Let's brainstorm.

['73 H1 Triple]

Your first problem is the rust on the crankshaft nose. Start with a wire brush and remove as much as possible. The put a piece of emery cloth ( 220 grit or finer ) on a flat file and while following the contour, remove the rust. ( the file is to keep the emery cloth flat and the square endge of the file will allow you to get close to the pulley ).

Since you ordered a 4-1/2" grinder with cutoff wheels, first safety tips. Eye and ear protection. The sparks are hot and will burn into your eyes.

Put the side handle on the grinder. If you can use the wheel guard, keep it in place. Use full leather gloves while grinding ( cloth back gloves will catch on fire --been there, done that ). A leather welding apron would be a plus too, other wise a couple of heavy shirts you don't mind burning up from sparks ( in case of grinder kick back ). If possible, try to hold the grinder in both hands with your elbows against your body. You want to make a precision cut, not hack the shit out of it.


Looking at the picture, here's the way I'd do it. Rotate the engine until the keyway is up at 12:00. Put a couple wraps of duct tape on the front of the crankshaft nose.

Very lightly and as accurately as you can, lightly score a line across from 10:00 to 2:00 getting as close to the crank as possible without touching the duct tape. Since you are going lightly, adjust the "line" up or down. You want to cut across the keyway. This will allow to get closer to the crankshaft with less chance of actually grinding it.


If you like your line, press a little harder and go back and forth a few times. KEEP CHECKING YOUR WORK.

If you see smoke coming off the duct tape, stop for bit to let it cool down. If you smoke the tape too much, that means you are transfering heat into the crankshaft and will be altering the temper ( making it softer and easier to bendand or wear )

If all goes well, you will sever the gear and the exposed keyway will give enough room to get the rest of it off the crankshaft.

Good luck

Jeff

[Triple]

FINISH HIM!!



FATALITY



ANGLE GRINDER WINS

[G-Rex]

That keyway looks pretty worn *and* twisted. Maybe it's just the photo..

Glad the grinder did the trick.

[Triple]

Originally Posted by G-Rex

That keyway looks pretty worn *and* twisted. Maybe it's just the photo...

Not the photo. It's fucked up.

But that's the problem with these cars. The keyway deforms, the key breaks, the timing is thrown off, and the crank pulley begins to wobble. That's why I had to remove the old crank cog in the first place: to access the keyway and repair it with Loctite 660 liquid metal.

Which I expected to harden like actual metal, but after 24 hours has still failed to cure. It's as gooey today as it was yesterday when I squeezed it out of the tube. According to thousands of other worn-crank Miata owners, this stuff fills all the extra space in the slot, keeping the key in place once the cog is torqued to the crank nose.

Right.

Also notice the broken bits of the lip around the crank seal. That's finesse, bitches.

Actually it's from a big fucking hammer.

[G-Rex]

Well, I wish you luck.

I'm not one to trust liquid metal, JB Weld, etc. on things like cranks. I'd be dropping the oil pan to swap in another crank, but that's just me.

Hopefully everything works good when you get it all put back together. Otherwise, you'll be going through most of this work again.

[pauldun170]

Originally Posted by G-Rex

Well, I wish you luck.

I'm not one to trust liquid metal, JB Weld, etc. on things like cranks. I'd be dropping the oil pan to swap in another crank, but that's just me.

Hopefully everything works good when you get it all put back together. Otherwise, you'll be going through most of this work again.

that

[derf]

If you are intent on saving the crank you could try to weld it and have the keyway machined out again, but even that would probably either deform the crank, weaken it or both, and you would have to remove it from the block or destroy the seals. Either way you really need to repair it correctly. The liquid metal or JB weld will last a few miles, but either way it will start to wear pretty fast pretty soon

[Triple]

Originally Posted by G-Rex

I'm not one to trust liquid metal, JB Weld, etc. on things like cranks. I'd be dropping the oil pan to swap in another crank, but that's just me.

This stuff isn't like cheap Walmart JB Weld. It's expensive, hard to find, and many Miata owners have used it with much success. I don't understand why it won't harden, however.

You aren't really relying on the liquid metal; for the most part, it's just there to keep things in place during reassembly. They key is keeping the whole assembly properly torqued down. Neglecting that allows the crank bolt to back out and the cog/pulley to shift on the crank nose.

Originally Posted by G-Rex

Hopefully everything works good when you get it all put back together. Otherwise, you'll be going through most of this work again.

The hell I will. If this doesn't work, I'll either sell it as a non-running roller or replace the engine with a warrantied, remanufactured unit. Dropping/replacing the crank can cost as much as replacing the entire long block.

[derf]

Damn, well, it did do the job