Speedometer Gear Ratio Reducer Fix
 

Me and my friend both were having problems with the Reducer for the speedometer. We went to the dealer only to find out they couldn't get the part anymore as it was discontinued and none of the other dealerships out of state were willing to give it up for them. So we both found ourself without overdrive or a working speedometer for a while. I figured id tear into the reducer and see what I could figure out. Below shows how i fixed it. Then i tore into my friends reducer and found he had the same problem. If your having problems with it and do not see any broken gears in there which I imagine they are hard to break seeing as they are hardened steel then try this before you go on a search.

Also. We both had the same symptoms happen as when a VSS goes bad. The speedometer was jumping around erratically and then it stopped.



First just drill all four of the rivets out. then pull the top off. This is what it looks like inside
https://www.dieseltruckresource.com/...67740895_0.JPG

Next just pull the gears out and clean them up. The post with two gears on it goes in the smaller hole. The post with one gear goes in the bigger hole.
https://www.dieseltruckresource.com/...67740892_0.JPG

Here is what I found to be the problem with the two reducers that I have pulled apart. As you can see in the picture below the gear has an indent in it. From the VSS spinning inside of it, it has worn back down to a circle hole instead of a square. You can see there is an indent there to square the tube off. Take a chisel or a screw driver and tap it slightly on all four sides until the speed sensor fits in there snug. Grease the gears with new multipurpose water proof grease. Then put it back together.
https://www.dieseltruckresource.com/...67740893_0.JPG

Heres a picture of how it works and how it needs to be put back together

https://www.dieseltruckresource.com/...67740887_0.JPG

The rivet it shut and try it out.

Nice job Dean!
I must have got lucky, when I replaced mine last fall, the dealer had it on the shelf..didnt say anything about it being discontinued...I sent all teh recipts with the truck when I sold it, so I dont the part number..:(

I just went outside and did this to mine. It seems as though this could have been the problem. I will know more in the am. Took about 30 minutes.

If it didnt fix it for good you might try filling the hole that you tapped down onto with epoxy and then sticking the VSS to the reducer and making a new square hole.