Opened Primary and....What is (was) this? ... and this?

I pulled the outer and inner primary covers off my Mark 3, because I wanted to deal with:
1) starter not turning over the engine - though there is plenty of spin in the starter itself (assume it is a busted sprag (again!) - but put on a Power Arc electric ignition last week, to replace the old analog Boyer, so hopefully this is the last time replacing the sprag)

2) oil leaking between the inner primary and the crankcase

3) clutch not feeling quite right

The good news:

- everything came off OK, with nothing requiring too much muscle or sweat

- source of oil leak was easy to spot. 2 of the 4 studs from the stator bracket through the inner primary to the crankcase were sitting loose. Thus the loose fit between the inner primary and the crankcase and the oil leak. Easy to resolve.

But ..... the bad news.....

Couple of issues:

1. Big metal chunks inside the primary case. I had to take a break for dinner and family stuff, so didn't finish my sleuthing yet. Anybody got a guess what this is from?



Here's a close up:



it kind of looks like the "teeth" from the sprag, but when I pulled the sprag, all the bits were there. Hmmmmm.... what could it be?

EDIT: Finished with dinner and family stuff for a little while and cleaned and laid out the pieces I pulled out of the primary case.

The result - looks familiar, but still not sure what it is/was - ideas?





2. Next mystery - behind the inner primary, on the main shaft

This was hanging on the main shaft, from behind the clutch assembly after I pulled the inner primary - didn't look in detail yet. Anybody want to hazard a guess? Kind of looks like part of an oil seal....?



Will get back to the assessment, and re-assembly in a day or 2.

Appreciate the sleuthing help.

Keith

Re: Opend Primary and....What is (was) this? ... and this?

pkeithkelly said:

1. Big metal chunks inside the primary case. I had to take a break for dinner and family stuff, so didn't finish my sleuthing yet. Anybody got a guess what this is from?

Click to expand...

They could be fragments from a broken sprag cage? Or maybe a broken clutch location circlip?

This is what my Mk3's sprag looked like after it disintegrated!

pkeithkelly said:

2. Next mystery - behind the inner primary, on the main shaft

This was hanging on the main shaft, from behind the clutch assembly after I pulled the inner primary - didn't look in detail yet. Anybody want to hazard a guess? Kind of looks like part of an oil seal....?

Click to expand...

Yes, that looks like the garter spring from the oil seal behind the clutch.

L.A.B.

I think you're right on the "garter spring"

But on the chunks of metal - it's not the sprag. It was in one piece and looks fine.

I just edited the post and added a close-up of the bits in a quasi-reassembly. Looks like a nut, though no signs of threads on the inner circumference - torn off maybe. But I still don't know what it is from.

Not the lock nut for the clutch adjustment screw, which is what it looks like partially reassembled.



Ideas?

A five-sided nut?

Batrider -

Yep, it's a 5-sided nut all right.

Looked at the pieces I pulled out today and see that the nut is missing from the anti-backfire device.

It is part # 06-4745, and can be seen in the diagram for the Mark 3 in Group 12, item 9.

Now what caused all that damage?

I had set the anti-backfire device carefully a couple of years ago, and think i even sent it to Fred at OldBritts to double-check my adjustment. (It is supposed to slip at >50 ft lbs of torque, thus (supposedly) protecting a backfire from damaging the sprag or related components.

Obviously it failed.

pkeithkelly said:

Yep, it's a 5-sided nut all right.

Looked at the pieces I pulled out today and see that the nut is missing from the anti-backfire device.

It is part # 06-4745, and can be seen in the diagram for the Mark 3 in Group 12, item 9.

Click to expand...

If it is 06-4745 then that's only part of the nut. Where's the rest of it?

pkeithkelly said:

Batrider -

Yep, it's a 5-sided nut all right.

Looked at the pieces I pulled out today and see that the nut is missing from the anti-backfire device.

It is part # 06-4745, and can be seen in the diagram for the Mark 3 in Group 12, item 9.

Now what caused all that damage?

