1"vs.11/8 prop shaft

Looking to get some knowledge because I am a new v drive owner and think I have vibration going through my shaft.
I was going to replace my shaft. I have a 1" shaft and was wondering what horsepower it will accommodate and if I was to upgrade to the 1 1/8" shaft what changes are involved?

Selbycnlb said:

Looking to get some knowledge because I am a new v drive owner and think I have vibration going through my shaft.
I was going to replace my shaft. I have a 1" shaft and was wondering what horsepower it will accommodate and if I was to upgrade to the 1 1/8" shaft what changes are involved?

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To upgrade to 1 1/8 you will need to either upgrade the tail shaft from the Vdrive or buy a 1" to 1 1/8" coupler (highly recommend the 1 1/8" tail shaft. That's the weak link in the drive, ask me how I know! Will have to drill the hull for bigger shaft, bigger shaft log seal, bigger strut and bigger prop. It's not cheap! As far as 1" shaft limit. You can ask 10 different people and get 10 different answers. We run a Cole tr2 and a Kurtis runner bottom, both are 1" running gear The Cole is 950hp and Kurtis is just a tick above 900hp. This past race we destroyed the tail shaft on the starting line, hit the air shifter at too high rpm and boom it went. What type of boat and what do you do with it?

Selbycnlb said:

Looking to get some knowledge because I am a new v drive owner and think I have vibration going through my shaft.
I was going to replace my shaft. I have a 1" shaft and was wondering what horsepower it will accommodate and if I was to upgrade to the 1 1/8" shaft what changes are involved?

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So, what is the deal you have now ?

It's a 19 ft hallett day cruiser about 550 hp. I will be sticking with the 1" shaft. When I upgrade to a tt motor I will take care of all that then but for now sounds unneeded. Where would you guys recommend I pick up a new shaft? What's a good brand? Who knows the most about v drives?

I would recommend an 'aquamet 22' 1" shaft, it should hold up to about 1500HP, IF everything is IN LINE .

To compare, I built a 20' open bow, ski locker, XM radio, tilt wheel, full interior, family ski boat, that ran 114 MPH at 6700 RPMs. (1018 HP @ 7100 RPMs on the dyno) It ran a 3 blade AZ Menkens prop for skiing .

Your boat should weigh less and then should be able to do more with equal power . (if set up correctly)

The set up correctly part is what I'm worried about. What are the variables I need to be worried about?

I'm running a 1" on my 21 Rc. 1000hp, three blade 11 1/4 x 16, and '50's in the Casale. I'd say it's also how you use it. If you're in the air a lot and landing hard, I'd suspect that's when they'll fail.

what is causing the vibration?? Have you checked the bushings in the strut?? Or the balance of the propeller?? Strut bushings is where I would start. They are cheep and easy to install (the second time).

SuperDave013 said:

what is causing the vibration?? Have you checked the bushings in the strut?? Or the balance of the propeller?? Strut bushings is where I would start. They are cheep and easy to install (the second time).

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The prop is at hill marine. I replaced the strut bushing a week ago. My next step was the shaft.

Back the boat (on trailer/safety collar on shaft) into water, start, put in gear (run up to vibration speed RPMs), does it still vibrate ?

Pull up ramp, remove prop shaft coupler (leave shaft in place, just slide it back) re test on trailer in water, testing the driveline less prop shaft . Does it still vibrate ?

IF the motor, driveline and gearbox don't vibrate, you may have a bent prop shaft or an alignment problem .

Is the 'new' strut bushing already showing signs of wear/sloppiness ?

Step by step ..........

I rather launch UCH and try the tests. Id be scared of the prop contacting the trailer. :yikes

wsuwrhr said:

I rather launch UCH and try the tests. Id be scared of the prop contacting the trailer. :yikes

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While it's sitting on the floor of your truck with the puller ?

AzGeo said:

Back the boat (on trailer/safety collar on shaft) into water, start, put in gear (run up to vibration speed RPMs), does it still vibrate ?

Pull up ramp, remove prop shaft coupler (leave shaft in place, just slide it back) re test on trailer in water, testing the driveline less prop shaft . Does it still vibrate ?

IF the motor, driveline and gearbox don't vibrate, you may have a bent prop shaft or an alignment problem .

Is the 'new' strut bushing already showing signs of wear/sloppiness ?

Step by step ..........

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Sounds good to me. I'll test it tomorrow and see what happens.

AzGeo said:

While it's sitting on the floor of your truck with the puller ?

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Dammit George. You got me, I didn't see the bold thread title. I just went back and looked.

Brian

wsuwrhr said:

Dammit George. You got me, I didn't see the bold thread title. I just went back and looked.

Brian

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oldschool said:

View attachment 564700

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Yep, it happens.

wsuwrhr said:

Yep, it happens.

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In my case, more often than not.

Well if you decide to go the full cha cha k monel 1.25 plan on about $200 a ft.:eek

How much power can a standard 1 1/8 shaft handle???

A family friend has an 1100 HP Spectra 24XS and he runs an 1-1/8. I vaugely remember him saying they went with that size and the boat was really heavy.

farmo83 said:

A family friend has an 1100 HP Spectra 24XS and he runs an 1-1/8. I vaugely remember him saying they went with that size and the boat was really heavy.

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Because of the shaft?

oh no sorry. they went with that size shaft as the boat was heavy. In years since this I've seen more powerful boats with 1 inch but they were much lighter then that heavy Spectra so it sort of made sense to me that a heavier boat would fatigue the shaft more. I was pretty drunk when that got brought up though so it maybe be BS.