Troy Bilt Horse Forward Interlock Safety Switch
Hi! Maybe a few people here might remember back to earlier this year when I posted on my journey to rebuild my Troy Bilt Horse tiller that was a basket case. Look back a few pages to ďTroy Bilt Horse Basket CaseĒ if your interested. Part of my many problems in rebuilding this tiller was dealing with NLA parts and one of these was the Forward Interlock Safety Switches. Now I figured out how to by-pass these switches and simply install a ďdead manĒ toggle switch to kill the motor. Others here on the forum thought I was committing a mortal sin by not having these safety interlock switches. I figured for many years old Horse tiller's didnít even have these safety devices so I would rebuild this tiller without this safety devices and I'd be okay, to each their own as the saying goes. Yet, it still bugged me that I was so close to having this tiller stock and all it was missing was these switches.
I was lucky that a fellow forum user here had these safety switches from I assume a tiller he was junking and sold me the assembly of micro-switches for the handlebars, the infamous plunger switch, and its associated wiring harness. Now the old micro-switches on tiller I rebuilt I was able to fix by very carefully cutting them open and cleaning the corroded contacts but the new used ones I bought were much better condition. The problem part on both my old Forward Interlock Safety Switches was the switch that sits above the spring plunger. This part to is NLA and to make matters worse itís a plunger type switch that makes or breaks which nine times out of ten gets so corroded that the plunger sticks or the wire going to the shaft of this little plunger switch corrodes in two. To add even more insult to injury Troy Bilt in there infinite wisdom engineered or sourced out this bolt type switch that has pipe threads not machine threads so if you think you can make one you better be one skilled machinist!
The new used plunger switch I obtained also had the plunger corroded (frozen in this weird bolt it sits inside in) so what to do? I decided to whip up a batch of my magical corrosion killer which is a 50/50 mix of Acetone and ATF (automatic transmission fluid) that beats Kroll, PB Blaster you name it IMHO. Plopped the whole switch down in a Mason jarof this mixture and hit the road on a month-long camping trip. When I came back I pulled it all out and with a drift I gently tapped, tapped, the center switch shaft button in the bolt and it broke free! Yet it was still very sticky and not freely operating so I needed to get the switch farther apart so I could clean out more of the corrosion. Thatís when I noticed the bolt head has little indents that hold a plastic top over the wire going into the shaft of this switch. By gently prying those back I was able to get to the top of the switch where this wire makes or breaks on a ring connector to the shaft of the switch. More soaking and then cleaning I was then able to totally free the whole switch up and get it operating. Installed the plastic top in the bolt head and sealed it with Silicon RTV so no water will never get into it and now I have a fully functional plunger switch. Now all thatís left is repairing one broken plastic holder that a micro-switch goes inside that fits into the handlebar and finding somewhere a replacement spring for one that completely corroded away that keeps the handlebar switch lever open.
Iím not sure if I will ever use this Forward Interlock Switch assembly in my tiller but I wanted to see if it can be repaired and maybe help others who want to repair these safety device and show them it can be done. Sorry this post is so long and my photo is so bad but it will show you the problem switch Iím writing about.