My Kraton EXB

[RV88]

The day she arrived. Fresh out of the box and the last time she will ever be this clean and shiny.

I promptly installed the electronics below:
- HobbyWing Max6 ESC
- HobbyWing 4985SL 1650kv motor
- Annimos 35Kg HV Servo
- Futaba T4PM transmitter
- Futaba R304SB 4-channel receiver
- Zeee 8000mah 3s batteries x2
- Robinson Racing 20t pinion

First mod was to reinforce the underside of the body. I laid down the drywall tape one strip at a time and used some hot glue on the corners to keep it in place. Once the whole body was covered I added a very generous amount of loctite power grab clear. I would dump a pile on the body and then spread it out by hand. I used the caulking gun sized tube of loctite. This made it much easier to dispense.

These next photos is what she looked like after running 3 sets of batteries during her first bash!

As you can see in the photo below, the rear of the chassis was getting pretty beat up. That led to my second mod which is the M2C Racing rear skid plate. The website said this wouldn't fit the stock EXB chassis, but it ended up fitting perfectly. Not sure if the v2 EXB chassis is different than the v1.

Overall this EXB is holding up great. The Max6 combo makes this truck a monster and I have a hard time keeping it on all four wheels. I’m currently dealing with a heat issue on the ESC. I’ve ordered a motor heat sink, fans, and a smaller 18t pinion to see if that helps.

 

[RV88]

The HobbyWing heat sink and fan I ordered came in today along with the 18t Robinson Racing pinion. I was able to easily stretch the heat sink to fit on my 4985SL motor but I had to trim a chunk out of it in order for it to clear the roll bar. The fan it came with is huge (50mm) but I'm not all that impressed with the speed it produces. I've got 40mm server fans coming so this will do for now. Charging a set of batteries now to test if the combo of fans, heatsink, and dropping 2 teeth on the pinion will help with my heat issues.

I went ahead and ordered the M2C Racing ESC plate and Rear Shock Tower Braces. Zip ties and servo tape don't hold the ESC too well and I've already sheered off a wing mount screw from a bad tail landing so the rear tower brace should help.

 

[RV88]

The M2C ESC mounting plate and tower braces came in yesterday. Quality product! Too bad the weather sucks and I'm still waiting on my ESC fan. Puts a damper on my bashing sessions for now. It was nice to get these installed last night though.

The long pin for the wing mount is temporarily removed to insert the tower braces. The braces take the place of the two red spacers that come stock. After that, it's just a matter of drilling holes through the shock tower with the provided drill bit in order to secure the screws and nuts that come with the kit.

The ESC plate is a drop in replacement for the stock plastic version. It also has pre-drilled/counter-sunk holes so you can screw the bottom of the ESC to the plate itself (screws included in the kit as well) no more broken zip ties!

 

[keefO]

I just ordered the MAX6 combo you installed for my EXB and after reading your thread, I am going to order those tower braces and the ESC plate, great pictures!!!

 

[RV88]

I just ordered the MAX6 combo you installed for my EXB and after reading your thread, I am going to order those tower braces and the ESC plate, great pictures!!!

Thank you! On the M2C website you’ll have to search for them under the standard Kraton 6s V1-V4 section. They aren’t listed under the Kraton EXB section for some reason. I’m just waiting for the weather to improve so I can give the new mods a durability test.

 

[RV88]

The two server fans I ordered came in today so I started wiring them up. I got one mounted on the motor heat sink. Waiting on the 3D printed adapter I ordered so I can mount the second fan onto the ESC. I’m hoping this finally solves my heats issues.

 

[RV88]

My ESC fan mount came in today. It attached perfectly to the ESC. I just had to remove the four small screws on each corner of the ESC, set the mount on top of it, and attach with the supplied hardware.

When it came to attaching the fan to the mount I had to get a little creative since there was no hardware for that. I purchased the fan separately so I didn’t expect there to be.

Everything is plugged in and running as it should. I’m using the BEC to power the fans for now at 7.4v. Even at this lower voltage they move quite a bit of air. Sounds like two tiny jet engines lol. If it’s not enough I’ll re-wire for 3s power.

