My Kraton EXB

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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.

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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.
Interesting. I've seen videos of people testing those fans. They make a lot of noise and move a lot of air. That may mean they are a good choice for motor cooling IF you have them held away from the motor far enough to use the airflow so there is little static pressure, but they would be a poor choice for an ESC fan where they are mounted in an enclosure right up against the heatsink and will need to work with higher static pressure?

I am testing one of those high flow fans to cool the motor on my Notorious, but it's currently -12 C so... can't really get any useful information. :wacky:
 
Interesting. I've seen videos of people testing those fans. They make a lot of noise and move a lot of air. That may mean they are a good choice for motor cooling IF you have them held away from the motor far enough to use the airflow so there is little static pressure, but they would be a poor choice for an ESC fan where they are mounted in an enclosure right up against the heatsink and will need to work with higher static pressure?

I am testing one of those high flow fans to cool the motor on my Notorious, but it's currently -12 C so... can't really get any useful information. :wacky:
I honestly never thought about it when it came to R/C’s. I did have to think about it when I built my PC though so it would make sense that the same principles apply. I’m having the same problem with the weather! No testing until it improves. :(
 
I honestly never thought about it when it came to R/C’s. I did have to think about it when I built my PC though so it would make sense that the same principles apply. I’m having the same problem with the weather! No testing until it improves. :(

Hmmm. It would be interesting to come up with some kind of a test bench rig to measure airflow to discover which type of fan is most effective in various mounting configurations. For example, a fan designed for higher static pressure may do better when mounted right against a heat sink, but that may change if you have a mount that has a heat sink with much deeper fins or that you stand off from the heat sink or motor farther.

When I run those high flow fans on the bench the things will levitate right off the bench from dead flat against it, but a heat sink is more constricted than that, so who knows. I think I can work out how to test the temperature drop of a heat sink more easily if I heat it to a specific temperature and then test different fans and different mounts to see what will most effectively drop the temperature down. I have some old brushed motors kicking around and a couple of heat sinks and fans to test. I can heat the motors up in the oven. Ok now you have me thinking...
 
Hmmm. It would be interesting to come up with some kind of a test bench rig to measure airflow to discover which type of fan is most effective in various mounting configurations. For example, a fan designed for higher static pressure may do better when mounted right against a heat sink, but that may change if you have a mount that has a heat sink with much deeper fins or that you stand off from the heat sink or motor farther.

When I run those high flow fans on the bench the things will levitate right off the bench from dead flat against it, but a heat sink is more constricted than that, so who knows. I think I can work out how to test the temperature drop of a heat sink more easily if I heat it to a specific temperature and then test different fans and different mounts to see what will most effectively drop the temperature down. I have some old brushed motors kicking around and a couple of heat sinks and fans to test. I can heat the motors up in the oven. Ok now you have me thinking...
Haha I think the weather is starting to get to you. If you do end up doing some testing let us know the results. It seems all the aftermarket fans you can buy from NTF, Dust Devils Fans etc are high air flow. Almost every video on YouTube shows how they’ll blow your socks off apparently lol.
 
Interesting. I've seen videos of people testing those fans. They make a lot of noise and move a lot of air. That may mean they are a good choice for motor cooling IF you have them held away from the motor far enough to use the airflow so there is little static pressure, but they would be a poor choice for an ESC fan where they are mounted in an enclosure right up against the heatsink and will need to work with higher static pressure?

I am testing one of those high flow fans to cool the motor on my Notorious, but it's currently -12 C so... can't really get any useful information. :wacky:
Don’t get me wrong, they will still work, they’re just not the optimal type. If you are into PC builds, there are types a fans you use for case fans (high airflow) and ones you use for heat sinks and radiators (high static pressure). Use the wrong type and your outcome will be worse off than using the correct style.
 
Don’t get me wrong, they will still work, they’re just not the optimal type. If you are into PC builds, there are types a fans you use for case fans (high airflow) and ones you use for heat sinks and radiators (high static pressure). Use the wrong type and your outcome will be worse off than using the correct style.
I built this one middle of last year. 😬

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The weather was finally nice enough to do some testing with the new fan setup! I did two 15 minutes runs before hitting LVC. The ESC temp was hovering around 105-110F and the motor temp was between 135-140F. Needless to say it was a huge improvement.

Unfortunately, what hasn’t improved are my driving skills. I sheered the wing clean off on a bad tail landing, and to make matters worse I wrecked part of my rear shock tower trying to remove the broken screws. I’m going to replace it with an M2C tower but I need some help with the wing replacement. Should I stick with stock wing parts or are the RPM parts better? Also, will RPM parts fit the M2C rear tower for the EXB, if I go that route?

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The weather was finally nice enough to do some testing with the new fan setup! I did two 15 minutes runs before hitting LVC. The ESC temp was hovering around 105-110F and the motor temp was between 135-140F. Needless to say it was a huge improvement.

Unfortunately, what hasn’t improved are my driving skills. I sheered the wing clean off on a bad tail landing, and to make matters worse I wrecked part of my rear shock tower trying to remove the broken screws. I’m going to replace it with an M2C tower but I need some help with the wing replacement. Should I stick with stock wing parts or are the RPM parts better? Also, will RPM parts fit the M2C rear tower for the EXB, if I go that route?

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All wings are gonna break on a bad tail landing. Just keep buying stock ones and try soaking them in WD40 before install.
 
