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JuniorWKR
2010.05.19, 08:18 AM
i have a mro3 that i use for my stock car... it runs a 70t turn motor... i have had the car for some time now but as of late no mattter what motor or gearing i put in it makes the motor run red hot.... i cant even make it through a 5 min qualifier... it has stock fets and a power cap... i have rebuilt the entire car to make sure that nothing was binding and it is as smooth as can be... i have removed the powercap to see if that was the problem and it wasnt... has anyone else had this problem and can it be the board... all the fets are in tact and seem to be in good condition to the eye... thanks in advance for the help...

JuniorWKR
2010.05.19, 08:45 AM
i guess what im really asking is wether its time for a new board or just fet the one i have...

Action B
2010.05.19, 10:28 AM
If the problem was the FETs heating up or the board, then I'd suggest changing the FETs to fix the problem. If its the motor that is heating up I can't think of a single reason that upgrading the FETs would make the motor less hot.

Have you tried swapping the motor? How hot is "red hot" after running for a bit my MR-03's motor is certainly too hot too touch.

The steps you have taken thus far appear to be the right ones.

Half
2010.05.19, 10:34 AM
Have you tried swapping the motor? How hot is "red hot" after running for a bit my MR-03's motor is certainly too hot too touch.

The steps you have taken thus far appear to be the right ones.
This.

Action B, my pn70t ain't that hot after a 10minutes main. I can touch it, although it certainly ain't the cooler place on earth...
Try another engine if you can. I've never measured the power coming off the board from the fets so I can be no help to tell if the problem is board or fets. But if steering works just fine, my guess is motor problem.
If not, it's power fet problem.

JuniorWKR
2010.05.19, 10:40 AM
this is my third motor i have tried... i have had this car since the 03 first came out and this problem has only been as of the last 2 -3 weeks... no matter what motor i run i cant make it through a 5 min qualifier..

Action B
2010.05.19, 11:08 AM
One time I put longer screws in my girlfriends cars motor can and it seemed to touch something in there and make it bind up some. I don't know if thats normal but I thought i'd ask if your using long screws to mount your motor?

I still don't see why FETs would make a motor hot, though.

I have seen a FET go bad without any apparent damage to the FET ONE time. Is the car also going slow/sluggish before its hot?

JuniorWKR
2010.05.19, 11:20 AM
yes.... its only running t about half speed

EMU
2010.05.19, 11:21 AM
Did you remove the small caps on the motor can?

Is the motor directly soldered to the board?

Are you using any comm drops in the motor?

What lubricant are you using on the bushings?

Can you change the spur gear or diff to see if that helps?

Have you adjusted the motors timing? Can you try a non 70t and see if you have the same issue?

Are the motor wires rubbing the diff shaft?

I had some issues with my MR03 LM car at the Carolina Cup race with a handout 70t, the motor was very hot, and I lost all of my speed after about 3 minutes of running. I geared down a little more, and lubed the bushings and it seemed to help. The motor still got a little hot, but much less than it did before, and speed was about the same. I didnt use comm drops, because they will gum up the comm...

Im kind of stumped, because you said you changed motors and had the same issues with all of them. I assume that they all work fine in other cars... Which leads me to think that you might be getting some binding in the drivetrain (diff/bearings), but I know you keep your stuff in good order... so I dont think that would be the problem.

What ICS settings do you have the motor frequency set to?

Action B
2010.05.19, 11:24 AM
Good suggestions EMU. One time my motor wire was touching my diff shaft I didn't think of that.

I can't say anything for sure except one time I witnesssed a car that had exactly the issue your describing except I'm unsure about the heat. I can't tell you what caused it but eventually a top FET blew obviously. When I removed the FETs and tested them apparently a bottom FET had continuity between two FET legs that weren't supposed to have continuity EVEN when off of the board. SO two circuits were shorted that shouldn't be Via the FET. When I changed the FETs for this guy at the track I changed nothing else and the car was 2x faster. I am unsure if his motor was hot though he was a newer guy and not as keen keeping track of that sort of thing.

This was on a 2.4 MR-02 board.

