Bukh 36 gearbox reverse problem

[Lutra]

Hi, I have a 1980s Bukh 36 gearbox attached to a saildrive. The engine is a fairly new Beta 38. Going from forward to neutral is no problem, but finding neutral from reverse is difficult. When the gear selector clicks into the neutral position, the boat remains in reverse. The only way to be certain to get to neutral is to go into forward, and then back to neutral - I don't suppose this is doing the gearbox much good. It also makes close quarter manoeuvring a bit nerve-racking especially as the Kiwi prop bites quickly and gets the boat going backwards very rapidly.

The cable and selector mechanism seems fine. I have checked the alignment of the cable. It lies at the right position when the selector and gear lever on the gearbox are in neutral.

I was hoping for some suggestions of things to try. I do actually have an even older Bukh gearbox. I'm not sure what condition it is in, and whether my mechanical skills are up to swapping it to test it. But maybe giving it a try, or more likely getting a mechanic to swap it might be my best option? Grateful for any thoughts.

 

[Biggles Wader]

When was the gearbox oil last changed and how long has this problem been going on?

 

[vyv_cox]

Take the cable off the gear selector on the box and check whether it works correctly by engaging it there. This checks that the problem is not in the linkage.

 

[SvenH]

I had the same issue a week ago. Going in to neutral can depend on very small differences in setting " the length of the cable", in my case it needed something like half a turn to get it working again.

With my Yanmar there is a spring in the coupling, working in both directions. So the neutral position is not absolute but the result of forces and positions.

 

[Lutra]

When was the gearbox oil last changed and how long has this problem been going on?

The oil was changed in April 2024. I’ve noticed the reverse selection becoming a problem over the course of this summer

 

[Lutra]

Take the cable off the gear selector on the box and check whether it works correctly by engaging it there. This checks that the problem is not in the linkage.

I checked this yesterday. While the different positions click positively into place with the lever on the box when the engine is not running, it is a lot less clear cut when it is running. What is clear though is that manually moving the lever on the box does not require going into forward before finding neutral after reverse. So I think I am going to try fine adjustments to the cable length to see if I can get it working better. Thanks for your advice.

 

[Lutra]

I had the same issue a week ago. Going in to neutral can depend on very small differences in setting " the length of the cable", in my case it needed something like half a turn to get it working again.

With my Yanmar there is a spring in the coupling, working in both directions. So the neutral position is not absolute but the result of forces and positions.

Thanks, I think this might be the issue. Going to try some micro adjustments