Airone Gearbox mystery resolved

[Alan Comfort]

Well, sort of. It tuns out that the bushing in the direct drive gear was not turning on the primary shaft. The gear should have easily slid off the shaft but It took some serious pressure, heat and penetrating oil  to separate the gear from the shaft. The gear came away, but the bushing stayed behind. Once the gear was off, I had to split the bushing to get it to part company with the shaft. No visible damage to the shaft and it does not appear to be bent. I expected to see some galling, but the shaft is clean. The mystery remains as to why this happened. The rest of the gearbox was nice and oily, but the primary shaft/bushing interface was dry, even after numerous applications if heat and penetrating oil.

I am hoping to find a replacement bushing from the usual sources. If not, it should be a straightforward exercise to spin one on the lathe. I'll be sure to lubricate the shaft and bushing during assembly and to make sure that the oil galleries in the shaft are not blocked.

The question remains: how and why did this happen?

Ciao, Alan in Roberts Creek

[PATRICK HAYES]

did you happen to roll any great distance with engine off? 

 

I was once on a vintage ride to Mount Tamalpais North of San Francisco. At the summit, someone had the brilliant idea to 'race' down in neutral with engine off.  Object was to see who could roll the furthest.  I almost won the distance of several miles. But when I finally stopped, I couldn't restart. Kick lever gear was fully locked and wouldn't release at end of kick. I had someone push start me. When I got back to my truck, all was good and free and bike normal since. 

Moral, shaft lubrication all comes from throw of of the crank. No engine running = no line anywhere. Oops.  Should have ran in neutral with engine at idle. 

 

Patrick Hayes

Fremont CA

 

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[PATRICK HAYES]

no engine running = no lube anywhere. 

Patrick

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[pouma1954]

Which is why you shouldn't tow a bike any distance without disconnecting the secondary chain.

Paul

Envoyé depuis mon appareil Galaxy

-------- Message d'origine --------

De : 'PATRICK HAYES' via Guzzi Singles <guzzi-...@googlegroups.com>

Date : 16/02/2026 22:45 (GMT+01:00)

À : guzzi-...@googlegroups.com, Alan Comfort <alan.c...@gmail.com>

Objet : Re: [guzzi-singles] Airone Gearbox mystery resolved

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[leo volmer]

Hello all :

Op maandag 16 februari 2026 om 23:00:21 UTC+1 schreef Paul Marx in France:

[leo volmer]

Some thing went wrong, so once again: i have 8 bushes in stock for the Airone. Part nr.: M 2128 bis. Just to check some sizes : inner dia :15 mm; outer dia: 18 / 20,5 mm; total length 44,5 mm. These are original NOS  Guzzi parts. If you are interested let me know, I'm in Holland.
       Regards, Leo

Op woensdag 18 februari 2026 om 18:16:24 UTC+1 schreef leo volmer:

[Alan Comfort]

Thanks Leo,

The nominal dimensions of the bushing that I removed are 17 X 20 X44 with a 3 X 25 flange.  i wonder if my primary shaft was modified at some time in the past?

Here is a photo:

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[leo volmer]

Or mine are for a smaller Guzzi engine. I was told they are for an Airone, but I don't have proof like a partnr. stamped in the bush. I know that the old Falcone has the same kind of bush in the " ingranaggio prese dirette" , but is bigger in size.

    regards ,

    Leo

Op woensdag 18 februari 2026 om 18:42:14 UTC+1 schreef Alan in Vancouver:

[Alan Comfort]

Part No. M 2128 is the right number for this bushing. The good folks at Guzzi Retro have one and it is now on its way along with some other parts for the Airone. Perhaps this bike will be ready for the 2026 riding season here in Canuckistan.

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[leo volmer]

Nice pic, and even nicer bikes!

Op woensdag 18 februari 2026 om 20:02:25 UTC+1 schreef Alan in Vancouver: