crankshaft woodruff key

[nachoman]

While changing out my timing chain over the weekend, I noticed the timing chain sprocket had been working on the woodruff key, to the point it had worn halfway through the key, and halfway through the sprocket. This was allowing the sprocket to rotate on the crankshaft a few degrees.

So, it looks like I need a new woodruff key. But where do I get one? Would napa carry this part? When I called napa, the guy couldn't seem to go back that far in his computer...

Thanks,
Kevin

 

[CoupeBoy]

If you've got it out go to NAPA or an older 'real' parts store and they will have a selection of keys for you to compare it against. Locally I have a store called Mac's that I bought a selection of keys from for $12 and they have been invaluable for keeping things rotating.

You may also want to take your crank timing gear to ensure you get a proper thickness since yours has been worn down a little bit. The part that engages into the crank should still be it's original thickness, so you should be able to compare the 2 ends.

-ron

 

[cobraguy]

This will happen when the harmonic balancer isn't pressing the crank gear tight against the step on the crank. Make sure you keep it clean. Crud getting between parts is a common cause. The bolt will taghten up then the crud washes out leaving the gear unpressed. this put the driving tension of the whole valve on that little woodruff key. Don't ask how I know or how expensive it gets when that key lets go at high RPM in a nonclearence motor.

 

[nachoman]

Interesting. There is some kind of stamped sheetmetal "oil slinger" between the harmonic balancer and the timing gear sprocket. It doesn't seem to fit right, and I was thinking of trying to re-assemble without that item, now I realize it may need to be in there to provide the proper spacing for things.

 

[CoupeBoy]

You definately need the slinger, otherwise the chain may not get oiled correctly.

-ron

 

[64falconsix]

try your local machine shop for the woodruff key , i bought one a couple of months ago for $1.75

 

[nachoman]

Well, napa didn't have one .

Looking at the thing, the key looks like a boat hull - like a large diameter woodruff key, but flat on the bottom. The crankshaft has a semicircular keyway and is not flat on the bottom. Do I have the wrong key? I am assuming one from a small block v8 won't fit.

My options now - try harder to find one. Or, I could weld up the notch that has worn into the old one, and file it back to shape. then I could re-install it the opposite way that it was. It looks like it is made from a mild steel. I'd rather find a new one, though, because failure would be a disaster!

Kevin

 

[nachoman]

I think cobraguy nailed it. There was some gunk on the oil slinger and the back of the balancer that indicated things werent tight enough, and that allowed the sprocket to work on the woodruff key. Looking at the design, the key really is only there to allign things, and if the crank bolt is tight enough, the taper on the back of the sprocket should wedge onto the tapered shoulder on the crankshaft, and nothing should spin. I managed to weld up the worn spot on the key and file it to shape, and now things seem to fit together well enough that I think I will try it. I just gotta be sure that crank bolt gets tightened to 85-100 ft-lbs!

Kevin

 

[nachoman]

Thanks to everyone's help. I got the car back together last night, and now I estimate 20% more power and a smoother idle. A few lessons learned:

1) always use a harmonic balancer installer tool to install the balancer. If you just use the crank bolt, it will eventually ruin/strip the first few threads in the crank. I ruined the first few threads, but luckily there were still enough threads to torque the crank bolt to 90 ft-lbs.

2) Installing a new timing chain is easy and inexpensive if you already have the timing cover off

3) I question whether those "harmonic balancer repair sleeves" do much good. my sleeve had a groove worn in it after only about 35,000 miles.

4) The crank bolt does more than just keep the balancer from flying off. Torquing it to 85-100 ft-lbs is crucial to keep the timing sprocket from wearing on the woodruff key. I did not realize this in the past, and had only been tightening the bolt to as tight as I could get it with a 3/8 inch ratchet handle. That's probably why the woodruff key had gotten so worn. The difference between 50 and 90 ft-lbs was about 1 full turn on the bolt!!

Thanks again for everyone's help!

Kevin

 

[hasa68mustang]

Just a fyi advance autoparts sells an assortment of those keys in their "help" section. I have no idea if they have the correct size though.