Let's brainstorm.

[Triple]

I need to remove the old timing belt cog from the nose of my Miata's crankshaft. After much soaking in much penetrating fluid, I have tried:

- Pry bars. The cog doesn't budge; rather, the lip around the inner edge of the cog breaks off.

- A puller. There isn't enough space between the block and the cog to fit the fingers of any puller I've ever seen.

- Drilling. The hardened metal laughed at my feeble Craftsman and broke the drill bit about 1/8" in. Then I discovered there was already a hole beside the one I was drilling. I tried hammering a nail (couldn't find my punch) into the hole, hoping the pressure would split the cog. Instead, I just made the nail impossible to remove.

- Cutting. Destroyed my Dremel trying to cut through the cog with the same wheels that have easily cut through chains in the past. Managed to dig a small trench with my reciprocating saw. I hammered a chisel into the cut in hopes of splitting the cog. No luck.

- Heat. I wanted to avoid this, but I eventually tried heating it with a propane torch. No movement. I let it cool and tried heating just the nail, hoping its expansion would split the cog. No dice.

I'm out of ideas. I can't put the car back together unless I replace this stupid fucking cog.

http://img.villagephotos.com/p/2005-11/1101556/cog-2.jpg

http://img.villagephotos.com/p/2005-11/1101556/cog-3.jpg

The healthy, patiently-waiting replacement:

http://img.villagephotos.com/p/2005-11/1101556/cog-1.jpg

[Amber Lamps]

It may be too late but I always spun hardened bolts in those "holes", they are normally threaded. Which pushes the gear out once the bolt contacts the metal behind the gear...:idk:

[Gas Man]

I'm still thinking puller. Most auto zones and such have a nice collection of pullers that you rent.

Or like tig says... but I don't see anything like that from your pics.

[azoomm]

Dry ice?

[pauldun170]

http://www.miata.net/garage/timingbelt.html
* 1990-'91: Remove the 21mm crankshaft bolt. This will be difficult. Put the car in 5th gear and engage the parking brake. Using a long breaker bar, crack the bolt loose.
* Remove the Woodruff key.
* Remove the timing belt pulley.
You may require a wheel puller to get this off.
* Remove the oil seal.
Be extremely careful not to score the crankshaft during the removal. This can cause leaks. The oil seal is a steel ring covered with plastic and rubber. The best way to remove it is to carefully cut the plastic and rubber and pry out the seal with a screwdriver. Be sure to put a piece of cloth between the screwdriver and the metal areas so you don't score anything. This takes a bit of work.
* Install the new seal
Coat the new seal with a bit of oil and press it firmly into place with your hands.
* Seat the seal
You need to drive the seal flush with the oil pump body. A large socket or pipe is good for this. I use a piece of pipe covered with tape to prevent damage to the seal. Drive the pipe against the seal with a hammer until it is seated flush.
* 1990-91: Replace the timing belt pulley.
* 1990-91: Install the Woodruff key.
* 1990-91: Tighten the crankshaft lockbolt to 80-87 foot-pounds.
* 1992 & later: Install the woodruff key and timing belt pulley.
* 1992 & later: You will need to install and remove the crankshaft bolt and pulley a couple of times, so install it, but do not torque it down.

http://forum.miata.net/vb/showthread.php?t=302020
http://forum.miata.net/vb/showthread.php?t=172497
http://forum.specmiata.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=44;t=002926;p=0

[TommyHotWheel]

Puller combined with heat and melt some parafin wax on to the shaft while its hot and then try to pull it off.

[Triple]

There isn't enough space between the cog and the block to fit a puller.

I tried heating the cog with the torch-- for about five minutes straight-- and then hitting it with an upside-down can of air duster, but it still wouldn't break.

[101lifts2]

I cannot really see from the picture, but are there 4 threaded holes in that sprocket? If so, then you use a puller in which all four bolts are threaded into the sprocket and are bolted to a plate some distance away from the sprocket. Then a center threaded bolt, which is threaded into the plate goes into the hole to push on the crankshaft. When this happens, the sprocket is drawn away from the crank. If there are indeed holes, you would have to make a special tool specifically designed to remove this thing.

[askmrjesus]

Managed to dig a small trench with my reciprocating saw. I hammered a chisel into the cut in hopes of splitting the cog. No luck.


:lol:

Dude, step away from the Miata before you hurt yourself.

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

JC

[Phenix_Rider]

I cannot really see from the picture, but are there 4 threaded holes in that sprocket? If so, then you use a puller in which all four bolts are threaded into the sprocket and are bolted to a plate some distance away from the sprocket. Then a center threaded bolt, which is threaded into the plate goes into the hole to push on the crankshaft. When this happens, the sprocket is drawn away from the crank. If there are indeed holes, you would have to make a special tool specifically designed to remove this thing.

Look at the new one- there are no holes.

But I like your idea. Take a 1/4" steel plate, four grade 8 bolts and the original center bolt (or a longer one the same pitch), and a handful of nuts and washers. Drill five holes in one 6" square piece of plate for the outer section of the puller, and make two strips with end holes to go behind the cog. If you can't get behind the cog, get a REAL 3/8" cutting wheel and cut slots in the sucker. Dremels are fine for little stuff, but real work needs full size tools.

[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]

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.

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.

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 :D

['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!!

http://www.harborfreight.com/media/catalog/product/cache/1/image/370x/9df78eab33525d08d6e5fb8d27136e95/i/m/image_6370.jpg

FATALITY

http://img.villagephotos.com/p/2005-11/1101556/cog-a.jpg

ANGLE GRINDER WINS

http://img.villagephotos.com/p/2005-11/1101556/cog-b.jpg

[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]

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]

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]

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.

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.

[azoomm]

Yeah, Loctite 660 doesn't fuck around. They now sponsor Racing for our Heros - they did a demo of that stuff for us. Incredible.

[pauldun170]

http://www.miata.net/garage/hsue/LoctiteCrank1.html

[101lifts2]

Looks like you fucked up the front cover housing. Better hope that crank seal doesn't leak.

[Triple]

Let's brainstorm, again.

I finally got the car running last weekend. It stuttered a bit as it choked down the last bit of old gas sitting in the lines (I drained the tank, installed a new fuel filter, and re-filled with fresh, ZERO-ETHANOL fuel), but it now idles smoothly and responds normally to throttle inputs.

One problem: use of the power windows, headlights, wipers, etc causes the engine to stumble. This was an issue before I parked the car two years ago, too, only then it would cause the alternator belt to scream as well. I've since installed a new alternator (had it tested before I left the store) and new belts. No more screeching, but it still makes the engine stumble.

Why?

[goof2]

Let's brainstorm, again.

I finally got the car running last weekend. It stuttered a bit as it choked down the last bit of old gas sitting in the lines (I drained the tank, installed a new fuel filter, and re-filled with fresh, ZERO-ETHANOL fuel), but it now idles smoothly and responds normally to throttle inputs.

One problem: use of the power windows, headlights, wipers, etc causes the engine to stumble. This was an issue before I parked the car two years ago, too, only then it would cause the alternator belt to scream as well. I've since installed a new alternator (had it tested before I left the store) and new belts. No more screeching, but it still makes the engine stumble.

Why?

Have you checked your grounds?

[TommyHotWheel]

Ground, make sure you have a good one.