kwin5946

Long story short: Did a first gear launch from a standstill and heard a loud pop and no movement. Towed the car back home and jacked it up, with some fiddling around I realized both half shafts sheared off from the differential end.

So I know the half shafts will definitely need replacing, but when I attempted to take off the 14mm bolts that hold the axle bucket to the diff the bucket would rotate after I applied a good amount of force therefore I was unable to take off the bolts. The car was in gear, so why did the bucket rotate? Is my differential shot as well?

windhund116

My guess is the force and energy needed to shear off both half-shafts could possibly do a lot more damage to other parts of the car seeing that torque. Are you running a Hellcat replacement engine?

Ok, joking aside, what is the HP and torque your engine is making?

kwin5946

I wish. Only mod is a K&N intake. What confuses me the most is how both of them sheared at the exact same time. Because given a torsen diff, if one side shears then there is no power going to other side.

windhund116

Did you go low traction to 100% traction surfaces?

kwin5946

No I was sitting on pavement. 255/40 Bridgestone RE tires

What's the best indicator of seeing if the differential needs replacing as well? I don't want to replace the half shafts only to find out I need to take them off again to replace the diff.

noodels

*The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.

B0neSt0ck

Are you the original owner of the car? If not,I would wonder if aftermarket axles were used to replace the oem ones at some point. Drain the differential fluid and see if some chunks of metal come out.

kwin5946

I am not the original owner. I have done multiple autocrosses, launches, and one burnout. Perhaps it was already on its way out.

I am going to drain the diff fluid and see what happens from there.

AusS2000

I find it pretty hard to believe you have sheared an axle shaft. The ring of the spider is the weak point. I've cracked two (separate incidents) but never sheared a shaft. I've also done a diff, but it was a gradual failure.

The diagnosis of both is pretty straightforward. You release the clutch, the car doesn't move but it makes a noise. If it's a steady click it's the spider. If it's a sickening grinding graunch it's the diff.