husqvarna 125L broken bolt, fix/replace crank case :(

Hey guys,

Working on my husqvarna 125L, a crank case bolt broke off. I tried grinding the bolt flat, punching the centre then drilling out but drill went off centre, now its a little crooked.

The only thing I can think of to do next is;

1. Use a dremel & try grinding the bolt surface flat again, then try again, with a left hand drill bit. I would need to buy a left hand bit and/or screw extractor.

or

2. Replace the crank case, which has been super hard to find, but may be easier/cheaper than mucking about with the bolt + buying tools.

Does anyone know where to find a spare (used) crank case section?

heres a couple pics,





Thanks

Don't know what sort of tips you have with yor Dremel but I have cut the entire bolt out of a set of vintage motorcycle cases on more then one occasion using a couple of carbide cutters.
You end up with a spiral of thread which can usualy be would out with a pick.
If you decide o go with the LH drill, use the Dremel to make a nice big pilot depression in the center of the bolt.
No need to make the face flat just so long as the pilot in the center is big enough to prevent the drill from wandering.

I use LH drills with great success.
Drill the smallest hole you are confident in doing without breaking the drill bit.
Enlarge this hole with a drill 2 to 3 sizes bigger in hammer mode and about 1/2 speed usually the bolt will wind up & out

A good welding shop could weld a nut on the bolt and extract the bolt.

Thanks guys

I have a rotary tool here with a heap of tips, will give that a try and see how I go.

Northbama: unfortunately the bolt is flush/recessed into the case, no way of getting a nut on there .. I should have tried that before attempting anything.. lesson learnt i guess :/

You guys all have good approaches. If the boss is buggered too much a new one can be added with heliarc very quickly by a good weld shop. Depending upon the price or availability of another case it might be cost effective to pay a "good" machine shop. If you are good with tools and on limited budget Bert's way...I also have had good luck with the left hand drills. Incidentally, don't know if you have the H Frt store, but they sell a little 4 pak about ?1/8 to 1/4" reasonably priced.

Thanks motoman

I'm leaning away from a machinist/weld shop as Im thinking the cost for them to do it (in Aus), it would be cheaper to pickup a used/2nd hand trimmer from ebay/gumtree or possibly find the replacement section of the crank case. :frown:

As far as I know, we don't have harbor freight in Aus, though I have looked at them. Only issue is I've been reading about "cheaper" bits/extractors being quite brittle & breaking, didn't want to risk it. postage from HF/Amazon etc.. is probably around $15ish too. I'll keep an eye out for some LH Drill Bits/Extractors and keep them on hand.. most likely will use them again in the future

I have to say I have never had any luck with a left handed drill bit. As a rule the reason the bolt broke in the first place it was too tight into the threaded bore. You are wasting you time and money on left handed drill bits. You would be much better off with a screw extractor like a eaz-out. To use the screw extractor make sure you very first drill a small hole all the way through the bad screw, not part way. This will help loosen it in its bore. The next step is to select the right size drill bit that your screw extractor takes and drill this hole all the way through the bad screw. At this point if the screw isn't messed up too bad it should come out. If not you will have to buy a thread repair kit. This kit should come with instruction's on how to use it. There are different company's that make these thread repair kits and I have used them with good luck. If the screw is loose enough to remove with a left handed drill bit you might try to remove it with a small pick and hammer which I have had luck doing also.

Widget said:

Thanks motoman

I'm leaning away from a machinist/weld shop as Im thinking the cost for them to do it (in Aus), it would be cheaper to pickup a used/2nd hand trimmer from ebay/gumtree or possibly find the replacement section of the crank case. :frown:

As far as I know, we don't have harbor freight in Aus, though I have looked at them. Only issue is I've been reading about "cheaper" bits/extractors being quite brittle & breaking, didn't want to risk it. postage from HF/Amazon etc.. is probably around $15ish too. I'll keep an eye out for some LH Drill Bits/Extractors and keep them on hand.. most likely will use them again in the future

Click to expand...

Cost is the lesser problem, unless you know people in the light engineering business you will be flat out even finding a machine shop, let alone actually getting them to take on the job.
If you are near a big city you might find one of the few specialist bolt removers but the retail price is around $ 90.00, trade was $ 25,00 but the last 3 shops I used have all closed down in the "I want it now" ,throw away everything made overseas "Smart Country".

