Differential build tip

[coleca]

I haven’t built an RC car in 35+ years and now I’m building an EB410.2. I had some problems building the diffs and hope this tip helps out someone else in the future.

I was very conscious of not tightening the screws on the diff too tight, but this led to a big problem. I didn’t tighten them enough. Make sure that the diff screws are flush with the surface of the spur gear. Rub your thumb back and forth over the screws, you shouldn’t feel any bump from the edge of the screw.

What happened with me was the screws were slightly elevated and this caused the diff to bind up once it was installed in the car. Once I figured this out and tightened the screws a slight bit everything was super-smooth.

The other tip I saw repeated elsewhere was to use your thumb and pointer finger only on the driver when tightening those screws so you don’t over tighten. Careful balance I guess.

 

[nub]

Something you can do is run a screw in and back out of each hole before you start assembling. It makes it easier to feel when the screw snugs up on final assembly if you're not cutting threads at the same time. I do this on all new diff housings.

As you mentioned though a flat head type screw shouldn't sit proud of the hole. It should be just below flush in most cases.