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Vibration in Reverse


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I launched our new Chaparral 216 Saturday. (Brand new first time in water) every thing went great. Only issue I am concerned about is a vibration during reverse. When you put the boat in reverse, the first few seconds is smooth. Then you notice a slight vibration that gets worse as you continue to reverse. The vibration will get pretty annoying, until you shift into neutral. This is experienced in smooth water. Changing reverse speed does not help. Motor is a 5.7L Volvo Penta with SX Drive. If you have any ideas what is going on or how I can fix this annoying issue I would greatly appreciate your help.

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A new boat is like a new car, nothing is perfect and there maybe some issues. It is under warranty. I would contact the dealership where you bought it from, I'm sure that they have some knowledge of this issue. Denny.

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A new boat is like a new car, nothing is perfect and there maybe some issues. It is under warranty. I would contact the dealership where you bought it from, I'm sure that they have some knowledge of this issue. Denny.

yep, dealer problem.

I had zero (0) issues with the last three (quality brand) cars we bought.

No issues right after after the delivery, and many years after ... just saying ... ;)

I wish boats were like cars ...

Me 2,

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I had zero (0) issues with the last three (quality brand) cars we bought.

No issues right after after the delivery, and many years after ... just saying ... ;)

I wish boats were like cars ...

I guess we'll have to wait until the Japanese start making boats

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I launched our new Chaparral 216 Saturday. (Brand new first time in water) every thing went great. Only issue I am concerned about is a vibration during reverse. When you put the boat in reverse, the first few seconds is smooth. Then you notice a slight vibration that gets worse as you continue to reverse. The vibration will get pretty annoying, until you shift into neutral. This is experienced in smooth water. Changing reverse speed does not help. Motor is a 5.7L Volvo Penta with SX Drive. If you have any ideas what is going on or how I can fix this annoying issue I would greatly appreciate your help.

Couple of questions:

1. How long/far are you reversing - out of a slip or for longer distances?

2. What speed/throttle are you reversing - idle speed or faster?

One theory is you may be cavitating the prop if throttling too many RPMs. If this is happening at idle speed, then sounds like it could be mechanical.

Is this in warm water? Wondering about lower unit lube condition/level/temp. I don't know what the water temp was when you launched but just wondering -- if it is as cold as our water is now, I would not expect lubricants to behave normally and I'm not sure there's any noise that my boat could make that would surprise me....

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Not heard of anyone with a new volvo having a vibration like that. I would expect it to be smooth like what I have with the Mercs. Get a hold of dealer and get him to look at it.

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Thanks for the input. I spoke with my dealer, he told me to check a few things. One of which was movement in the drive. It looks like the pins that attach the hydraulic cylinders to the drive unit are under size. This is allowing the drive a little movement when you pull up on it. I am machining new pins .006" larger tomorrow and will test Saturday. I will post pictures and a report then. Hope it works.

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I would get it back to the dealer and not take any responsibility (and potential liability) for fixing a brand new boat/drive.

If you must, make sure that the metal you are machining is exactly the same. Even if that is similar but different alloy it can start the galvanic corrosion.

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I appreciate the concern about warrantee, but I have always preferred to do my own maintenance and service, with the help of the internet and forums ( you ). So I will give you an update if you are interested.
I finished machining the 4 new pins. I machined them .006" larger than the old pins. They are installed with new stainless steel cotter pins. The fit is snug, not at all sloppy, and not a press fit either. I took the boat to the lake today to test the new pins. The results were great. Nice smooth reverse function with no vibration. I will post a few pictures of the new pins.
Thank you for the good tip about galvanic corrosion. I did a little research and choose to use bronze, because it is a good bearing, corrosion resistant, and very strong. Both bronze and stainless steel are noble catholics and are close to each other on the chart. Both metals can cause corrosion in the base metal. The anode is used to protect the base metal. Zinc for saltwater, magnesium for freshwater.

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The new pins look great ... very professional.

One more point to check or keep in mind ... these pins transfer the majority of propulsion force from the prop to the transom and boat. They need to be as strong as the ones they replace. The shearing forces there are extreme ... you do not want these pins to get out of shape even a little bit as removing them then will be difficult or impossible.

Sorry, can't help with the up/down movement assessment as my boat is far away.

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