The hand throttle in the 1969 Porsche 911E is a cable-operated lever mounted next to the driver's left knee. It allows the driver to set a fixed engine speed independently of the foot pedal, useful for warming up the engine or maintaining a steady RPM during certain driving conditions. Understanding the hand throttle's components is essential for proper maintenance and restoration of this iconic sports car.
Understanding the Hand Throttle System
Why a Hand Throttle?
In the late 1960s, the Porsche 911E featured a mechanical fuel injection system (Bosch MFI) that required a specific cold-start procedure. The hand throttle let the driver hold the throttle open during warm-up, preventing stalling and ensuring smooth idle. It also gave drivers a way to set a constant cruise speed without using the foot pedal, although this was less common.
System Overview
The hand throttle system consists of a lever inside the cabin, a cable, pulleys, brackets, and linkage connecting to the throttle body. The diagram for the 1969 911E shows a straightforward mechanical path. The lever pulls a cable that runs through the firewall, around a pulley near the left shock tower, then to the throttle linkage on the intake manifold. Each part has a specific part number and name.
Detailed Parts Diagram for the 1969 Porsche 911E Hand Throttle
The following list describes the key components shown in the factory parts diagram. Use this guide to identify parts on your own car when inspecting or replacing the hand throttle.
1. Hand Throttle Lever (Part Number 901.423.401.00)
Located on the driver's left kick panel, the lever is a black plastic knob on a metal arm. It pulls upward to open the throttle and pushes down to close. A friction lock holds the lever in position. The lever mounts to a bracket with a single bolt.
2. Hand Throttle Cable (Part Number 901.423.501.00)
This is a flexible Bowden cable with a threaded barrel at one end (for adjustment) and a clevis pin at the other. The cable runs from the lever through a grommet in the firewall to the engine compartment. Length is approximately 1.5 meters.
3. Cable Guide Bracket (Part Number 901.423.601.00)
A metal bracket bolted to the left side of the transmission tunnel near the pedal cluster. It holds the cable sheath in place and ensures smooth motion without rubbing.
4. Pulley Assembly (Part Number 901.423.701.00)
In the engine bay, a pulley mounted on the left inner fender (near the engine tin) redirects the cable around the corner. The pulley is plastic with a metal bracket and spring-loaded to maintain tension. The cable wraps around the pulley groove.
5. Throttle Rod (Part Number 901.423.801.00)
A short metal rod connecting the cable to the throttle linkage. One end attaches to the cable clevis, the other to a ball joint on the cross shaft. This rod transmits the pull from the cable to the throttle plates.
6. Cross Shaft Bracket (Part Number 901.423.901.00)
A cast aluminum bracket mounted on the intake manifold. It supports the cross shaft that links both throttle bodies. The hand throttle rod connects here via a ball socket.
7. Return Spring (Part Number 901.423.301.00)
A coil spring attached to the cross shaft and a fixed point on the engine. It pulls the throttle closed when the hand throttle lever is released, ensuring a fail-safe idle return.
8. Adjustment Barrel (Part Number 901.423.401.01)
Located at the lever end of the cable, this threaded barrel allows fine-tuning of cable slack. Turn the barrel to increase or decrease cable tension, affecting idle speed set by the hand throttle.
Diagram Layout
In the factory diagram, parts are numbered sequentially. The lever (1) connects to cable (2). The cable passes through bracket (3) into the engine bay, where it routes around pulley (4). The cable end attaches to rod (5), which connects to cross shaft bracket (6). Spring (7) provides return force. Adjustment barrel (8) is at the lever. Additional hardware like clips, washers, and cotter pins are listed but not shown in the primary diagram.
Common Issues and Adjustments
Sticking or Stiff Lever
If the hand throttle lever is hard to pull or won't stay in position, the cable may be corroded or the pulley frozen. Remove the cable, lubricate with WD-40 or cable lube, and check the pulley for smooth rotation. Replace if cracked.
Idle Not Returning Properly
A failed return spring (part 7) can cause the throttle to hang. The spring should be strong enough to close the throttle when the lever is released. Check for broken coils or stretched spring. Replace with original-spec spring.
Adjusting Idle Speed via Hand Throttle
To set a specific RPM with the hand throttle, pull the lever to desired position and tighten the friction lock. Use the adjustment barrel to fine-tune cable tension so that the lever holds the rpm steady without creeping. A typical cold-start idle is around 1500-2000 RPM.
Replacing the Cable
When replacing the hand throttle cable, route the new cable exactly as the old one. Secure the cable at the firewall grommet, pass through the pulley groove, and connect to the throttle rod. Adjust tension so there is a slight slack with the lever fully closed.
Final Recommendation
Maintaining the hand throttle system on your 1969 Porsche 911E ensures reliable cold starts and smooth idle control. Keep the cable lubricated, inspect the pulley for wear, and replace any stretched springs. Consult the factory parts diagram for exact naming and part numbers. For restoration, source original or high-quality reproduction parts from Porsche specialists. A properly functioning hand throttle is a small but critical detail that preserves the driving experience and authenticity of your classic 911.