Sterndrive clunk on engagement

[Bowlerhat]

I have a B3 leg driven by a Mercruiser 260 diesel. Just had the cone clutch changed and engagement ahead and astern is instantaneous but also accompanied by a loud clunk, that doesn’t sound overly sympathetic to the drive train. Is it a new clutch thing, ’normal’, or something else, please? My last clutch engaged quietly but was shot and took around 8 seconds to engage, so I don’t have a good comparison. Our last boat was shaft drive on KAD43s and was very smooth. Thank you.

 

[bowler]

First what its worth, any alpha 1 sterndrive I have heard engages with a bang so to speak. I assume Bravos are the same?

 

[NBs]

Hi,

that's just right, then when the engagement is soft, then you know you're getting into trouble.

Nbs

 

[simonfraser]

Hi,

that's just right, then when the engagement is soft, then you know you're getting into trouble.

Nbs

yep that is when the cones are wearing out and are going to slip

 

[oldgit]

Hi,

that's just right, then when the engagement is soft, then you know you're getting into trouble.

Nbs

and with VP legs as well.

 

[waynes world]

and with VP legs as well.

I was wondering the same, also how you tell if the clutch is bad or going bad when not fitted to the boat without stripping the drive.

 

[petem]

I was wondering the same, also how you tell if the clutch is bad or going bad when not fitted to the boat without stripping the drive.

I can't imagine any other way.

 

[waynes world]

I can't imagine any other way.

My thoughts aswell. Bit of a pig to fit them and launch the boat to jave to drag it back out to fix the clutch.

 

[Bowlerhat]

Thanks Team. That’s reassuring.

 

[spannerman]

Alpha drives don’t have a cone clutch like Bravo and VP drives, they have a dog clutch which is simply a crash in and out gear selection. Problem is people shift slowly to avoid the clunk but instead get rrrrrdddddd as the dogs skip over each other resulting in a rounded shoulder which eventually when worn will jump out gear. With Alphas and outboards its far better to be very positive when shifting so the dogs engage first time, and when changing direction pausing to allow the prop to stop instead of forcing it to go from 300rpm one way to 300 rpm the other way instantaneously, especially with SS props which have a lot of momentum.

 

[bowler]

Alpha drives don’t have a cone clutch like Bravo and VP drives, they have a dog clutch which is simply a crash in and out gear selection. Problem is people shift slowly to avoid the clunk but instead get rrrrrdddddd as the dogs skip over each other resulting in a rounded shoulder which eventually when worn will jump out gear. With Alphas and outboards its far better to be very positive when shifting so the dogs engage first time, and when changing direction pausing to allow the prop to stop instead of forcing it to go from 300rpm one way to 300 rpm the other way instantaneously, especially with SS props which have a lot of momentum.

Top advice.

 

[Bigplumbs]

Alpha drives don’t have a cone clutch like Bravo and VP drives, they have a dog clutch which is simply a crash in and out gear selection. Problem is people shift slowly to avoid the clunk but instead get rrrrrdddddd as the dogs skip over each other resulting in a rounded shoulder which eventually when worn will jump out gear. With Alphas and outboards its far better to be very positive when shifting so the dogs engage first time, and when changing direction pausing to allow the prop to stop instead of forcing it to go from 300rpm one way to 300 rpm the other way instantaneously, especially with SS props which have a lot of momentum.

Like most outboards. New put them in gear slowly they need to go in firmly to stop the RRDDDD as you say. Tentative is not the order of the day

 

[QBhoy]

Wee bit of miss guidance here perhaps. A bravo should not clunk into gear like an alpha at all. Should be smooth. That’s the whole idea of the cone clutch. An alpha is straight cut dogged.

 

[spannerman]

I don’t know which diesel engine you have, mechanical injection or D- tronic or common rail. But if the idle speed is too high this can cause a clunk on gear selection. If its a CR then the idle is determined by the ECU and not adustable. If you tell me your engine type I can say what the idle speed should be.

 

[Bowlerhat]

Thanks QBhoy and spannerman. I certainly expected a smooth engagement, I have to say. I have the Mercury 3.0LTDI 260HP, which I think is common rail direct injection.

 

[spannerman]

Yep idle speed ECU controlled on this engine, hopefully it will quieten down once the new clutch beds in.

 

[QBhoy]

Thanks QBhoy and spannerman. I certainly expected a smooth engagement, I have to say. I have the Mercury 3.0LTDI 260HP, which I think is common rail direct injection.

No probs. Spanner man has a good point there about the clutch bedding in, as time goes on. Hopefully that’s the case. When these outdrives are matched to a diesel like yours, there is no give the way a petrol engine might have. As in…a diesel would not drop or relent its rpm, engaging into gear. A petrol would. Definitely worth making sure the rpms at idle aren’t too high and harsh for a smooth engagement. All the best.

 

[Bowlerhat]

Thanks again to QBhoy and Spannerman. I’ll adopt Plan A - i.e. let things settle down over time. I hadn’t thought about the greater torque on a diesel either. Thanks.