The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: UncleD on 05.01. 2019 07:31

Title: Major screw up...miracle required (broken bolt)
Post by: UncleD on 05.01. 2019 07:31
Fitting an SRM sump to the A10 today. 

Two of the studs had been replaced with oversized bolts so I had the appropriate helicoil on hand.  The holes didn't need drilling so I just ran the tap through them a couple of times to clean them up.  The first helicoil fitted easily however the second caught on something on the way in but with a little force screwed into the appropriate depth.  When I inserted the bolt as a test run however it caught so I progressively pushed it a little and the backed off hoping to straighten out whatever was catching it...

...yep, I pushed too hard and the bolt snapped off in the engine casing.  There was copious obscenities.

Anyway, what can you do?  I got out the extractor bits and drill and started to work on removing the broken bolt end.

5 hours later (laying under the bike on the concrete floor in 38 degrees) and I have all but drilled away the offending bolt as the extractors just don't grip enough to turn the bolt.

The trouble is that I am now a little off centre and in danger of damaging the engine casing.Im not sure if I have drilled away any of the the helicoil but it is not moving and is refusing to let go of what is left of the bolt.

I am at the end of my expertise.  Any tips ?

Is this the greatest excuse ever for an engine rebuild?



Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 05.01. 2019 08:21
Oh BUGGA.
Which one is it, top or bottom?
Well you've learnt one lesson. Never force a helicoil/recoil. If it snags (jumps a thread/cross threads) pull it back out by unwinding it. I'd say there was some of the old bolt thread left to upset it.
Time to get the old Dremel and diamond burr to eat it out. If you can get it thin enough you might be able to pick it out with a sharp scribe.
Once all the steel is out we'll have to think of a repair. Leave that with the minds trust to chew over.
Cheers
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Swarfcut on 05.01. 2019 08:42
 UncleD.... If you have any of the bolt left, try a parallel sided splined bit, typically a long nosed TORX bit hammered into the off centre hole in the bolt.  Stands a good chance of gripping, just slightly oversize will do. Conventional  stud extractors have a taper which spreads the stud and are rarely successful with small diameter holes.

  As Musky says the helicoil will have to be persuaded out with a sharp scribe. With a bit of luck this may leave a thread still capable of supporting a new helicoil. If not, depending on the size of the hole  you end up with, the answer is a custom insert to allow a standard bolt or stud, or a shouldered  retaining stud, 1/4" stud then bigger diameter to suit the size of the hole butchered in the crankcase. This will need a coarse thread, where it fits into the crankcase, typically Whitworth or M8 or M10 if you are extremely unlucky.
 
 Shit happens....     But this is merely a ripple on the millpond of life in the grand scheme of things.

  Swarfy.


  Additional.....    on reflection Slymo's following solution of the insert plug will be easier. The oil sump plate can be used as a drill guide to locate the mounting stud.  Stick with studs ....saves wear on the crankcase threads and avoids possible blind hole bottoming and crankcase damage.

  Thanks Slymo.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Slymo on 05.01. 2019 08:44
That is a nasty problem! I would suggest the best and most permanent solution would be to remove all the offending material including the helicoil (possibly with further drilling and then a good easyout?) and then drill tap and plug wound with an oversize plug of aluminium or brass in order that you can re drill and tap to 1/4" cycle or bsf. Definitely go back to studs as bolts are likely to see tye same problem again in the future.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Steverat on 05.01. 2019 09:08
This sounds easier than it is, but have you considered building up the casing with an aluminium braze like "Lumiweld". It is not a weld so there's no melting of the parent metal, and so no deformation, but its very strong and can be drilled and tapped, and looks like aluminium. The problem would be access of course and the need to get the substrate really clean for the braze to adhere, but I think you could do it in situ. Do you know someone with a pit in his garage? If you can park the bike across it that will save the backache a bit.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 05.01. 2019 10:01
G'day fellas.
Once all the steel is out the sump plate can be used as a guide (make a steel dowel to fit in the sump hole the size of the tapping drill 5mm) to drill the hole deeper and tap that.
Cheers
Title: Re: Major screw up...miracle required (broken bolt)
Post by: UncleD on 05.01. 2019 10:11
It is the hole on the timing side, closest the front wheel.

