Custom/Hybrid Need advice on best driveshaft......just blew out 3rd one in a year:(

[Tommygunz]

So here's my problem. I had blown out a driveshaft/midshaft combo on my Superjet this summer and replaced it with a used set and blew those out in 3 weeks..... I do ride almost every day though. So I purchased a new midshaft and driveshaft from watercraft superstore and ran that the rest of the year. Then I took it out of my superjet and put the entire setup in my Gen 2 bob and I just blew that out tonite

Does anyone know who makes the strongest setup? A friend of mine just got one from wps and it looks pretty strong. I'm sick of dropping 300+ for junk that doesn't last.

And my pump and shafts are all perfectly in line in case anyone was questioning my setup.

Thanks again for any input!

 

[OCD Solutions]

How much spline engagement do you have?

 

[raytherace]

Maybe the midshaft is too much press in the housing ??

 

[Tommygunz]

How much spline engagement do you have?

I'm gonna pull it apart tomorrow to get some pics but I know its as far as they are usually set. What engagement should I look for measurement wise?

 

[Waternut]

Where are they breaking? This part is the most important.

Spline engagement should be a little short of bottoming out inside the midshaft.

 

[yamanube]

Looking at the splined end of the driveshaft how much of it has full teath on it and how much of it is rounded off?

 

[raytherace]

I'm gonna pull it apart tomorrow to get some pics but I know its as far as they are usually set. What engagement should I look for measurement wise?

check your spline on the driveshaft, if its too tight in the midshaft, the end of the spline will be a little bit more open that usual.

 

[Tommygunz]

I'm sure its at full engagement. And they are just rounding off the splines- not breaking at all. Has anyone used wps driveshafts?

 

[yamanube]

It really sounds like you have an alignment issue, when you jump do you let the motor rev to the moon before it hooks back up in the water?

 

[steve-uk]

well to answer the original question...OEM is best and seems like you are pretty much paying oem prices....

and then secondly, to go through tat many also seems like everyone else has said and there is an alignment issue

 

[OCD Solutions]

I would ask how much power you are running but the guys running 16mm strokers are running the same shafts as you and not having issues so that can't be it.

Constant unloading/loading of the pump combined with your particular riding style? Everyone has their own special timing for brapping the throttle on take off or landing jumps and if you are hitting the throttle just as water hits the pump it could be too much shock loading.?.?.?

Too soft of engine mounts allowing for too much engine movement? Hardened rubber on the midshaft dampner? Triton solid Billet Midshaft housing, (long shot but...)

 

[Tommygunz]

Thanks for all the feedback guys!

I'm only running a 760 so the motor isn't the culprit.

Motor mounts are oem. Coupler dampener is oem and seems good.

Hopefully after teardown tomorrow I can find some clues as to what the issue could be.

 

[yamanube]

Alignment.

 

[McDog]

I'm voting on alignment too. Post your procedure for determining alignment for some feedback.

 

[ryan]

and dont use wsm shafts get yamaha shafts.

 

[Lucaumpits]

send a pm to jetmaniac,

 

[john zigler]

WPS sells WSM shafts.

stick with OE parts.

 

[kevbo]

Buy a new OEM mid and drive shaft, also get new O-rings for the mid shaft. The splines MUST be clean and greased with moly or aluminum complex grease. Make sure to perfectly clean the driveshaft tunnel before reassembly. This area always holds sand and ANY sand will wear out the splines very quickly. Then work on the engine alignment.

 

[Tommygunz]

Thanks again for all the feedback! As soon as I posted this my good friend Chadman154 immediately texted me and said he has both parts ready for a build and I could get em to get back on the water gotta love the enthusiasts in this sport and all the help that everyone is willing to give! Ill post pics up this afternoon when I get ski torn down. Thanks again guys!

 

[Waternut]

One thing I want to point out when aligning an aftermarket hull... When guys aligned a stock superjet, they just eye balled the driveshaft coming through the bulkhead and tried to get it center. You can't do that with an aftermarket hull because the hole in the bulkhead is totally arbitrary. You HAVE TO install the pump and then slide the midshaft over the driveshaft without it hanging on the driveshaft (because hanging the midshaft will bend the driveshaft down slightly) and see if the mounting holes line up. Then shim the pump accordingly until the midshaft holes line up.

BTW, I hammer the throttle every time I enter the water after a jump and have been doing that for years. I'm running a big bore with total loss so I'm spinning the engine up pretty good before it gets shocked as it hits the water. It's brutal on the driveline but that can't be your problem because I haven't had a problem yet.