Freestyle Is my driveshaft cracked?

[Yami-Rider]

I notice a line half way around my driveshaft I have never noticed before, is it cracked?

Shaft is from a 1998 SJ.

 

[Yami-Rider]

I lightly sanded and buffed it, still can see a straight line half way around

 

[OCD Solutions]

Spin the impeller on. If that crack is just inside the front lip of the impeller in a place that would make impeller removal a holy living hell then yes, that is a crack and that is a known weak spot.

 

[OCD Solutions]

Be very glad you caught it while you have the impeller off. It is not a fun day to remove an impeller once they snap.

 

[Yami-Rider]

Mmm. It's just inside the impeller. I was told by a reliable source that is a weld/fuse seem. So maybe it's ok? Lol. I have seen them break there before..

 

[OCD Solutions]

It is a weld/seam and that is why they fail right there.

Having had it happen to me once already, I wouldn't risk running it. Not because it would really hurt anything but it will cost you twice. Once when it snaps and ruins your day of riding, and then again when you spend an afternoon trying to recover the impeller off it.

 

[Yami-Rider]

Ya. I'll get a new driveshaft, just stuck this shaft on my new mag pump, should of looked it over better before install :-/.

 

[Twake]

I've seen that on many shafts. Never had a problem with them.

 

[speedysprocket]

If shaft breaks, thread a nut on the pump end of the drive shaft and put the nut in the vice. Then take your prop off. Loosening the prop tightens the nut, since the prop is left hand threaded.

 

[Yami-Rider]

If shaft breaks, thread a nut on the pump end ....

This is what I was thinking last night, I could messure it, or do you know what size nut I need?

 

[speedysprocket]

This is what I was thinking last night, I could messure it, or do you know what size nut I need?

I have it at home. I'll check for you.

 

[xXx Octane xXx]

If that is an OEM driveshaft, I wouldn't worry about it. Yamaha utilizes a rotary friction welding process to join the two sections of their drive shafts. This process displaces up to 1/4" of material on each piece when the two parts are fused together and that excess material is sheared or ground off to match the diameter of the rest of the shaft. The location you have pictured corresponds to this weld location.

If that is modified driveshaft that has been shortened to work for your application where a GTAW process was used and a filler metal has been added, then you might have something to worry about.

 

[xXx Octane xXx]

M20 X 1.5 Left Hand Thread.

 

[augustaf]

Yes, M20 x 1.5 , right hand thread

 

[Ducky]

Yes, M20 x 1.5 , right hand thread

Lol, I just sat at my work desk playing righty-tighty, lefty-loose with my hands in the air to figure out if it needed to be right hand or left hand thread on the back of the pump. Right hand thread makes sense!

 

[xXx Octane xXx]

Sorry, you are correct. Right hand thread for the end of the driveshaft and left hand thread for the impeller.

 

[Proformance1]

If its all stock from the factory that's the way they were all made. Some aftermarket shafts are made in one piece for this reason. Its more costly, but with higher hp, less failures there.

 

[Yami-Rider]

Ok, cool. Thanks for the help everyone.

 

[BombThreat]

Why not do a red dye test instead of guessing?

https://en.m.wikipedia.org/wiki/Dye_penetrant_inspection

 

[OCD Solutions]

I've got to be honest, I think I would rather run the shaft to failure and then just deal with getting the impeller off the broken shaft than go through that red dye inspection process.