ZF8 Speed Ratio Question

[Skilid]

Isnt 4th gear the issue

If you look at the change between each gear ratio

1>2nd 0.64
2>3 0.66
3>4 0.80
4>5 0.76
5>6 0.76
6>7 0.82
7>8 0.78

You would expect the ratio change to be less as you go up higher in the gears, 4th gear really should be between a 1.62 ratio or less.

Maybe ask BMW technical? There will no doubt be a good reason. 3rd gear covers the all important 0-100 time. Its probably purely for that and that alone that the whole gearbox is messed up.

Yes. It’s 4th that is shorter compared to everything else, even all of the higher gears. Just seems odd.

It doesn’t affect my enjoyment of the car in any way, but when you’re changing down through the box you can almost skip it!

 

[jpaul]

as suggested I'd think it was a WLTP optmisation, with 4th low to provide a low gear that permits a lot of the test to be done in one gear without downshifting,
the wltp acceleration/speed profile probably won't be demanding for a 300bhp engine.

if you look at how it operates though you are re-using 4 basic gear elements in different combinations to give the 8 speeds, so you've got to optimise/make compromises

ZF 8HP The new 8 Speed Automatic​

 

[Chris Wilson]

If you look at the torque graph of the engine it may offer some clue.

 

[Diddums]

gearbox map

This is some Mal X level of stupid