JuniorWKR
2010.05.19, 11:36 AM
Did you remove the small caps on the motor can? (no)

Is the motor directly soldered to the board?(yes)

Are you using any comm drops in the motor?(no)

What lubricant are you using on the bushings?(reflex on the none brush side)

Can you change the spur gear or diff to see if that helps?(yes)

Have you adjusted the motors timing?no Can you try a non 70t and see if you have the same issue?no only tried new 70t's as thats the class

Are the motor wires rubbing the diff shaft?(no)

I had some issues with my MR03 LM car at the Carolina Cup race with a handout 70t, the motor was very hot, and I lost all of my speed after about 3 minutes of running. I geared down a little more, and lubed the bushings and it seemed to help. The motor still got a little hot, but much less than it did before, and speed was about the same. I didnt use comm drops, because they will gum up the comm...

Im kind of stumped, because you said you changed motors and had the same issues with all of them. I assume that they all work fine in other cars... Which leads me to think that you might be getting some binding in the drivetrain (diff/bearings), but I know you keep your stuff in good order... so I dont think that would be the problem.

What ICS settings do you have the motor frequency set to? (either low or med... definitly not high)

it is really starting to bother me as i have tried everything but the board as that is the most expensive piece to replace... im hoping a fet job would fix it but dont wanna waste my time doing fets if its ultimatly the board...

JuniorWKR
2010.05.19, 11:37 AM
Good suggestions EMU. One time my motor wire was touching my diff shaft I didn't think of that.

I can't say anything for sure except one time I witnesssed a car that had exactly the issue your describing except I'm unsure about the heat. I can't tell you what caused it but eventually a top FET blew obviously. When I removed the FETs and tested them apparently a bottom FET had continuity between two FET legs that weren't supposed to have continuity EVEN when off of the board. SO two circuits were shorted that shouldn't be Via the FET. When I changed the FETs for this guy at the track I changed nothing else and the car was 2x faster. I am unsure if his motor was hot though he was a newer guy and not as keen keeping track of that sort of thing.

This was on a 2.4 MR-02 board.


yeah im really hoping its the fets...

EMU
2010.05.19, 11:38 AM
Try the fets... As Brandon said above, there could be a short that is causing the problem. Im still a little stumped... I would say try a faster motor, and see if it still gets hot and runs slow.

Tjay
2010.05.19, 12:12 PM
I don't really care much of my motors. I never clean them, change brush or even check if it is hot or whatnot. I just drive and collect all the dirt in the comm/brush on both stock and mod motors until a good buddy of mine Larry (Felix2010), had showed me that a clean and well maintained motor makes a difference. With a motor dyno, my old gunked up PN70 was getting 22k rpm @ 4.8 volts and without changing anything but just cleaning it with motor spray and lubing the bushing, it went back up to 24k rpm and made the motor cooler than how it was. This is what I started doing just before the KO GP race in April. Now, I have my motor spray and air can in my tool box at all times.

First, what you need to do is to get a temp reader. This way we know exactly what you mean by "getting hot". Because mine is on fire. ;) Well, it was on fire until I forced myself to start maintaining my motors. I think my PN70 was getting up to 120-130 degree F while my mod motor is only at 90-100 degree F within 10 mins of runtime. I haven't checked mine lately but thanks for reminding me. :) Maybe I should look into that aswell and see what a good temp would be for this motor.

I have mine geared at 13/51= 3.92 but then again our track has 26 tiles... Also;

1. check if you're using 21mm wheel. This can also cause over heating...
2. Check on the car's weight as well, anything under 180 is good.
3. check bushing if there's no binding. Some of these motors bushings are not aligned thus, causing the armature to bind on the bushing.
4. Check the end bell (motor cap) if it is properly seated. Sometimes when they close the endbell, there's still a little gap between the motor case/cover. Have them properly seated.
5. Sometimes the brushes are too think causing too much pressure on the commutator. Break the motor in properly for less drag on the brush/comm.

Good luck and keep us posted!

EMU
2010.05.19, 12:18 PM
Good info TJ :) I dont clean my motors enough, or at all for that matter... I definitely should, especially after reading your post ;)

JuniorWKR
2010.05.19, 12:31 PM
i clean and relube my motors after every run... i feel that they always run the best that way... and i find that spraying it while the motor is under power cleans it better... com and brushes appear to be much cleaner then just spraying alone..

