broken chaincase fixing screw

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o0norton0o

o0norton0o

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I was reassembling my primary and I broke the front chaincase fixing screw's head off. The screw's shaft is still in the crankcase. I am thinking of somehow turning it further until it drops into my crankcase and pulling it out of the sump with a magnet...

Does this sound feasable? crazy? suggestions please... Do I have to worry about it hitting the crankshaft when I try to turn it inward to drop into the sump? thanks
 
if you intend to screw it in, just check the depth of the other 2 holes to make sure the screw doesnt hit the crankshaft before it falls.
 
Consider backing it out if it turns. Might be easier and less risky than screwing into that crankcase and then go fishing. Maybe a small punch to pop a centering mark and a reverse twist drill or maybe as simple as a dental pick and working it out.
 
Couldn't you just remove the inner primary again and remove the remainder of the shaft with a vice grip?
 
Hi.
You will need to rotate the crank so there is clearance inside the cases.
The face just clears the cases. The arrow shown is from another [forum] thread.
Good luck with your option. With the primary off, the thread should be proud of the case - if it broke the head off.
Ta.
 
thanks all...... Great suggestions.

If I try to thread it inward, I will take a different screw out and check the depth to verifiy my ability to use the fishing method. (great idea madass)

reverse drilling it and backing it out with an easy out would be nice. I am going to get the proper bits and EZ out tommorrow (when I have a cooler head) I'll probably drill a hole in the head of the screw and make a colllar out of the screw head to center the bit when I drill the screw shaft.

The bolt broke off flush with the crankcase and left a little stub on the head of the screw. ( I also put blue loctite on the screw.... damn it) no vise grip possible, but good idea...

... I'm thinking more clearly now that I have a few good ideas... thanks
 
Put a propane torch to it and casing and reverse it out as mentioned before. Torque values are low. I would only drop it inwards to crankcase and sump extraction if this fails. Just the way I would approach it first. Good luck.
 
I definitely wouldn't screw it inwards! If you can get hold of enough of it to screw inwards why can't you unscrew it?
If you have or can borrow a MIG welder you could tack something on the end of the broken bit to unscrew it, the heat would probably help with the Locktite issue too!
Good luck.
 
daveparry said:
I definitely wouldn't screw it inwards! If you can get hold of enough of it to screw inwards why can't you unscrew it?
If you have or can borrow a MIG welder you could tack something on the end of the broken bit to unscrew it, the heat would probably help with the Locktite issue too!
Good luck.
Click to expand...
+1
 
I would 1st try a reverse LH drill bit from good hardware on online order to expect bit to bite in pretty quick and spin it right out, otherwise I have had welder tack on a stick or even a wire held a tad to seriously heat the fastener then hold breath for 20 sec or so to let alu swell then twist right out.

https://www.google.com/?gws_rd=ssl#q=LH+drill+bits
 
I got it out!

I drilled it with a 9/64th bit and EZ outed it with the smallest EZout. The real headach was disassembling the entire primary side that I had just put together after a gear box rebuild, but there was no way to work on the stud with the inner cover in the way. (although I did use a Vix bit in the inner cover hole to drill a dimple in the stud so I would get a centered hole without using a punch) It took very little torque to make the blue loctite let go.. Needless to say I am relieved.

Thanks for all the suggestions.
 
How did the head break off? I would think the threads would strip out first, it's not such a thick area for a bolt. But I put studs and nuts in there myself ala hobot.
 
DogT said:
How did the head break off? I would think the threads would strip out first, it's not such a thick area for a bolt. But I put studs and nuts in there myself ala hobot.
Click to expand...

I think I tapped the tab of the retaining washer flange to get it started to bend it into place a little bit too hard and I cracked the shaft of the screw. Later, while I was pinching the washer tabs tight with a channel lock plyers, all it took was a touch and the head of the screw fell off.

What I learned was,........ Don't mount the washers with the flange hammered flat. Leave a slight bend in them because you can still get a socket on the bolt that way, and it also leaves the flange sticking up enough to easily just pinch it against the screw head once it's tight...

Stupidity and old habits die hard.... Sometimes I need to break stuff to learn..
 
Hi o0norton0o.
Experience is just another word for 'made mistakes'.
This forum provides OPE (Other Peoples Experiences).
Glad it worked out so well for you - thanks for the feedback.
Ta.
 
Thanks, I was curious because I always think I'm going to strip those threads out when attaching the inner primary.
 
ewgoforth said:
These threads were helicoiled from the factory.
Click to expand...
I am a little confuse about this statement, unless it is a mis-punctuized question. I have never heard of anything being helicoiled from the factory.

And just to add, I think helicoils are a "last resort with no other options to get you through to where it can be better resolved" solution.
 
No helicoils that I'm aware of , just threadcuts into the rather thin aluminum casing , so be careful not to overtighten the 3.
 
Someone in my bikes previous life must have stripped one out because it's a 3/8" instead of 1/4". No heili-coils in my crank cases but yeah, the thread in the case must be all of 1/4" long. The bolt is only 5/8" long and then there's the thickness of the inner primary case, washer and the gasket to go through. I'm surprised there's not more problems there, must be a low stress area.
 
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