10.1 Transmission - ZF 8HP70 (845RE)¶
Type: 8-speed automatic transmission
Model: ZF 8HP70 (Chrysler 845RE)
Donor Vehicle: 2015-2019 RAM 1500 EcoDiesel 4x4
Torque Capacity: 520 lb-ft (factory), 700+ lb-ft (built)
Controller: Turbolamik TCU 2.0 with basic wiring harness
Adapter Kit: Custom (in progress)
Specifications¶
| Specification | Value |
|---|---|
| Manufacturer | ZF Friedrichshafen |
| Model | 8HP70 (Chrysler 845RE) |
| Donor | 2015-2019 RAM 1500 EcoDiesel 4x4 |
| Type | 8-speed automatic, 4WD |
| Torque Capacity | 520 lb-ft (stock) |
| Weight | ~225 lbs (dry) |
| Length | ~27.5" |
| Fluid Capacity | ~9 quarts (pan drop service) |
| Fluid Type | ZF Lifeguard 8 (or equivalent) |
Gear Ratios¶
| Gear | Ratio |
|---|---|
| 1st | 4.714 |
| 2nd | 3.143 |
| 3rd | 2.106 |
| 4th | 1.667 |
| 5th | 1.285 |
| 6th | 1.000 |
| 7th | 0.839 |
| 8th | 0.667 |
| Reverse | 3.295 |
Controller - Turbolamik TCU 2.0¶
Model: Turbolamik TCU 2.0
Variant: Basic Wiring Harness (CAN)
Product Page: Turbolamik TCU 2.0
Manual: Turbolamik Manual
| Specification | Value |
|---|---|
| Supported Trans | 8HP45, 8HP50, 8HP55, 8HP70, 8HP75, 8HP90, 8HP95 (Gen1/Gen2/Gen3) |
| Shift Speed | 50-150ms |
| Drive Modes | 8 configurable (Street, Race, Offroad, etc.) |
| CAN Protocols | ECUMaster, Haltech, AEM, Motec, MaxxECU, etc. |
| Transbrake | Yes |
| Virtual Clutch | Yes |
| Price | ~€1,880 (~$2,000) with basic harness |
Why Turbolamik over MaxxECU:
- Supports all 8HP generations (MaxxECU is Gen1 only)
- Works standalone with Cummins ECM (no torque reduction dependency)
- Proven ECUMaster CAN integration (compatible with PMU24)
- 10+ years development, not beta
Electrical Requirements¶
Power¶
| Circuit | Wire Gauge | Source | Destination | Notes |
|---|---|---|---|---|
| TCU Power | 14 AWG | PMU OUT16 | Turbolamik harness (1.8m) | 15A, CONSTANT (must stay on) |
| TCU Ignition | 18 AWG | Ignition bus | Turbolamik harness | Wake-up signal |
| TCU Ground | 14 AWG | Engine bay ground bus | Turbolamik harness | 700mm lead from harness |
Note: TCU power must remain active at all times - if power is cut before TCU goes to sleep, adaptations won't save.
CAN Bus Integration¶
| Connection | Wire Gauge | Source | Destination | Notes |
|---|---|---|---|---|
| CAN H | 20 AWG | Turbolamik harness | Cummins J1939 tap | Twisted pair with CAN L |
| CAN L | 20 AWG | Turbolamik harness | Cummins J1939 tap | Twisted pair with CAN H |
The Turbolamik communicates with the Cummins R2.8 ECM via J1939 CAN for:
- Engine RPM
- Throttle position
- Vehicle speed
CAN Tap Location: Same tap point as PMU24 and Dakota Digital (Cummins body harness)
Sensors & Inputs¶
| Sensor/Input | Type | Notes |
|---|---|---|
| Input Speed Sensor | Internal to trans | Hall effect |
| Output Speed Sensor | Internal to trans | Hall effect |
| Transmission Temp | Internal to trans | NTC thermistor |
| Range Sensor (BTSI) | Internal to trans | Gear position |
| Shifter Input | Electronic shifter | Kilduff (factory 8HP70 connector) |
| Brake Switch | Digital input | Unlock from Park |
Aux Outputs (TCU → Vehicle)¶
| Output | Function | Destination | Notes |
|---|---|---|---|
| Aux Out (Reverse) | 12V when shifter in R | PMU In 3 | Drives PMU OUT22 (Reverse Lights) |
| Aux Out (P/N) | 12V when shifter in P or N | Starter P/N interlock relay | Required gate for cranking the engine |
| J1939 broadcast | Gear position, trans temp, mode | BIM-01-2 J1939 → HDX GEAR | Shares Cummins J1939 bus |
Shifter¶
Model: Kilduff 8HP70 / 8 Speed ZF Shifter for Swaps
Finish: Red with Skulls
Product Page: Kilduff 8HP70 Shifter
| Specification | Value |
|---|---|
| Dimensions | 10" L × 4.5" W × 5" H |
| Handle Height | 11" (tallest) |
| Type | Electronic (no cables) |
| Positions | P-R-N-D, +/- manual |
| Connection | Factory 8HP70 connector |
| Mounting | Center console |
Manual Mode (+/-): Allows manual gear selection for rock crawling, engine braking on descents, and technical terrain.
Wiring: Electronic shifter connects directly to transmission controller. No shift cables required.
Drive Mode Switch¶
| Specification | Value |
|---|---|
| Type | Rocker switch (SPDT or 3-position) |
| Location | Dash rocker switch panel |
| Connection | Transmission controller mode input |
| Position | Mode | Use Case |
|---|---|---|
| Up | Sport | Higher shift points, firmer shifts |
| Center | Normal | Daily driving, highway |
| Down | Tow/Haul | Engine braking, grades, towing |
Wiring: Low-current signal wires from rocker switch to transmission controller mode input pins. Exact pinout depends on controller selection (Compushift vs US Shift).
Cooling¶
| Component | Notes |
|---|---|
| Trans Cooler | External cooler recommended |
| Cooler Lines | -6 AN or factory hard lines |
| Thermostat | 180°F bypass thermostat recommended |
Adapter & Bellhousing¶
| Component | Source/Part Number | Notes |
|---|---|---|
| Adapter Kit | Custom | R2.8 to 8HP70 (in progress) |
| Flexplate | Adapted from AX15 kit | R2.8 to 8HP70 (custom adapter) |
| Pilot Bearing | TBD | If required |
Outstanding Items¶
- Order Turbolamik TCU 2.0 with basic wiring harness
- Install Turbolamik TCU on 8HP70 mechatronic (soldering required)
- Route TCU power from PMU OUT16 (14 AWG, CONSTANT)
- Connect TCU CAN to J1939 bus (same tap as PMU/Dakota Digital)
- Install Kilduff shifter in center console
- Wire drive mode rocker switch (dash panel) to TCU mode inputs
- Complete custom adapter kit for R2.8 to 8HP70
- Complete flexplate adaptation from AX15 kit
- Determine transmission cooler size and routing
Related Documentation¶
- Transfer Case - NP241OR connection
- PMU Inputs - J1939 CAN bus tap
- Cummins R2.8 - Engine CAN integration