Is there enough meat on the crankcases to drill and tap, then use a longer bolt for the clutch slave cylinder?

[Gimlet]

JB Weld any good.???

I wondered about that. It claims to bond aluminium. A neighbour is an aircraft engineer and he recommended the 5T epoxy.

I'm minded to try it and if it doesn't work there's Big Red's bridging tang solution.

[Gimlet]

Is there enough meat on the crankcases to drill and tap, then use a longer bolt for the clutch slave cylinder?

No unfortunately. The spigot is a spacer for the slave as well. Needs to sit exactly as before or it won't push square.

[Druid]

Is there enough meat on the crankcases to drill and tap, then use a longer bolt for the clutch slave cylinder?

No unfortunately. The spigot is a spacer for the slave as well. Needs to sit exactly as before or it won't push square.

Yes. I meant use a longer bolt through the broken off spigot but if there's not enough metal to drill and tap a deeper hole...

It looks like there are 2 other mounting bolts, might be worth trying JBWeld. Otherwise you need to find a good aluminium welder

[iansoady]

I'm a great fan of JB weld but I don't think it would be strong enough here. It does look as though there would be enough meat behind to drill & tap. Drill the thread out of the snapped off bit and assemble everything so that you can use that as a jig to get the hole in the right place (although it does look as though the original drilling has left a nice starting point). It would then be worth getting a bead of weld round the broken off bit when it's all assembled to add a bit of support.

[Gimlet]

I'm definitely don't want to risk drilling any further into the crankcase. The slave bolts need a good 10 mm of thread to engage with and there's no way I'm going to get that. I would guess the casing is only about 3 mm thick and if I go through that's the engine wrecked.

I'll try epoxy bonding in the first instance because there's nothing to lose. The only issue is if it lets go will the slave still function or will I end up stranded. When the chain came off it must have whacked the banjo bolt or the hydraulic line because the banjo was loose, fluid was leaking and lever pressure had gone. I assumed the slave body itself was fractured but that doesn't appear to be the case. It means though that the slave hasn't been operated when only held by one screw. That would happen if the bonding repair failed. What if that broke the other spigot as well..? Can I ever ride across Europe or even to Scotland again wondering whether my repair is going to hold..

Fabricating a failsafe bracket off the clutch case screw may be the only route to peace of mind.

Edit: just been on Trevor Pope's parts fiche to order a new chain catcher and I looked up the crankcase while I was there. You can't buy one side, you have to buy both halves as a matched pair with bearings already in place and they cost £1700... Then there's the cost of engine out and a complete strip down and rebuild with all new gasket kits etc. If I hole that crankcase with a drill the best bike I've ever owned is a write-off...

[Dodgy69]

I agree, in the first instance, stick that bit back, JB etc. See how that works, any movement etc, then look how you can add additional support, bridging etc.

The alternative ain't worth thinking about.

[GuzziPaul]

How about welding a bolt onto the case like a stud. Admitedly it may need a washer or some other form of spacer making, but that must be easier to weld than trying to get the snapped spigot welded on.

[exportman]

How about welding a bolt onto the case like a stud. Admitedly it may need a washer or some other form of spacer making, but that must be easier to weld than trying to get the snapped spigot welded on.

Actually weld a bolt, or screwed rod onto the casing and drill the snapped spigot ( adjusted to allow for the weld)to use as a spacer over it

[Big Red]

The only problem I see with trying to bond the broken part back on is if it lets go, you could possibly wreck the complete engine if the other mount for the slave cylinder fractures the casing or breaks of completely.
If it was mine, I would be looking to make up a bridge between the other two mounts mentioned and making the slave mount in the middle of the bridge. The slave mount can even be a bolt from behind and through the bridge and washers to space the gap to the slave so it sits straight. There will be a bit of messing about getting it all to fit behind the covers and it may be seen, but better than writing it of or spending a fortune on new crank casings.

[iansoady]

The slave bolt wouldn't need 10mm to engage - if you use a stud which stays in place with a nut on top 5mm would be adequate.

How do you know the casting's only 3mm thick? It would be easy to test drill (say 3mm) till you break through. It may be thicker than you think. That wouldn't commit you to anything.

That's what I'd do anyway.

ps you can't weld a stud on as you can't weld steel to alloy......

[Gimlet]

I think all welding is out of the question. It's too inaccessible and the heat is far too risky with so many components nearby. I'd have to split the crankcases to be sure in which case I might as well buy new ones.

The only way is a flying bracket mounted off the two nearest clutch case screws as Big Red first suggested. It will be extremely awkward and night be a job for a proper engineer. The slave has to present absolutely perfectly or it won't work.

I have some mild steel plate and it it's not too thick I could at least make a prototype that fits and have it powder coated, or if it looks too scruffy I could always hand it to an engineering shop and get them to fabricate a tidy replica in stainless. I'm inclined to think that if it's going to show anyway it's better to flaunt it and bling it up than try and hide it, in which case a bit of nicely finished brushed stainless would look better than powder coated mild steel that doesn't quite match.
Either way the bike is now massively devalued. It won't be going anywhere now.

[Gimlet]

Incidentally the thing above the clutch push rod with the gouge taken out of it is the clutch oil jet. I'd need to file the damage smooth before it can be unscrewed but it looks to be otherwise unscathed and unless a clutch problem develops there is never any need to remove it.