Keyway repair

[Chriss750]

Hi all. Can anyone recommend a repairer for a damaged crankshaft keyway. Cause I think running with a loose rotor.
Thanks Chris

[iansoady]

There was a discussion on the C10/11 forum about using jbweld in a similar situation. I know not an "engineering" solution but some found it to work. Personaly I've used JB weld with success for damaged castings and the like.

The rotr is held in place more by the tightness of the nut (as you've discovered) than by the key itself.

[V500]

Not just the "tightness" of the nut, but the well-fitting taper as well.
Often a custom-filed up key plus a gentle lapping with fine grinding paste will do the job.

[JulianS]

There are various hi spec Loctite industrial strength retaining compounds which might assist, could be worth researching.

[limeyrob]

As above, lap it, clean the  threads and tighten with Loctite and it should be OK.  What makes you think its a loose rotor?  It is (as said above), possible to file up a slightly wider key and that is a good fix since it leaves the crankshaft alone.

[V500]

I would be unhappy to use any compounds on the taper (not the nut), a) because at some point it'll need to come off again, and b) the strength of the "taper grip" will be compromised by anything which sits between the taper faces.

[DAVE BRADY]

Hi,

Crankshaft is parallel rather than tapered. With a bit of work with a file an over wide key can be fettled to fit the worn shaft and the rotor. The key should be protrude enough so that the rotor needs to be tapped on rather than a sliding fit and if the rotor has been loose for while it may not be the tight fit it needs to be so use some bearing retainer and then make sure the nut is tightened to 60lb/ft with a torque wrench.

Dave.

[DMadigan]

The keyway is for the timing alignment. The nut keeps it from moving. Clean the key slot and key with brake cleaner. JB weld or Loctite Quickmetal in the gap of the keyway and spray the bore of the rotor with dry lube, then assemble. The dry lube will keep the rotor from sticking. You might need some heat to remove the key later.
Check the rotor timing mark against a degree wheel.

[V500]

Timing alignment on a two-stroke maybe, which I assume this isn't. Spraying dry lube sounds like a recipe for disaster.
The key prevents shock loads from breaking the taper hold.

[DAVE BRADY]

Hi,

This is on a parallel shaft so no taper.  On the gearbox shaft it is the taper that holds the clutch centre on. Light lapping and a sharp tap on assembly fixes the two tapers together.  It is this that needs a puller and some effort to release it.

Dave.

[Rog1]

There was a discussion on the C10/11 forum about using jbweld in a similar situation. I know not an "engineering" solution but some found it to work. Personaly I've used JB weld with success for damaged castings and the like.

I used JB Weld on a damaged keyway on a launderette tumble dryer, in 2020. It's been fine. The keyway was in a parallel shaft on the drum spindle, securing the drive sprocket

The dryer starts easily with wet washing machine loads that were up to 13kg dry.

[limeyrob]

JB weld and a good 60 lbft should keep it fixed.