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Discussion Starter · #1 ·
So whilst checking valve clearances today (and despite my torque wrench definitely being set to 14Nm), one of the cam cover bolts sheared in two and I stripped the thread of another at a measly 7Nm (torque wrench is a Sealey, calibrated and pretty new).

Bike's 9 years old and 2 previous owners so a warranty claim is presumably off the cards (even if I had evidence that I didn't over torque it). For the stripped thread I managed to get the cam bolt out without leaving any remnants inside the cam cap, but the sheared bolt is another story. Basically half the bolt is still stuck in the cap.

I know that I can't buy a cam cap without the cylinder head assembly, so will a helicoil be sufficient? Restoring stripped threads is dark magic as far as I'm concerned, I've been very lucky to have stripped extremely few in my time and when I have they've been on easily replaceable parts.

I have another question about properly reading the valve clearances but right now that's a bit of a moot point. Perhaps later...
 

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Discussion Starter · #2 ·
And for the sake of anyone who stumbles across this thread (and myself, in case of stupid assumptions):

- Presumably I should only take one cam cover off at a time? They're both on the exhaust side. That's a pain as it means two trips to the local bench press (I know they're hand drillable...but...still. I've had enough excitement for one day. I'm going to go calm down and relax by BASE jumping).

- And logically it makes sense to have the valve closed (i.e. the 'pointy' bit of the cam lobe facing AWAY from the shim to limit the pressure from the valve spring on the uncapped camshaft).
 

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Try not to use a torque wrench to get the bolts in- especially on blind-drilled holes in an aluminium engine component (axel bolts and whatnot- sure to save a few seconds- but there is not as much risk of crossing threads on those components- but these too you naturally spin the nut on as far as possible by hand first). On any engine casting- use your fingers (or even the socket on an extension) first to get them into into the hole a good distance and feel that the fastener is going easily into the hole. Once you "feel" that bolt is not cross-threaded with your fingers- then us a regular ratchet to get the fastener all the way seated and snug. Then (and only then) swap the socket and use the torque wrench.


LEFT HANDED DRILL BIT to get broken bolts out!!!
 

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Once you get the broken section of bolt out, a helicoil is the best method of thread repair. It is even stronger than the original thread, in aluminium.
 

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Discussion Starter · #5 ·
LEFT HANDED DRILL BIT to get broken bolts out!!!
Good point, thanks. Didn't even think of an LH bit. Before, I was edging towards doing this with a hand drill and vice, but I can't see my drill (DeWalt D024K) as having anywhere near enough torque to drill a hole with a cobalt bit at low speeds - and I ain't going near that thing at high speed!
 

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Discussion Starter · #6 ·
Once you get the broken section of bolt out, a helicoil is the best method of thread repair. It is even stronger than the original thread, in aluminium.
Thanks, I suspected as much. I'm tempted to do all the cam caps with helicoils (Time-Serts are an ass to get here in the UK), just to have the peace of mind of a stronger mount.
 

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Thanks, I suspected as much. I'm tempted to do all the cam caps with helicoils (Time-Serts are an ass to get here in the UK), just to have the peace of mind of a stronger mount.
Time Serts are nowhere near as good as helicoils anyway, in aluminium. Helicoils have the advantage of being a stainless steel diamond shaped insert that sits between two threads - the harder you crank it down, the more it digs in. I know - eventually the outer thread in the aluminium would strip out but these things will take much more than just a bolt in an aluminium thread because the helicoil, bolt and aluminium threads tend to brace each other.

If you have the opportinity, helicoiling all the threads is a good idea and you would use the same torque settings as before.
 

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Discussion Starter · #8 ·
Thanks again, appreciate the on-going help.

I just spoke to my local mechanic and he instantly recommended a helicoil. I was going to take the cam caps off separately and take them to him (ugh) but he said there'd be no harm in taking more than one off at a time as long as I didn't move the chain whilst they were off. He also said he would do it with a hand drill.

He's also charging £25 per helicoil. Thoughts?

Cheers.
 

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With one snapped off and one stripped something wrong with the torque wrench settings. I've never read this happening on this bike before.

That said.....you need a fix and I would toss that torque wrench.

This is why I often just tighten everything down by hand, hand tight and call it good. I've had torque wrenches get me into trouble a few times. Often with steel going into aluminum.

Good rule of thumb, "never use a torque wrench going into aluminum", just do it hand tight, I don't care what all the experts say about that, I do it all by hand feel and stay out of trouble. I've never had bearings go out or otherwise.

Helicoil will be the only option. The one that need dtrilled out will probably end up needing a helicoil as well.
 

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He's also charging £25 per helicoil. Thoughts?
Bleedin 'ell... Last time I had one done at a shop it was £3... mind you, that was in the early 90's... I've done my own since I found out that you can buy kits.

For less than 25 quid you can get a kit from fleabay and do this yourself. The kit contains 10 inserts, an insertion tool, a drill bit and a tap. You can do them one at a time if you do them yourself.

