Bevel gears wont part

[Wildcat]

Hi all

Newbie here, looking for advice/ideas.

I am stripping a Narrowcase 5-speed Scrambler (I think) engine stored since the late '70's.
It came with a bunch of mostly JoMo Triumph desert sled cast-offs sent to Taiwan from the States at that time as scrap!

My issue is that the bevel gears, which should lift off with the head, will not separate in the coupling.
Otherwise, the dismantling has been straightforward.
Now just waiting on a mate who's away to post a flywheel puller so that I can split the cases.

Tried wiggling, jiggling, pouring copious amounts of ATF/acetone mix down the tube in the hope some will work its way into the sleeve, then
waiting weeks. Tapping, levering, heat gun, blow torch, all to no avail.
At one point, the two parts moved apart about 6mm, but that was it.

Before I get destructive, does anyone have any suggestions other than to Dremel the tube off to get a better look at what is going on with the sleeve?

I've uploaded a photo as an attachment but I'm unsure if it will display in the post!

Screenshot_20250502_164945_Gallery.jpg

If it works, you can see the crank bevel gear, head, barrels etc are already removed.

Thanks
Mike

[IanHood]

Are you able to turn the tube clockwise or anti-clockwise? If you can then it is likely that the sleeve that slips over the upper and lower shafts is nicely rusted to them. Others may have better ideas but you may end up have to destroy the tube to get access to the sleeve (to apply some heat etc. directly).

Ian

[Wildcat]

Hi Ian

The tube moves freely in all directions.
So yes the issue is in the sleeve.

Mike

[IanHood]

In that case Mike, I think your only option is probably to destroy the tube. I wouldn’t lose too much sleep - they seem to be one of the few parts that are relatively widely available (narrow and widecase tubes are the same from memory).

Ian

[George]

Hi I had the same problem and had to destroy the tube to get at the sleeve (Oldham coupling) that I split with careful use of the dremel. Good luck. Replacement parts are available. The tube comes with different lengths, check before destroying it.

[Jordan]

I know I'm being picky, but in the interest of not confusing people - it's not an Oldham coupling.
If it was, it's very unlikely it would become stuck because those are made with the ability to slide radially but with no backlash when applied to non-coaxial mating shafts. The close-fitting sleeve on the Ducati coupling ensures nothing but coaxial shaft alignment.

[Wildcat]

Hi I had the same problem and had to destroy the tube to get at the sleeve (Oldham coupling) that I split with careful use of the dremel. Good luck. Replacement parts are available. The tube comes with different lengths, check before destroying it.

Thanks and noted.
The tube is pretty beaten up anyway.
I do have another in slightly better nick (hopefully the same length) in a box of bits, somewhere, I think!

Mike

[LaceyDucati]

Hello Mike

You could make an adaptor plate to screw to the two M6 holes of the tunnel, with a central tapped hole to suit a slide hammer. If you used something like 12mm alloy plate this could clamp the bevel shaft to the tube. Unless it is very corroded I suspect a slide hammer would shift it.

Regards Nigel

[blethermaskite]

I have a slide hammer with a threaded shaft that you can fit a small 3 leg puller to with skinny 4mm jaws......if you could get or contrive something like that to clamp under the bearing, (as Nigel suggests) I think a slide hammer would get it out. Cheers George

[Wildcat]

Thank you Nigel and George, for your suggestions.

I don't have a slide hammer.
I do have a spare tube and a Dremel!

I suspect it is very corroded, so a £35 cheapo eBay slide hammer may not work, but I will give it a go

Cheers
Mike