The Stovebolt Site Forums The Shop Area General Truck Talk 1953 3600 - Stoplight Switch Mounting Problem

1953 3600 series. Not sure if this belongs here or in Electrical. PO had brazed a metal piece to the stoplight switch arm. Obviously was having as problem in the arm being too far away from the pedal.

Switch failed, and I got a new one. Installed it in the same holes, as shown in the Factory Assy Manual Sec 12 Sheet 4.05 Part 3707902. Must say that the manual seems to shoiw the switch arm pointing left, tpoward the driver's side, rather than right. But can't see how to change that.

Anyway used same switch as PO (NAPA SL128). But the the actuating arm is nowhere near the pedal and would never work properly. I adjust the pedal closer to the firewall by using the master cylinder adjusting nut, but that would never be enough, either.

Whassup? Anyone know?

Thanks, Harry

Hi Harry,

Here is information from my 55 first series truck. Hope it is relevant to you. The stop light switch points to the right or passenger side. My truck also has a very specific embossed section the brake switch mounts to.

This page is from the 54 shop manual. It shows the brake switch pointing also to the right or passenger side of truck. http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm1238.html If you have the 53 manual it may have a similar diagram.

Great job identifying the issue and posting relevant pages in the FAM.

Here ya go Harry, this is a ‘50, 3600 but it should be the same as the ‘53. The new
switch in the second picture is the one that all of the vendors carry from Counterpart.
Don’t see why you would be having a problem if you have the correct switch, it’s
a simple two screw install.
http://www.pbase.com/dennygraham/image/137963486/large
http://www.pbase.com/dennygraham/image/137963488/large
I avoid buying parts from my FLAPS because most of the time the kid behind the
counter has no idea what he’s looking for and they really do not have much that
will fit these old truck.

Denny Graham
Sandwich, IL

Harry -

Make sure that both mounting screws are tight. If one of the holes is enlarged, it may allow the switch to move out of position. The previous owner may have tried to compensate by using the switch you described.

You probably have the wrong switch. Some applications use a switch with the lever on the opposite side. Often the parts stores get them boxed wrong even if the part number on the box is correct.

Thanks to all of you. Now I will send the pix I should have taken in the first place. Here they are:
http://share.shutterfly.com/share/r...80031ecd658bfd733&sid=8AZOGLNu0bMmRP
I think I have the correct switch, and I did mount it correctly. I tried an ohmmeter, and the lever arm has to be almost level before it cuts off.

So, I looked for the obvious - maybe the pedal is too far from the firewall. I redid the master cylinder adjustment to bring it closer, but then the bottom end bangs on the steel flange beteen toe plate and firewall, especially when I remove the bumper. Even with max adjustment at the threaded turnbuckle, I could not get the switch to cut off.

Once again, thanks for your help. Maybe the pix raise some thoughts?

There is no bumper on the brake, only the clutch. On mine the master cylinder turnbuckle is threaded onto the shaft all the way to were the shaft is flush with the bottom of the U in the turnbuckle. Is your return spring for the brake pedal hooked up? FAM sect 5, sheet 2.00 shows how to adjust the clearance of the brake pedal.

You can put a piece of vacuum/fuel hose over the lever on the switch.

Ed's got it Harry, there isn't a rubber bumper on the brake lever just the clutch, that's whats holding it from coming back far enough to trip the switch. Did you look at this picture: http://www.pbase.com/dennygraham/image/137963486/large

Simple fix, cut that rubber sucker off!

DG

Problem solved. Very strange, but the reason is actually visible in the one picture I posted that shows the rubber bumper. That's where the problem was, but it wasn't the bumper itself.
Look at the picture again, and notice what the bumper is bumping against! Where there should be a smooth joint between the firewall and toe panel, mine has a 1/2 flange sticking out, for about 6 - 8 inches laterally. Both the brake AND clutch pedals were hitting that flange before they ever got close to bottoming out. The PO probably placed the rubber bumber there to prevent metal-to-metal clanging. Because the pedal was hitting the flange way down low, there way no way it could ever actuate the stoplight swith.
So, I used boltcutters, hacksaw, vise grips, and a wrecking bar to cut and/or bend the flange. When it was gone, I adjusted the brake cylinder clevis as suggested, reinstalled the switch, and everything works great!
Thanks again to all of you for getting my brain cells working again.