There's nothing to it really - use a good cordless drill on its slowest speed and go in with the drill bit carefully, making sure the drill is vertical and that you follow the original hole, until you feel it bottom out. Then go in with the plug tap supplied and tap the new thread. For M6x1 this will be M8x1. Screw the insert in with the insertion tool (the tool has a slot in the end which engages with a tang on the end of the insert - this end goes in first). Stick the supplied punch in the hole and whack it with the palm of your hand. This breaks off the tang. Empty the hole of debris and reassemble the cam cap onto the bike.

Its a good idea to hold the cam cap in a vice while doing the job, protected with rag. Even better if you can get access to a bench drill with vice. Alternately, if you take the kit, with all the cam caps (suitably marked) to your local college, the engineering lecturers there will appoint their best student to do the job for you, for free. Its practise for the student.
 

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With one snapped off and one stripped something wrong with the torque wrench settings. I've never read this happening on this bike before.

That said.....you need a fix and I would toss that torque wrench.

This is why I often just tighten everything down by hand, hand tight and call it good. I've had torque wrenches get me into trouble a few times. Often with steel going into aluminum.

Good rule of thumb, "never use a torque wrench going into aluminum", just do it hand tight, I don't care what all the experts say about that, I do it all by hand feel and stay out of trouble. I've never had bearings go out or otherwise.

Helicoil will be the only option. The one that need dtrilled out will probably end up needing a helicoil as well.

+1 on the helicoil: they work great.

One problem with torque wrenches is using them near the limits of their range. A lot of guys have one wrench that's great for
torquing lug nuts, but too heavy for small nuts. A wrench good for 14nm might have a range of 0-30nm since most torque wrenches
are less accurate at the upper and lower ends of their scales.
 

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So this has just happened to me whilst I was taking the cam cover off. I was hoping there might be some thread that I could get some pliers around but no joy.

I'm guessing that I can just remove the cam cap and have it drilled out and a helicoil fitted, or is there another option? I haven't done anything like this before so may take it for someone else to do, don't fancy the £1k cam replacement quoted in world of triumph!

I was really bummed, was hoping to save some cash not taking it to the dealer for this service, bike had 8k on it but it's 7 years old, so now wondering if it needed doing in the first place.

Sent from my LG-H815 using Tapatalk
 

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Discussion Starter · #13 ·
In the end, I was very lucky with mine. I took it to a local motorcycle shop to have the helicoil put in and they were able to rescue the threads. I also like to the idea of doing as much of my own maintenance as possible (even if it means, er, learning from mistakes!)...You can do it yourself (I was quoted £25 per helicoil for the shop to fit it) - but, honestly, in my opinion I decided that learning how to do this would be time better spent on an old piece of thread lying around from a broken component. Not on a £1k cylinder head.
 

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I bought a new torque wrench just to make sure I torqued up the low torqued bolts correctly and the torque wrench made by Draper (which are usually honest tools) and at 10NM it was not accurate at all !

It was cranking to about 15NM before clicking, even though it was showing 10NM on the wrench FFS

Just to note, I was trying the wrench out on another bolt that could handle much higher torque settings before I tackled the delicate cam followers EEK

Could have had a major disaster on my hands but I'm not a mechanic or anything but spannered for years so had a feeling it wasn't right
 

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Discussion Starter · #15 ·
A lesson I learned from this is that torque wrenches with a range that ends in quite a high number (e.g. 10 - 80Nm) are VERY poor on the lower end of their range. On my 10 - 80, I wouldn't dream of using it at less than 25, and I bought a 2 - 15Nm for the lower ranges.

Sorry you had to learn this the hard way (incidentally, exactly the same way as I learned...)
 

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So this has just happened to me whilst I was taking the cam cover off. I was hoping there might be some thread that I could get some pliers around but no joy.

I'm guessing that I can just remove the cam cap and have it drilled out and a helicoil fitted, or is there another option? I haven't done anything like this before so may take it for someone else to do, don't fancy the £1k cam replacement quoted in world of triumph!

I was really bummed, was hoping to save some cash not taking it to the dealer for this service, bike had 8k on it but it's 7 years old, so now wondering if it needed doing in the first place.

Sent from my LG-H815 using Tapatalk
I stripped a cam cap out last year, and after much research, I decided to go with Time Sert rather than Helicoil.
Time Serts are definitely more expensive, but are super secure.

It was my first time ever dealing with something like this on my own, so I was quite stressed, but it ended up being super easy.
Just take your time, follow the instructions exactly, and you'll be fine.

Since I have them anyway, I was thinking of drilling out the remaining 3 caps and inserting a Time Sert as preventative maintenance.
 

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All good advice guys, I've walked away from the bike for a few days to gather my thoughts and read about the options you talked about.
I will ring around a few garages for a quote just for an idea.
Hopefully I don't strip the cam cap bolts when I get it out!


Sent from my LG-H815 using Tapatalk
 

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Get a good quality Torx bit for the cam cap bolts

I used a breaker bar and pushed my hand down on the bit to hold it down too

I hate torx screws , they are never deep enough to get a secure grip
 
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