I’m hoping this solves my heat issues, but I won’t be able to test until the wind and rain let up here in CA. Can’t wait!

 

[L3phturn]

What fan mounts/grilles are those? What size and length screws?

 

[RV88]

What fan mounts/grilles are those? What size and length screws?

The fan mount I got from a seller on eBay. It’s specifically made for the Max6 ESC. This seller also sells fans that go with the mounts, but I purchased my own fans and wired them myself so I only needed the fan mount. The screws for the fans are 3x40mm I believe. I re-used them from an old heatsink I had. Link to the eBay page:

https://www.ebay.com/itm/3D-Printed-HobbyWing-Max6-40mm-Fan-Mount-/303809498132

 

[keefO]

Just curious what your temps were on your ESC? I am only asking because I ordered the MAX6 with the hope of eliminating the risk of overheating during normal use. Thanks!

 

[RV88]

Just curious what your temps were on your ESC? I am only asking because I ordered the MAX6 with the hope of eliminating the risk of overheating during normal use. Thanks!

what motor are you going to be running with your Max6? I think that has a lot to do with how much heat the ESC will build up.

When my ESC would enter thermal shutdown I would take a measurement with my temp gun. The motor would usually be around 160-170F but that was without a fan, so the motor didn’t have me worried. The ESC would be in the 140-150F range. I’m not sure how accurate that was with the ESC shroud and fan in the way though. It’s supposed to shut itself off at 207F according to the built in settings, so I’m assuming internally it was hotter than 140-150F.

 

[L3phturn]

The weight of the truck, size and weight of wheels and tires, ambient temperature, throttle usage, and most importantly terrain all impact heat.

 

[keefO]

what motor are you going to be running with your Max6? I think that has a lot to do with how much heat the ESC will build up.

When my ESC would enter thermal shutdown I would take a measurement with my temp gun. The motor would usually be around 160-170F but that was without a fan, so the motor didn’t have me worried. The ESC would be in the 140-150F range. I’m not sure how accurate that was with the ESC shroud and fan in the way though. It’s supposed to shut itself off at 207F according to the built in settings, so I’m assuming internally it was hotter than 140-150F.

I am going to be running the same setup (motor/ESC) that you are, actually supposed to get them tomorrow if the USPS tracking is correct, with DBoots Backflips and usually a 5000mah 6s lipo and I run it on my track which is pretty smooth terrain. I never had my ESC shut down due to exceeding its thermal limit, but I always hit my current setup (MAX8 w/1950kv motor with 17/50 gearing) after I run with my temp gun just to see how it is doing under normal load. I am seeing temps around 160-180F and its cold out, thats what led me to the MAX6 purchase, I was assuming that it would be much more capable of handling my EXB`s weight year round without having to really worry about anything out of the ordinary. I guess the thing that caught my attention when I was reading your post was the extra precautions you were taking after installing the larger system, and I started to look around and see that you were not alone in taking those measures. In your opinion, do you think that it is more a necessary step to install the heatsinks/fans or more a precautionary one?
Again I really appreciate your insight on this, I want to make sure I get it right!

 

[RV88]

I am going to be running the same setup (motor/ESC) that you are, actually supposed to get them tomorrow if the USPS tracking is correct, with DBoots Backflips and usually a 5000mah 6s lipo and I run it on my track which is pretty smooth terrain. I never had my ESC shut down due to exceeding its thermal limit, but I always hit my current setup (MAX8 w/1950kv motor with 17/50 gearing) after I run with my temp gun just to see how it is doing under normal load. I am seeing temps around 160-180F and its cold out, thats what led me to the MAX6 purchase, I was assuming that it would be much more capable of handling my EXB`s weight year round without having to really worry about anything out of the ordinary. I guess the thing that caught my attention when I was reading your post was the extra precautions you were taking after installing the larger system, and I started to look around and see that you were not alone in taking those measures. In your opinion, do you think that it is more a necessary step to install the heatsinks/fans or more a precautionary one?
Again I really appreciate your insight on this, I want to make sure I get it right!

