Pics of broken driveshaft

[Fishermark]

I am able to post some pictures of my broken upper driveshaft (This is in reference to this post)<br /><br />Notice two things:<br /><br />How cleanly it is broken and how nice and "new" the gear looks. No wear at all! <br />

<br /><br /><br />Unfortunately the lower drive shaft is stripped as well. Too many broken parts to fix economically, I will be buying a new one. <br />

 

[bigbrownbuku]

Re: Pics of broken driveshaft

aftermarket alphas are dirt cheap these days. be sure to check the prices on this forum for replacement. getting very hard to justify some alpha rebuilds with the cost on a new replacement being so low.

 

[Fishermark]

Re: Pics of broken driveshaft

Yep, I've already found a brand new drive for $1,195. The best price I could find to rebuild it was in the $800 range, and that's with using used parts. With brand new shafts, gears, etc.. FORGET ABOUT IT! $$$$<br /><br />I don't know if the lower shaft stripped first and then the upper shaft broke, or visa versa, or simultaneously. I also have no idea what caused the break. The prop showed absolutely no damage. It's a mystery!

 

[marinemech1]

Re: Pics of broken driveshaft

the upper shaft looks like an impact but the lower appears to be alignment my theory upper shaft broke first causing driven gear to start jumping about which is the alignment problem<br />buying a drive may be safest bet

 

[Bt Doctur]

Re: Pics of broken driveshaft

Im with marinemech1,impact first .cracked the upper shaft and wobble action took out the lower shaft.

 

[achris]

Re: Pics of broken driveshaft

??????<br /><br />I've never seen impact break an upper drive shaft like that. Usually impact will break in one of two places. Either the 'O' ring groove directly under the splines on the lower drive shaft, or the same shaft but at the bottom end, just above the pinion gear. <br /><br /><br />I agree that wobble killed the splines but could someone explain to me how a shaft who's job is just to keep the driven gear straight and is not transmitting any load be broken by impact? All I can think of is that the preload wasn't set correctly, allowing the gear, and shaft, to chatter thus causing a stress fracture, ultimatley the break. Would be real interesting to see the outer bearing races.<br /><br /><br />Chris............

 

[Fishermark]

Re: Pics of broken driveshaft

Chris,<br />The bearings looked fine. Well, the upper bearing did anyway - it looked brand new in fact. The lower bearing (the bigger one) had some wear - there was some pitting on the bearing surface and the race as well, but I've certainly seen worse. There was also no chattering or growling or anything like that - nothing to give any indication that there was something amiss. I believe it was Rodbolt who mentioned in a previous post that this particular shaft had been known to break for no particular reason. <br /><br />For what it is worth, the mechanic who looked over my outdrive has seen and rebuilt a lot of Mercruiser units and he said he had never seen one do that before.

 

[FreeBeeTony]

Re: Pics of broken driveshaft

Is the lower unit locked-up? Could this have caused the stripping of the lower driveshaft and failure of the upper shaft?<br /><br />Just a thought...........

 

[Fishermark]

Re: Pics of broken driveshaft

No, the lower unit turns fine. I haven't taken it apart like I have the upper unit, so I couldn't tell you if there are any broken parts in there, but the drive shaft turns freely and it will go into forward and reverse gears with no problem.<br /><br />This of course is just academic at this point, I've already decided to purchase a new outdrive, but as the saying goes, "Inquiring minds want to know." I mainly posted this because there was a lengthy discussion on the post linked above, and I finally had the opportunity to post some pictures.