Author Topic: 156 jts VDC  (Read 456 times)

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sportiva

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156 jts VDC
« on: April 01, 2020, 08:21:25 PM »
My Fiat Romeo 156 JTS has VDC, I have tested the system a few times and can varifiy that it detects wheelspin and cuts power to the driven wheels during traction loss. If I turn it off and accelerate a little quickly on a wet road it acts like any old FWD car and goes everywhere but straight ahead, if I turn into a roundabout with VDC off it just PLOUGH UNDERSTEERS. Then at the same rounderbout with VDC ON the car stutters and limps into a bowl of jelly and then finally gathers it self together and lets me drive it the rest of the way around the corner.
At no time do I feel that any brake vectoring is being applied.
So my question is does the Fiat Romeo 156 VDC system detect yaw and apply braking to the wheels to if it is needed.   
« Last Edit: April 01, 2020, 08:26:46 PM by sportiva »
3.0 GTV6 156JTS

75 2.5
2.0 Alfetta Sportiva #22
1.8 Alfetta
1.2 alfasud
2 75 parted out
15 alfettas parted
10 gtv parted
5 alfasuds parted
156 sele

bazzbazz

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Re: 156 jts VDC
« Reply #1 on: April 01, 2020, 08:27:42 PM »
I assume so, that is why it has a steering sensor under the steering wheel.
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2004 Alfa 156 2.0 JTS Sportwagon (Patty)
2000 Alfa 156 2.0 TS Selespeed with Sports Pack
(Eibach 2.5 Lowering Springs)
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sportiva

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Re: 156 jts VDC
« Reply #2 on: April 01, 2020, 08:31:44 PM »
Fair point baz does the system apply braking to different wheels if activated.
I don't think so. I feel the system if activated  has a seizure shuts down power, then wakes up after the event and hands control or lack off it to whom ever has hold of the steering wheel.
« Last Edit: April 01, 2020, 09:00:19 PM by sportiva »
3.0 GTV6 156JTS

75 2.5
2.0 Alfetta Sportiva #22
1.8 Alfetta
1.2 alfasud
2 75 parted out
15 alfettas parted
10 gtv parted
5 alfasuds parted
156 sele

bazzbazz

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Re: 156 jts VDC
« Reply #3 on: April 01, 2020, 09:46:26 PM »
Do understand the VDC system on the 156 is a very early example of the systems incarnation.

Comparing it to say the system on the latest Guilia is like comparing a Gloster Gladiator with an F-16.  ;D
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2004 Alfa 156 2.0 JTS Sportwagon (Patty)
2000 Alfa 156 2.0 TS Selespeed with Sports Pack
(Eibach 2.5 Lowering Springs)
(Bilstein Sports Dampers )

Craig_m67

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Re: 156 jts VDC
« Reply #4 on: April 02, 2020, 11:32:56 AM »
Yes, it absolutely brakes the relevant wheel to correct skids/slips etc.

I found this out to my amusement on Sooty (1.9JTD Sportwagon, still lives) after replacing the steering wheel and clock spring incorrectly (1 spline out).  She would drive down the road perfectly for about ten metres (straight), then as soon as I turned the wheel even slightly, she would rapidly pulse brake the opposite side of the car, get really upset (beep, beep, beep) and then tell me that the VDC was turned off (centre display)

Was hilarious fun for about 5minutes.
Did demonstrate that it worked though whic was kinda cool.

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sportiva

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Re: 156 jts VDC
« Reply #5 on: April 02, 2020, 04:25:16 PM »
baz
yeah I realize it is an early system and when I did deliberatly force the car to act on my behalf and I did it more than once, the power was cut and the car dropped enough engine revs that I needed a lower gear (manual) to be able to pull away safley . I figured I could do better if I just back off and adjust the steering and throttle input myself, but I also knew that when I did push the car hard into my test roundabout I was above the cars normal level of ability, I did it to understand what happens when the VCD does intervene. My chosen rounabout is a large 3 lane job and I do it at 3 in the morning on the way to work and at or below the speed limit I'm not being a d!/K head when testing the limits of my 15 year old 156 .

Thanks Craig nice story of learning as you go.
« Last Edit: April 02, 2020, 06:01:20 PM by sportiva »
3.0 GTV6 156JTS

75 2.5
2.0 Alfetta Sportiva #22
1.8 Alfetta
1.2 alfasud
2 75 parted out
15 alfettas parted
10 gtv parted
5 alfasuds parted
156 sele

poohbah

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Re: 156 jts VDC
« Reply #6 on: April 02, 2020, 05:39:32 PM »
One of the good things about series 1 cars is no VDC...

Only time I've really been "inconvenienced" is trying to negotiate a large diameter two-lane roundabout at +50kph in heavy rain. In which case, yeah it does just plough straight on  :D
Now:    1999 156 V6
             1981 GTV
Before: 2001 156 V6 (sadly cremated)

warsch

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Re: 156 jts VDC
« Reply #7 on: April 22, 2020, 10:13:58 AM »
What works for the platform to battle understeer is to lift of accelerator or even tap the brakes in the corner.