angus5

[quote]ORIGINAL: rx7devil210



I just blew my third spur gear out lol even on drift tires... Yea im running the aluminum motor mount from hot racing. what should i do?? Anyone else having problems blowing out their spur gear? Help would be nice thanks.

[/quote

Ok well a lot of people have posted about stripping spurs and I will say that there are two problems for sure:

1) the stock motor mount is crap - you can get the HPI alloy mount (I have it) but it is only marginally better as it uses the same stupid "cam" style adjuster which is a joke - the Hot-Racing one looks like it uses regular slots by and oif so will give you much better (more positive) mounting, I will verify this soon enough and then most likely get one -

2) the Hot racing aluminum spur (AND the stupid metric stock cheese spur)is GARBAGE - I knew this and only bought the HR one with the intention of removing the spur and mounting a proper plastic spur ( like a Robinson or Kimbrough) to the alloy hub / shaft drive assy...

Here is what I did - (BTW I did contact H-R and got no response from them about spur gear problems and the possibility of using a plastic one)

I found that the H-R spur had a 3 bolt pattern which in fact lined up to some of the holes in a Kimbrough gear (gear designed for ball diffs) - the issue is the large hole in the HR mounting hub - so I used a reamer to ream the hole slowly till it fit snugly and then needed to countersink the screw holes in the gear and it bolted on.

I used a 72 tooth spur and the smallest pinion that will now work is 23 teeth but am now running 25t which is just great with the Traxxas 3500 torque monster.

As I said before this is the best mod ever! The car is so smooth and after a couple battery packs there is no sign of the mesh changing or any noticeable wear.

As a side note I did previously manage to use a Robinson machined gear too but had to drill my own holes and could only use 2 screws, this ran fine for a couple packs too (even smoother) but I figured that 3 screws was a wothwhile tradeoff.

I feel that the gear mesh issue is a multi-faceted problem -

1) the mtr mount is not solid

2) even after you install a better mount (the HPI one) the chassis itself will flex, allowing small changes in mesh under torque

3) the stock and H-R gears are CRAP

4) the whole car is obviously made to handle the 27t brushed motor just fine so it needs upgrades to handle much more

5) since the car is entry level, the people running / fixing the car are not generally as good at spotting / avoiding / fixing problems