Cobb Custom Features: Ford TransBrake Tuning Guide (18-19)

Table of Contents

Applicable Vehicle:

Mustang EcoBoost (AT Only)
- 2018 - 2019

Available On:

AccessTuner and AccessTuner Pro HL
- After version 2.0.0.0-15966
OTS Maps
- Maps post V401

How to Use COBB Transmission Brake and Bump Box

COBB Custom Features: Ford EcoBoost Mustang Transmission Brake and Bump Box

Overview

Introduction:

The transbrake feature is an excellent tool for launching the AT (10R80) equipped EcoBoost Mustang. By simultaneously applying line pressure to both the reverse and 1st or 2nd gear clutch packs, the vehicle is held stationary. This allows the driver to depress the accelerator pedal to not only build engine speed, but also to get the engine loaded up and the turbo spooled for a full-power launch. This feature creates a lot of stress on the entire driveline when used, and should be used at the owner's risk.

We also have two staging control features: Bump mode and Creep mode. Those familiar with our transbrake and bump feature present on the '15-'17 EcoBoost Mustang will recognize bump staging - this will temporarily disengage the transbrake while loaded to allow the vehicle to move forward. Creep mode is a new feature that we have introduced into the '18+ EBM 10R80 calibration - this will slowly move the car forward for staging purposes, but will be less bouncy than Bump mode.

How to Use Transbrake:

Bring the vehicle to a complete stop, with your foot on the brake. Move the shifter into either 'D' or 'S'.
With your foot still on the brake, depress and hold the left paddle shifter. After one second, remove your foot from the brake. The vehicle will remain stationary.
Still holding the left paddle, depress the accelerator pedal. Load will increase with greater pedal position.
When ready to launch, simply release the left paddle. The vehicle will then begin accelerating.

How to Use Bump:

On the Accessport, navigate to the 'Tune' menu, and select 'Adjustments'. In this sub-menu, select 'Staging Control'. Toggle staging control such that 'Bump' mode is active.
Engage transbrake and depress the accelerator pedal (see 'How to Use Transbrake').
When you're ready to stage, continue holding down the left paddle, and depress the right paddle. The car will 'bump' forwards.
If you have not staged far enough, hit the right paddle again to bump. Continue until you are staged appropriately.
When fully staged, release the left paddle to launch.

How to Use Creep:

On the Accessport, navigate to the 'Tune' menu, and select 'Adjustments'. In this sub-menu, select 'Staging Control'. Toggle staging control such that 'Creep' mode is active.
Engage transbrake and depress the accelerator pedal (see 'How to Use Transbrake').
When you're ready to stage, continue holding down the left paddle, and depress and hold the right paddle. The car will 'creep' forwards for as long as you hold the right paddle.
If you have not staged far enough, continue holding down the right paddle. Let go of the paddle when you are staged appropriately.
When fully staged, release the left paddle to launch.

ATP Configuration

Load Target:

We have created a custom transbrake-specific load targeting system to offer ultimate launching control without influencing power available while driving. When transbrake is engaged, and accelerator pedal position has exceeded the table value for 'Transbrake Load Target Pedal Threshold', load targets will be hijacked by the custom transbrake load target.

The default value and OTS calibration value for this pedal threshold is 40%. This means that while transbrake is engaged and APP is between 0% and 40%, load control will be handled as it normally is while driving via throttle requested torque, load limits, etc. Above 40% APP, the load target values will be replaced by those found in the tables 'Transbrake Load Target (1st Gear)' or 'Transbrake Load Target (2nd Gear)', depending on the currently selected gear.

While this load target hijack is active, you will see Airflow Limit Src. = 5 (LSPI) and Load Desired (TQ Control) will reflect the load limit from these tables. Notice that these tables have an axis of APP - this will allow you to modulate engine load when launching to adjust for variable traction conditions.

In addition to modulating engine load via APP, the Accessport has a load offset adjustment that will allow the user to increase or decrease load when launching. The minimum and maximum values for adjustment can be found in 'Transbrake Load Target User Adjust (Max)' and 'Transbrake Load Target User Adjust (Min)'. The functionality of the AP adjustment will be covered later in this guide.

Consider an example:

The user is launching in 1st gear, so load targets will come from the table 'Transbrake Load Target (1st Gear)
APP is 100%

With no load offset changes, Load Desired (TQ Control) will be 1.600%.

If the user adjusts the load offset to its maximum of +0.500%, Load Desired (TQ Control) will be (1.600+0.500) = 2.100%

If the user adjusts the load offset to its minimum of -0.500%, Load Desired (TQ Control) will be (1.600-0.500) = 1.100%

Safety Thresholds:

In order to avoid unneccessary drivetrain abuse, we have created a handful of safety factors to either inhibit or exit the transbrake feature. You will be able to tell that a safety has been triggered when RPM is limited to 1000RPM to decrease engine load; the transbrake will continue holding the car stationary until the left paddle is released. You can also rely on the monitors Transbrake Safety Source and Transbrake Inhibit Source to identify the safety that was triggered. The safety source will indicate the

Active Time: when transbrake is engaged, a timer starts; when that timer exceeds the value found in this Active Time (Max) table, the safety system will be triggered.
1. Default Value: 10 seconds.
Clutch Slip: when transbrake is engaged, the ECU will continuously monitor the slip of the reverse clutch pack. If clutch RPM exceeds the value found in this Clutch Slip (Max) table, the safety system will be triggered.
1. Default Value: 50 RPM
Engine Coolant Temperature: ECT (Min) and (Max) tables determine the active range for transbrake. If ECT is outside of this range either before transbrake is engaged, or falls outside of this range while transbrake is engaged, the safety system will be triggered.
1. Default Min: 150*F
2. Default Max: 240*F
Transmission Fluid Temperautre: TOT (Min) and (Max) tables determine the active range for transbrake. If TOT is outside of this range either before transbrake is engaged, or falls outside of this range while transbrake is engaged, the safety system will be triggered.
1. Default Min: 125*F
2. Default Max: 239*F
Knock Count: if the cumulative knock count total across all cylinders exceeds the count found in this table while transbrake is active, the safety system will be triggered.
1. Default Value: 2 knock counts.

Staging Control:

Staging control configuration can be split into two separate categories: Bump and Creep.

Bump control is pretty simple - you have a realtime table controlling the duration of the bump (Transbrake Bump Time), and a table that controls bump ramp out (Transbrake Bump Ramp Out Time). Bump ramp out an important factor for avoiding the sort of violent rocking back-and-forth that can happen on a conventional bump system. This ramp out time will slowly decay the line pressure change back into a fully-stopped transbrake. Even with this, the vehicle will rock basically no matter what when bumped.

Creep mode has more complex control. The core of the system is the Transbrake Creep Slip Target. This is an RPM target for slip on the reverse clutch pack. When creep is activated, line pressure to the reverse clutch pack is decreased to permit slip. There is a base, feed-forward pressure table as well as P and I controls. The PI system will account for control over error between slip target and slip actual.