964Andrew

Watching Doug DeMuro video on the 959. In it he shows the torque split ratio gauge in place where the clock would be in a 964. It got me thinking, if the two cars 959 and 964C4 are closely related in terms of the all wheel drive system, would it be possible to see the torque split percentage in a 964C4? I read somewhere (maybe on Rennlist) about methods to connect one of the spare bulbs to show when the PDAS system activates the front wheels. If that is possible maybe the torque split "%" is also available though one of the behind dash connectors?



Anyone explored that before?

Thanks!
Andrew

velocitylover

onceover

I cant imagine what one of those gauges is worth...

964Andrew

Surprisingly not insanely expensive, in line with what I expected really: https://www.pelicanparts.com/cgi-bin...&I1.x=0&I1.y=0

Thanks!
Andrew

964Andrew

Link to 959 Parts Catalog for those interested - https://www.dropbox.com/s/mhxnlj36it...01988.pdf?dl=0

Thanks!
Andrew

Bigsix964

That's got some impressive distance on the odometer for what it is.

Goughary

I would love to have a gauge setup. Not sure if i would get rid of my clock...but this is interesting.

Any thoughts on how to set up a gauge for the system? Or to make this conversion?

964Andrew

I will be digging in to this shortly.

Thanks!
Andrew

spartansix

I am guessing that this gauge is essentially measuring pressure to the longitudinal and lateral differential locks, same as the two pressure gauges in the C4 Leichtbau.
The lights indicate different traction modes - I assume these are different settings for the aggressiveness of the lock engagement given a specific accelerometer input.
I expect that this requires a different ABS/PDAS controller since the C4 Leichtbau (based on a 964) used 2 master cylinders and 2 sets of pressure valves/gauges to achieve the same end - if it were possible to plug in this gauge or have the PDAS controller switch between dry/wet/snow settings using a single brake fluid reservoir like in the 959, I'm sure Porsche would have done this to avoid having to engineer a new solution (and maybe save extra weight) on the Leichtbau.

964Andrew

Quite possibly you are right. I thought thou the C4 Leichtbau had the gauges inline with the proportioning valves for manual adjustment so they possibly were analog and only displaying the current driver set pressure bias. The 959 look to be all electric based on their behavior in the video. I will dig in to the electrical system of the 959 and see if I can find any similarities.

Thanks!
Andrew

JasonAndreas

If you disabled the PDAS on the control unit you could probably hook up two lutron dimmer switches to control everything...

Goughary

Whoa.

-nick

Bigsix964

This is becoming a fascinating read. The more I go over about the AWD / PDAS the more I realize I need education on it. I have a few questions:

Google search of the related keywords yields a Streather PDF as first result. I’m aware of the controversy surrounding his literature by now, but I’d assume this at least is largely accurate:

“The PDAS is a non-integral electronically controlled………system utilises the AWD G64 transmission….system failure has no affect on the normal operation of the permanent AWD. The PDAS is activated and de-activated only when required to assist….developed from the mechanically variable differential drive control system used in the Porsche 959…”

So the bold indicates that a C4 experiencing PDAS malfunction will simply have a static split of the normal 69/31 R/F during a corner spin / stuck in mud etc.. This is my first source of confusion because there’s then something more permanent (mechanical) maintaining the R/F split regardless of the PDAS input.

Assuming some recreation was indeed possible, would Jason’s lutron dimmer concept practically open the door for C4 owners to dime the longitudinal adjustment and send 100% to the rear wheels (“switchable” C2) while the front system rolled along as an idler? Or is that laughably oversimplified? I suppose that wouldn’t be too great anyway as far as drivetrain loss but it is fun to think about. I can certainly understand why one would not want to lock the lateral adjustment as that would equate to driving a 4wd car on dry roads and the associated damages to the tires, drivetrain etc…

Or am I misunderstanding the principle behind installing manual articulation as the permanent split would not be affected? I.e. I don’t totally understand whether or not harnessing these adjustment parameters would allow for personal long term settings or just “My rear wheels are stuck so I’m going to flip the assist on instead of the ECU doing so”?

In a C4 Lightweight, how interactive would someone racing the car be with the manual adjustments? Would they, for example, be reaching down and manipulating it in real time or simply using it to trial different settings? That may seem like a stupid question. Two hands on the wheel etc. but I cannot completely envision how those would be utilized because I haven’t seen cars with it in action.

Sorry for the long post.

964Andrew

For the 959 gauge to work it has to be driven by ABS control unit because the ECU's are completely different.


Without the 959 electrics manual it is impossible to know for sure, I think I will start gathering some signals with a multi-meter.

Thanks!
Andrew