Sketer The Stig's Sketer adventures
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The Stig
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She is heavy. I have 2 fans on it, 15t pinion, 2 fans and 4s only. Everything runs smooth. Tested it. And it is a kuron 825 instead of the 725. Strange thing is. Opened the jammed centre diff expecting the worse. Nothing is broken. Haven't got a clue why the diff jammed
Horatio
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Sounds to me like it's the motor that's seized, rather than the diff. The Kuron 825 is a hot motor. It's tough enough getting it to stay cool on 13t, so I'm not sure how the temps would manage on 15t - on the Kronos at least. 13t/52t is 64mph, so just wondering if 15t might be a big ask?She is heavy. I have 2 fans on it, 15t pinion, 2 fans and 4s only. Everything runs smooth. Tested it. And it is a kuron 825 instead of the 725. Strange thing is. Opened the jammed centre diff expecting the worse. Nothing is broken. Haven't got a clue why the diff jammed
View attachment 5753
AngrySection8
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I'd think a 15 would be okay on the sketer, shorter tire anyway so the rollout would probably be similar to the kronos on a 12t or 13t I'm guessing. What's odd about the 825 is we've all experienced the temps it produces in our corallys but I'm running one in my savage flux off an 8bl150 G2 on a pair of 4s packs in parallel, 13lb truck spinning kagama wheels/tires, geared 20/44 which makes it go 42mph-slightly slower than a stock corally truck, yet I can beat that truck hard for 20 minutes straight and to date the hottest I've seen is 108°f on the motor, 98°f on the esc, no fan on motor either due to no room, not complaining just makes me scratch my head.Sounds to me like it's the motor that's seized, rather than the diff. The Kuron 825 is a hot motor. It's tough enough getting it to stay cool on 13t, so I'm not sure how the temps would manage on 15t - on the Kronos at least. 13t/52t is 64mph, so just wondering if 15t might be a big ask?
CCB-MN
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That is a bit of a head scratcher.
Brushless motors generally work very similarly to one another and there really are only a few things that cause heat. It’s just weird that the 825’s seem to run considerably hotter in certain vehicles. Probably in most cases, the most common heat source is going to be resistance, whether it’s due to mechanical or electrical resistance I don’t know. Mechanical is usually pretty quick to locate, there are usually some tell tale signs. I don’t notice any unusual mechanical resistance in any of my TC cars that isn’t also present in any of my other non TC branded rc’s. Seeing this, I would lean towards electrical resistance but that also opens up an entirely new can or worms. The only 825’s that I currently run are all tied to TC esc’s. This means that, while I’m assuming it’s probably a motor issue, (most likely a sub component that is failing or not working as it should or excess supply voltage that’s leading to magnetic saturation). It’s really tough to know for certain without more testing.
To be fair, I’m running the 825 in my SSTE along with a TC esc, and I'm not seeing the same heat spikes that I get in the Kagama running the same size gearing.
I’ve got a few different motors and esc’s lying around at the moment so if I have a chance I’ll try to pair up the 825 with a few different esc’s and see what I get for temps.
On a side note, I’m running the newer Castle 6S capable Cobra in my Tekno, no fans, less air flow, and it never gets anywhere near what I generate for heat in the Kagama.
Weird.
Brushless motors generally work very similarly to one another and there really are only a few things that cause heat. It’s just weird that the 825’s seem to run considerably hotter in certain vehicles. Probably in most cases, the most common heat source is going to be resistance, whether it’s due to mechanical or electrical resistance I don’t know. Mechanical is usually pretty quick to locate, there are usually some tell tale signs. I don’t notice any unusual mechanical resistance in any of my TC cars that isn’t also present in any of my other non TC branded rc’s. Seeing this, I would lean towards electrical resistance but that also opens up an entirely new can or worms. The only 825’s that I currently run are all tied to TC esc’s. This means that, while I’m assuming it’s probably a motor issue, (most likely a sub component that is failing or not working as it should or excess supply voltage that’s leading to magnetic saturation). It’s really tough to know for certain without more testing.
