SoCal Jet Boats

Misc. => Suggestions / Support => Topic started by: mkatena on April 29, 2017, 09:50:07 PM

Title: Hull Vibration
Post by: mkatena on April 29, 2017, 09:50:07 PM

I currently have a vibration when I take off and once I get on plane it dissipates but when ever I get on the gas it becomes more noticeable. I have went thru the pump and all good there. I have adjusted the degree pitch of my motor as well (did that several times). I had new u joints put in last summer when I fixed the seals on the motor. Could it be my u joints? Possible incorrect ones? I am currently at a loss and any help would be much appreciated. Thx.


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Title: Re: Hull Vibration
Post by: GT Jets on April 30, 2017, 10:50:04 AM

Sounds to me like the drive line splines are too deep into the pump and the yoke is bottoming out under power.

There should be 1/4"-3/8" of free movement on the yoke splines from bottoming. Major engine damage could result if left unattended.

Not saying for sure, but what it sounds like to me.

Another thing to look for is a cracked flywheel/flexplate or a broken motor mount.

Good luck.

GT

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Title: Re: Hull Vibration
Post by: 69kona on April 30, 2017, 11:25:57 AM

Quote from: GT Jets on April 30, 2017, 10:50:04 AM

Sounds to me like the drive line splines are too deep into the pump and the yoke is bottoming out under power.

There should be 1/4"-3/8" of free movement on the yoke splines from bottoming. Major engine damage could result if left unattended.

Not saying for sure, but what it sounds like to me.

Another thing to look for is a cracked flywheel/flexplate or a broken motor mount.

Good luck.

GT

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X2 ☝🏻️☝🏻☝🏻 check this


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Title: Re: Hull Vibration
Post by: mkatena on April 30, 2017, 05:10:01 PM

Motor mounts are good. Flywheel/flex plate is good. I had the motor out to fix the seals and then replaced the u joints. Ever since then I have had a vibration. I know the mounts weren't move on the stringers so I am sure I have enough movement on the yoke. How would I check the movement without removing the driveline from the motor, or is that what I would have to do?


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Title: Re: Hull Vibration
Post by: HardLuck Baker on April 30, 2017, 05:21:38 PM

I had the same issue once after having my motor rebuilt. Turned out that the flywheel that was replaced was wrong.


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Title: Re: Hull Vibration
Post by: GT Jets on April 30, 2017, 06:46:36 PM

Any chance you flipped the flex plate around backwards?

What drive line assembly? Have a picture?

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Title: Re: Hull Vibration
Post by: Blue2184 on May 01, 2017, 07:21:31 AM

Quote from: GT Jets on April 30, 2017, 06:46:36 PM

Any chance you flipped the flex plate around backwards?

What drive line assembly? Have a picture?

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Gt don't some of those driveshafts have to be "clocked" a certain way? Maybe he has it say 180* out when putting in the new u joints? Just thinking out loud...


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Title: Re: Hull Vibration
Post by: GT Jets on May 01, 2017, 12:03:06 PM

Quote from: Blue2184 on May 01, 2017, 07:21:31 AM

Gt don't some of those driveshafts have to be "clocked" a certain way? Maybe he has it say 180* out when putting in the new u joints? Just thinking out loud...


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Yes, but unless it's a splined shaft drive line, it would be very difficult to do. Typically it's very difficult to blow it on a double cardan deal.

GT

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Title: Re: Hull Vibration
Post by: Blue2184 on May 01, 2017, 12:04:43 PM

Quote from: GT Jets on May 01, 2017, 12:03:06 PM

Yes, but unless it's a splined shaft drive line, it would be very difficult to do. Typically it's very difficult to blow it on a double cardan deal.

GT

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Gotcha... just thinking out loud...


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Title: Re: Hull Vibration
Post by: mkatena on May 01, 2017, 09:27:47 PM

Here is a pic of my drive shaft assembly. It has an "H" Bar.


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Title: Re: Hull Vibration
Post by: mkatena on May 01, 2017, 09:29:02 PM

The flex plate was not removed when the motor was pulled out. I just pulled the motor to do all of the seals since it sat for a few years.


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Title: Re: Hull Vibration
Post by: mkatena on May 01, 2017, 09:33:15 PM

Now looking at how the motor is sitting the front is not parallel to the pump. I was told that the u joint that is bolted to my motor should be at the same degree as the shaft that goes into the pump. Kinda at a loss a bit as this is the first jet boat that I have done work on and everyone tells me that the angle of the drive shaft needs to be between 3 and 5 degrees.


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Title: Re: Hull Vibration
Post by: GT Jets on May 01, 2017, 10:21:35 PM

Quote from: mkatena on May 01, 2017, 09:27:47 PM

Here is a pic of my drive shaft assembly. It has an "H" Bar.


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Anybody else see it?

First off, the engine alignment is in the wrong ball park.... Not even close.

Second, what retains the joint caps on the splined yoke?

GT

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Title: Re: Hull Vibration
Post by: J2 on May 02, 2017, 06:10:58 AM

Quote from: GT Jets on May 01, 2017, 10:21:35 PM

Anybody else see it?

First off, the engine alignment is in the wrong ball park.... Not even close.

Second, what retains the joint caps on the splined yoke?

GT

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I 1st noticed the H bar angle up which didn't seem correct, then the cap looking like it's working it way out due to the missing retainer. Pretty close to a much bigger issue.

Title: Re: Hull Vibration
Post by: 76Challenger on May 02, 2017, 07:47:16 AM

Quote from: J2 on May 02, 2017, 06:10:58 AM

I 1st noticed the H bar angle up which didn't seem correct, then the cap looking like it's working it way out due to the missing retainer. Pretty close to a much bigger issue.

First thing I said to myself...well that ain't right... I knew you would set him straight GT.

1977 Challenger

Title: Re: Hull Vibration
Post by: mkatena on May 02, 2017, 08:15:46 AM

There "C" clips on the inside of Caps that retain them on splined yoke. Should my "H" Bar be level with no angle?


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