Z3 Automatic transmission 4 vs 5 speed

[BMW Z3 2.0]

Hi fellow Z's!

I just joined Zroadster.org after buying a 1999 Z3 2.0 automatic. And I love it! BMW's smallest inline six is very, very smooth, as is the transmission. I was thinking that the four speed suited a 1.9 better because it means lesser gear hunting but it turns out to be a relaxed combi with a six cilinder as well.

I'm pretty happy with the four speed till so far but only because of the (very) high final drive gear that's been applied (4.44 ratio means more torque to the rear wheels ). In Europe BMW also equipped this transmission with a sport mode switch in addition to A/M mode, which I use frequently because the sport mode adapts to the whole gear program.

I am intrigued by BMW's choice for the GM 4LE auto transmission. Why did they fitted this in the 2.0, 2.3 and 2.8 and not the GM 5L40-E or ZF 5HP five speed that were also available during that period 1997-2000?
Since 1991 a 325i or 328i e36 already had a five speed auto. A five speed became available for the Z3 but only when new engines arrived (M54 2.2i 2.5i and 3.0i) after 2000.
So since a five speed automatic fit into a Z3, why did BMW initially choose the four speed in stead of the five speed in the M52 Z3's?

 

[BMW Z3 2.0]

No one, any thoughts? One day I hope to resolve the mystery . One theory might be that BMW considered a four speed in combination with high final gears more suitable for a Z3 m52 and m52tu in stead of the five speed GM 5L40-E.
It's a fact that BMW never chose for the more modern ZF4HP22E in any model series for unknown, but good?, reasons. The only alternative left was the GM4L30-E. Only with the third gen Z3 six cilinder engines (M54) they offered the ZF5hp auto. (which was the better automatic ofcourse.)

 

[Woodsta888]

Hi,

I don't think there are that many auto owners on here and those on manuals wont really know or be that interested in why BMW chose X auto box over y.

Sounds like you know and understand as much as anyone

 

[BMW Z3 2.0]

I learned that BMW fitted the 4L30-E also in the brand new e39 528i in the US. While in EU we got a a five speed for the e39 528i.. As I remember well, in the EU we already had a ZF 5 speed in the e34 5 series!
So maybe, because the Z3 is US made, there might be an explanation that for the US market there was somekind of ruling or license to equip the four speed auto, and because of the small numbers, EU cars also got that transmission.

 

[Brian4]

Hi @BMW Z3 2.0 I have a year 2000 auto and it is fitted with the GM5L 40 auto box which is the steptronic box. I believe they fitred this box to the year 2000 onwards Z3 certainly in europe. It is the same box as fitted to the E39 5series. Bmw seem to have gone over to the ZF boxes now.

 

[DrWong]

Anyone had experience of both Steptronic and manual? I’d be interested in how quickly the auto accomplishes the shift itself compared to doing it manually.

Because, you know, race car driver an all that..

 

[BMW Z3 2.0]

@Brian, My topic was only for the Z3 m52TU. All M54 got the fivespeed Steptronic.
@DrWong: The steptronic handshifting option in the Z3 five speed automattic is funny for a few miles but it is still an 'auto-shift' experience. You cannot compare it to a smg type of shifting. If you would like to shift yourself in a Z3, buy a manual.