Woodruff keyway repair

Hi guys
Wondered if someone might have some pointers for me on how to repair a
woodruff (are they called this in the US? Half-moon shaped disk) keyway on
a steel shaft.
Background:
Crankshaft is steel
Woodruff key is approx 5mm thick (3/8ths I think)
The alternator pulley bolt (on end of C/shaft) became loose and allowed the
pulley to chatter. Unfortunately this has allowed the key to chatter too &
has opened out the keyway slightly.
I took the pulley, preheated with a MAPP gas blowtorch, zapped it with the
MIG and allowed it to cool. I then spent a fair while with needle files
re-dressing the keyway. (Heavy pulley 110A 240V mig, C25 mix)
How might I be able to repair the crank? It will have to be done in situ.
Would hitting it with MAPP, MIG and careful use of a Dremmel suffice?
(I wondered about making a copper key to give me a non-stick surface to
weld up to.)
I really don't want to weld a key in permanently
I've used Quicksteel for the time being.
Thanks :)
Reply to
Balders
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Mill a woodruff slot on the other side of the shaft?
GWE
Reply to
Grant Erwin
How bout making a new key out of thicker stock, make the bottom part a tight fit in the wallowed out slot in the crank, then narrow the top part to fit the pulley Get a good trial fit, then use Loctite bearing mount to secure the key in the crank and let it set before final fitting the pulley..... Joel in Florida
Reply to
joelblatt
Does this pulley mount on a taper? Or a straight shaft?
Pete
Reply to
Pete Snell
wrote: How bout making a new key out of thicker stock, make the bottom part a
^^^^^^^^^^^^^^^^^^^^^ Or, a related idea: Make a key that is tapered, so you can partially insert it in the slot. Heat it red hot and pound it in. Then wrestle it out with pliers and grind on it until you can fit everything together securely.
Reply to
Leo Lichtman
Too easy to get wrong, I'd also have to get someone to machine a keyway into the pulley :'(
Reply to
Balders
That sounds like an idea, cheers :)
Reply to
Balders
Thats what I do all the time
Gunner
Reply to
Gunner
Pete, it's a straight shaft. It's actually a Subaru Impreza crank that's fitted to a vehicle. I've heard of a fair few that have done this - not just Subarus. I wonder why they don't machine a longer slot in the crank and insert a square section longer key, say 1" - 1.5"
If it all goes very pear shaped it would probably be easier to get a donor engine. Well there's always the weld the pulley option first ;) All for the sake of a bolt and a 10p (20c) key!.
Reply to
Balders
A step key, eh? Old-timers' repair method, but one that works well.
Reply to
John Husvar
Eh, beg pardon. Why? Wasn't it the shaft keyway that was enlarged? The pulley won't care where it lines up with the key or am I missing something?
Reply to
John Husvar
Wow, That seems like a problem waiting to happen (guess it did...) What about putting a pin in the face of the pulley and indexing it to a hole in a thick washer, held by the nut? It would take some of the load off the key.
Pete
Reply to
Pete Snell
Ahhh, very sorry John. I didn't say there's the cambelt/ign sensor drive pulley directly behind this one so no going 180° out Both pulleys have a slot in them. There's only one woodruff key which spans (just about) both pulleys. The key is approx 1/2" across its flat - miniscule compaired to the pulleys.
It's the key slot in the crank that I need to be able to repair properly now. Instead of having parallel sides it's more like this (ASCII art time)
\ | \ | |_|
It's also in situ, to strip and get machined wouldn't be worth the grief. A 2nd hand engine would be a better option after the "weld the bugger on" option.
Thanks for the replies so far, much appreciated
Reply to
Balders
Not uncommon, not just Scoobies either. I read a few articles about Land Rovers etc failing the same way. Your plan sounds good. There's 2 holes in the cam belt pulley already, would need to drill one in the back of Alt pulley & pin .
Will also seriously consider Joe's very helpful idea. Then I will still have the weld it on option if all else fails ;)
My tools are limited to hands, mig, Dremmel, files & a small pot of elbow grease :)
Reply to
Balders
I was thinking Subaru also. The only time I've ever seen this problem was on a friends Subaru. We ended up finding a used engine and having it installed. I was told that the crank is heat tempered, and welding would weaken it.
Reply to
Bob F
I would clean the keyway well, put an isolator on the side of a new key, perhaps thin tape so the key will be removable, install the key and fill the buggered gap with JB Weld (filled epoxy) and let cure. Reinstall the pulleys, apply thread locker to the nut and sock it down tight. I'd expect it to last for years that way.
Reply to
Pete C.
Threadlocker on the pulleys themselves wouldn't hurt either. The threadlocker is removable with heat well below that which would be a problem for a heat treated crank.
Reply to
Pete C.
I have always thought that woodruff keys were generally only intended to index parts and not to drive them. I would certainly look into some form of better security for the pulleys if this is a common failure.
Don Young
Reply to
Don Young
to machine a keyway
was enlarged? The
I missing
cambelt/ign sensor drive
woodruff key which spans
its flat -
repair properly
(ASCII art time)
worth the grief. A
the bugger on"
of a new key,
the key and fill
Reinstall the
tight. I'd
Time's a wasting! Better use JB Kwik! Actually JB is totally worthless in a case like this, you've a much better chance using Devcon plastic steel, it will take a lot more pressure than jbweld. phil kangas
Reply to
Phil Kangas
It is quite common to see the setup the O.P. described - a single woodruff key in the nose of a crankshaft. I've got a couple of Peugeot diesels in a boat built exactly that way and they are at least twenty years old.
Of course they all have a Big Bolt to hold things together that should be as tight as you can get it.
Bruce-in-Bangkok (correct email address for reply)
Reply to
Bruce in Bangkok

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