# sheared woodruff key bf 840



## shotgunred5050 (Apr 4, 2017)

So I posted a bit ago about a strange noise from my starter. It would spin but not engage the crank so I was thinking one way starter clutch. Pulled left cover off and when I pulled the flywheel off the woodruff key came out in two chunks with shavings all over it!!!!! Went to dealer and bought a new key put it all back together with new one way clutch and new starter new gaskets, etc... Replaced all the water pump bearings and seals also. Now its starting up fine but I worry how long its going to last. The slot in the crank where the key goes is a little wollowed out and it does have a 1/16 or less side to side movement before you can feel it engage the crank when you wiggle it left and right by hand. Any advice? My neighbor is a mechanic and he said maybe I can put a super tiny weld in the slot and then file it down till the key fits in there tight??? Sounds not too easy, but so does replacing the crank???? Are these 840 kits known to shear off keys?? I have noticed a few times when I shut it off a pretty hard ker chunk sound so I imagine it has weakened over time and it finally snapped. Anyone else with this problem?


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## shotgunred5050 (Apr 4, 2017)

heres the picture of the slot


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## NMKawierider (Apr 11, 2009)

The key shouldn't bare any load other then keeping it in time and shear if necessary. The flywheel to crank taper , like the primary clutch is the main means of holding it in place with the correct torque. But I see it has spun on there a few times and has been loose for a while first so it now it's lost material and may not fit correctly to the crank. Still...you have to try. Clean it up good, slap a little JB weld in the slot, install the key, slide on the flywheel and find the center point. Hold with the primary clutch and torque the retainer of...hell 10lbs over what the book calls for and hope it stays. If not, its new crank and flywheel time.


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## shotgunred5050 (Apr 4, 2017)

I saw a you tube where someone put lapping compound on the taper of the crank, slid on the flywheel and turned it in one direction a few turns. Then they cleaned off the compound and seated the flywheel with a dead blow hammer and piece of pipe, new woodruff key installed. I did not do that this time I just hope it holds for my long weekend at royal blue!! It would really suck to drive all the way there and have a dead machine. And we all know the 840 kits are a you know what to pull start!


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## NMKawierider (Apr 11, 2009)

shotgunred5050 said:


> I saw a you tube where someone put lapping compound on the taper of the crank, slid on the flywheel and turned it in one direction a few turns. Then they cleaned off the compound and seated the flywheel with a dead blow hammer and piece of pipe, new woodruff key installed. I did not do that this time I just hope it holds for my long weekend at royal blue!! It would really suck to drive all the way there and have a dead machine. And we all know the 840 kits are a you know what to pull start!


What exactly did you torque the retainer to?


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## NMKawierider (Apr 11, 2009)

Let me put this another way. The book calls for it to be torqued to 94ftlbs. If it wasn't, the result is.. well.. what you have now. And if it isn't right now, in it's condition, I would expect it to shear at any time. Even if it is torqued to spec, the damaged crank and rotor hub will cause it not to wedge as it should.


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## shotgunred5050 (Apr 4, 2017)

I torqued it past 80 because that's as far as my torque wrench goes. I will get a better torque wrench and be gathering gaskets and parts to fix it again. I really hope it holds until Sunday when I'm coming back from the trip. I just don't have time to tear into it again before the trip or I would start now. So would you try the lapping compound method and j b weld the slot?? Also its gonna be hard to get a file into that small of a slot to file it until the key fits tight in there. Any more advise?


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## NMKawierider (Apr 11, 2009)

shotgunred5050 said:


> I torqued it past 80 because that's as far as my torque wrench goes. I will get a better torque wrench and be gathering gaskets and parts to fix it again. I really hope it holds until Sunday when I'm coming back from the trip. I just don't have time to tear into it again before the trip or I would start now. So would you try the lapping compound method and j b weld the slot?? Also its gonna be hard to get a file into that small of a slot to file it until the key fits tight in there. Any more advise?


It's going to depend on how much material has already been warn off but personally I wouldn't do anything that took more material off. I would just over-torque it by about 5-7lbs and hope for the best. Otherwise its a new crank and rotor.


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## shotgunred5050 (Apr 4, 2017)

Made it two days on royal blue and the brute fired up every time. I did however lose a nut on right front upper control arm and it came loose and shot me into the ditch!?!?!?! now its brand new lock nuts all the way around. Anyway back to the key way, I really do not want to rebuild this motor again I am looking for the best jb weld/quick fix on the slot for the key way. I plan on just running it until it breaks I guess its only a matter of time. Just wondering if anyone on here has been through this before or may know of a good way to fix it almost as good as new crankshaft good.


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