Crank/Keyway problem. Please help

[AE86BLISS]

I seem to have ran into a problem.
I remember reading about some one on here using JBweld and placing the new key in place over night and it being fixed but I can not find the thread that it was posted in.

Here is a pic of my Crank's Keyway slot. :yikes:

 

[jetjock]

Don't do that. A recent issue of Machinist's Magazine detailed this exact repair. It was even a Toyota. The repair involved welding (something others have done) by fabricating a carbon key, adding filler metal, and finishing to fit. The results were excellent.

 

[AE86BLISS]

Is there a link or way I can get more info and or a how to of this repair.

 

[hvyman]

How did this happen?

Do you have access to a welder?

 

[CyFi6]

Don't do that. A recent issue of Machinist's Magazine detailed this exact repair. It was even a Toyota. The repair involved welding (something others have done) by fabricating a carbon key, adding filler metal, and finishing to fit. The results were excellent.

But can this be done in situ? And if not, is it really worth the money/effort/risk considering how available our cranks still are?

 

[jetjock]

I'll try and find my copy but since it's been a while I can't make any promises. The process is what was stated though. Fabricate carbon key, filler added, finish to fit, replace key with new, install dampener

But can this be done in situ? And if not, is it really worth the money/effort/risk considering how available our cranks still are?

Well, they did it and as an weldor myself I don't see any real obstacles. The snout has a fair amount of mass and even then the area behind the key it can be kept cool if needed. Not a lot of welding is involved. Iirc mig was used.

Whether it's worth it only the OP can decide. I was simply pointing out the option because I'd actually come across it in a publication. Best be isolating the car's electrical system though...

 

[Supracentral]

We did this repair on Will Neely's 730 RWHP 7M many years ago. He dropped the motor in at his house and didn't have access to the 1" drive impact guns we use to get that insane torque spec. He used a breaker bar, but it wasn't enough. It worked its way loose and chewed the hell out of the keyway. We filled the slot using a TIG welder, then reground a new slot into it and put a new Toyota key in it, and then torqued it to 195 ft/lb. He never had a problem with it. Then he sold the car years later to a kid up in NC who blew it up, but that keyway repair was never a problem. It's a sound repair if done properly.

And yes, we did it 100% in the car, no problem, the crank has enough mass.

 

[RazoE]

My 7M had this on my 86.5 when i got it, just welded in new material and did the same...

 

[jetjock]

There ya have it. In the article they used the carbon key to fill what was still serviceable of the way and keep the shape while they welded around it but there's no reason the other approach couldn't be used. May even have to be done if things are badly chewed up.

 

[mkiiichip]

Once the hole is filled, what do you use to make the new notch? The only thing I can picture being maneuverable enough, is something like a dremel, and I dont see that going well.

 

[hvyman]

I would just fill the corner up and then grind it smooth. THere is enough room for a mig/tig you could easily get a die grinder/cutoff wheel with a carbide bit or something.

 

[zby67]

damn i never thought of welding it so i bought a new crank.... would of saved me some money lol. couldnt he put the key way in and fill around it making the key way stuck in the crank but still works?

 

[Crypton2006]

I did that on a subaru. Has been over a year now with no problems.

Sent from my SCH-I800 using Tapatalk

 

[CyFi6]

Make sure you mic the snout though, if it wobbled enough to make the end of the snout of the crank smaller than original just repairing the keyway isn't going to do it. I had a crank here that had the same issue (though looked a lot worse) and the area where the damper sits was .050" smaller than the rest of the snout just because it had been beat so hard. Also, the threads inside the crank were so damaged that the bolt would wiggle inside of them. When I put the same bolt in a good crank it was nice and tight so the actual threads in the crank were damaged rather than the bolt being damaged.

 

[suprarich]

That was me that posted about using a faux carbon key and welding the snout years ago. Not real hard to do, but i always wanted the crank out of the motor and would clean the snout up on the crank grinder. One 7m crank I did that to is now at 1200 hp with no problems.

 

[GrimJack]

There is a special tool to cut a new keyway... I'll be damned if I can remember what it's called, a friend of mine (millwright) told me about it years ago. Decent machinist probably knows what it is, though.

 

[AE86BLISS]

As soon as photobucket.com is back up I have a few more pic's I noticed the crank/timming pulley (not ballancer) has a grove in the middle from the wood ruff/Keyway and the key/ruff that is in the crank looks smashed. I can't seem to get it out of the crank. Looking for a good idea how to remove this as well if any one has an idea or trick that would really help me out. If you look really hard you might be able to see it in the pic.

 

[IJ.]

There is a special tool to cut a new keyway... I'll be damned if I can remember what it's called, a friend of mine (millwright) told me about it years ago. Decent machinist probably knows what it is, though.

Keyway Cutter

 

[AE86BLISS]

How did this happen?

Do you have access to a welder?

I have no real idea how this happened. Only thing I can come up with is the owner before me may have caused this by hitting the crankshaft bolt with an impact gun too much. My friend had to come over with a braker bar that was twice as long as I am tall and with him on the end (300lbs+) he's a big guy. He broke 2 braker bars in the process. This is also with using the ballancer pulley tool to hold it in place. I'm happy I didn't use the starter to brake the bolt loose, may have cause more problems if I would have done so.

Also I have no access to a welder.......

---------- Post added at 01:46 AM ---------- Previous post was at 01:39 AM ----------

Tell me what you think.
Thanks.

 

[GrimJack]

Keyway Cutter

I'd have remembered something with a name that easy. Doesn't look quite the same, either, from the description this wasn't a rotary tool... is there a reciprocating version of the same thing?

Not that it really matters, as long as it'll cut a new keyway.