In case it’s of interest, when the ZF 5HP24 transmission started production in 1996 it was quoted as having a maximum input torque capacity of 420Nm.

When it was specified by BMW against the 440Nm M62 engine it’s torque rating, as luck would have it, suddenly became 440Nm (hence it was designated the A5S440Z).

The 4.6is engine produces (at least) 480Nm peak torque.

It could be argued, therefore, that the old transmission is being somewhat ‘overstretched’ in this application.

To beef it up, ZF fitted the 4.6is transmission with a larger L51-type 12” torque converter (and therefore a bigger bellhousing). The D brake - used in 3rd & 5th gears - had an extra clutch plate in it (5 plates instead of 4) and the upper valve block was modified to accommodate revised designs for the B & E clutch valves.

To differentiate between them the 4.4i E53 transmission is an ‘029’ model and the 4.6is is an ‘034’ model.

Phil