Timing drive shaft damage

You are spot on about the fatigue bit

 

Mike, on second thoughts, I think I was actually wrong in this case-- getting old :-( As with conrod bolts, the huge 3824kg clamping force is well beyond the cyclic bending moment on the shaft so the fatigue is not such a big issue.

 

Absolutely. It would be most interesting to learn, how this exotic damage could happen and not only how to fix it.
The damage looks as if it developed over a prolonged period and not suddenly. Failed/seized bearings are causing different damages like badly worn bearing seats on the shaft where the inner race is located.
I fear, that the steel suffered structural damage and fatigue and the part is far beyond its original strength specs. Restoring such a damaged part to its original specs would be more expensive than a new part. Welding material onto it and cutting without further structural tests is a hack job IMHO.

Best from Germany
Martin

 

The nut was loose so the cyclic force was on the key/slot which wore over time. As I mentioned before, the nut should clamp the pulley to the gear via the bearing’s inner race.

 

Agree the woodruff key walked out to the point of near failure....which could not occur without jam nut backing out.
Machining it new is certainly within reason, or agree with everyone this is a very important component...

We would joke, "find a low mileage GTS driven by a hair dresser" and salvage that....but that's no longer PC.
Ordering a new one I suppose is!!

 

No mystery. Someone left the pulley nut loose at some point. They dont come loose, they are left loose. Not worth fixing. There are a huge number of junk, blown up and parts core engines out there. Get a used one.

 

No. You still have a bad shaft from the sounds of it. It should be a tight press fit

Can't imagine why you repaired it. I was just offered all the used ones I wanted for under $100 each. Guy told me he had a box full of them.

Do you know how many 308 engines have been parted out?

 

Is it the repaired shaft that is wobbling? That’s a clue. If the wobble goes away when you tighten the pulley nut then your shaft is not tight in the bearing. I’m assuming the timing cover is on with new inner bearings? Don’t forget the thin conical washers facing the right way against the inside clips.