CCKW stop light switch

[RANGER]

Some CCKW owners choose to eliminate the original hydraulic switch, as it is found to be "unreliable". 562,000 CCKWs left the factory as well as 600,000 WWII Jeeps not to mention the millions of other 30s-50s vehicles made in the USofA.
What usually causes them to fail is old stale gummy brake fluid, or brake fluid contaminated with years of rust and crud.
A properly maintained vehicle with components that are properly serviced will not have any problems with the original Hydraulic Stop Light switch. They are low priced ($10-$12) and readily available as NOS thru surplus dealers and local automotive stores.

[Jason]

I will go with Ranger on this one. The hydraulic brake switch is the way to go. Modern cars and trucks still use this system. Some of the reliablity issues might be do to Hacked wireing. Origanaly there was power down to the switch then return to the headlight switch to select between Service stop light and Blackout Stop light.

Just as a curiousity does all you folks Blackout stop light work?


Jason

[RANGER]

My experience has been to fix vehicles right the first time and not have to spend time constantly tinkering every time there is an event coming up. Using correct parts worked fine for the WWII Army and is still practiced in todays' Army. The Army does train mechanics in the use of expedients, but that is for emergencies, or temporary repair. That is what the Bull Dog Tape and Mechanics Wire was issued with the vehicles for. I just love to peek under hoods of "restored" CCKWs.

[Tim in TN]

The only problem I have with the original switch is that it takes more preesure then is needed to stop an empty truck.

[RANGER]

It is possible that the switch is faulty, it may be gummed up inside, or just plain sticking. The other possibility is that your Master Cylinder is also gummed up with age and requiring extra pedal pressure.

[Tim in TN]

It's all new, but the switch maybe the problem. Thanks

[RANGER]

Think about it, the switch was used on millions of American vehicles, they are so basic, that there is little that can happen. Dirt and age are about all that can happen.
In addittion to CCKW, the Switch was used by Willys, and Ford on Civilian Vehicles thru the late 70s. Filko Part# is SLS-24, which can be easily be converted to Carquest and NAPA part Numbers. GM (Delco Part No) is 1997725.

[Capt Lee P]

Hi Tim,

I had the same problem you had. I put six (6) brand new switches on and still the brake lights won't come on unless I put excessive pressure on the brake pedal. Solution: I went to my local Harley-Davidson dealer and bought a motorcycle switch which activitates at lower pressure and have never had a problem since. (8,000 miles later). I know it is not orginial but it works great and you can't see the difference from the orginial style.

Lee

[RANGER]

Six switches and no stop lights indicates that a problem existsand there insufficient hydraulic resistance to activate the switch, possibly in the Hydrovac relay valve. The problem with a new stop light switch may also be an indicator of an air bubble at the switch or the Hydrovac needing attention as the pressure from the Master Cylinder goes directly to the Hydrovac, the relay valve uses the hydraulic pressure from the master cylinder to open a port to allow vacuum to boost hydraulic pressure.
Many collectors have Hydrovacs in need of service, some just need lubrication as described in the LO. Some have attempted to rebuild their own with out sufficient knowledge of correct rebuild procedure and may have damaged it in doing so. Bendix warns NOT to hone the bores of the slave cylinder or relay piston sleeve as it causes excess clearance. Minor imperfections are to be removed with 00 steel wool, or one of those 3M scuff pads as used in body shops. There are many precautions as to the correct assembly of the components and steps to take so as not to damage the components as they are assembled. Leather and Rubber components each have specific steps to be taken in order to prepare them for installation, including lubrication of certain components.