1942 Hudson Commodore Custom Series 25 Brake Light Switch Guide
Understanding the unique hydraulic brake light switch in your classic Hudson.
- The 1942 Hudson uses a hydraulic pressure switch, which is known to be less reliable than modern mechanical switches.
- Common failures are brake lights not working at all or staying on continuously, which can drain your battery.
- The only new parts available are aftermarket reproductions; Standard Ignition is the primary brand.
- Many classic car owners choose to convert to a more dependable mechanical switch to avoid repeat failures.
Is Your Brake Light Switch Failing?
For a vehicle like the 1942 Hudson Commodore, the brake light switch is a simple component, but its failure can cause serious safety issues. The symptoms are usually straightforward.
- Brake Lights Don't Turn On: The most dangerous symptom is a complete failure of the brake lights. The internal contacts of the switch can wear out or fail, leaving the electrical circuit open. This means drivers behind you will not know you are stopping.
- Brake Lights Stay On: The switch can also fail in the closed position. This will cause the brake lights to stay on constantly, even when you are not braking. This can confuse other drivers and will drain your car's battery, possibly leaving you stranded. Some classic car owners have discovered a dead battery was caused by a brake light switch that was stuck on.
Choosing the Right Aftermarket Switch
For a 1942 vehicle, finding "New Old Stock" (NOS) or new OEM parts is nearly impossible. The market for your Hudson consists entirely of aftermarket reproductions.
Standard Ignition (SLS27) is the available aftermarket brand for a direct replacement hydraulic switch. As a company, Standard Ignition produces a wide range of automotive electrical components.
A Note on Hydraulic Switches and Modern Fluids
Owners of many classic cars from this era report that modern brake fluids, particularly DOT 5 silicone fluid, can cause premature failure of reproduction hydraulic brake light switches. Some switches have been known to fail, stick on, or even leak. While a direct replacement is the easiest option, be aware that its lifespan can be unpredictable. Some owners in classic car forums have had to replace these switches frequently.
Pro Tip: Consider a Mechanical Switch Conversion
Because of the potential reliability issues with hydraulic switches, many classic car enthusiasts modify their vehicles to use a more modern, dependable mechanical brake light switch. This type of switch is mounted near the brake pedal arm and is activated by the pedal's movement rather than by fluid pressure. This conversion is a more involved job but often provides a long-term, reliable solution that is not affected by brake fluid type.
Brake Light Switch Replacement Cost
The cost for a new aftermarket hydraulic brake light switch is very low. However, installation can add to the total cost, as it requires opening the hydraulic brake system.
| Part Type | Price Range |
|---|---|
| New Aftermarket (Standard Ignition) | $15.52 |
| Shop Labor | $90 - $150 |
Note: Labor costs are estimates and can vary by location and shop. Replacing a hydraulic switch requires bleeding the brake system, which increases labor time.
Frequently Asked Questions
Why can't I find an original Hudson brake light switch?
Automakers and their parts divisions typically do not manufacture parts for vehicles that are over 80 years old. The original supply has long been depleted. The only options are used parts from specialty salvage yards or modern aftermarket reproductions.
Is it difficult to replace the brake light switch on my Hudson?
Replacing the hydraulic-style switch is more complex than a modern mechanical one. It involves unscrewing the switch from the master cylinder or a brake line junction, which opens the sealed brake system. After installing the new switch, the entire brake system must be bled to remove any air that entered. This process can be difficult for a DIY mechanic without the proper tools and experience.
Will modern brake fluid damage the new switch?
There are reports from classic car owners that modern DOT 5 (silicone) brake fluid can shorten the life of reproduction hydraulic switches. If you are using silicone fluid, you may experience more frequent failures. Some owners recommend sourcing low-pressure switches from motorcycle suppliers, like Harley-Davidson, as they are often designed for DOT 5 fluid.
What is the difference between a hydraulic and a mechanical switch?
A hydraulic switch, like the one originally on your Hudson, uses brake fluid pressure to get activated. A mechanical switch is a simpler design that uses the physical movement of the brake pedal to trigger the lights. Mechanical switches are generally considered more reliable and are a popular upgrade for classic cars.
Technical Specifications
OEM Part Numbers: J201466
Attachment Method: Screw-In Terminal Type: 2-Terminal Activation Style: Hydraulic Pressure
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.