I had set the anti-backfire device carefully a couple of years ago, and think i even sent it to Fred at OldBritts to double-check my adjustment. (It is supposed to slip at >50 ft lbs of torque, thus (supposedly) protecting a backfire from damaging the sprag or related components.

Obviously it failed.

Click to expand...

Once the nut on the antibackfire device has been moved to adjust it it must be thoroughly locktited and staked or tig welded or it will unscrew itself and this is what you end up with. Jim

oh oh.
It didn't unscrew in all those pieces so look for other damage too, and is the cylindrically shaped remainder still in place or where is it?
All the best.

No sign of the "shoulder" portion of the shouldered nut, at least not yet. I will go through everything thoroughly to see what else has been damaged by the flying pieces.

It has to be there somewhere !?!?!

I was sure the nut was very secure and had been locktited when checked a couple of years ago - but apparently it wasn't secure enough.

Jim says it should be "staked" or tig welded.

I assume "staked" means the nut and it's threaded shaft should be drilled and either safety wired together or have a pin through them - right???

Tig welding seems very, well, permanent, though I guess if it is adjusted properly (to slip when torque reaches 50 lbs), it will never need to be taken apart again.

pkeithkelly said:

No sign of the "shoulder" portion of the shouldered nut, at least not yet. I will go through everything thoroughly to see what else has been damaged by the flying pieces.

It has to be there somewhere !?!?!

I was sure the nut was very secure and had been locktited when checked a couple of years ago - but apparently it wasn't secure enough.

Jim says it should be "staked" or tig welded.

I assume "staked" means the nut and it's threaded shaft should be drilled and either safety wired together or have a pin through them - right???

Tig welding seems very, well, permanent, though I guess if it is adjusted properly (to slip when torque reaches 50 lbs), it will never need to be taken apart again.

Click to expand...

"Staked"---- is using a sharp pointed hardened steel punch and peen the threads as close to the nut as possible--preventing the nut from backing off. Best to get some of the nut as well as the threads mashed together---several locations as well---maybe three or four.

pkeithkelly said:

No sign of the "shoulder" portion of the shouldered nut, at least not yet. I will go through everything thoroughly to see what else has been damaged by the flying pieces.

It has to be there somewhere !?!?!

I was sure the nut was very secure and had been locktited when checked a couple of years ago - but apparently it wasn't secure enough.

Jim says it should be "staked" or tig welded.

I assume "staked" means the nut and it's threaded shaft should be drilled and either safety wired together or have a pin through them - right???

Tig welding seems very, well, permanent, though I guess if it is adjusted properly (to slip when torque reaches 50 lbs), it will never need to be taken apart again.

Click to expand...

I have used locktite and then staked them with a punch and they have held. The nut has to be removed and de-greased so the locktite has a chance to hold. Then use lots of red locktite and adjust it before it starts to set up and then stake it in place for a backup.
On my own bike I just used the tig welder and spot welded a couple places and it has been fine for years. If I need to re-adjust it I would need to use a cutoff blade to remove the weld but I suspect it could be done. It was quick and easy and as you say-somewhat permanent -but I haven't had to worry about it. Jim

The hexagon pulling off the sleeve nut in the anti-backfire device is the reason that I binned my starter about thirty years ago.

Back in those pre-internet days, I had no idea about the Boyer low-voltage problems and the engine backfired hard on trying to start. There was an almighty clunk and fortunately it didn't start so it was quite easy to see what had happened. The body of the nut was still in place but the hexagon part had shattered, allowing the device to move apart.

It would seem that the nuts are simply not of sufficient strength to cope with the force of the slipping device going all the way and I didn't want to risk it happening again, perhaps with the parts finding their way into the chain.

Someone wrote: "Staked"---- is using a sharp pointed hardened steel punch and peen the threads as close to the nut as possible--preventing the nut from backing off. Best to get some of the nut as well as the threads mashed together---several locations as well---maybe three or four.


there is an axial slot cut into the shaft. The short collar of the nut is peened down into this slot once the torque value is set and verified, Loctite is a big plus.
As hes been previously mentioned, the threads should be solvent cleaned before Loctite application if you chose to use it.
All the best.