DP-SM Vibration underway

[callen369]

Morning guys,
I have a decent vibration when underway. More pronounced with the drive all the way down, lessens a bit when trimmed up a bit, but does not change much when turning. Only have a small dent on one of the props that has been there a while and never caused an issue before. I guess I should start by running the motor in the driveway and observing the prop for wobble?

 

[jerryjerry05]

Yup, in the drive start it up.
The vibration could be the gimbal?
Possibly the alignment?

I was changing the oil in the lower units and took the stbd. prop off to grease the splines.
When I put it back on I reached over and spun the prop.

I noticed a SERIOUS wobble. The shaft was straight and no wobble/ vibration while going.

I looked at the prop and the center hub had shifted and the prop was on crooked.
It's now in my scrap pile.
From 25years in the salt the alum has corroded and it's rotting away.

 

[bruceb58]

Have you had your drive off lately to check the condition of the u-joints?

 

[Thalasso]

My money is on the bent/dented prop.

 

[callen369]

Have not had the drive off.....boat was new to me in June....have done a lot of engine maintenance....just not made it to the drive yet. I do not have the vibration when the engine is revved in neutral....which leads me toward the props and/or lower unit....as the u joints and all would still be spinning in neutral...

 

[alldodge]

Pull the prop and rev it to see if it goes away

 

[bruceb58]

Have not had the drive off.....boat was new to me in June....have done a lot of engine maintenance....just not made it to the drive yet. I do not have the vibration when the engine is revved in neutral....which leads me toward the props and/or lower unit....as the u joints and all would still be spinning in neutral...

Sometimes, you need a load on the u-joints so you can't count them out yet.

 

[callen369]

Ok, before I pull the drive......

I decided to pull the props and change the drive fluid to check for contamination, and because I'm not sure how old the fluid is. While doing so, I noticed the washer and e-clip for the port trim ram is missing, and while the ram while not come off, it will wiggle.

Do I continue and pull the drive...or install missing hardware and test? I will note that the bellows appear to be in good shape, the fluid was good, and the grease ports were loaded when I got it, and I grease it regularly.

 

[Tail_Gunner]

Put the drive on muffs pull the prop and see if she vibrates..then proceed to taking the drive off it maybe where no man has gone before........:facepalm:

 

[callen369]

I will run it on muffs and check... I pulled the props and dropped them at the shop to be overhauled. Ordered the bellows kit, so the drive will come off this week. Have to replace the shift cable due to a leak anyway. Wish me luck....

 

[callen369]

Any recommendations on replacement u-joint? Like to pick 2 up just in case mine is corroded.

 

[evantful]

Any recommendations on replacement u-joint? Like to pick 2 up just in case mine is corroded.

For U-Joint replacement on a DP-SM it depends on the style of Universal Joint you have installed.

There are two versions,
-The Rockwell, which was used from 1997-mid 2000
-The GKN, which was used from mid 2000 and on

The Rockwell model has spiders that are meant to be serviceable. The GKN is not meant to have the spiders replaced, but needs to be replaced as an entire assembly

I wouldn't use the year of your boat as the end all to what model you UJoint assembly you have. If you can, take a picture of the Spiders and I can better tell if you have a serviceable U Joint and point you to replacement part numbers.

 

[callen369]

Well, drive r/r was smooth, everything in good shape. Took it out and ran smooth first 10 minutes, then had engine problems. Fouled plug, turned out to be bad plug wire. swapped wires to t/s, and fouled another plug. yay!!! I am a pro at changing plugs on this motor.