My upgrade/replacement parts came in yesterday so I spent a few hours putting it all back together! I also cleaned and added fresh oil to all of the diffs will I had them out. Not pictured is the ceramic bearing kit I order from Jim's bearings. I'm hoping ceramic bearings will save me some headaches down the road.
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Re-installing the end caps for the pivot balls was probably the hardest part. M2C sells a tool so you can actually put some pressure on the cap to get it screwed in. Well, I didn’t order that so I ended up making my own with the Allen wrench that came with the car and some layers of shrink tube. The shrink tube stops the Allen wrench from traveling too far allowing me to exert pressure when rotating the end cap.
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The M2C rear shock tower is very beefy. Took me twice as long to drill the holes for the shock tower braces lol. The fit and finish is also excellent.
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I purchased a stock EXB wing mount replacement. I also had to order the 3x20mm button head screws to go with it since I sheered them off in the crash.
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Serious beef mode. What does it weight when fully ready to run?
I actually hadn't weighed it yet but you got me curious so I went ahead and did it. She's a healthy 15.2 lbs or 6.8 Kgs if you like the metric system lol. That's with body, tires, and 2x Zeee 8000mah 3s hard case batteries installed as well.
 
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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.
Agreed. Have mostly the same set up as the OP. Stock Max 6 fan bent a blade on first major air. Had a new(ish) Traxxas 3475 fan I had in a BLX185. It’s a high CFM fan used in the XMaxx. About $23 on Amazon and is a direct fit for Max 6. Plug length is fine too.
 
I thought I had solved my heat problem but it turns out I was wrong. Even with the big 40mm fans the ESC was still reaching thermal cutoff. I got tired of it and reached out to HobbyWing for a replacement. It took a lot of emails and I had to explain my setup in great detail, but they agreed something wasn’t right and sent me a new ESC. I also had to send in my old one for them to “analyze” but once I provided a tracking number for the old one they sent me a new one.

While I was waiting I also upgraded my motor heat sink to the X-Maxx version. I do like this heat sink a lot better than my old one, but it did need quite a bit of “love” with the dremmel to make it fit the way I wanted.
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While I was at it I converted both of my fans to accept 3s power. Now they both blow like a hurricane. 🤣
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The X-Maxx heat sink was quite a bit bigger than the old one so I also had to make some room for the fan so I could clip the body properly.

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Hopefully this finally resolves any heat problems. I’ll be testing with the stock ESC fan for now. Probably won’t even connect the motor fan for the first test. I’d like to get a baseline first. Fingers crossed!
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Hopefully this finally resolves any heat problems. I’ll be testing with the stock ESC fan for now. Probably won’t even connect the motor fan for the first test. I’d like to get a baseline first. Fingers crossed! [/B]

That motor has a finned can. That means there is very little contact area between that heat sink and your motor. You need to rig something up to test your fans blowing directly on the can with no heatsink. Those are volume fans not pressure, so stand them off from the motor say a 1/2”. For testing just use double sided tape and zip ties to hold the fans so they blow on the motor can.

I would run your first test without the heatsink on it. Measure your motor temp in the center of the end bell. Find a spot to measure your ESc temp as well. Run for 1 minute to get it a little warm and let it rest a few minutes until it stops cooling and get your baseline. Run for 5 minutes and measure the same spot and record it. Let it rest until the temp drops to your baseline, put the heat sink on while you wait. Then run just with the heat sink on (no fans) and run for 5 minutes and repeat. Then with one fan and then two. Finally test with one and two fans blowing on the motor with no heat sink.

I found brackets that clamp around the motor and hold the fans in place without a heatsink. That is what I am running. I will test this in the spring, but it’s-15 C here so I don’t think my tests will be meaningful at the moment.
 
That motor has a finned can. That means there is very little contact area between that heat sink and your motor. You need to rig something up to test your fans blowing directly on the can with no heatsink. Those are volume fans not pressure, so stand them off from the motor say a 1/2”. For testing just use double sided tape and zip ties to hold the fans so they blow on the motor can.

I would run your first test without the heatsink on it. Measure your motor temp in the center of the end bell. Find a spot to measure your ESc temp as well. Run for 1 minute to get it a little warm and let it rest a few minutes until it stops cooling and get your baseline. Run for 5 minutes and measure the same spot and record it. Let it rest until the temp drops to your baseline, put the heat sink on while you wait. Then run just with the heat sink on (no fans) and run for 5 minutes and repeat. Then with one fan and then two. Finally test with one and two fans blowing on the motor with no heat sink.

I found brackets that clamp around the motor and hold the fans in place without a heatsink. That is what I am running. I will test this in the spring, but it’s-15 C here so I don’t think my tests will be meaningful at the moment.
So I opted to keep the motor heatsink on and the motor fan off for the baseline. The ESC went into thermal protection after almost exactly 5 minutes. I realized this happened because the fan on this BRAND NEW ESC lost a fan blade and failed in those first 5 minutes. HobbyWing needs to step up their fan game! Motor temp was about 140F on the rear of the motor can and about 130ish on the motor heat sink, so the heat sink was actually doing its job pretty well.

For the second test I added a 40mm fan to the motor heat sink and a 40mm fan to the ESC. Both fans got power directly from the 3s batteries that run the truck. This made a significant difference. I was able to actually run a set of batteries down to LVC for the first time. It took about 20 minutes of aggressive driving to hit LVC, motor temp was 130F at the rear of the can and the ESC was around 115F. Ambient temps were around 60F for these tests BTW.

Unfortunately, I was having a little too much fun doing double backflips and had one very poor landing which resulted in me splitting my front bulkhead in two pieces. Whoops...Now I have to decide if I want to go aluminum on the bulkheads or not.
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