*I didn't weld this, I swapped out an entire s4 t2 rear subframe and diff for the s5 since the old diff was shot, the welder was a novice and will remain nameless *

It actually worked well for awhile till I started upping the power. It finally let go last night on a hard launch.

It ended up shearing the mount off the front subframe. Luckily I have some spares lying out back. You can't see it in these pictures, but it also ripped the heavy gauge sheet metal off the front of the subframe where the weld was anchored. Time for a pinion snubber?

 

I've been dealing with the same thing. I thought about adding a damper...kinda like a engine damper, or even a steering damper like what can be found on big tire 4x4. For now, it's gonna be the mazdacomp one.

 

I have heard that the pinion snubber works very well, I've also heard the solid mount tends to break ****,

 

Yeah that's a pinion snubber. It pushes down on the pinion (front nose of the diff) to prevent it from lifting. Energy suspension makes one I think, in red polyurethane. Just gotta figure out how to securely mount it between the brake cables.

 

I've also thought about straps, to limit to amount of travel. It's got to be allowed to move some, otherwise things WILL crack.

 

The exact same thing happened to me a month ago. Sheared that mount right off at the tabs. I don't even know how it happened, my car is an N/A.

I ended up making a custom diff mount and welded it to the subframe, the metal is significantly thicker. Let's see if it breaks now.