Hot Rod Forum banner

Crankshaft Keyway Stripped

10K views 24 replies 6 participants last post by  4 Jaw Chuck 
#1 ·
So, long story short, I got in a fight with a telephone pole, lost (totaled my car), but the engine is salvageable. I have a forged eagle crank in a 383 sbc, and when I went to take off the damaged crank pulley, I noticed the balancer was loose. Not good. The balancer, when it was loose, came right off, along with the keyway portion of the crank (the little part that the balancer slips on). What are my options? Can a new one be welded on? Are there balancers specially made for this? Please tell me I'm not down a crank, as everything else is just fine, although it wouldn't be *that* bad since I'm taking the engine out anyways, it would just mean more $$$$$$.

Thanks for any input.
 
#3 ·
carsavvycook said:
It sounds to me like the snout of the crankshaft is "broken" off?

If so; The crankshaft is junk.

Dang telephone poles anyway :thumbup:
No, not the snout, but the little keyway that the balancer slides onto, that is located on the snout, so you know the balancer timing marks in relation to crankshaft movement is spot on.

Me - 1, Telephone - 0.

It put me in the hospital for 10 days, but I want to get back in it more than ever. It just hurts way too much to look at my car, and what was.
 
#5 ·
eloc431962 said:
your saying you sheared the key way off .and you did this in the accident so what hit the crank to do this. cole
Yes, I sheared the keyway off. Nothing hit the crank, but the abrupt halt of everything moving inside did. As far as I know, that's all the damage to the engine itself, but it will be put on the stand shortly and gone through. I just want to know what my options are at this point.
 
#6 ·
when you get it in the stand just remove whats left of the key way.go to the parts store and get another one and tap it back into the slot in the crank where the old one came out of.they make several different sizes.so tak whats left with you when you go to get a new one. cole
 
#7 ·
eloc431962 said:
when you get it in the stand just remove whats left of the key way.go to the parts store and get another one and tap it back into the slot in the crank where the old one came out of.they make several different sizes.so tak whats left with you when you go to get a new one. cole
Cole, we may not be talking about the same thing. Let me post a picture to better explain. Maybe I am not understanding. Let me know.

 
#8 ·
mrdreex said:
No, not the snout, but the little keyway that the balancer slides onto, that is located on the snout, so you know the balancer timing marks in relation to crankshaft movement is spot on.

Me - 1, Telephone - 0.

It put me in the hospital for 10 days, but I want to get back in it more than ever. It just hurts way too much to look at my car, and what was.
The "key", or the "keyway"?

The "key" just taps into the "keyway" groove in the crankshaft snout. If the crankshaft snout groove is square cut on it's sides, not tapered in anyway, you may be able to reuse it.

Thank God you are OK :thumbup: The car can be replaced, you can't! :D

PS: Some pic's of the crankshaft would be nice!
 
#9 ·
If the balancer slid right off and did not require a puller to remove it, then you have another problem. The balancer has to be a press fit onto the crank, the key is there to align it and not to carry the load. If it slip fits and inspection and measurement show the balancer to be okay, then the crank is junk.
 
#11 ·
ericnova72 said:
If the balancer slid right off and did not require a puller to remove it, then you have another problem. The balancer has to be a press fit onto the crank, the key is there to align it and not to carry the load. If it slip fits and inspection and measurement show the balancer to be okay, then the crank is junk.
My balancer was somewhat distorted, so I think it came off due to that. It went on just fine, I don't think the impact would have altered the outer diameter of the snout any, could it?

I just took some pictures. You can see the balancer and how it stripped off the 'key' (I guess I used the wrong term, my fault) Some of it is still left in the crank, but I'm not sure if you can see it from the picture.

And, incase any of you were wonder, that's what a 70 Nova looks like when it meets telephone pole going 45. She was my heart and soul.

RIP.



 
#13 ·
eloc431962 said:
you are a very lucky man.looks to me like you are going to have to replace the balancer.when you do your tear down your gonna have the crank looked at anyway right.then they can tell you if its ok.let the machine shop tell you thats the best way to be sure. cole
Yes, the balancer will need to be replaced, but is that all that I need? The whole 'key' sheared off, and that's what the balancer 'grabbed' onto.

You say you can just replace that key? How so?

The engine still turns over, no binding or anything that is noticeable, but I just did a rough move of it. That's when I noticed the balancer was a little loose.
 
#14 ·
mrdreex said:
My balancer was somewhat distorted, so I think it came off due to that. It went on just fine, I don't think the impact would have altered the outer diameter of the snout any, could it?

I just took some pictures. You can see the balancer and how it stripped off the 'key' (I guess I used the wrong term, my fault) Some of it is still left in the crank, but I'm not sure if you can see it from the picture.

And, incase any of you were wonder, that's what a 70 Nova looks like when it meets telephone pole going 45. She was my heart and soul.

RIP.



In your last photo the balancer is broken at the groove cut for the key.
 
#16 ·
eloc431962 said:
you just tap whats left of the ole key.and take it with you and get another and tap it back into place.very simple proceedure or you can let the machjne shop do it after you let them check the crank out. cole
So, I tap what's left of the key (which is still on the crank) out/off, go to the store and get another one? Is the key a press fit in the crank snout or something? It looks as if it was machined that way from the factory. I guess I'm just not understanding how it's simple, as it looks like it would require some welding, and that is something I do not have. Thanks for all the help.
 
#17 ·
mrdreex said:
You say you can just replace that key? How so?
The key is simply a piece of steel bar stock that fits into grooves cut in both the balancer hub and the crank snout. Remove the broken pieces (there is probably "half" a key still in the groove in the crank snout) and replace with a new key. The balancer was loose because you cracked its hub. I'm willing to bet that whatever cracked the hub may have also bent the snout of the crank, so you had better get that checked.
 
#19 ·
joe_padavano said:
The key is simply a piece of steel bar stock that fits into grooves cut in both the balancer hub and the crank snout. Remove the broken pieces (there is probably "half" a key still in the groove in the crank snout) and replace with a new key. The balancer was loose because you cracked its hub. I'm willing to bet that whatever cracked the hub may have also bent the snout of the crank, so you had better get that checked.
Thanks joe. Could you tell me which key I may need, or is this something I will need to figure out?
 
#20 ·
Looks like the balancer took some impact, it looks split at the keyway, but the crank will be ok if a new balancer fits tight and passes a magnaflux test (mandatory). The remainder of the key will have to be dug out of the crank keyway with a small chisel and/or pick, and the keyway examined for stretch(mushroomed edge). I'd say you have about a 50/50 shot at the crank being save-able. Don't skip the magnaflux!
 
#22 ·
ericnova72 said:
Looks like the balancer took some impact, it looks split at the keyway, but the crank will be ok if a new balancer fits tight and passes a magnaflux test (mandatory). The remainder of the key will have to be dug out of the crank keyway with a small chisel and/or pick, and the keyway examined for stretch(mushroomed edge). I'd say you have about a 50/50 shot at the crank being save-able. Don't skip the magnaflux!
Thanks ericnova72, I was unaware that the key was replaceable. It wasn't obvious by just looking at it.
 
#25 ·
The crank needs to come out to be dialed out for straightness, its probably bent at the snout.

Don't take chances here, there may be damage inside the engine you can't see...for example the front cap may be bent/cracked/sheared the cap bolts etc. You need to carefully inspect everything including the bearings.

Sudden stops for an engine can even twist the crank, bend the rods, crack the pistons. Thats why "totals" like your car are usually sold for scrap. Not much can be salvaged and finding the bad parts can be more expensive than building new.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top