I think the best answer I can give you is, it depends. On my setup I'm running a 20t pinion w/stock 50t spur on a 1650kv motor. After about 10 minutes of doing 65-75% power laps around my local dirt bike track the ESC usually shuts itself off from the heat. If you kept a 17t pinion you may not encounter the same problem. I currently have an 18t and 20t pinion. I tested both pinions without any fans (The ESC fan barely worked and was missing a blade and I had no heatsink or fan on the motor) and the ESC hit its thermal limit within 10 minutes for the 20t and about 12 or 13 minutes for the 18t. Unfortunately, I have not had a chance to test both pinions with my new fan setup due to the weather being terrible in my area. I will definitely report back my results and let you know if it's a worthwhile modification once the weather clears and I can test it out.

 

[L3phturn]

You need a decent fan on the ESC for starters. Without a fan that works properly of course it will thermal easily.

What temps are you measuring on the center of the motor end bell after 10 minutes? If you are hitting 180 you will likely damage the motor.

If you have a decent fan on the ESC and motor and you run for 5 minutes and measure more than 160 on the center of the end bell of the motor... gear down. I’d go down two teeth and then if it is running cool try going up one and measuring temps at 5 and 10 minutes.

 

[RV88]

You need a decent fan on the ESC for starters. Without a fan that works properly of course it will thermal easily.

What temps are you measuring on the center of the motor end bell after 10 minutes? If you are hitting 180 you will likely damage the motor.

If you have a decent fan on the ESC and motor and you run for 5 minutes and measure more than 160 on the center of the end bell of the motor... gear down. I’d go down two teeth and then if it is running cool try going up one and measuring temps at 5 and 10 minutes.

Motor temps were around 160-170 without a fan or heatsink. I agree with you on the gearing. I'm waiting for this weather to clear so I can start some tests now that I have a solid cooling setup on both the motor and ESC.

 

[L3phturn]

Motor temps were around 160-170 without a fan or heatsink. I agree with you on the gearing. I'm waiting for this weather to clear so I can start some tests now that I have a solid cooling setup on both the motor and ESC.

That's marginal but OK. With fans you should be able to safely gear up. It's been a high of -10 C here in Ottawa this weekend and the next few days so I have no worries about temps getting too high right now.

 

[RV88]

That's marginal but OK. With fans you should be able to safely gear up. It's been a high of -10 C here in Ottawa this weekend and the next few days so I have no worries about temps getting too high right now.

The plan is to test with the 20t first and see how that goes. I’ll drop to the 18t or lower as needed. Temps aren’t as cold here but the wind and rain won’t let up!

 

[jondilly1974]

The two server fans I ordered came in today so I started wiring them up. I got one mounted on the motor heat sink. Waiting on the 3D printed adapter I ordered so I can mount the second fan onto the ESC. I’m hoping this finally solves my heats issues.

View attachment 121726

View attachment 121727

While the fan pictures may work for you, just know it’s the wrong type of fan for this job. What you have here is a high airflow fan and it is poorly designed for your purpose. What you need is a high static pressure fan since it is mounted so closely to a heatsink. I can tell by how close the fan blades are to overlapping each other.

Here is an image of a fan designed to be near a heatsink or radiator. You will notice the large gaps between its blades. This will usually signify its type vs the close overlapping blades of your fans.

 

[RV88]

While the fan pictures may work for you, just know it’s the wrong type of fan for this job. What you have here is a high airflow fan and it is poorly designed for your purpose. What you need is a high static pressure fan since it is mounted so closely to a heatsink. I can tell by how close the fan blades are to overlapping each other.

View attachment 122344

Here is an image of a fan designed to be near a heatsink or radiator. You will notice the large gaps between its blades. This will usually signify its type vs the close overlapping blades of your fans.

View attachment 122345

Thanks for the info! I bought/wired both fans for about $12 so I’m not too worried about it if I have to go a different route. I basically followed a tutorial on YouTube for the wiring and they happened to use these fans so I figured I’d give it a try.