I'm in the middle of replacing some damaged gears at the front of the engine, and I got stuck:
The camshaft can spin a few degrees upon removing the bolt holding the camshaft gear on the camshaft. It shouldn't because that's why there is the woodruf key. Both the slit in the camshaft and in the camshaft gear are partially worn out, and using a new woodruf gear didn't fix the problem.
I'm warrying that the camshaft may spin even after tightening the bolt, and I won't really know about it immediately.
What can I do? And is this a serious problem? It spins only a little.
Can I try putting in a metal layer to make things tighter?, e.g. cut from a can?
I'm looking for an economy solution...

And why did it happen? Could be because of the problems that happened when the balance gear on the crank shaft got dameged, and the timing gear on the crankshaft got loose, see my thread:
"Can I run the engine without the balance belt?"
Or maybe when the bolt holding the cam gear got loose a year ago?

Anybody had similar problems?

 

Make sure you buy the woodruff key from the dealer ONLY! An auto parts store/hardware store key is a little smaller.... Ask me how I know....

 

I did buy it from a dealer, but the problem is not the key. Ideally, both the camshaft and the cam gear should be replaced, but that's not feasible for me.
Anybody has a solution?

 

Buy some shim stock from a good autoparts store.

 

This seems very similar to the crankshaft failure problems that occur in early (and my) Miatas. Basically, the crankshaft bolt fatigues and doesn't clamp down as hard. It is the friction that keeps the pully and shaft turning and not the woodruff key (the key is in there only for alignment). When the friction is lessened, the force of turning everything gets transferred to the key and keyway, wearing it out.

There is a Locktite fix the people have had luck with on the Miata's crank pully. If it's stong enough for that, it should work on the camshaft. Check the fix link and you should be able to modify it for your fix.

BB.

 

I acknowledge this, but am very surprised. I thought the key was meant to fix the gear on the cam, and the bolt was only meant to keep things together.

My case is similar to the one described for Miata, but it's more like the edges of the slits are worn out, not the "faces". Right now, I lean towards thinking that this problem happened when the bolt got loose a long time ago, but I never noticed negative consequences after replacing the allen bolt with a 12-point bolt for the cam.

 

OK

 

This will be a challenge but I've make keyways work for a long time with shimming. Not a desired fix but better than nothing. I've also seen "special" keys that are over size. Also seen keys that are offset to change timings.

Best you get a replacement cam gear if not another cam to match it. If you do look for another cam get one from an 86 or later. Has a bit longer opening on the exhaust side. A few more horses.

 

I'll try making shims. The challenge is to make sure the shims are tight fit, so that they don't fall out. Considering that the key is only for alignment, there shouldn't be too high forces acting on it after tightening, as a proper torquing of the cam bolts seems to be an issue.
I'm going to stay away from permanent glueing as it would be impossible to take the key out in the future.
I also thought about making a custom-fit woodruf key using an angle grinder, but this would be many hours of work, and probably several attempts to do it right. I probably won't do it now, but I wonder what kind/grade of steel should be used for this purpose?

 

I think careful shimming is the best option. Good luck. You may want to price out a used cam shaft and sprocket. Check with George B. at 944 Ecology.

 

There are considerable forces on the cam pulley. Just try to turn one by hand with the timing belt off.

If you can find a decent machine shop they might be able to broach the cam pulley to a larger size and cut the cam too. A good automotive store should have the hardened woodruff keys to match. Still you may be able to buy a cam and pulley used for the same money.

 

I had the same problem with my car. The previous owner or a bad mechanic must have been doing the belts, saw it was loose ane rammed a flat-head screwdriver in then broke it off in there. Needless to say it need replacing, that INCLUDED the upper balance shaft!!! I wouldn't reccomend putting it in loose because with the scewdriver in, it got loose again, and tore the hell out of my balance shaft belt. I was luck it didn't take out the timing!!! IF you go to a dealership, over $$1100 but i went to a salvage yard, forty five dollars, in immaculate condition, came with the gear and key as wel. ANd if you run it without the baklance shafts, well DON"T do that first off, and it would vibrate the living daylights out of the car. Just go to a salvage yard and pick up the balance shaft, if you can get the key and gear new.

 

I put some shims. Because the slit in the camgear is not regular, I didn't manage to make it fit perfectly: about 1.3 deg total play. I hope it's good enough for timing, and I hope friction from the bolt holds the cam gear strong on the camshaft.
Anyway, I finished, and the belts track OK now (didn't before), and there are no strange noises either (there were before). I drove the car for almost 100 km yesterday and today. So far so good. We'll see.
If I ever need to redo it, I would put a new cam gear, and a custom fit woodruf key.

 

Be careful, for my sake... I had a valve job because of a loose woodruff key (that's my best guess why). When I opened everything up to look at the situation, I found the cutout in the camshaft was damaged and that there was free rotation. Overtime, the key must have worked itself out enough to fail under unusual load, in turn screwing the timing enough from four valves to need replacing.
It didn't seem to me that the car slowly progressed in sounds or vibrations either, it just failed one day, while cruising along at a reasonable pace.
I got a camshaft from a 924S, it was pretty cheap - you might look into that. Replacing the camshaft is a chore, but better than a valve job...

 

well, I hope it works better for me. But eventually I might do a better job as you suggest.