It was an anticlimax to say the least when WL Toys finally launched their first factory brushless cars. Due to the cheap ESC but moreso the tall gearing they were plagued with issues of cogging - the stuttering of the motor as it struggles to move from pole to pole at low speeds and the loss of torque as a result. You can see this issue in my review of the Eachine EAT14 which has the same problem. WL Toys solved this problem with a hasty update to V2 with a shorter gearing and a higher kv motor. Here is the new 124017 V2 and 124016 V2 (it's hard to find the V1 any more)

I've already written this article to show fixes based on parts available at the time but now I have a new fixed based on newly available parts from the V2 that should solve your problem for just $27 (or as cheap as $15 if you reuse your motor) . Read on and follow me as I "fix" my 124017

As per this article I have fixes for the cogging in the 124016, 124017 and Eachine EAT14 which have the shorter gearing that I prefer however they are not especially cheap fixes though remain my favourite in terms of performance.

If you want to keep the improvement cheap and quick though there are 2 new options for you:

1. Buy the 4300kv motor, mount and 19t pinion all from the V2 spec as a preassembled kit here for just $27. This will give you the V2 powertrain with a top speed of 71km/h and zero cogging
2. Buy just the motor mount and 19t pinion from the V2 and re-use your 3400kv motor. Top speed will be down to around 55km/h but cogging will be gone. I quite like this speed and efficiency if you plan on bashing

The WL Toys 124016 and 124017 (and the Eachine EAT14) have a major issue with cogging - the stuttering that occurs when accelerating from standstill or low speed and is a major downside to these recent releases. Cogging in your car is not by bad luck but by design choice; in the search for top speed bragging rights, the tall gearing has really compromised these cars ability to accelerate. Never fear, QuadifyRC to the rescue! I'll give you 3 and a bit options on how to fix this issue by addressing the root cause rather than by going on a wild goose chase and addressing the wrong things.

As soon as I found out WL Toys and Eachine had retained the big 27t pinion from the brushed models I knew they would be fast but were going to be poor on acceleration. This turned out to be correct as you can see on my Eachine EAT14 review which has the same running gear as the 124016 and 124017. You can get away with this big pinion on a brushed motor (like with the 144001, 124018 and 124019) because of the way they work but not on a brushless motor because of the way they differ mechanically. Cogging is when the electromagnetic field invoked by the motor is not strong enough for the motor rotate and catch the next pole thereby getting out of phase and rocking back and forth; it's that jiggle your car make before it takes off. So what causes it? The motor can not generate enough torque for the given load. The 2845 is not a small motor for a car this size so it is safe to assume that it is the load that is unreasonably high due the very tall (fast) gearing.

Since we know the root cause we need to address it directly in order to get the best quality solution but before I do that I'll let you know the things that will NOT fix it: