broken prop shaft!!! 87 trutrak 2

[briand45 0]

Hello everyone!! so, I rebuilt my 87 tru trak 2 from stringers on up . New EVERYTHING,- .. First test run- everything sonds and works great, then as I'm about to put her back on the trailer, I shift into reverse, and POP! driveshaft snaps. It broke right at the rear  side of the coupler.   The break was clean and the fresh break was very dark in color.. Anybody have any ideas as to what happened, or have see this before?? I dont think my packing was tight... maybe mis alighnment, or previous crack.. any thoughts???  Thanks

-Brian

[jtryon 24]

misalignment is pretty likely given that you rebuilt everything recently.  did you check the alignment when you put it back together?

[briand45 0]

I did align as well as I could- It just seemed to me, using a feeler gauge between the coupler and trans flange is not a very accurate way to align.-  Is there a better way than that?  After all, I doubt any coupler is dead on perfectly aligned to the shaft.. Its just bolted over the taper.. I'm sure there's a certain amount of 'wobble''  between the shaft and coupler- making any measurement with a feeler gauge useless.. am I worng in thinking this?

 

Edited June 1, 2020 by briand45
additional info inserted

[Timr71 30]

I had the shaft break on my Falcon after a stringer up restoration too. My issue wasn't alignment. The history of the boat that I restored involved salt water use + I think the previous owner had hit something with the under water gear.  Anyway, my shaft broke near the strut. Best we could tell, there was pitting in the shaft that weakened it.  I bought a replacement and haven't missed a beat since. I was lucky though that all of it held together even though it was fully separated. The strut bearing kept it all there, so my prop didn't end up on the bottom of the lake.  Good luck!