To be fair, I’m running the 825 in my SSTE along with a TC esc, and I'm not seeing the same heat spikes that I get in the Kagama running the same size gearing.
I’ve got a few different motors and esc’s lying around at the moment so if I have a chance I’ll try to pair up the 825 with a few different esc’s and see what I get for temps.
On a side note, I’m running the newer Castle 6S capable Cobra in my Tekno, no fans, less air flow, and it never gets anywhere near what I generate for heat in the Kagama.
Weird.
Interne Uebersetzeng 3.31 ist zu lange !!!!
The Stig
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Yeah, going back 2 14t on my big and heavy girl. Ordered new diff cups for centre diff and 2 new drive shafts for front and back. They where bad 2. If the diff is still running rough i need to replace it for a new Erik van Ravenstein version. The Kuron 825 is send to TC in Belgium. They will have a look at it. No movement it the motor at all.
Will keep you guys posted. Thanks for the help guys
Will keep you guys posted. Thanks for the help guys
Horatio
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I think the lower, easier gearing on the flux makes it easier on the 825, which is a low-wind motor. The Kronos XTR on 13t/52t is good for 60+mph on 6S, so must be drawing a helluva lot more current - thus all of us solving the heat problems with fans, heatsinks etc.
Looks awesome btw!
Yes - you need to do it!!Yeah, going back 2 14t on my big and heavy girl. Ordered new diff cups for centre diff and 2 new drive shafts for front and back. They where bad 2. If the diff is still running rough i need to replace it for a new Erik van Ravenstein version. The Kuron 825 is send to TC in Belgium. They will have a look at it. No movement it the motor at all.
Will keep you guys posted. Thanks for the help guys
View attachment 5767
AngrySection8
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I don't think it has "lower, easier gearing", what I'm saying is the flux does 42 on 4s, per the chart @Koma71 listed the corally does 43 on 4s, pretty close in my eyes and my kronos on 4s/stock gearing running twin fans on the motor typically sits in the mid 130°-140°f range, that's why I scratch my head as to why it runs a solid 30° cooler in one vs the otherI think the lower, easier gearing on the flux makes it easier on the 825, which is a low-wind motor. The Kronos XTR on 13t/52t is good for 60+mph on 6S, so must be drawing a helluva lot more current - thus all of us solving the heat problems with fans, heatsinks etc.
Looks awesome btw!
Yes - you need to do it!!
AngrySection8
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- Radix
For what it's worth I ran your numbers (assuming you're running stock tires or a tire of the same height) through a speed calculator and your current setup put you at 38.7mph, a kronos on a 12/52 gearing was 39.4 so depending on the weight of your rig and the terrain you're running you're probably safe running the 15t, this is where a temp gun is your friend, only way to truly know for sure.Yeah, going back 2 14t on my big and heavy girl. Ordered new diff cups for centre diff and 2 new drive shafts for front and back. They where bad 2. If the diff is still running rough i need to replace it for a new Erik van Ravenstein version. The Kuron 825 is send to TC in Belgium. They will have a look at it. No movement it the motor at all.
Will keep you guys posted. Thanks for the help guys
View attachment 5767
Horatio
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13t input / onto 43t crown is 3.307 - it's taller than typical race Truggy gearing which is normally 10t / 46t = 4.600.
Ultimately, no one can really say this Corally internal gearing is too 'long' (high) if people insist on using bigger pinions than the stock suggestions by Corally for the 825.
It's a very 'hot' motor - 2050kv and no slouch on 4S or 6S.
It's a mystery why the 825 should run cooler in a Flux than in a Corally rig. If the rollout works out about the same, perhaps the driveline might be nice and free in the Flux?
The Stig
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Well, the bearing from my Kuron 825 is totally wasted. I send it to corally and they found it. Great service because they can fix it and send it back to me for only 20 euro's. For that price i cant fix it myself (time spend) Again, there customer service is great. Motor is 1 year and 8 months old.