Dremmel...ok, there's a thought.

Oversize torx bit...can't make things worse.

Luminweld...new territory but she understand the principle.

Thanks for the ideas to move forward (and no mention of a rebuild)!
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Swarfcut on 05.01. 2019 10:17
G' Day Musky, Happy New Year.

     Always difficult to appreciate the other guys situation but on the face of it drilling and tapping the hole deeper as you suggest is by far the simplest answer, assuming there is  enough material below the existing hole.

  Lying on concrete at 38 degrees sounds  like luxury to me.

  Swarfy.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: bsa-bill on 05.01. 2019 10:20
This is related but a bit late for uncleD but I'd welcome any comments, I bought a set of left handed drills some time ago,  never used them as yet, anybody had any success with them in removing broken studs
Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 05.01. 2019 10:33
Depending on how much damage there is to the hole a timesert or big-sert https://timesert.com.au/  or  http://www.crosstools.com.au/oversize-big-sert-thread-repair-for-badly-damaged-hole.html
You'll still need to make a jig to ensure the hole is in the right spot and square.

G'day Swarfy, HNY. I try to make things simple but am guilty of over thinking at times.

G'day Bill, yes they work if the broken bolt isn't bottomed tight.

Cheers
Title: Re: Major screw up...miracle required (broken bolt)
Post by: RichardL on 05.01. 2019 14:13
Musky, and all

I have done helicoils for the sump plate while on the center stand, but this here is a more complicated job. If no pit, maybe the bike can be laid over on an old mattress or something. Bikes do, occasionaly, end up on their sides.

BigSert or other oversized insert seems much better and easier than plugging and drilling out the plug. I seem to recall seeing an insert-in-insert product once, but can't recall the name. I do recall that it seemed hsrd to come by, even in 6mm.

Two other things mentioned here I would avoid. First, trying to drill out rather than wind out the old helicoil. May not work, then leaves not enough to unwind. Second, Lumiweld.  I've been trying it. Watched the videos and it's not as straightforward and easy as it looks (at least, for me). I was working on what would have been a scrap timing cover and it did melt through, twice.

EDIT: Not saying Luniweld is no good, but making the bottom of your crankcase an early experiment seems ill advised. My A7 crankcase is at the machinist right now and one of his jobs is to rebuild (by welding) one of the sump screw bosses. Not a job I trust to myself.

Gotta go.

Richard L.


Title: Re: Major screw up...miracle required (broken bolt)
Post by: duTch on 05.01. 2019 16:41
My youngster had a bodgy helicoil in his Hoonda head, so tried to clear it with a tap-which also snapped off- inside (no protrusion)...a bit harder than a stud, but we got it out with a previously mentioned diamond Dremel tip (having the three flutes in the tap helped)...in hindsight, some cutting oil may have helped..
 
Title: Re: Major screw up...miracle required (broken bolt)
Post by: groily on 05.01. 2019 16:55

I had to do this exact same job on mine due to 2 broken studs (discovered when fitting the SRM bit, and explained the weepiness), and it has been OK for years.

I made a guide jig from half inch plate with the 4 quarter inch holes very carefully marked out and drilled in the right places (I clamped the stock for the jig to the original sump plate), attached it to the crankcase by the 'good' corners, and used the 'empty' holes as guides to get the busted bits out. Drilled out to just under  85% tapping drill size for the original thread, picked out a few remnants with a scribe, drilled to final tapping size, ran plug tap down them - and was lucky enough to get away with it. But I didn't have a buggered helicoil to contend with - just the old studs.

I found it very worthwhile to make the first drill bit into a home-made end mill or slot drill by grinding the tip off to get a flatter-ended cutter that didn't tend to wander and/or fret against the guide, and it was also helpful to have shortened it as much as possible to get 'rigid'.

In this case I'd follow the same routine, drilling undersize to start with and increasing to the size needed for the helicoil tap. Which would mean taking the jig off to enlarge the guide hole, maybe more than once, and doing the sequence several times. You should end up with a clean threaded hole that will still accept the intended helicoil if there's a god; but as he's not always at home when we need him, you might have to go bigger, and settle either for a stepped stud if you can sort one out.

