Hey All,

Trying to get my head around something,

If you have an LSD front diff e.g cusco or wavetrac etc. Does the ACD system even do anything? or does the LSD override the clutches and does what it wants?

 

The front diff manages the slip left and right of the front axle, while the acd manages slip between the front and rear axles

 

I see, Is there a way to just pressurise the clutch packs and leave it locked up all the time or something then?

 

So heres the things I know from customers, friends, or direct experience.

1) With a wavetrac front and TRE rear diff, a disabled ACD (bad tune file) makes the car nearly un-driveable on track. One end gives up and in an unpredicable way. You may get snap understeer or snap oversteer. And once it starts, its hard to catch. Things just go bad fast and it was basically something you could not aggressively drive on track.
2) Just swapping in a VCU will control that, and does a pretty good job at it.
3) With a torsen front, you may see crazy wheel speeds on an inside front on corner exit that a VCU cant keep up with. Even an ACD may not keep up with it or in my case with a fully broken front diff may actually break ACD disks.
4) You cant guess at what the ACD is doing based on the maps. We can adjust maps with an idea towards what it should do but we still dont fully know all the interactions with slip or how maps are selected. You'll need to log pressure at the diff to understand how much lockup is being applied at any given time.
5) People have gone really fast on a VCU but hypothetically the ACD has an advantage.

 

If you did that you would basically be converting it from AWD to something more like a 4x4 and like a 4x4 (in 4x4 mode) you would not be able to go very fast and handling would also suffer.

 

i see. Damnit, trying to work out this bloody ACD fault after re wiring it. stupid thing wants a signal to come from the ABS Ecu for 5 seconds. Wish i could get it disabled inside the ecu or something with a bench flash

 

How did you rewire it? Did you get the wheel speed sensors wired into the ACD?

IIRC, there are some old threads on here about ACD with ABS delete. The 06 RS models shipped without ABS, so it's doable.

 

Yup it used to work when i had a plug in ecu without abs i had to make a special box up tho to simulate abs voltage.

Ive got a couple ideas to try.

All the wheel speed sensors are correct etc

 

06 RS doesn't come with ABS but it does have wheel speed sensor for ACD. i dont know how ACD can manage to function properly if you send it fake wheel speed signal.

 

You dont send it fake wheel speed signals. The wheel speed signal goes from sensor to ABS ecu to ACD. U got to take the wire from the ABS plug and cut it and route it directly into the ACD ecu.

Ive also discovered u need to earth the ACD to ECU idle detect pin and swap the pin49 ABS ecu detect wire to pin 50 and ground it