Tjay
2010.05.19, 12:45 PM
I think I have at least 8-10 PN70 motors that I got from the handout races in early 2009. None of them were ever cleaned.. If I need a PN motor, I just grab one from this box and run it. Not knowing that those debris in the comm/brush can actually make a difference. Even 300-800 rpm gain is a MUST in stock racing. ;)

Eugene, I'm sure you already know that. You're just being lazy like me. :D :)

EMU
2010.05.19, 12:48 PM
We only use the 70t for one class over here, so I just run it... I dont even change tires or do any setup work to the car anymore. Pure laziness. But it also can be sandbagging, if you look at it that way ;)

CristianTabush
2010.05.19, 01:01 PM
This has bad FETs, written all over it, one or more of them are about to go... If nothing has been changed and you have replaced motors and gears, it is the only thing left that could be bad... Dead giveaway is excessive heat and not running at full speed.

Action B
2010.05.19, 01:41 PM
At this point it seems the only viable possibility.

Change them out it doesn't cost that much!

I do MR-03 boards for $25 and provide the FETs if you feel uncomfortable doing them yourself and don't have a local guy that can do them.

JuniorWKR
2010.05.19, 02:42 PM
do fets have a shelf life?... lets say something like 1000 hrs of operating time?

Half
2010.05.19, 04:25 PM
do fets have a shelf life?... lets say something like 1000 hrs of operating time?

Electronic components do wear over time. But to be fairly accurate or an average of working time depends largely on operating conditions.
Let's say that these FET's should handle an 70t for years and years (anything <10years). But, like anything electronic, is largely dependent on work temperature, ripple tensions, etc.
The FET's on the Z's are power fet's so they have a high gain on current. This tend to reduce the life cycle alot compared to other standard tension gain fet's.

CristianTabush
2010.05.19, 07:26 PM
do fets have a shelf life?... lets say something like 1000 hrs of operating time?

To put it simply, yes... But it usually is a long time. It does not mean you could have not gotten a bad one, that just went bad quickly. I am pretty certain your problem is FET related though. I am 99.9% sure that this should be your problem.

machgo5go
2010.05.19, 08:21 PM
To put it simply, yes... But it usually is a long time. It does not mean you could have not gotten a bad one, that just went bad quickly. I am pretty certain your problem is FET related though. I am 99.9% sure that this should be your problem.
Well JR, so now is your chance to get some Magic FET's so you may break into the mid 7's!;)

egonzalez
2010.05.19, 08:43 PM
do fets have a shelf life?... lets say something like 1000 hrs of operating time?

If you think it’s your fets (primarily your forward fet)…. You could run the car on your stand and measure it’s temp going forward and then going backwards. It might not be the best test, but you might be able to see a difference between the two fets as it relates to heat they are generating … The same test can be done to measure the power each fet is distributing to the motor…

EMU
2010.05.19, 09:10 PM
Edel, just remember that the motor may have timing, so it will give different temps fwd and rev.

egonzalez
2010.05.19, 09:31 PM
Edel, just remember that the motor may have timing, so it will give different temps fwd and rev.

Couldn't he reverse the motor wires when testing his reverse fet? You should still be using the same timing but a diffrent fet...

EMU
2010.05.19, 10:44 PM
Yes, I was going to say that... but didnt have time (wasnt supposed to be on the computer at work).

CristianTabush
2010.05.19, 11:49 PM
At this point, just replace your FETs... No need to test to see which FET is bad and which is good. Replace them with some higher quality, new FETs. If it still does not work, then your board has gone bad (maybe a bad trace).

JuniorWKR
2010.05.23, 07:00 PM
just wanna thank everyone for their help.... i replaced the fets and the car is running great... i guess i got to remember to take that into consideration the next time one of my cars is starting to slow down and the motor is getting hot...

JuniorWKR
2010.06.08, 02:53 PM
so after replacing the fets and taking it for a few laps around the track the car felt great... i didnt touch the cat again till our next race night... got out in the first qualifier and the car was blazing... half way throught the qualifier the friggin thing went back to half power... i swapped the motor and went back out for second qualifier and it was fast again... and once again half way through it died... i tried everything... motors, batteries, differnt presets using the handheld programmer.... no matter what i did as soon as the motor got hot the board died down... i wound up just replacing the board...

every thing is ok now as i ran 5 straight packs of batteries and the car never lost pace... but i sure would like to know what went wrong with the board..

herman
2010.06.08, 11:01 PM
nice read... must have been a bummer that you had to change out your board after doing almost everything...

happy to hear that you got everything in order after replacing the board...

couple of questions though... what motor were you using after you swapped fets? does it go back to half power even if you use the stock motor? if it doesn't maybe you could still use the board for stock races... what fets did you use to replace the old ones? you might want to hold on to the fets on the old board.. don't know when you will need them... :D

EMU
2010.06.08, 11:28 PM
Herman, I think he has only used a PN 70t motor in the car, before and after the issue.

