When reading the post about a previous case that was the drive shaft/ spline it was surmised that somehow the spline wore out that is absolutely hogwash a square spline will break the shaft before it can "hop" over the teeth. It can ONLY slip if it is pulled out of the socket.

There is a clear error in manufacturing that allows cars to leave production line with a drive shaft that only sockets into the TC by a few mm. The engine shifts forward a few mm over time as the subframe or engine mounts or TC mounts wear and it can pull out enough that the spline will slip.

If there is compression from guibo (joo-boh) then it's in as far as it goes but something is stopping the shaft from going in far enough.

Before I replaced my perfectly good but 4mm too short drive shaft I would see if there was a way to modify the lip/seal etc that stops the spline from going in far enough. The washers (or maybe some threaded inserts) to add a few more mm on the guibo side could stave off replacement.

Sounds like youve already had it off so round two: this time actually measure how far in the female side of the spline goes in, make a reference mark on the shaft and somewhere like the center bearing so you can determine how far in the shaft isn't going and measure how far into the inner spline the shaft COULD go.

Then look up the two part extended axle.

My bet: BMW designed it properly then realized they couldn't get the damn thing in at the point in the assembly line, somebody fogured out they only needed 5mm spline engagement to have 150% torque so it passed and the used cut off shafts ever since. (I can see no other good reason they would not have enough proper spline engagement like 20-30mm like the front dif has (and those are half the torque)

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)