Haldex gen: 5

[Steaman]

Has anyone noticed any improved response time in the Haldex quattro system with generation 5 (A3 2017 and later)?

The decision-making for the BorgWarner (Haldex V) all-wheel-drive system’s electronically controlled multiplate clutch is now handled by the same electronic brain as the stability control, traction control, ABS, and more.

source: http://www.caranddriver.com/reviews/2017-audi-s3-sedan-first-drive-review

 

[paradigital]

It is quick to respond, I've had the rear end step out when pulling out of damp T-junctions.

I'm still interested in changing the clamping values in VCDS though

 

[GSB]

The source material from Car & Driver is misinformed. They seem to suggest that some critical change in the AWD architecture has taken place with the facelift, yet the facelift is using exactly the same Heneration 5 Haldex hardware that has been in the 8V since launch.

What won't have changed then, is the response time in the hardware. And since the decision making is still handled the same way by the same processors connected to the same CANbus it's been connected to since 2012, that won't have changed either. What has changed though is the tuning of the system. The facelift now offers three selectable modes, that tend to put more or less torque transfer into the rear axle, much greater ramp rates, when you cycle through Comfort - Auto - Dynamic.

 

[Steaman]

The hardware response time is only 60 milliseconds and is not limiting the performance. I thought the communication related to the Powertrain was done over the Flexray Bus, not the slow Can Bus.

 

[GSB]

Wiring diagrams in Elsawin seem to indicate a canbus connection...

 

[Steaman]

The All-wheel drive controller and the ABS controller are connected to Flexray (10 Mb/s ) and Powertrain CAN ( 500 Kb/s ), at least on A7 4G.

 

[GSB]

The All-wheel drive controller and the ABS controller are connected to Flexray (10 Mb/s ) and Powertrain CAN ( 500 Kb/s ), at least on A7 4G.

Just CAN on the lowly A3 by the look of it.

 

[Steaman]

But it is not that bad, there are a number of separate CAN bus "tracks".

The suspension Can Bus only handles Suspension, All-wheel Drive, Steering, Parking and ABS. Would be interesting to know the speed on the Suspension CAN Bus high.

 

[paradigital]

To be fair, the bandwidth of the bus is irrelevant, the amount of data transmitted and received by the various powertrain components won't need anywhere near that 0.5Mb/s.

Bandwidth does not translate to latency in any way unless the bus is saturated (which it won't be).

 

[AndyKnight]

I found this quite interesting.

 

[Steaman]

To be fair, the bandwidth of the bus is irrelevant, the amount of data transmitted and received by the various powertrain components won't need anywhere near that 0.5Mb/s.

Bandwidth does not translate to latency in any way unless the bus is saturated (which it won't be).

I fully agree, but the bandwidth gives the overall capacity and combined with type and amount of controllers can indicate if latency can be expected.