Disabling The Torque Vectoring Brake System (TVC)

Discussion in 'Fiesta ST Road Racing' started by McRib 1s Back, Aug 4, 2014.

  1. McRib 1s Back

    McRib 1s Back Well-Known Member

    Until my last track day at WSIR, I hadn't really noted the need to disable the brake-system based "torque vectoring" we have on our lovely FiST. In fact, I thought it was kinda cool for the street.

    This conversation is now about a dedicated track car. Now that I run stickier R compound tires, have the suspension more or less dialed-in with coilovers, etc., I think I've bumped into some pretty unnatural feeling stuff with this system.

    While I have noticed it plenty in the past, it was never weird. Now it only seems weird and steps in when I'd rather it just kept out completely! To be clear, I always run with the stability system turned off. The first time this happened, I thought it was left in "on/sport". It wasn't.

    I had the benefit of back-to-back sessions, with another driver. My co-driver agreed. Really, I was relieved he saw it the same way. He's the better driver, and has way more track/race time than I have (and is a Time Attack Champion with his built 350Z, but is fast in any car!).

    What do you guys think? I've added this to my list of stuff to do, but haven't sorted out exactly what I'll do to disable it. I'd imagine a fuse/relay removal would be the least intrusive. A brief read on the Focus forums turned up a story about "sensor removal" (and "more understeer"). I'm not worried about that. On a final note, I'll say that I've read that our system is considered a second generation version of the system that a Focus has (meaning stuff there may or may not prove useful on our FiST).
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  3. RodMoe

    RodMoe Well-Known Member

    Ken from Mountune had mentioned a possible MR tunes with Torque Vectoring adjusted to work with a Quaife LSD so it is possible you must just have to find the right area to massage..
  4. Cligedy

    Cligedy Active Member

    I would expect that the system uses the same wheel speed sensors as the ABS. Pulling the ABS fuse would likely disable both systems.
  5. McRib 1s Back

    McRib 1s Back Well-Known Member

    I'm sure that would work, but I was looking for something less "brute force". ABS is actually useful on this car!

    This reminds me of the evolution ABS went through. In the early days (like the early 90s!), we'd disable it -- it just wasn't sophisticated enough to deal with varied conditions. Today, ABS is standard and simply works great. Even the cheapest cars have have multi-channel, mutl-wheel sensors that do a great job (even on the track). I recall reading about a test where a few modern cars were timed with/without in lots of conditions (GRM?). The conclusion was that modern ABS is a good thing (and better than most of us can manage to brake, even in the dry). Also, you don't risk flat-spotting your tires! Maybe we'll have similar conversations in the future about TVC! :)

    Okay, so I want to keep ABS and ditch our TVC. This might actually be easy, but since my car is still on the trailer, I haven't poked around much...
  6. Mr UFO

    Mr UFO Active Member

    Up here at Oregon Raceway Park we have TONS of elevation change and at the same time off cambered transitions. Where I really feel the TV get weird is going up hill, turning right and off camber. The car can't quite figure out what it's trying to do. It's so unnatural. Wish we had full off/off/off :)
  7. McRib 1s Back

    McRib 1s Back Well-Known Member

    Yes, indeed. Now that I'm sensitive to it, I can feel it in any sharp transition! Let's track this bugger down!
  8. McRib 1s Back

    McRib 1s Back Well-Known Member

    I ran this past Ken last night, and will see if Randy has any ideas about handling this through the ECU.
  9. sourskittle

    sourskittle Member

    On my G35 we would unplug the "yaw sensor". Since the car had no idea what the lateral force was on the car was, it couldn't/wouldn't make adjustments. This was for stability control ( the G35 uses the rear brakes to make the car turn just like the fist does, even with its VDC turned completely off). I realize the fist is mostly looking at wheel speed sensors for torque vectoring, but maybe disabling one of its inputs will shut down the whole system...
  10. sourskittle

    sourskittle Member

    I think our yaw sensor is right behind the rear seats, you can see it from the hatch area. Unless... I'm looking at something else, and I have no idea what it is , lol.
  11. Jeff

    Jeff New Member

    Tvc is a wheel speed sensor differential based brake application
  12. Joe Schmoe

    Joe Schmoe Member

    You don't want to go and start unplugging sensors without knowing how they are tied into the ECU. An unplugged yaw sensor might equate to no airbag deployment in an accident. No, I wouldn't rely on the SRS light to tell me something was wrong.
  13. sourskittle

    sourskittle Member

    The yaw sensor does not have any effect on the air bag, that is what the impact sensors in the front grill are for.

    But that is just an idea that may or may not work. I'm fine with this crappy E-diff thing right now.

    I know the G35 guys never had an issue with ABS or air bags when unplugging the yaw sensor. This being a newer car, maybe it won't be as kind.
  14. raamaudio

    raamaudio Active Member

    I hope the TVC can be tuned to optimally work with the Quaife since I have one installed. If not for the Quaife I would be looking into disabling it as well!
  15. McRib 1s Back

    McRib 1s Back Well-Known Member

    Thanks, I think this is a useful tip. I'm still interested in the least invasive way to disable TVC.

    Also for others that are concerned about adjacent systems -- remember, I'm doing this for a dedicated track car. I wouldn't recommend it for a street car. I have no need for airbags. The only system aid I'd like to keep is ABS!
  16. McRib 1s Back

    McRib 1s Back Well-Known Member

    That might be. I had a conversation with Randy about this, but my questions were centered around a way to fully defeat it -- and he didn't have anything to share about that.
  17. DSGMach395

    DSGMach395 New Member

    The air bags rely on the impact sensors and the accelerometer in the air bag control module; i know this because the company i work for makes the module. The yaw sensor used by the stability control system is typically in the EBCM. I believe it is made by continental, therefore the yaw sensor should be in the EBCM.

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