Large Vibrations

[Toymanator]

I had my son (still blame myself) back the boat (1987 Supra Saltare direct drive) into our barn for the winter. The back half of the barn isn't level and he buried the prop in the dirt. The prop guard on the trailer broke off on one side prior to this and was going to be one of our winter repairs. I am kicking myself now for not repairing it sooner. Without checking it he began winterized the boat, part of the winterization he started the boat and put it in drive for 10 seconds. He said that he heard a vibration coming from the drive shaft and later checked to see that the prop was buried in the dirt. To make matters worse he jacked up the front of the trailer to help drain the remaining water out of the boat. When I pulled the boat out this spring and started it there was a large vibration where the shaft connects to the transmission.

Can I pull the prop and put it in drive for a few seconds to see if the vibrations continue? I am assuming if I do this it will tell me for sure if the prop shaft is bent. If the vibrations stop then I will know that I need to recondition the prop. (I will count my lucky stars if it is only the prop) Could it also just be the bushings?

If it is the prop shaft, where is a good place to order a new one? Any other parts I should order while I am at it? Anything else I should check?

[michael hunter]

Take the prop to a good prop shop and have it checked. While the prop is off start by looking at the shaft prop end with the shaft spinning if its not perfectly straight it will need to be straightened or replaced. Finally look at the strut make sure its still straight and the prop shaft is going through the shaft log in the center of the opening. I had good dealings with General Propeller out of Florida for a prop shaft. I finally found a good prop repair shop here in Georgia that knows inboard props . You may want to contact your insurance both auto and boat and see if it is covered.

[cadunkle]

Shaft is probably bent, and likely the strut as well. Check around the strut mount for cracking inside and out. You can remove the shaft and roll on a flat surface to get an idea if it's bent but best to put it in a lathe and check runout witha dial indicator. You can do similar with two wood blocks with a V cut in them, spin the shaft and check with a dial indicator. Not as accurate but if it's bent bad you'll know. Mine had either .002" or .003" runout when I was checking it for a vibration. Alignment fixed it, no prob with runout.

Strut if not mangled too bad can probably be bent back to straght. Maybe some heat to assist. With new bushings and a straight shaft it should rest about in the center of the log at neutral position in the cutlass bearings.

[scottschmitt]

It doesn't take much of a ding in the prop to make it vibrate. Unless the prop is perfect, pull that and get it sharpened and aligned. Hopefully that's the issue.

The strut bushing is cooled by water pulled into it, so can't put it in gear very much on land.

Drive shafts can be purchased at Skidim: http://www.skidim.com/Drive-Shafts/products/1160/ if you can't get yours fixed.

[Blackntan90]

My manual for the 1990 Mariah/Bravura says the strut bushing should be replaced at 300 hours- more often in sandy or silty conditions. I would not put in drive out of the water as stated, as this will prematurely wear the strut bushings. Good luck!

[Toymanator]

Thanks for the help guys, I will see if I can get a video up later today. I am still waiting on a prop puller but should have it tonight.

[2500HD]

you canrun your boat on land if you have a hose to wet down the strut and the shaft through hull.

[Toymanator]

Shaft is probably bent, and likely the strut as well. Check around the strut mount for cracking inside and out. You can remove the shaft and roll on a flat surface to get an idea if it's bent but best to put it in a lathe and check runout witha dial indicator. You can do similar with two wood blocks with a V cut in them, spin the shaft and check with a dial indicator. Not as accurate but if it's bent bad you'll know. Mine had either .002" or .003" runout when I was checking it for a vibration. Alignment fixed it, no prob with runout.

Strut if not mangled too bad can probably be bent back to straght. Maybe some heat to assist. With new bushings and a straight shaft it should rest about in the center of the log at neutral position in the cutlass bearings.

I ended up taking it in to a shop since I don't have anything to spin it on. They pulled the shaft, and told me when they spun it they couldn't see that it was bent anywhere. When they were spinning the prop by hand prior to removing the shaft they could tell that it was more difficult to spin in certain areas. They pulled out the dial indicator and found that the shaft is bent up near the prop. They quoted me $406 for a new shaft and coupler. I looked around online and found this place www.proppitch.com that will build a new shaft and it will be around $250 shipped to my door. (does not include a new coupler) The shop said that they could use the old coupler but recommended an engine alignment while putting in the shaft. It looks like the strut and bushing are still fine.

[Blackntan90]

+1 on the engine align. Look on the net, there are several good videos. It is not too hard, mostly time consuming. Take your time and get it right.

[Toymanator]

I dropped off the prop shaft yesterday, they called me in the evening to tell me that the shaft is in and everything was back working. He then told me he tripped as he was stepping over my engine and fell on the throttle linkage. He broke off the linkage for my perfect pass. They said they are trying to source the parts and it will most likely be another week before they can get it put back together. I am now wondering if I should ask them for a discount on the labor, or if they will let me take out one of there boats next week while mine is still getting repaired. Has anyone had any experience with a shop breaking something on your boat? What did you get in return for there mishap? I don't want to be too critical I know stuff happens, but I am now out my boat for another week.