Timing Gear Woodruff Key Free Play

[Missionguzzi]

I'm rebuilding a 1972 V7 Sport (with timing gears) which has serious noises coming from the front/top.  After removing the complete top end and timing cover to seek the culprit, I noticed that the crankshaft gear had a lot of play in both directions, clockwise and counterclockwise, which I could move by hand, and which made a loud clanking or tapping into the camshaft gear.  I then removed all the gears and found the crankshaft woodruff key on the bottom front of the timing case, but uncertain if it was never installed properly, or whether it fell out when I took the gear off the shaft.  I reinstalled the woodruff key and the crank and cam gears, and still notice a little movement in both directions, but not as much as before.  I did NOT tighten the gears, just slipped them on over their respective shafts.  My question is whether there should be ANY play in the woodruff gear fitting, or should it be quite tight, allowing no movement of the gear on the crankshaft.  The woodruff key fits a bit loose in both the crankshaft and the timing gear slot, that it, I can easily insert it and remove by hand, and it seems on previous jobs, the woodruff key was quite tight, needing pliers to remove from the crankshaft.  Any tips or observations will be welcome.  Thanks.

[moto]

I wonder if it is the correct woodruff key. It could be an inch measurement key substituted by a previous owner who thought it would be close enough. I would measure the width with a caliper, and also look for the spec.

[Alfetta]

hard to believe that a woodruff key could "fall out".  typically they are trapped once in the assembled state. However you are working with an Italian machine...   so there is that...

[Old Jock]

I don't know about the Woodruff key on the V7 but are the torque loads on the shafts and transmitted to the gears not generally held by a taper?

I had to replace Woodruff keys on a HiCam, loose after checking at reinstallation.

I'm not saying what I did was correct but I measured the shafts and gears cutouts where the key would sit then purchased the nearest oversize keys I could find. As I recall purchased from a bearing supplier and they were cheap as chips, so I purchased quite few to try. Then I just ground them down as required, must have worked as they haven't dropped out (yet anyway)

As I recall removing keys from a few Guzzis on stripping down the Gear to shaft fit was a sliding fit, so the gear could slide off the shaft (once the taper had been broken) but there was very little play if any. The woodruff key as it was installed into the shaft was pretty tight, requiring a punch and hammer to slide it out from the half circle cutout on the shaft

[John A]

It needs to be tight, snug anyway
If a new key doesn’t tighten it, I’d make a custom key.

[Missionguzzi]

Thanks for all the input.  I also have always found woodruff keys to be snug in the keyway, usually requiring pliers or drifting them out.  I measured the existing key, and it doesn't correspond to any standard metric key sizes (but Guzzi may not have used a standard key).  The width of the keyway is right at 3mm, and the key is about 2.98mm; pretty close, but it is also worn and uneven across the sides.  Also, the height of the "arc" is 5.54mm and the length is 16.23mm, none of which are standard metric sizes.  I suspect this was a replacement key someone rigged up.  I'm ordering a new key (fortunately still available, P/N 91702355) and I hope that is correct and provides a tight fit.

[John Croucher]

I lost my woodruff key.  Found a package of woodruff keys at Harbor Freight.  Put the bike back to gether and then found the lost key.  Harbor Freight has a multi pack of keys of various sizes.  I have enough keys to last for the rest of my life. 

[MattP]

The key should be tite how ever the key just times every thing the nut holds the gears tite so it cant work back forth ect.

[Moparnut72]

The key should be tite how ever the key just times every thing the nut holds the gears tite so it cant work back forth ect.

Yes, that is the way it works at least as far as I have seen.
kk

[moto-uno]

  Oh this should be fun, 3 1/2 months ago I paid (in advance) for the same key on the 1100cc Jackal motor I have in my Peterbuilt and it still hasn't arrived and they have
yet to even suggest an arrival time ! Kinda pathetic  . But I jury rigged another one and it's fine, at least it made the 2000km round trip to the national in Oregon.

[Canuck750]

The woodruff key is most likely metric and someone lost the original and tried using a SAE key.
I recently needed a replacement key for a Benelli project, after measuring the shaft it was apparent that no std SAE key would fit properly and being only 2mm wide I wasn’t keen on filing a SAE key to fit.
I ended up purchasing various metric woodruff keys on EBay, supplied from China, it took about two weeks for them to arrive, minimum order was 50 each for under $10 per size.
Like SAE woodruff keys, the metric keys come in standard sizes, typically described as the width and overall height in millimeters.

[Missionguzzi]

Received the new, correct Woodruff key from my parts dealer in Wisconsin, and it fits perfectly.  Upon reassembly of the timing gears, there is no slop whatsoever and they all turn like clockwork.  Just goes to show that the smallest, cheapest item can cause catastrophic harm if it's not right.