My SRM gizmo came with caphead screws which I saved or some other job, because if ever there's a place where studs and nuts (nylock or double nuts even with lockwashers), is a must-have, this is it. Maybe SRM have moved on by now, as I'm sure a good few people will have mentioned they didn't like screws where studs are obviously far better.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: duTch on 05.01. 2019 17:43

 groily, without going too far off-thread (so to say)- did you do that with the engine in place ?  *respect*  *beer*....I'm reminded that I have a simple stripped thread, and made a kind of 'jig', but upside down is very tricky...decided it can wait as there's enough thread to hold a longer socket cap screw  *bash*... for now
Title: Re: Major screw up...miracle required (broken bolt)
Post by: kiwipom on 05.01. 2019 19:28
This is related but a bit late for uncleD but I'd welcome any comments, I bought a set of left handed drills some time ago,  never used them as yet, anybody had any success with them in removing broken studs
hi guys, a challenge indeed here but `Left hand Drill Bits sounds like a good idea to me, i have in the past used one of these where after a small amount of drilling it grabbed the offending stud and wound it out, cheers
  p.s. must get some for myself. 
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Steverat on 05.01. 2019 20:22


Here's an example of what can be done with Lumiweld. The surface had to be smoothed with a file first. The screw was left in the hole - the Lumi doesnt stifck to it, so it forms its own thread in the solidifying Lumi. We used acetylene for speed, but of course Nick was careful not to overheat.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 05.01. 2019 20:58
G'day fellas.

I've never used Lumiweld and if the job goes really pear shaped it may be the only answer. Just waiting to see the outcome of the bolt/helicoil removal.
Cheers
ps: modified posts to get back on track.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: UncleD on 05.01. 2019 21:18
Morning all,
Can't say I'm looking forward to the day in the shed today but this is where the journey has led.

I will give the torx head a crack but only once or twice...I don't want to be jamming things in there too much.  Second strategy will be Dremmel and pick, Dremmel and pick... ad nauseum... until either the helicoil gives up or I do.  The biggest challenge is the position of the bike...it's not only hard to reach, but also hard to see (damn these eyes).

After that, it's probably going to require dismantling the engine to allow the use of more precision equipment.  In reality, even if the helicoil comes out, Inserting a sound /square replacement is probably going to require this as I suspect it was the working angle that got me into this position in the first place.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: RichardL on 05.01. 2019 21:23


Here's an example of what can be done with Lumiweld. The surface had to be smoothed with a file first. The screw was left in the hole - the Lumi doesnt stifck to it, so it forms its own thread in the solidifying Lumi. We used acetylene for speed, but of course Nick was careful not to overheat.

That's a nice job similar to the videos, but I would call that a less critical spot by a, likely, more experienced user. Doesn't mean a person can't practice and develop the skill.

Richard L
Title: Re: Major screw up...miracle required (broken bolt)
Post by: groily on 05.01. 2019 21:29
I did duTch. But it was awkward.
I'm very lucky as I have a dilapidated barn big enough for a four post hydraulic lift I got from an internet seller of ex-garage stuff about 16 years ago. (Very handy as you can get 4 bikes up at once if necessary, for group therapy.)
Otherwise it would have been 'drain the fluids, off with the battery, and an old mattress', which would have worked too.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: wortluck on 05.01. 2019 21:34
I have nothing technical to add to the excellent comments, but I would like to say we have all had the, "You f*&^&*, b*&^%*, &*^%, son of a b*&^%$" moments. *problem* *problem*  One of these came yesterday when my wife pulled into the driveway in our one year old car clipping my car and leaving dents and scrapes down half of her car. *clap* *clap* *angry* *angry* *angry*  I checked mine and found the headlight all over the place.  Just got in from filling the dent in the wife's car - headlamp on mine fixed. *wink2*

Just goes to show that if you don't screw up (pun not intended) your own day, someone else will oblige. *razz* *razz*
Title: Re: Major screw up...miracle required (broken bolt)
Post by: chaterlea25 on 05.01. 2019 22:24
Hi All,
From memory using oxy acetylene is not recommended for lumiweld ??
Original Lumiweld is darker in colour than the ally
I have used Lumi and another similar product, "technoweld" ?? this comes in a coiled wire not rods like lumi
It is nearer in colour to ally,
There used to be a guy at all the bike shows "welding" up holes in coke cans and joining up bits of old broken castings and selling technoweld, I haven't seen him for a while now though

