Driveshafts coming apart under load

[Ben]

I went wide open throttle in first gear while moving slowly, and i would assume at around peak torque my drive shaft came apart where the yoke/bearings are.

Its still bolted to the hub and still inside the gearbox, it just came apart – the boot flew off, the three or four bearings that are attached to the shaft went who knows where and I had to limp the car home.

I figured I had a bad drive shaft, so I got two new ones, replaced them both – accelerated in first gear again and BANG – same thing….

What is causing this?

Car in question – 2009 Subaru Forester XT, 5 speed manual, Making 200kw at the wheels, minor mods.

Topic

[Steve Klein]

If I am reading this right, you replaced the entire driveshaft and U-joints? Did the U-joints fail the first time around?

[Ben]

Circled Bit is the section that comes apart, the band that holds the boot is forced off and bearings inside spit out with it coming out of the housing

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[Steve Klein]

The only how I can see that happening is if your engine is moving too much during heavy throttle. Check motor mounts. Or, if the CV joint was not fully seated when installed.

[Ben]

I am starting to think the same thing….maybe bush’s in the control arms? Though it would need a massive amount of movement to pop the thing apart

Things to note;
Engine mounts are new
Pitchstop is new
Clutch is new
Car doesn’t make any weird noises while driving gently
gears select fine and no grinds while changing gears

[Ben]

Think I may have found the problem, engine mount looks to be cracking..

Subaru Engine Mount

[Author]

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