California Gearbox? noise

Hello, I am new to the forum and Guzzi ownership. I have a 75 T3 California that makes a horrible noise and vibration which seems to come through the left footboard, it only seems to happen on the overun never on acceleration.
I have replaced the UJ to no avail. I have taken the gearbox of and have noticed the starter ring is chewed, is it possible for the starter gear to hit the ring on the overun?
Any advice welcome

I’ve never experienced this but the Cardan Joint is the usual suspect but if you’ve replaced it I assume you examined the support bearing for the joint at the same time.
What is your gearbox oil like? Any signs of nasty bits of metal or a severe discolouration?
I wouldn’t think the starter dog would hit the ring on overrun but if it is not disengaging properly I suppose you would notice this regardless of accelerating or over-run. My suspicion would be the gearbox itself and if you’ve got the bike that far apart it would be worth having a look inside for worn bearings or gears.

this may sound stupid" but it cured an exact problem on my cali3. the down pipe(heder) on the exhust was to close to the lower frame rail that when the engin warmed up the pipe expanded and caused vibrasion and a terrible nosise when i shut the throtle. the heder flange had come lose.( it dont cost nowt to have a look) best of luck. mick,

this happened to one of mine as well

happened to my advanced brake pedal, had the brakes in bits 3 times before i sussed it was the zorst.

Thanks, have just looked at the exhaust and it is really close to the frame. I will try moving it.
Thanks for the advice

thanks for the prompt reply. I will pluck up courage and open the gear box up.

Yup on my LM111.

Check EVERYTHING else before hand,

UJ bearing
Exhaust touching frame
Sidestand or it’s spring touching frame/zorst
Even (although it has recently been done) the UJ itself.

Before delving into the gearbox.

Also unless you are pretty good engineering wise talk to Nigel at NBS as he does often do a service exchange on gearbox , I did that over 10 yrs ago it was a heck of alot less than ripping a gearbox apart and replacing parts myself, convenient too.

A worn U/J normally produces vibration in the RH footpeg.

Your description does seem like the issue of the LH exhaust touching the frame, which I am looking to sort on my 2004 Cali; another similar noise turned out to be the heat shield on the LH silencer: the bolts were tight, but the plate was still loose because the washers had rusted away. A trivial issue but the noise was horrible.

Bit difficult not to look into the gearbox whilst it is out,but it would be strange to have a fault in the gearbox that wasn’t apparent under load as well as on the over-run. To look at the gearbox now it’s out would only really cost you a few pounds for gasket and oil seals but knowing what to look for is more difficult. Depending on your ability and whether you are time or cash rich you could go the guaranteed route of letting NBS look at the box or look yourself or put it all back together and hope it is only an exhaust knocking - but be prepared to pull it apart again if not .It does sound quite possible though.
Starter ring gears can show quite a lot of wear and give no trouble but there should be no contact with starter when dis-engaged.Can you post pictures of it to get advice here, and where in the country are you?

Good luck