The biggest problem with these products is getting the area of the casting up to correct temperature to get the metal to bond properly, hard to do on crankcases and so on

I now usually get a friend who is a whiz with the TIG to do my ally repairs

As to accessing the underside of bikes, once I hung a Yam SRX upside down on a gantry crane as a pebble had fallen down the plughole into the cylinder  *problem* *problem*

John
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Daithi on 06.01. 2019 01:54
UncleD,
I hope you are having a cold one by now and have the sump back on.

Just to throw my 2¢ in.. Don't use an ez-out if you can avoid it, as you have snapped a bolt already there is a fairly good chance it will snap. Been there... it sucks .

Here is my take
Remove the battery, petrol and oil tank and if you have to ask to herself to pass the mattress out the bedroom window, do it. You really don't want to stuff this one up. You need to be square with the sump to succeed here.
Get your hands on (depending on what size you have drilled to) a TOP quality "left hand" tap and die set. Thread the offending hole and with a bit of luck the heat and friction will shift the helicoil as you do. If you have no joy then get a doner hi-tensile bolt and thread it up as a new stud to suit. This may just get you out of a hole and back on the road for the mo. Best of luck!
Dave
Title: Re: Major screw up...miracle required (broken bolt)
Post by: kiwipom on 06.01. 2019 02:44
I have nothing technical to add to the excellent comments, but I would like to say we have all had the, "You f*&^&*, b*&^%*, &*^%, son of a b*&^%$" moments. *problem* *problem*  One of these came yesterday when my wife pulled into the driveway in our one year old car clipping my car and leaving dents and scrapes down half of her car. *clap* *clap* *angry* *angry* *angry*  I checked mine and found the headlight all over the place.  Just got in from filling the dent in the wife's car - headlamp on mine fixed. *wink2*

Just goes to show that if you don't screw up (pun not intended) your own day, someone else will oblige. *razz* *razz*

 I bet it was your fault for leaving your car in the wrong place, cheers
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Steverat on 06.01. 2019 07:13
Hi All,
From memory using oxy acetylene is not recommended for lumiweld ??
Original Lumiweld is darker in colour than the ally
I have used Lumi and another similar product, "technoweld" ?? this comes in a coiled wire not rods like lumi
It is nearer in colour to ally,
There used to be a guy at all the bike shows "welding" up holes in coke cans and joining up bits of old broken castings and selling technoweld, I haven't seen him for a while now though

The biggest problem with these products is getting the area of the casting up to correct temperature to get the metal to bond properly, hard to do on crankcases and so on

I now usually get a friend who is a whiz with the TIG to do my ally repairs

As to accessing the underside of bikes, once I hung a Yam SRX upside down on a gantry crane as a pebble had fallen down the plughole into the cylinder  *problem* *problem*

John

You are right but oxy acetylene is able to get the parent metal temperature up quickly so it actually works fine so long as you don’t overdo it. Best to practice on something first. Nick is already a skilled welder and he got the hang of it straight away - but having watched him do a couple of jobs now I think I could do it too. Even with my shaky hands.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: UncleD on 06.01. 2019 10:39
Evening all,
Firstly a huge thank you to all.  While none of the suggestions were miracles, all were encouraging and informative and after all, there is only one way out of the Poo like this...cool, persistent and careful!

I went shpping this morning and bought a variety of Dremmel bits, a new scribe and pick set and even one of those jeweller,s magnifying, LED headpieces!

At the end of the day it was the Dremmel & pick method.  Dremmel away a thread of bolt...pick and pull a thread of helicoil ...and repeat until both are removed.  I had a couple of breaks when my swearing threatened to escalate to throwing things...remember, cool, careful and persistent.  Eventually all the junk was out and even a bit of stud from the PO which caused the fiasco in the first place.

I managed to get all the crap out with minimal damage to the substrate such that I could screw in a new helicoil.  The cherry on top was that the broken sump bolt was long enough to be used until I can find a replacement.

