I think I'm really in the proverbial

[Disaster Area]

Hi,
Before I start the post proper, I swear that I was gentle, I didn't over tighten anything and I worked slowly and methodically.
I have just replaced the pushrods on the RH cylinder, following Haynes, then adjusted the rocker end float and valve gaps following Steptoes guide. (Thanks for that sticky, it made more sense than Haynes' version.) I put everything back in it's place, I had no bits left over and start to put the rocker cover back on. I tighten the bolts gently, top right, bottom left, top left and it wouldn't cinch tight. I took the bolt out and tried again. Nothing. On opening up the cover the thread that the bolt screws into fell into my hand.

I now only have three functioning rocker cover bolts and one peice of threaded metal, which is sat on my desk.

On a scale of 1 - expensive, how bad is this and what are my options?

There's only one thing for it. and lots of it.

Thanks in advance for sympathy and mickey taking,
DA

 

[Daithi]

Hi D.A.
One of the gurus will be along shortly with more expert advice
but in the meantime, those bolts don't need a lot of pressure to seal and
I'd be inclined to think three bolts would be enough to seal the cover for
a while till you can pick up a helicoil. Fitting the coil is easy and fairly
cheap.
As I said you'll get better advice shortly but I don't think it's as bad as you
might think.

Daithi

 

[northengit]

Sounds like as you say " the thread fell into your hand " it may have been over tightened before and pulled the thread' or it may be an old helicoil that was previously fitted thats popped out..... either way its not to difficult to re-helicoil as the bolts are not set to such a great torque ' think its about 6 Nm but I may be wrong.

 

[Disaster Area]

Hi,
Thanks for the constructive replies so far. I'm not to sure how much metal needs to be remaining for helicoil to work, but this isn't just a case of a stripped thread. The bit that fell out is 180 degrees worth of the thread casing, so there is only a half of the thread remaining on the bike.

There must be a way to reattach it. I'm tempted to try supaglue...

In the meantime, the vodka is working a treat. (Please note, I'm twelve hours ahead of most of you, so its Saturday evening here.)

Cheers,
DA

 

[Daithi]

Hi,
Thanks for the constructive replies so far. I'm not to sure how much metal needs to be remaining for helicoil to work, but this isn't just a case of a stripped thread. The bit that fell out is 180 degrees worth of the thread casing, so there is only a half of the thread remaining on the bike.

There must be a way to reattach it. I'm tempted to try supaglue...

In the meantime, the vodka is working a treat. (Please note, I'm twelve hours ahead of most of you, so its Saturday evening here.)

Cheers,
DA

Feck, that's a different story alright. Either build up the casing with weld
and re-tap or use the three other bolts for strength and use chemical metal
puttied onto fourth bolt just to help.
Nurse those Vern might have some clever solution.

 

[PhilBolton]

Photo???

 

[Disaster Area]

And now with pictures

Let's hope this works...

 

[Tarka]

I had two such cases of this damage following a crash.

There was *just* enough thread to carefully screw in a short bolt.

I got some 6mm screws and bored holes down their length in successively larger sizes.....on a lathe.....from 1mm to the tapping drill size for M6.

Using these I managed to bore down and thread the lower part of the damaged 'pillar' and then reuse the original rocker cover studs.

 

[Colban]

Can you glue/weld/chemical metal a length of studding into the remains of the hole so it projects through the valve cover and fasten with a domed nut?.

 

[Mech]

Looks to me that it has been helicoil before. I have used in the past with great success stuff called Innotec 2C- Metal its a 2 part putty you mix together when set it can be drilled and taped but I have never used it inside an engine I have how ever used it to block a hole in a carb float chamber so once its set it resists petrol so oil should not be a problem. It will need a good key and must be free of oil if you use this stuff(clean area with thinners electrical cleaner etc).
It was bought at Morley motor factors in Derby but i would expect any trade motor factors would sell it.

Hope this helps and good luck

Steve

 

[(RIP) Kaister]

you've got a couple of real options.

best choice would be weld it up and re-drill and tap

next choice would be similar to Tarka - but i'd overdrill it to take an M10 bolt with an M6 thread inside it.

you can buy locking thread repair fasteners for GRP/carbon that are similar to above - but you need some metal around them.

called 'Keysert' available in AUS .. http://mdmetric.com/pdf/keysert.pdf

maybe a combination of insert and chemical metal will do it ? - use brake cleaner before adhesive to degrease thoroughly

 

[Disaster Area]

Light at the end of the tunnel?

Thanks for the advice so far, it really is appreciated. I've got no idea if it was helicoiled before, this was the first time that I had ever had the cover off, it being a reasonably new bike to me.

How about this for a plan: Get some of the Innotec 2C (or similiar) and make a column of it in the shape of what snapped off. Wait for it to set, hopefully letting it key into what original thread is left and then carefully try and cut another thread (6mm?) into it and use the original bolt. Oh, and try not to torque it up to gorilla levels?

In the meantime, is she safe to ride? At the moment I feel like thrashing it with a branch Cleese-style.

DA
p.s. on the upside, this whole episode finally made me buy site sponsership...

 

[Daithi]

IMO

It's one of the upper bolts, the chamber does'nt fill up with oil and isn't under
great pressure, at worst there might be a small amount of oil seep through.
I'd nip up the other three till I got some one to build it up with weld metal
then drill and retap it.

I might be wrong, but I don't think so.

 

[Nin]

What Mech says. Used that stuff on outboard motors and it works a treat. Just make sure you throughly degrease first. Soak it in a solution of clothes washing powder and water for half a day and it will come up a treat - I kid you not.

 

[Pukmeister]

How about this for a plan: Get some of the Innotec 2C (or similiar) and make a column of it in the shape of what snapped off. Wait for it to set, hopefully letting it key into what original thread is left and then carefully try and cut another thread (6mm?) into it and use the original bolt. Oh, and try not to torque it up to gorilla levels?

It sounds OK however the 'helicoil' insert is usually screwed in after the original pulled threads are drilled out and enlarged with a bigger tap provided in the helicoil kit. Your hole with the helicoil removed is most probably a size up from M6.

If you glue up the hole with 2C you may find it difficult to pick up the correct centre for the hole again when re-drilling. The other problem is being able to degrease the threads sufficiently for the repair material to bond strongly. In my personal experience as a marine engineer, any chemical metal products are best when in thick(ish) layers, a thin layer (such as half a thread) may debond easily and break away.

I think Motomartins idea of drilling out the end of an M10 bolt to accept an M6 thread in its centre and create a sleeve is a clever solution. Obviously making the 'sleeve' using a lathe is the best way to do this to keep the centres aligned.

You can simply drill the damaged hole out oversize in stages to 8.50mm (presuming you use M10 metric coarse thread of 1.25mm pitch), tap with an M10 thread, then loctite the M10/M6 sleeve you made in the hole and you have a very solid permanent repair.