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Offline mrjay15

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Snapped engine mount bolt
« on: 09 November, 2017, 07:03:49 PM »
Hi all I was wondering if I could get some help riding along the other day I noticed my crash bung wobbling so I pulled over and noticed the bolt has snapped it's hasn't been dropped or banged does anyone have any advise on how to get the remaining part of the bolt out without having to take it to the garage £€$ as your probably aware you have about 2inches of room to play with is there any way of dropping the engine just enough to drill it out without having to take whole engine out

Offline Rev Ken

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Re: Snapped engine mount bolt
« Reply #1 on: 10 November, 2017, 12:30:36 PM »
I managed to drill it out 'in situ'. Once I managed to punch a dimple as near the centre of the broken bolt, and started a pilot hole I used a socket that fitted over my drill (a size just smaller than the bolt diameter) to help keep my drill aligned to the lug, I successfully drilled it out. I then ran a tap through to remove the remains of the original bolt's thread.  (I have the tap if you want to borrow it). My fall back was that if I cocked it up I could drill the lug to accept a bolt and nut, although that would mean not having a crash bung.

I have a fair amount of experience in mechanics, and wouldn't advise it for a 'novice', but like you I was worried about the cost of getting a garage to do it! It might be worthwhile getting a good garage to look at it to work out how they might do it and do as much of the preparation work as you can to reduce the cost.

Good luck!
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Offline mrjay15

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Re: Snapped engine mount bolt
« Reply #2 on: 10 November, 2017, 12:34:15 PM »
Thank you for your quick reply I will look into it on my next day off

Offline Bifferman

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Re: Snapped engine mount bolt
« Reply #3 on: 10 November, 2017, 12:38:40 PM »
Customary to introduce yourself and have a go at the search facility before weighing in with your first quest for help.

Having said that :405: and I am sorry to hear of your little issue.  Not quite sure why you would need to drop the engine or even removing it to sort the problem - a picture would certainly help.  You will probably have guessed by now that this exact same topic has been covered on here many times before and nobody (?) has had to drop the engine.  Anyway this may help you:-

Firstly it is unusual for an engine bolt to simply sheer off unless either it has been the recipient of some external force as in the bike may have been dropped or even knocked off its stand at some time past (or even a 'SAD' incident).  The R&G bolts (what make are yours?) are very high tensile and will fracture if subject to external force or, possibly if they have been over tightened when fitting.  The R&G fitting instructions warn of over tightening and the torque required for their bolts, as compared to the shorter OEM bolts is something like 10Nm less.  The bolts are also fitted dry so if you do lube them then the torque will need to be reduced to compensate for the extra slip of the bolt against the thread of the mounting lug thread.  We have considered on here previously why this is so and it may be that R&G designed their product so that the bolts will snap off  after an impact to lessen the chance of you getting even more severe damage to the engine mounting lugs themselves.   Whatever, if the bike has been subject to an impact, even a relatively minor one R&G do strongly recommend that they are replaced.

You will need to drill (slowly) the bolt and insert an easy-out to remove the bolt but even if you get the drill in dead square the bolt may prove to be stubborn in its extraction.  Reason for this is Galvanic corrosion.  The bolt is a high tensile steel (unfortunately not a stainless steel bolt) and it fits into an alloy threaded lug.  The alloy corrodes against the steel bolt (not the other way round) sometimes to the extent that the female thread is eaten away.  Some have had no problem removing the bolt remains, some have suggested applying heat in the form of a heat gun but at the risk of the finish on the engine casing.  One (moi :001:) suggested the age old method of wrapping the lug with snapped off bolt in towelling and applying boiling water (quite a lot) over the towel which most always will expand the lug just enough to make it possible to release the bolt (coefficient of expansion is greater in the alloy that the steel bolt).

Should the galvanic corrosion be severe you will have reduced thread within the lug to grip the new bolt.  One possible (bodge in my view) would be to use a strong version of Loctite and hope that this is sufficient to keep the new bolt in place - it may well work knowing just how good Loctite is and what do you have to loose.  Alternative might be to re thread the hole and use a wider diameter bolt but will it fit through the bung ?  Another possibility is to put a similar dia but longer bolt through the open lug and secure with a spring washer/loctite etc (I think someone has done this).  To me the best remedy would have an engineering shop (garage :164:) to fit a T-Sert into the hole which will provide a better union that you had when the bike was new.

