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CatmanV2

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48,543
Quick question on the ZF gearbox in my car. I’ve noticed that when in manual mode on initial throttle application in all gears there is a sensation that feels like clutch slip for about half a second after throttle application. I know it’s not a clutch as such as it’s a traditional 6 speed auto but having had similar slush boxes before I haven’t noticed similar behaviour. Say I’m in second gear at 2500 rpm with a steady throttle and then quickly increase throttle, the revs jump a few 100rpm and then drop back down a little and then the car starts to accelerate as drive is “taken up”. I would expect once in gear that engine speed and road speed would be “locked” once your rolling.

Not a big deal but normal?

Probably not a lot to worry about, but how many miles on it?

C
 

c4sman

Member
Messages
1,243
Do a battery reset and then take it for a good drive to adapt to your own driving style.
Interesting. Will give it a go. Does that mean it softens the response because I’ve been driving it so gently (which I have to admit I have :D ). The car is booked in on Monday for a front end plus PPF, so I haven’t really been going quickly to minimise any new stone chips until I get it back, which is why it may have assumed I’m a bit of a lightweight and added extra “slush” to the box!
 

philw696

Member
Messages
25,113
Interesting. Will give it a go. Does that mean it softens the response because I’ve been driving it so gently (which I have to admit I have :D ). The car is booked in on Monday for a front end plus PPF, so I haven’t really been going quickly to minimise any new stone chips until I get it back, which is why it may have assumed I’m a bit of a lightweight and added extra “slush” to the box!
Modern auto transmission's are very complex pieces of kit not like a Borg Warner from the 70's anymore.
 

Gazcw

Member
Messages
7,696
Quick question on the ZF gearbox in my car. I’ve noticed that when in manual mode on initial throttle application in all gears there is a sensation that feels like clutch slip for about half a second after throttle application. I know it’s not a clutch as such as it’s a traditional 6 speed auto but having had similar slush boxes before I haven’t noticed similar behaviour. Say I’m in second gear at 2500 rpm with a steady throttle and then quickly increase throttle, the revs jump a few 100rpm and then drop back down a little and then the car starts to accelerate as drive is “taken up”. I would expect once in gear that engine speed and road speed would be “locked” once your rolling.

Not a big deal but normal?
Cannot say I noticed that before in my qp.
 

Oneball

Member
Messages
11,071
Quick question on the ZF gearbox in my car. I’ve noticed that when in manual mode on initial throttle application in all gears there is a sensation that feels like clutch slip for about half a second after throttle application. I know it’s not a clutch as such as it’s a traditional 6 speed auto but having had similar slush boxes before I haven’t noticed similar behaviour. Say I’m in second gear at 2500 rpm with a steady throttle and then quickly increase throttle, the revs jump a few 100rpm and then drop back down a little and then the car starts to accelerate as drive is “taken up”. I would expect once in gear that engine speed and road speed would be “locked” once your rolling.

Not a big deal but normal?

It is actually a clutch. Most autos for the last 20 years have a torque converter that can be locked solid with a clutch. Not sure why but in the more modern ones this isn’t just on/off as it used to be but controlled by the ecu to give some slip. I’d suggest that’s what you’re experiencing.
 

c4sman

Member
Messages
1,243
It is actually a clutch. Most autos for the last 20 years have a torque converter that can be locked solid with a clutch. Not sure why but in the more modern ones this isn’t just on/off as it used to be but controlled by the ecu to give some slip. I’d suggest that’s what you’re experiencing.
Really need to fix my somewhat sedate driving style after a reset!
 

Alan Surrey

Member
Messages
990
My 2008 QP with ZF gearbox does something a bit like this too:
In gears 4, 5 and 6 it behaves as if the clutch is fully engaged almost all of the time - it feels like metal all the way from the engine flywheel to the wheels within tens of milliseconds of a gear change. Lovely to my way of thinking.
Gears 1, 2 and (I think) 3 are quite different - it feels like an old fashioned torque converter automatic (well, we know it has a torque converter fitted, though perhaps we expected it to be managed differently to this by the electronics) Revs seem to be proportional to the acceleration required. I can live with this, especially around town, below 40 mph, when this behaviour seems to be most prevalent, but it is not really what I would prefer.
Well, that is how mine seems to behave.
 

c4sman

Member
Messages
1,243
My 2008 QP with ZF gearbox does something a bit like this too:
In gears 4, 5 and 6 it behaves as if the clutch is fully engaged almost all of the time - it feels like metal all the way from the engine flywheel to the wheels within tens of milliseconds of a gear change. Lovely to my way of thinking.
Gears 1, 2 and (I think) 3 are quite different - it feels like an old fashioned torque converter automatic (well, we know it has a torque converter fitted, though perhaps we expected it to be managed differently to this by the electronics) Revs seem to be proportional to the acceleration required. I can live with this, especially around town, below 40 mph, when this behaviour seems to be most prevalent, but it is not really what I would prefer.
Well, that is how mine seems to behave.
Thanks and Interesting, have you tried the suggested battery reset?
 

Tallman

Member
Messages
1,833
I had a feeling of slippage on pulling away, sometimes in a corner. I spoke to the dealer and he suggested it was maybe the clutches in the diff. I also asked him about replacing fluids, he said that should normally not be necessary until about 50k miles for the gearbox and even longer for the diff (ZF, 2012 4.7) My car only has about 18k miles So it shouldn’t be that, I do wonder what is could be then though..

This ZF is also used in BMW and a host of other high performance cars, so there should not be any Italian gremlins to blame..

https://en.wikipedia.org/wiki/ZF_6HP_transmission#6HP26
 

Tallman

Member
Messages
1,833
I had a feeling of slippage on pulling away, sometimes in a corner. I spoke to the dealer and he suggested it was maybe the clutches in the diff. I also asked him about replacing fluids, he said that should normally not be necessary until about 50k miles for the gearbox and even longer for the diff (ZF, 2012 4.7) My car only has about 18k miles So it shouldn’t be that, I do wonder what is could be then though..

This ZF is also used in BMW and a host of other high performance cars, so there should not be any Italian gremlins to blame..

https://en.wikipedia.org/wiki/ZF_6HP_transmission#6HP26
Just to add, he reckoned the clutches of the diff shouldn’t really be the issue, they last a VERY long time - also they use synthetic oils so those should not break down.
 

Ebenezer

Member
Messages
4,443
It hasn't been mentioned for quite a while now, but there used to be a lot of grumbling about the "take off" from stationary being hesitant with the ZF, and especially causing concern at roundabouts if you wanted to slot confidently into the traffic stream.

The answer was the FD DBW, which although doesn't mess with the ZF gearbox ecu, gives a more positive start and faster gear changes by tricking the ecus into thinking that the engine revs are higher than they actually and adjusting the gear changing accordingly. Of couse I may have completely misunderstood the whole thing and it could be snake oil!

I have had the DBW for the ZF for more than 6 years now so can't remember what it's like to drive without it.

Eb
 
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c4sman

Member
Messages
1,243
PPF first! I picked up a lovely stone chip shortly after deciding to get the front PPF’d.
That’s annoying. It goes in Monday and has been confined to the garage for quite a few days just in case. Hoping for an uneventful trip to the detailer tomorrow morning :oops: