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      12-14-2011, 05:07 PM   #80
NTTY
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Drives: 135i (E82)
Join Date: Jul 2009
Location: Switzerland

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Quote:
Originally Posted by Drivaar View Post
Damn, impressive downshifting... I'm curious to see the tech specs of the new transmission versus the old 6-speed ZF (which for many years seems to have been the best non-DCT auto transmission out there...)
Hi,

ZF 6HP Second generation specs (like the 6HP21 installed on 135i/335i) are:
- upshifting = 300ms
- Downshifting (tractive mode) = 80ms
- Downshifting (coasting mode) = 200ms
- Kickdown = 80 ms

Source ZF: http://appsprod01.zf.com/zf.productD...n_EN_2006s.pdf

And a little comparison:



From this document: http://www.apra-europe.org/dateien/d...chatronics.pdf

Note: with latest software upgrade, BMW improved a lot the upshifting of the 6HP, by letting the engine rev a bit more when upshifting. Also, the engine electronics gives a lot of gaz when downshifting in coasting mode to simulate a tractive mode, which makes all downshiftings really quick. No source for this information, just my personal experience with my car.

ZF 8HP specs:
- upshifting = 200ms
- Downshifting (tractive mode) = N/A
- Downshifting (coasting mode) = N/A
- Kickdown = N/A

Source: ZF WebSite

From my initial tests of the new ZF8HP in the new F20, I can't really make a difference in upshifting or downshifting speeds compared to my 6HP.

The new 8HP is very interesting because the first 6 speeds are really shortened, which improves a lot accelerations.

Anyway, whatever is the gearbox (Getrag DKG or ZF auto), BMW always finds a way to improve a lot the driving experience (the DKG in the M3, and even with the N55 engine is just a beast, while all other double clutch gearboxes are boring).

Cheers.
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Last edited by NTTY; 12-14-2011 at 05:22 PM.
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