One way or another there are a few solutions.  However I would consider replacing the corresponding bolt on the other side of the engine while you are at it as this may well have been stressed due to the failure fn its opposite number.

Andy
 :149:

p.s.  Just read Rev Ken's post;  What he did not mention is that after drilling the old bolt out he inserted a Helicoil thread which is good but if you are getting someone to do the job for you then I would recommend a T-Sert (similar sort of thing to a Helicoil but better technology).   
« Last Edit: 10 November, 2017, 12:54:49 PM by Bifferman »

Offline mrjay15

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Re: Snapped engine mount bolt
« Reply #4 on: 10 November, 2017, 12:46:24 PM »
Thank you for your reply

Offline Rev Ken

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Re: Snapped engine mount bolt
« Reply #5 on: 10 November, 2017, 04:38:43 PM »
Hi Andy - I was prepared to fit a Helicoil, but managed without it, at least that is how I remember it. If necessary I'll get my son to check, while reminding him he is supposed to be buying it off me.....! By the way I always understood that R&G fitted LOW tensile bolts so they bent before sheering to avoid the engine lug from breaking.
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Offline Bifferman

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Re: Snapped engine mount bolt
« Reply #6 on: 10 November, 2017, 05:33:53 PM »
*Originally Posted by Rev Ken [+]
Hi Andy - I was prepared to fit a Helicoil, but managed without it, at least that is how I remember it. If necessary I'll get my son to check, while reminding him he is supposed to be buying it off me.....! By the way I always understood that R&G fitted LOW tensile bolts so they bent before sheering to avoid the engine lug from breaking.

Hi Ken

You are probably right about the tensile thing, unlike with a gold coin my teeth cant tell the difference with steel :164:.   No need to get your young'n to check but do nag him over stumping up for your old steed, he's had it for a while now so tell him you will be adding interest at the BofE statutory rate (a mean 8%).. 

No worries I can do a search of times past on here but my rusty brain prompted me into thinking that you bought a Helicoil kit, if you managed without you did exceptionally well.  The local garage uses T-Serts and I have to say that I do prefer them, it is like inserting a real steel thread so the bolt will bite into steel and not into alloy, much better. 

On another topic, I am sad at selling the Swan but I really don't use her much at the moment and anyway Lesley never liked it so we got a MG Midget instead so we can go out together now.  Bridget is a thousand smiles a minute even if she does only cruise at 55-60mph :001:

Kindest regards

Andy
 :149:
« Last Edit: 10 November, 2017, 06:15:26 PM by Bifferman »

Offline Rev Ken

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Re: Snapped engine mount bolt
« Reply #7 on: 11 November, 2017, 08:07:10 PM »
*Originally Posted by Bifferman [+]
Hi Ken

You are probably right about the tensile thing, unlike with a gold coin my teeth cant tell the difference with steel :164:.   No need to get your young'n to check but do nag him over stumping up for your old steed, he's had it for a while now so tell him you will be adding interest at the BofE statutory rate (a mean 8%).. 

No worries I can do a search of times past on here but my rusty brain prompted me into thinking that you bought a Helicoil kit, if you managed without you did exceptionally well.  The local garage uses T-Serts and I have to say that I do prefer them, it is like inserting a real steel thread so the bolt will bite into steel and not into alloy, much better. 

On another topic, I am sad at selling the Swan but I really don't use her much at the moment and anyway Lesley never liked it so we got a MG Midget instead so we can go out together now.  Bridget is a thousand smiles a minute even if she does only cruise at 55-60mph :001:

Kindest regards

Andy
 :149:

I hope the Swan goes to a good bird keeper, and that your MG midget gives you many a happy time - I like the frog-eyed Sprite, but even that is too costly and I'm still enjoying my bike - with my soft top 'mobility scooter' in reserve. (2003 3.2S Porsche Boxster)
Yesterday is History, Tomorrow is mystery, Today is a gift....

Offline Art

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Re: Snapped engine mount bolt
« Reply #8 on: 14 November, 2017, 01:42:58 PM »
If needed I wouldn't hesitate in recommending the use of a Heli-Coil for this application. The repaired thread will be stronger than the original thread and a M12 x 1.25 Heli-Coil kit will set you back a paltry £12, a M12 x 1.25 Time-Set kit will set you back ten times!

 


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