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Audi A4 gearbox shaft failure

The shaft carrying 4th/5th/6th gears on my '07 A4 sheared between 4th and 5th gears. Only 51000 on the clock, I am the only owner, and the car only lightly driven. Looks like metal fatigue. Anyone heard of a similar event? Audi seem to have not heard of anything like it, but my discussions with them still at an early stage. Of course, way out of warranty!

Consumers are on the verge of DEMANDING 100,000 mile power-train warranties…I suspect your voice will join them…

Assuming that you have complied with Audi’s maintenance schedule, my thought on the topic is:
Considering the price that you paid for this machine, if I were you, I would persist in politely demanding “Good Will” assistance with this repair. Hopefully, Audi Corporate will see the light, and will help you to offset the cost of this repair.

I’ve done a lot of manual transmission repair and can’t say as I’ve ever seen or heard of a metallurgical failure. That’s not to say that it can’t happen but the odds are so remote it’s tough to read much into it.

Every hard failure I’ve seen has either been owner induced or caused by lack of oil; either out of or too low.
If the oil level was full then I agree with VDCdriver about asking for some Good WIll assistance on this.

You could have a metallurgist analyze the failure to determine what went wrong. The metallurgist could easily check the hardness of the surface metal as well as the interior. Fatigue failures are relatively simple to see as they have consistent visual patterns but the cause may be less obvious. It might have been what is commonly called a tool mark resulting in a stress riser or else a localized metallic defect or possibly a heat treatment deficiency. A known good sample would be required to complete the analysis or else the factory specification for the part including the metal specification, surface finish and heat treatment required as would be provided on an engineering drawing.

This would, of course, be expensive where possible and then being out of warranty, what could you do with the results? Audi would most likely be found at fault but sometimes things just happen that should not happen that are reminiscent of the early days of vehicle engineering and manufacture.

It is possible that what happened to your Audi could have happened with any brand.