Re: DIY Torsion level control switch conversion
Posted by HH56 On 2023/5/15 11:34:48
Did some experimenting on a damaged switch where the main stationary pivot contact leaf had been broken, the limit pin bent, and one of the spring legs had broken -- literally, a total throw away switch under normal repair criteria. Since this is only an experiment to prove a concept and is not an easy mod -- unless you are good at working with miniature items, cannot suggest it as a standard fix for possibly dirty pivot side contact issues. If someone wants to develop farther or sees a need for such a repair here is a starting point. .
First repair was to get the broken spring out. Disassembled the switch by removing the spring actuator cam. That small item is staked onto the top of the lever shaft and holds everything together on the pivot side. It is a fairly shallow stake so with a little persuasion using gentle taps from underneath while being careful to alternate positions so as not to bend the actuator it came off. This freed the spring and let the pivot contact assy slide off the shaft. Was then able to drive out the bent pin to straighten or replace it. Also made a new spring. If the contact leaf had not been broken the switch could have gone back together and the actuator restaked on the shaft. Because of the broken contact and need to figure out how to repair that I decided to reattach the actuator with a screw instead of the stakes so drilled and tapped the shaft.
There is not a lot of room or many options when trying to find something to replace the broken contact. Riki had mentioned possibly using microswitches to eliminate dirty pivot contact issues but finding some off the shelf switches small enough to fit was a challenge. Also wanted them to be easy to mount so as not to require any hard to make changes to the switch. Not sure what size they are technically but smallest switches I could find are about 3/16 wide, 1/2 long and 3/8 high. Contacts are rated at 1 amp AC so with relays only needing 120mA at 12v DC to energize, the switches should be OK even with deciding to use a non standard wiring connection. For mounting to the bracket needed small screws so used some 1-72 x 3/8 screws which is the largest diameter that will fit the holes in switch.
Decided to make a bracket and mount the switches as an assembly using the existing pivot side of the contact to actuate the switch levers. The bracket assy approach only needs two holes drilled in the TL switch bottom for a couple of 2-56 x 1/4" screws. There is just enough room in front of the pivot block to drill and tap new holes without disassembling anything on the switch. Once the holes are finished the bracket can slide on from the front so switches are on either side of the pivot side contact. The slight side to side motion activates the switches but because of the motion and layout, the contact sides are reversed so wiring needs to be changed accordingly. The existing fixed leaf contact is not touched and pivot side contacts remain intact. Since my fixed leaf was broken I went ahead and cut the wire feeding 12v to the old leaf contact but in actuality, since only the isolated microswitch actuating levers touch the contact assy that step should not be necessary on a good switch. You will need to solder a wire so it somehow connects to to the light green control switch terminal to bring power to the new microswitches. Due to space and flexibility needs I used 20 ga wire to connect to the microswitches both for power and to connect to the relay triggers. .Since I was also changing the bimetal timer to relays power was connected at the same location where the terminals enter the switch. I also chose to use a quick disconnect in the 12v wire to the microswitch assy so as to be able to remove the entire assy as a unit in case a switch needed to be changed in the future. Space is extremely tight at the microswitch on the cover side so care needs to be taken in wire routes and when replacing the cover so as not to short, pinch or damage any wires.
Mod works well on the bench but with the stock TD relays, still has the 10 second delay. Should work on a car but I will not be able to test it and do have a concern about sensitivity. This version has only about half as much dead zone before the microswithes activate as there was with the original contact arrangement. If it turns out the TL responds too often the position of the switches or actuating levers would need revision and a change may mean a different bracket made.
Attach file:
Broken switch.jpg (175.68 KB)
Rep Switch.jpg (145.36 KB)
56TorSwitch1 3.jpg (183.89 KB)
First repair was to get the broken spring out. Disassembled the switch by removing the spring actuator cam. That small item is staked onto the top of the lever shaft and holds everything together on the pivot side. It is a fairly shallow stake so with a little persuasion using gentle taps from underneath while being careful to alternate positions so as not to bend the actuator it came off. This freed the spring and let the pivot contact assy slide off the shaft. Was then able to drive out the bent pin to straighten or replace it. Also made a new spring. If the contact leaf had not been broken the switch could have gone back together and the actuator restaked on the shaft. Because of the broken contact and need to figure out how to repair that I decided to reattach the actuator with a screw instead of the stakes so drilled and tapped the shaft.
There is not a lot of room or many options when trying to find something to replace the broken contact. Riki had mentioned possibly using microswitches to eliminate dirty pivot contact issues but finding some off the shelf switches small enough to fit was a challenge. Also wanted them to be easy to mount so as not to require any hard to make changes to the switch. Not sure what size they are technically but smallest switches I could find are about 3/16 wide, 1/2 long and 3/8 high. Contacts are rated at 1 amp AC so with relays only needing 120mA at 12v DC to energize, the switches should be OK even with deciding to use a non standard wiring connection. For mounting to the bracket needed small screws so used some 1-72 x 3/8 screws which is the largest diameter that will fit the holes in switch.
Decided to make a bracket and mount the switches as an assembly using the existing pivot side of the contact to actuate the switch levers. The bracket assy approach only needs two holes drilled in the TL switch bottom for a couple of 2-56 x 1/4" screws. There is just enough room in front of the pivot block to drill and tap new holes without disassembling anything on the switch. Once the holes are finished the bracket can slide on from the front so switches are on either side of the pivot side contact. The slight side to side motion activates the switches but because of the motion and layout, the contact sides are reversed so wiring needs to be changed accordingly. The existing fixed leaf contact is not touched and pivot side contacts remain intact. Since my fixed leaf was broken I went ahead and cut the wire feeding 12v to the old leaf contact but in actuality, since only the isolated microswitch actuating levers touch the contact assy that step should not be necessary on a good switch. You will need to solder a wire so it somehow connects to to the light green control switch terminal to bring power to the new microswitches. Due to space and flexibility needs I used 20 ga wire to connect to the microswitches both for power and to connect to the relay triggers. .Since I was also changing the bimetal timer to relays power was connected at the same location where the terminals enter the switch. I also chose to use a quick disconnect in the 12v wire to the microswitch assy so as to be able to remove the entire assy as a unit in case a switch needed to be changed in the future. Space is extremely tight at the microswitch on the cover side so care needs to be taken in wire routes and when replacing the cover so as not to short, pinch or damage any wires.
Mod works well on the bench but with the stock TD relays, still has the 10 second delay. Should work on a car but I will not be able to test it and do have a concern about sensitivity. This version has only about half as much dead zone before the microswithes activate as there was with the original contact arrangement. If it turns out the TL responds too often the position of the switches or actuating levers would need revision and a change may mean a different bracket made.
Attach file:
Broken switch.jpg (175.68 KB)
Rep Switch.jpg (145.36 KB)
56TorSwitch1 3.jpg (183.89 KB)
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=256983