The Audi 2.0 TT (MK2 quattro) employs a cardan-shaft with flex couplings that is connected to the 3-pin input flange to the Haldex coupling with three M10 bolts. The RS3 uses a similar arrangement with three similar M10 bolts.
1) A standard 2.0 TT develops 350Nm (258 lbf ft) of torque @ 1600 to 4200 rpm
2) A standard RS3 develops 450Nm @ (331 lbf ft) of torque @ 1600 to 5300 rpm: that's 28% more torque through those same three M10 bolts.
3) A stage 1 ECU upgrade for the RS3 is claimed to produce 447 lbf ft of torque "throughout the power band": that's 35% more torque than a standard RS3 and 73% more than a standard 2.0 TT (through those same three M10 bolts).
Something here has to give, you'd think. Photographic evidence of a current failure shows that ALL 3-bolts have sheared at the connection of the (cardan-shaft) rear flex coupling to the 3-pin input flange to the Haldex.
Now, good engineering practice would have the load being transmitted across the shank/major diameter of a bolt, but in this application the load is being applied across, or very close to, the root diameter of the thread, and this may well be the issue as the shank diameter of an M10 bolt is 10mm (10.0/9.7), but its minor thread diameter is only 8mm (8.3/7.9 according to tables): that's a 25% reduction.
So think on if you have an uprated ECU in your RS3, especially if you've alternative sticky and/or oversized tyres, and enjoy launch control, as it could well prove expensive.
Just my own thoughts and sums mind, feel free to disagree
In the meantime I'll not be using launch control on my standard ECU controlled RS3.
Hope this helps...
1) A standard 2.0 TT develops 350Nm (258 lbf ft) of torque @ 1600 to 4200 rpm
2) A standard RS3 develops 450Nm @ (331 lbf ft) of torque @ 1600 to 5300 rpm: that's 28% more torque through those same three M10 bolts.
3) A stage 1 ECU upgrade for the RS3 is claimed to produce 447 lbf ft of torque "throughout the power band": that's 35% more torque than a standard RS3 and 73% more than a standard 2.0 TT (through those same three M10 bolts).
Something here has to give, you'd think. Photographic evidence of a current failure shows that ALL 3-bolts have sheared at the connection of the (cardan-shaft) rear flex coupling to the 3-pin input flange to the Haldex.
Now, good engineering practice would have the load being transmitted across the shank/major diameter of a bolt, but in this application the load is being applied across, or very close to, the root diameter of the thread, and this may well be the issue as the shank diameter of an M10 bolt is 10mm (10.0/9.7), but its minor thread diameter is only 8mm (8.3/7.9 according to tables): that's a 25% reduction.
So think on if you have an uprated ECU in your RS3, especially if you've alternative sticky and/or oversized tyres, and enjoy launch control, as it could well prove expensive.
Just my own thoughts and sums mind, feel free to disagree
In the meantime I'll not be using launch control on my standard ECU controlled RS3.
Hope this helps...