Losi Mini B Motor Conversion Latrax 7575x 7575R

[DeepLCG]

I have two Losi Mini B's. One brushless and this nearly 100% stock buggy. The stock setup doesn't get much run time, being that it is so sluggish compared to the brushless. Most of the time, it get's driven around a tennis or basketball court with cones setup. I want to keep the stock radio, since it fits so nicely in the rubbermaid with the two cars nestled together. Also it's a nice, small radio for kids and new drivers.

I decided to go with the brushed Latrax 7575x motor over brushless. Also choosing the X over the R version, for the increased run time, since it draws fewer amps / lower overall KV by around 2k, in comparison to the R. I think the 7575x hits about 20,000 at 4V according to a video I watched months back. I'll likely run my own test, once I pick it up from the hobby shop today.

Anyway, I had the Latrax compatible HR motor plate already. You can see how the elongated motor mount slots differ from the stock motor and plate. Also a 59t metal spur gear along with the stock pinion and additional 23&20t.

Wondering if anyone has done this conversion. Looking for advice on if the stock ESC/RX combo and 7575x play nice together. Also, what spur/pinion setup has worked well for you, based on wherever you drive your MiniB / MiniT.

I'll report back on how things go.

Here are some pics of what I have so far.

 

[9x19]

No minis here, but I expect the Latrax brushed will work just fine with the Losi ESC.

BUT... you have rust on your spur gear!!! Drop and give us 20... and count em out!!

 

[DeepLCG]

No minis here, but I expect the Latrax brushed will work just fine with the Losi ESC.

BUT... you have rust on your spur gear!!! Drop and give us 20... and count em out!!

Thank you for the vote of confidence on the Losi stock ESC. Hobby shop was closed, got there too late.. but will be getting the 7575x in soon.

Far as rust, just keeping it real. But seriously, will be taking it off, scrubbing it down with steel wool and treating it with WD40 corrosion inhibitor . Crazy how a part sitting in a sealed bag can oxidize, before it has even been installed. I've basically treated nearly every non-stainless tool in the basement with the inhibitor, for the same reason.

 

[DeepLCG]

I purchased the motor at the hobby shop yesterday. They only had the 7575R in stock, so I decided to just go with this higher KV / higher Amp draw version. Perhaps the battery won't last as long, but I'll definitely get the speed I am looking for. I can always dial it down, using the dual rate on the stock controller.

In this picture, I discover the screw holes on the latrax motor are too far apart for this HR motor plate. I had it sitting around for a few years, so couldn't remember if I had purchased it in preparation for installing this motor. Either way, I decided to make it work.

In these pictures, several attempts to round out the slot with a 1/4" drill bit. Cleaned up and installed the motor along with the 20T pinion paired with the 59T spur. The motor did not come with screws. I had the hex and phillips screw in my Latrax parts bin. Just an FYI, if you are doing this mod.. go with a Latrax specific motor plate and order some screws for the 7575X/R. Cleaned up the rust on that spur, in those last few pics.

Soldered the motor on and fired up the radio. First time... the rear wheels wouldn't move when the car was set on the ground. Turns out the spur nut needs to be tightened down quite a bit. Success! I kept the gear mesh a little loose, but no binding and blazing fast speed! The two metal gears do make quite a bit more noise than the plastic/metal combo. Sounds like a mini version of my Tekno 410.3. But.. tons of power and speed on the carpet in our basement. Going to re in stall the spur/pinion cover plate and take it for a test drive today. I will report back on the results.