Ambassador 750 final drive noise

[valleydog]

Hi guys , I am a new member here and need some advice please.
I have a ratted out old Ambassador 750 that has been my daily ride for the last 23 years , her name is Alice and I love her to bits.
Last week I was doing about 60mph and heard a sudden noise as if the mainstand had touched the ground for a split second.
Parked at the shop , still running fine.
I came out and tried to start but the engine would not turn over , awful noise from the left head , so I trailered her home (the first time she has ever let me down ).
It transpires that the left intake valve seat had dropped out.
I am in South Africa where parts are hard to find , luckily I found a second hand head and repaired the piston , found rings from a Datsun 240 Laurel and got her running well again.
However , since then there is a regular "clunk " noise from the rear drive , harsh metallic noise and I can feel it in the rh foot peg.
It is most pronounced at small throttle openings and low rpm in all gears.
On deceleration it is quiet .

Any ideas or similar experiences before I strip anything?

Thankyou in anticipation .

[ray bear]

Hi Valleydog, you have Mario from thunderbikes in Perth Western Australia which is just across the Indian Ocean from you who carries a good range of the main mechanical components for the loops and you may have a carrier bearing on the way out just behind the universal joint  or it may even be the joint itself on the way and you would replace them together , check all the cheap bits first before you get carried away with the final drive but at least  drop the oil from the drive , it may shed some light on whats  happening . cheers bill

[jacksonracingcomau]

Need to have a look
Universal joint first suspect, but get it apart, sad but no choice.
Pull out pinion from drive box, gears do drop eventualy but uj happens sooner
Al bits available

[valleydog]

Thanks chaps.
I drained the drive and had a look via the filler hole.
2 teeth broken on the pinion and one broken on the crown wheel.
I can get a complete used drive from a 1000sp .
Does anyone know if the crown and pinion will fit to an Ambassador?

[Rolf Halvorsen]

Originally you have 8/35 (Pinjong/Crown Wheel) as all of the big Guzzi from early 70.

Since it is summer where you live - my advise for you is to buy whatever final drive you can get fast and cheap. The 1000SP has 7/33.

If you are not satisfied with that one - then rebuild your original.

I can do this, but I live in Norway (high cost country). There must be others closer to you and possible cheaper.

Rolf

[Antietam Classic Cycle]

Thanks chaps.
I drained the drive and had a look via the filler hole.
2 teeth broken on the pinion and one broken on the crown wheel.
I can get a complete used drive from a 1000sp .
Does anyone know if the crown and pinion will fit to an Ambassador?

The crown and pinion will fit, but will need to be set up (shimmed) by someone that knows what they're doing or they won't last long. An Ambassador (usually) has an 8/35 gear set, this equates to a ratio of 4.375:1. The 7/33 gear set equates to a ratio of 4.714:1, so the bike will be geared a bit lower as a result.