Many thank to all for keeping me focussed and positive ...now for my next major F'up!
Title: Re: Major screw up...miracle required (broken bolt)
Post by: RichardL on 06.01. 2019 16:40
Whew! Good for you. Did you do this all while laying under the bike? If so, is there a circus near you that needs a contortionist? Since you won't need it here, now might be a good time to start practicing your Lumiweld technique. *smile* *work* *whistle*

Richard L.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: UncleD on 06.01. 2019 21:11
Yep, laying under the bike...lifted about 40cm by a jack, but still only far enough away that my eyes could focus! 

The difficulty was having the tools in the right place so I could pick them up by feel as I couldn't lift my head far enough to see them.  The swearing was when my system broke down and I had to get up to find something...who needs to go to the gym for sit-ups and stomach crunches!
Title: Re: Major screw up...miracle required (broken bolt)
Post by: BSA_54A10 on 07.01. 2019 08:36
I am not a fan of Lumiweld or any of the similar products either.
Most of them are just a zinc based alloy, which s why they are a darker colour , a lot more bluer.
In sub critical places like a chaincase where the foot peg has gone through, fine but on the oil pump mount, you are dancing with the devil.

The thermal expansion of all of these alloys is nothing like that of aluminium - silicon alloy that the cases are made from.
Secondly it does not adhere to dirty metal which is why when the demonstrator is showing off the stuff, they usually blow a hole in the casting so it has a nice clean surface then proceed to fill the hole with the Lumiweld
Most of them are around 5% Al where there is a eutetic point as seen in this diagram https://www.researchgate.net/figure/The-Zn-Al-equilibrium-phase-diagram-26-The-vertical-thin-line-represents-the_fig5_239521389 (https://www.researchgate.net/figure/The-Zn-Al-equilibrium-phase-diagram-26-The-vertical-thin-line-represents-the_fig5_239521389)
Compositions either side of that point will be workable ( mushy ) for a short period before they solidify which is where you are working by scraping the surface under the "weld" puddle with the stainless brush or titanium scraper to break up the oxide layer on the parent metal. It is thermodynamically similar to lead wiping and chemically not too far off either.

Note this diagram is simplified  to a binary one and remember you are trying to repair an Al-Si or Al-Si-Cu alloy not pure Al.
Zn & Si do not alloy so the Zn has to disolve ( like sugar in your tea )  into the Al ( Alpha phase ) in the casting and push the Si out of the way.
The Si accumulates in the grain boundary regions making the repair very stiff & quite brittle.

For a region such as under the oil pump, real welding is the only option and I would go with torch welding rather than electric welding.
Been a long while since I have been playing in this region but from memory there are some cross drillings that run very close to the mounting stud holes & I fear that you may have breached one of them so now the helicoil is out have a very close look at the hole with your new magnifiers .
Good luck
Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 07.01. 2019 10:26
G'day Trevor.
The topic went a little sideways. Its not the pump but the sump where the problem is. A stud hole for the sump plate.
Cheers
Title: Re: Major screw up...miracle required (broken bolt)
Post by: cyclobutch on 07.01. 2019 16:12
Man that's good work. I'd barely wanted to read on from the earlier posts.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: BSA_54A10 on 08.01. 2019 08:26
G'day Trevor.
The topic went a little sideways. Its not the pump but the sump where the problem is. A stud hole for the sump plate.
Cheers

I will claim old age .
On a sump plate hole, 50/50.
Lumiweld should hold if you can get the cases clean enough.
I would still go with a weld.
Or even an alloy plug peened so it can nor screw itself out then drill & tap a new hole for the stud.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: Slymo on 09.01. 2019 18:54
Ive used an alloy plug with a corse thread and high strength loctite to great effect in the past. If you are going to go on using a bolt rather than a stud though Id put in a steel insert.
Title: Re: Major screw up...miracle required (broken bolt)
Post by: muskrat on 09.01. 2019 19:09
Yes a plug of the same (similar) material if the hole is really buggered.
With my through bolting of the head and barrels I thread the head (alloy) bolt holes and make alloy studs to screw in and machine off. Then drill the holes 1/2 a hole off. Same with the barrels with cast iron studs.
Same could be done down there.
Cheers