Let's brainstorm.

[Turbo Ghost]

When you tried the heat/duster trick, you needed to cool the shaft not the gear. The gear needs to be hotter than the shaft so it's bigger. You might also try (if there is room) heating it then striking it with a hammer back towards the motor to shock it loose. You could also take a dremel and cut a slice down one side then split it with a chisel and hammer. Good luck!

[Triple]

Originally Posted by askmrjesus

If you can't fit a puller in there, grind the arms down until they fit.

Others have tried this, and the puller generally bends/breaks before the cog moves. This is a fairly common problem with these cars; it's the result of a botched crank-nose repair. Liquid metal used to fill a worn key-way bonds the cog to the crank if it's installed before everything cures.

Originally Posted by 101lifts2

I cannot really see from the picture, but are there 4 threaded holes in that sprocket?

I believe older Miatas had threaded holes in their crank gears for this very purpose. Mine does not. I only found one hole and it wasn't threaded; I think someone else may have drilled it in an attempt similar to mine.

Originally Posted by Turbo Ghost

When you tried the heat/duster trick, you needed to cool the shaft not the gear. The gear needs to be hotter than the shaft so it's bigger. You might also try (if there is room) heating it then striking it with a hammer back towards the motor to shock it loose. You could also take a dremel and cut a slice down one side then split it with a chisel and hammer. Good luck!

I tried most of what you posted.

I ordered a 4-inch angle grinder with some cutting wheels. Here's hoping I don't damage the crank in the process of cutting the gear...

[Turbo Ghost]

Had I been awake longer when I read your post, I would have retained the facts you had already mentioned instead of repeating them!
As for heat, propane is a no go usually. You really need oxy/acetylene to be able to heat the gear very quickly while not heating the shaft it's on. I had the same problem with a radius arm nut on my bronco. Not even a 3/4" impact would budge it. I torched it with my mapp torch and got it nice and orange but, it wouldn't budge with the impact while hot! Hit it with the oxy/acy and it came right off!
Do you know anyone with a plasma cutter? You could cut half of it off while leaving just enought to protect the shaft yet, thin enough to break loose.
If you use the grinder, I would recommend putting something like a sleeve or nut or even duct tape wrapped thickly around the protruding part of the shaft to protect it in the event you slip and hit it.
Be careful, wear eye protection and good luck!

[Rangerscott]

Ideas coming off my noggin. Bare with me cause I see how rusty things are so I'm just gonna throw ideas out there.

1. Unbolt the oil pump, crack it off, now you have room to fit puller. Yup you'll need a new oil pump.

2. If you have steady hands you can torch a good line through that without going into the crank. I did this with getting the wedding ring off my rear axles that holds the bearings on.

3. Drop the crank shaft and take it to a machine shop so they can take it off.

4. Buy another crank shaft. Preferably one that doesn't have a cog rusted onto it. LOL

[Particle Man]

It's a Miata - doesn't the engine weigh like 20 lbs? Pick it up and drop it on the concrete

['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.

[derf]

Damn, well, it did do the job

[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.