Author Topic: Are there sync rings in the gearbox?  (Read 455 times)

Offline JesperN

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Are there sync rings in the gearbox?
« on: October 04, 2025, 06:49:07 AM »
Hi. I have a heavily modified Lemans 4 that has approx. 140 000 km by now. The gearbox is awful. I shimmed the selector drum last winter. Didn't help much. Nothing inside looks bad or worn down. But the synchronization between the higher gear is bad. I have changed all the bearings. But are there anything in the gearbox that functions as sync rings? Never thought about this before.

Another thought is that the selector drum and possibly the forks are worn. Is this a common issue on high mileage Guzzis?

Sincerely Jesper



« Last Edit: October 04, 2025, 06:50:36 AM by JesperN »

Offline n3303j

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Re: Are there sync rings in the gearbox?
« Reply #1 on: October 04, 2025, 09:09:56 AM »
All gears are in constant mesh. Synch rings are for engaging mating gears. These gears are always engaged. Shifting only determines which gear is locked to the output shaft. Crude but effective drive dogs there CLUNK and you are rolling. With practice it can become click if you are not in a rush.


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Offline wirespokes

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Re: Are there sync rings in the gearbox?
« Reply #2 on: October 04, 2025, 08:46:17 PM »
  Here's a good YouTube on the old five speeds:

https://www.youtube.com/watch?v=c1WIjtceX-A&t=1134s

It might even be able to contact him with your questions if you can figure it out from the turtorial.

Offline JesperN

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Re: Are there sync rings in the gearbox?
« Reply #3 on: October 05, 2025, 08:12:06 AM »
  Here's a good YouTube on the old five speeds:

https://www.youtube.com/watch?v=c1WIjtceX-A&t=1134s

It might even be able to contact him with your questions if you can figure it out from the turtorial.

Thanks. Have seen it. Was very useful when i opened the gearbox last winter.
Regards Jesper

Offline guzzisteve

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Re: Are there sync rings in the gearbox?
« Reply #4 on: October 05, 2025, 08:45:24 AM »
There are shifting dogs that get rounded off and at higher rpm's won't mesh to allow gear engagement.
« Last Edit: October 05, 2025, 03:15:29 PM by guzzisteve »
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