Thread: Cut new key in crank. brisbane southside.

One short fusion tack on the side that has been rolled would do it. Its just a locator. Agree though the tig can get a little hot so definitely no long beads or anything.

Originally Posted by bee utey

Glue the key into the crank with liquid metal, clean it up when set then fit pulley etc and tighten it up properly. The key is for accurate location, not for drive forces.

Had a very similar problem with a 302 Windsor.........but it was the cam timing way out and it wouldn't start.

This happened at a garage, where it used to get serviced, after I filled it with petrol.

Left it there for the boys to figure out, which they did. The solution was a new key glued into the crank slot.

No probs for many, many kms after that. Then I sold it. (dumb **** !)

DL

Originally Posted by 350RRC

Had a very similar problem with a 302 Windsor.........but it was the cam timing way out and it wouldn't start.

This happened at a garage, where it used to get serviced, after I filled it with petrol.

Left it there for the boys to figure out, which they did. The solution was a new key glued into the crank slot.

No probs for many, many kms after that. Then I sold it. (dumb **** !)

DL

Aah yes, Ford engines with a suspicious bottom end knock in them. If you caught them in time all you needed was a crank bolt and washer out of a later engine to stop the key from fretting further. Must have retro fitted a couple of dozen crank pulley bolts back in the day. Beats me how Ford thought it was a good idea to just bash the pulley on to hold the timing gear in place.

The crank woodruff keyway is flogged a bit probably, I would avoid putting any localised heat source on the crank, (TIG etc). IMV that would be providing a stress raiser for a crack to propagate from.

SS304 AND ss316 are similar strengths to keysteel, (about 500 mpa ), and easy to find. (bearing service will sell keysteel)

You could hand file and shape a new key to fit the crank and fit it with bearing blue to make a nice fit, ( tap it in with a small hammer or spanner).
then file it to suit the balance pulley, it a common engineering repair,, "stepped key".
If you don't make a good job of it a little plastic steel or devcon will help. I would "blue" the pulley and crank as well to make sure they have good contact area.

cheers simmo

Since starting down the path of hobby machining, the idea of welding, brazing, quik-metal etc for this kind of repair just dismays me. It really is such a simple machining task to do the job properly. Anyone with a milling machine of a suitable size would be able to perform this task.

Originally Posted by POD

Since starting down the path of hobby machining, the idea of welding, brazing, quik-metal etc for this kind of repair just dismays me. It really is such a simple machining task to do the job properly. Anyone with a milling machine of a suitable size would be able to perform this task.

Agree, repair properly.

Originally Posted by POD

Since starting down the path of hobby machining, the idea of welding, brazing, quik-metal etc for this kind of repair just dismays me. It really is such a simple machining task to do the job properly. Anyone with a milling machine of a suitable size would be able to perform this task.

Wouldnt the correct way be to fill the old keyway, machine it and then recut another keyway entirely?
If so that would involve welding and certainly would not be a simple task. Crank removal and what not.

To just cut a bigger keyway is not the proper way either as that could have the potential to unbalance your crank.

Certainly any machining assumes the crank is removed from the engine.
I think I would approach the job by cutting in the original location with a larger size woodruff cutter and using a larger key, then either slotting the pulley keyway to suit or machining a step in the woodruff key. Not sure that balance is an issue as the space left by any material removed in cutting the keyway is then occupied by the key. I guess there's a void in the female part at either end of the key, which would be slightly wider. I don't have any direct knowledge of balancing cranks but I wouldn't think that such a small change in mass at a point so close to the rotational axis would affect balance enough to be a concern.
I've done lots of dodgy backyard repairs myself over the years, but since the machining caper has been de-mystified for me it is all so much simpler to do it right.