Why Your T2 Loses Vacuum After EV Conversion
The original VW T2 relies on engine intake vacuum to power its brake booster. When you remove the internal combustion engine and install an electric motor, that vacuum source disappears completely.
Without vacuum assist, the brake pedal becomes extremely stiff — dangerously stiff. You need at least 18–22 inHg of vacuum at the booster to maintain the original pedal feel and stopping power.
The solution: an electric vacuum pump system that reproduces the vacuum your T2's factory brake booster expects.
Two Vacuum Braking Solutions Compared
| Solution | How It Works | Pros | Cons | Best For |
|---|---|---|---|---|
| Electric Vacuum Pump + Reservoir | 12V pump creates vacuum stored in a reservoir; feeds factory brake booster | Preserves stock pedal feel, cost-effective, easy to source, simple wiring | Requires mounting space for pump + reservoir; pump noise | Most T2 conversions |
| Electric Brake Booster (Vacuum-less) | Replaces factory booster with electrically actuated unit | No vacuum system needed; compact | Expensive, complex integration, different pedal feel | High-budget builds with custom pedal boxes |
For nearly all VW T2 conversions, the electric vacuum pump + reservoir approach is the practical choice.
CMVTE Vacuum Pump Options for VW T2
1. GMT 12V Electronic Vacuum Pump (Recommended)
The GMT 12V Electronic Vacuum Pump is designed specifically for EV conversions. Key specs:
- Voltage: 12V DC (matches T2 auxiliary system)
- Application: 2–5 ton vehicles — perfect for T2 (approx. 1.5–2 ton)
- Durability: High IP rating, designed for continuous EV duty cycles
- Includes: Vacuum pump, pressure sensor, mounting bracket
- Compatibility: Works with factory VW T2 brake booster and master cylinder
2. 12V Vacuum Pump Booster (Compact Alternative)
The 12V vacuum pump booster is a more compact unit suitable for tighter spaces. It provides brake assist for EVs where the original vacuum source is removed.
Key Specs: What to Look For
| Parameter | Requirement for VW T2 | Why |
|---|---|---|
| Voltage | 12V DC | T2's original electrical system and EV DC-DC converter both output 12V |
| Vacuum Level | 18–22 inHg | Factory VW T2 brake booster requires this range for proper assist |
| Reservoir Size | 1–1.5 liters | Provides reserve for 2–3 brake applications after pump stops |
| Duty Cycle | Frequent / continuous | EVs cycle the pump more than ICE vehicles (no constant engine vacuum) |
| IP Rating | IP67 or better | Underside-mounted pump must resist moisture, dust, road grime |
T2-Specific Installation Guide
Mounting Location
The VW T2 engine bay (now empty after EV conversion) offers ample space. Recommended mount locations:
- Original engine bay floor — secure with rubber vibration-damping mounts
- Battery tray area — if the HV battery is under-floor, use the former engine bay side wall
- Under the rear seat — for Westfalia camper conversions with rear-mounted batteries
Wiring
- Power the pump from the 12V auxiliary battery or DC-DC converter output
- Use a pressure sensor + relay to auto-activate the pump when vacuum drops below the threshold
- Connect the vacuum line from the reservoir to the brake booster's existing vacuum port
- Ensure your DC-DC converter can handle the pump's peak current (~10–15A)
Noise Dampening
Electric vacuum pumps produce a noticeable hum. To maintain the quiet EV experience:
- Mount the pump on rubber isolation bushings
- Use braided vacuum hose to reduce vibration transmission
- Consider placing the pump in a ventilated but sound-dampened enclosure
Pneumatic Diagram
The basic layout:
Vacuum Pump → Check Valve → Vacuum Reservoir → Vacuum Switch/Sensor → Brake Booster
↓
Pressure Sensor (triggers pump ON at ~18 inHg, OFF at ~22 inHg)
FAQ
Can I keep my original VW T2 brake booster?
Yes. The electric vacuum pump system is designed to work with your factory T2 brake booster and master cylinder. This is the simplest and most cost-effective approach.
How long does the vacuum reserve last if the pump fails?
With a 1–1.5 liter reservoir, you have enough vacuum for approximately 2–3 full brake applications — enough to stop safely. This is why a properly sized reservoir is critical for safety.
Does regenerative braking replace the need for a vacuum pump?
No. Regen braking slows the vehicle but does not actuate the brake pedal or booster. At low speeds or during emergency stops, the friction brakes must function independently. The vacuum pump is still required for the braking system to work properly.
What is the typical power draw of a 12V vacuum pump?
Most EV vacuum pumps draw 5–15A peak during operation. The pump runs only intermittently (a few seconds at a time), so the average draw is low. Ensure your DC-DC converter has sufficient capacity.
Do I need a vacuum pump if I use an electric brake booster?
No. An electric brake booster (like the iBooster) replaces the vacuum booster entirely. However, it requires CAN bus integration and significantly more complex installation. For a T2, the electric vacuum pump is the simpler and more reliable choice.
Get the Right Vacuum System for Your T2
Browse CMVTE's Braking Systems collection to find the vacuum pump and components for your VW T2 EV conversion.
Not sure which pump fits your T2? Contact our team with your T2's year, motor controller model, and battery pack voltage — we will confirm compatibility.
View Vacuum Pumps Contact Support
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