HH56 wrote:
If the switch fails, here is one way to eliminate the bimetal timing section and sometimes erratic contacts in the stock control switches by adding solid state time delay relays. No idea which vendors are selling the exchange switches so here is an option if an owner wants to do a conversion himself. Different relays may work better or not at all but I chose these because they were fairly inexpensive and readily available.

The relays I used are by INITEQ number INRXTD12X30B and are currently sold as a pair by Amazon. These are 12v 30 amp contact automotive type relays. Some Ebay vendors also sell a similar relay. Riki shows another brand in one of his posts. Space is extremely tight inside the control sw box. The INITEQ relays are 1 1/8” square x 1 15/16“ long. The flag terminal brings total length to 2 1/4”. Any larger relay may not fit and not sure if there would need to be any mods to the mounting bracket showing on the type relay Riki purchased. The easily found TD relays all seem to have a delay of 10 seconds which is longer than the factory specified 5-7 second delay but still a reasonable number.

First step was to unsolder 4 wires and unscrew the old relay bracket to remove the complete relay assy.

I could not find a way to avoid cutting the bimetal strips out of the box and still have the relays fit. A Dremel with cut-off wheel was used to cut the bimetal assy off the swivel bracket just as is done with the other solid state conversions. A couple of the old contacts were bent out of the way on the phenolic circuit board at the bottom to make room for the new support plate but nothing else needed cutting.

A hole was drilled in the pot metal for a new ground stud connection and two new wires were soldered to the existing pink and yellow terminals going to the outside. NOTE: Because the terminals have a large mass you will need a fairly high wattage soldering iron for this —at least 200 watts. New wires were also soldered back onto the terminals connected to the contacts operated by the lever and torsion bar. A regular wattage soldering iron will work for those. Because space is so tight I chose to use insulated flag style quick disconnects to connect the relays but those do need a special crimper. Another option would be to solder wires directly to the relays. If you do that make sure not to overheat the relay terminals and carefully insulate the terminals after the wires are on so they can not touch the cover.

A plate was also made to support the relays above the still existing contacts on the switch bottom. I chose to use a 1/16 thick phenolic material with dimensions of 1 7/8 x 2 1/8. Holes were drilled and countersunk in the plate to utilize the old relay bracket screw mounting location and threaded holes. The plate was placed on 1/2" standoffs using 3/4" screws. Note that the original relay bracket screws in the switch are an odd size -- 5-40 thread. That size is available but not typically found at local hardware stores. You could use easier to find 4-40 screws thru the original holes with a nut under the box to hold the screws or drill and tap the holes for 6-32.

IF you have a 55 switch, electrically they are the same with the main difference being the location of the terminals on the bottom. 55 switches had 3 exposed screw terminals and they are in different spots. Pink and Yellow wires would need to go to the different terminal locations.

Here are a few photos of a 56 switch as well as the new wiring diagram. NOTE: The wiring diagram is for the 56 Negative ground switch conversion. Wires 85 and 86 on each relay would need to be swapped for the 55 Positive ground. Both configurations test well on a bench but I will not be able to crawl under to test the conversion in a car.