Brushless 4×4 RC Truck

Just wanted to give a quick update and share my experience with my Losi Baja Rey brushless 4×4 RC truck today. My son and I were out bashing our RC’s.

Jumping and Bashing

We were jumping and racing around and having some fun. We ran a battery out jumping (a battery lasts for 30-35 minutes) when that battery died, we grabbed another battery and decided to run in the dirt for a while.

Losi Brushless 4x4 RC truck

Running Dirt Strip

This time we were going to run the battery at the dirt strip. The dirt strip was fun for a bit. We only got about 10 minutes of run time when all of a sudden, The Losi made a horrible noise when I give it throttle.

I stopped and looked the truck over and did not see anything that indicates a problem. So, I went back to running and when I took off, I got on the throttle pretty hard.

Sure enough, it made a loud grinding type of noise. Again I checked it over and did not see anything.

I gave it throttle while I was holding it in the air and it seemed fine. Could not hear any noises.

Then I put it down and took off, this time a little more cautiously with the trigger and the noise appeared to be gone.

So I figured I got a stone stuck somewhere maybe that worked its way out.

Tried Racing – Failed

Now my son and I are gonna race a little. I punched it on the takeoff and what do ya know, the noise is back.

I gave it lite throttle on takeoff and everything is fine. “If” I punch it, The noise is there. “It” is a hard acceleration issue. “I’d” I run it easy, it is fine.

When I hold the truck in the air to see where it is coming from, It does not do it. “I” can only duplicate it when it is on the ground and under hard acceleration. This made it very difficult to pinpoint.

Well, I put it on the ground at my feet and held the front of the roof at the windshield. Lifted the truck slightly to take just a little weight off the tires so they will spin on the ground but still have a decent drag.

This allowed the noise to be heard, “As” well as allow me to pinpoint it to the front differential.

Losi Baja Rey

Yup, I Broke It

“I” have had this truck for a little while and I run probably two batteries through it every day. This is a great brushless 4×4 RC truck and has been very durable.

There have been only a couple of minor things that I have had to replace. Those are due to me beating on it pretty had.

Losi has had some issue with this. The stock differential case is made of plastic and rather flimsy plastic at that. This means that after a while of bashing, the torque and heat allow the diff case to flex.

Under heavy acceleration the torque that is put on the pinion gear will cause the diff case to flex and that allows the pinion and ring gears the move apart enough to cause some grinding noise.

The Fix to this issue, You will need to replace the front diff case with an upgraded aluminum case. The case only needs to be replaced.

The diff gears do not need to be replaced (in most cases) the gears used in the Losi are very tough and usually do not get hurt.

Broken Losi Baja Rey

Now if you keep running it like this and bashing hard with it this way long enough, then you probably are going to end up putting gears in as well.

“If” you stop running and fix it when you start noticing this noise, you will be able to save all the internals and end up with a cheaper repair.

Cheap Fix – Parts Available

There are many retailers you can pick up this upgraded diff case from. Your local hobby shop should be able to get one for you, or you can buy online from places like RC, and are great places to buy from online.

The upgraded diff case cost $49.99 from my local hobby shop. So for $50 and 30-45 minutes of time, I was back up and running.

OK, that’s all I got for now, “I” will be adding a post on how I did the front diff repair later on this week so be sure to sign up to get email updates for my new posts. Just click the email button below.

As always, Feel free to leave me a comment and let me know your thoughts. All comments are welcome and I will reply to them promptly.

2 thoughts on “Brushless 4×4 RC Truck

  1. Hi, I have the losi baja rey and its doing some weird things. I have not had the noise issue you mentioned, but i will keep that in mind thank you. my losi takes a long time to go into reverse and sometimes when im running it will just stop on its own. it does not do it all the time. sometimes it will not go when i hit the throttle, i have to hit it a few times then it kicks in. other times it will just stop even when im on the throttle. Do you know why? thank you.


    1. Hello Jack,
      Make sure to check the battery connector, make sure the wires are in securely and the connectors (on battery and truck) are fully seated when connected. If it is not a battery connection issue, then you may have a faulty speed controller (ESC) and may need to replace it. If you have any other questions be sure to let me know. Hope you have a great day.


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