Prop shaft blues

[uuhyeah]

My 90 sunsport keeps eating prop shafts. There is no vibration and the prop has not struck anything. I checked the engine mounts and there is no movement. Everything seems to be aligned. What the #!*K, over?

Any suggestions, besides sinking it?

[SupraNut]

Can you give more of a description of what you mean by "eating" prop shafts? I had one shear off right behind the strut a few years back...looked like someone took a hacksaw to it, the break was so clean. The part was not cheap but I replaced it myself and no problems since.

[uuhyeah]

The shaft is shearing at the coupler that joins to the transmission. This is an indication of misalignment, but every time I replace the shaft, it is aligned. The break is clean, just like yours.

I am going to try to have someone align this shaft with a micrometer, maybe it will show where it is out of balance.

[Catdog2]

Sounds like the alignment at rest is ok.

So, maybe the engine and trans are shifting during load while the strut stays fixed.

Maybe the key is to observe the situation with the cover off. If movement isn't clear, maybe try to rig up a little pencil / pointer system to measure how far ( if at all ) the big components are moving.

Just theory --- I have no experience with this...