As for buying a replacement again too many shinny bums making too much profit from too small a turnover means that a thing you buy in the USA it will be 4 to 10 times that price down here, if it is stocked at all.
I started buying things from Jacks two years ago. For this exact reason.
Generally their orders ship in a day or two then taks 5 to 10 days to get here by USPS/ Austpost or 10 to 20 days by Fedex / DHL etc.
Parts ordered from All Powers Melboure warehouse that are in stock take 5 weeks to get to the dealer.
Honda Parts 5 to 10 days , MTD parts, monthly order so 7 weeks if I just miss a cut off or $ 100 special order fee.

Let me persist on the joy of left hand drill bits. If you can center punch the broken shaft half way accurately (meaning access) a left hand drill bit can be started with no lubricant while using a variable speed drill motor at half speed . As the drill lips bite they create vibration wich will often loosen the broken bolt and even back it out. Example , Pontiac Fiero exhaust manifold studs notorious for snapping. Twice I have used a left hand bit. The H Frt drill bits are "DrillMaster" which are the top end of the H Frt drill selection IMO.

I am sorry to learn that Australia lacks machine shop and weld shop coverage. The up side is that people learn to do it themselves. So now I will revert to an earlier age when I only had basic tools. (I now have a mill ) If I were trying to save the part I would try level the bolt top to try another center punch, then proceed. It looks like corrosion is not a problem , rather fatigue or over torque so the broken part may be surprisingly loose. It looks small in dia , but try making a pointed punch and carefully driving in the punch at the radius in a counter clockwise direction . Select a couple points on the broken shaft and repeat lightly. Sometime they move. If you destroy the boss you might be able to file it flat and shim up.As you file blue the boss and take readings of the washers you use to build up. Will this work? Maybe. Leak? Maybe. There are people who swear by the squeeze tubes of metal epoxy.


Reynoldson''s approach is good, but alignment is difficult with out a mill or at least a drill press table, and as he says, the drill must travel a ways into the shaft. However if you have a drill jig ( as in angle drill jig, it might work.) I also note he mentioned the punch chasing technique.

If you do cut down the "boss" and create a corner be sure to radius the corners and polish out scratches-stress cracking area.

A bit of a political rant.

If that were the case I would be overjoyed.
However what will happen is they will leave their massivly too large house full of German appliances, wearing their Italian cloths, get into their Japaneese cars, drive down to the American owned big box store and buy some new piece of Chineese made junk with a Japaneese name on it, then on the way home ring the radio station on their Korean made phone & complain that their freshly graduated child can not get a job & why dosn't the government do some thing about it.
I have to be a mobile mechanic because it would cost me $50,000 to $ 75,000 pa to run a workshop in compulsory government ( all 3 levels ) fees , insurances & tax. And that is if & only if I could get the shop approved working out of a disused farm house which is a 0,00001% chance as it is below the 100 year flood level so will be an enviromental pollution risk should it flood, where as the 20,000 tons of sewage sludge down the road at the top soil blender is apparently not.

Malcom Frazer, who dies last week was our last Prime Minister who was not Rhodes Scholar and actually had some non academic skills (farmer) and could manage something more difficult than changing a light globe.
Thus the government puts zero value of any type of manual / technical skills training.
All of out technical schools are closing down or converting to vitally important courses like accounting, advanced acounting and even more advanced accounting .
Since Prime Minister Keeting ( Rhodes scholar with a 140 IQ ) government has been anti "smoke stack industry", apparently we are all going to be accountants. ( can't Americans add ? )

We still consider a foreigh company buying a local one as an "investment" into this country as if the shareholders of Ford are concerned about the welfare of Australians.
Just to add insult to injury the last budget removed all Commonwealth subsatities towards trade education so now an electrician , plumber, mechanic ,welder , fitter etc will have to find $55,000 to $ 150,000 to pay for their trade course which did not make the news because all of the University graduate journalist gave all the press time to deregulation of university fees, I mean what do we need more of journalist or plumbers ?

Six years ago we bought some mills, lathes & a shaper, only to find we can not even pay to learn how to use them as there are no adult colleges who teach machining and trade school ( TAFE ) will only take us on if we get an apprenticeship . So as I have not touched a lathe or mill since I was 18 it is a long slow self education with lots of broken tool tips and bit of steel flying around the shop ( that does not exist ).