Ariel Owners Motorcycle Club

Here is my latest disaster. After a good winter hack and nearly home something let go in the primary chain area. (1938 VH)

There was a sudden scraping sound which sounded like some tinware was dragging along the ground. My guess is that the nuts have come off the crankshaft (again). This casing will soon be more weld than original metal.

That's nasty. Good bit of winter road gunge on there though!

That's a pain Dave.

Dave,
you are not having much luck with that primary...be interesting to see what has given way this time

Cheers
Alan

Now it's a bit warmer and lighter I threw a few spanners around last night to examine the damage. The inner primary case has also broken and I was surprised that the outer has also broken at the rear as well as the front.

I expected to see the nuts on the crank shaft undone but they are not, looking at the whole lot I can’t see any evidence explaining why this violence has occurred and hope it's not something more sinister lurking within.

For the moment the Ariel is dead until I can find a new set of primary cases (please let me know if you know of a pair for sale).

It looks like the primary chain is sitting on the bottom of the case so if the chain is that slack it’s walked over the crank sprocket and rammed the front of the case out. Has the gearbox moved forward on its mounts and the drive chain gone tight ? Bob.

I feel for you, Dave. The result couldn't have been worse! What on earth could have caused it?
regards
John

BobWard wrote:It looks like the primary chain is sitting on the bottom of the case so if the chain is that slack it’s walked over the crank sprocket and rammed the front of the case out. Has the gearbox moved forward on its mounts and the drive chain gone tight ? Bob.

I was wondering about that as it does look slack. It could have become slack after the un-diagnosed violence but we will never know. I think that if the chain was slack it would have made some noises to give warning and at the time it was running like a Swiss watch with no nasty sounds and the engine was not under great load as I was coming down a three mile gentle hill. The grinding sound and case cracking was almost instant.

Hi
I don't believe the chain could be slack enough to ramp over the sprocket - I'd be searching for something that has come adrift and been carried around between the chain and sprocket. Where is the inner case retaining bolt from just aft of the engine sprocket?
Regards Mick

My thoughts are still with gearbox moving forward as you mention travel down hill was this using the rear brake causing the back drag, please check for tightness of the drive chain as this may confirm that the box traveled forward. Bob
Edit :- Having just seen previous post you can check the drive sprocket teeth if a stray part rode over the drive sprocket you Will see the thee damage to one or more teeth where the object wedge in between chain and sprocket. Bob