At the least, this will be helpfull for others that may have similar issues...

herman
2010.06.09, 03:30 AM
thanks for the info emu... :D

dxm2
2010.07.06, 01:53 PM
Hi everyone,
Just bumping this because I had a similiar issue last night. New MR03 and the motor died after about 4 mins. The motor was a new PN 32turn. Oddly enough, I had this car running fine on an Xspeed the week before, so it maybe the new PN 32 is too hot for the stock MR03 electronics. Also, this motor is sold without caps. It was really, really fast before it died! I'll try the xspeed again and see if it runs for over 5 mins.

Mike Keely
2010.12.19, 09:24 PM
so after replacing the fets and taking it for a few laps around the track the car felt great... i didnt touch the cat again till our next race night... got out in the first qualifier and the car was blazing... half way throught the qualifier the friggin thing went back to half power... i swapped the motor and went back out for second qualifier and it was fast again... and once again half way through it died... i tried everything... motors, batteries, differnt presets using the handheld programmer.... no matter what i did as soon as the motor got hot the board died down... i wound up just replacing the board...

every thing is ok now as i ran 5 straight packs of batteries and the car never lost pace... but i sure would like to know what went wrong with the board..

I have this same thing happening but I put a new board in the car and it is still doing the same thing. The only thing that I have not done is changing out the chassis.HELP!!!

unearthed name
2010.12.19, 10:16 PM
maybe you should check your gear mesh. maybe it's too tight. my friend fried his fets because he set-up his gear mesh too tight.

Mike Keely
2010.12.20, 05:16 AM
No, that's not it. The mesh is fine. Tried three stock motors. Running 12 pinion and a 54 spur. Thanks though.

Tjay
2010.12.20, 12:15 PM
Hi Mike,

You may try the following:

Electrical:
-replace your motor wire
-solder your motor wire to the board (click here (http://fastpaceracing.com/content/how-solder-motor-wires-board))
-make sure the connection between the +/- board wire to the battery tabs are tight, not loose (mine is not solder btw, but I always check them. Soldering them would be best).
-I'm sure you've tried replacing your motor with new ones but, have you tried borrowing someone else's motor that works? Maybe try that also. It's possible to get bad motor from the same batch.

Mechanical:
-make sure rear tires are not rubbing on the body.
-remove pinion and check if your rear diff can move freely if you spin it by hand.
-make sure the motor screws are not too long
-some motors, when tightened on the motor screws tends to bind inside. I dont know why but I'm thinking its the bushing or the screw holes are off center but anyhow, check on that also.
-check the rear pod bearing cups and make sure you're using the same and in the same position. OFF center shaft can also cause resistance=over heating motor.

Good luck!

I have this same thing happening but I put a new board in the car and it is still doing the same thing. The only thing that I have not done is changing out the chassis.HELP!!!

Mike Keely
2010.12.20, 09:19 PM
Checked all of this. Not using the stock rear pod. Using a PN pod. Sending the PC board back to Kyosho. Thanks MK

vash
2011.02.14, 09:36 AM
Had a very similar issue Saturday. Fet's are new and have run fine for two or three practice sessions but over the weekend car seemed ok at first then fell off a cliff. The car we be ok for about 30 seconds before really slowing down. After a 5 min qual the motor was really hot, hotter then it should have been. Tried more then one motor. Broke down the motor that has been on the car for weeks and there was uneven brush wear. I checked the voltage and amp draw to the motor(no load) and seems ok I guess. Voltage is very close to power coming from cells and amps stay under 2 if you punch it. Is this problem usually the board? Thanks

vash
2011.02.21, 09:23 AM
suggested to me it might be the pinion. Switched pinions making sure it was on tight and my issue seemed to go away

arch2b
2011.10.10, 11:46 AM
i've had a similar problem with stock motors in my mr-03. took brand new box stock motor and after 5 minutes it's nearly hot enough to melt the stock motor pod. the overall speed drops off significantly after a few minutes. the chassis is stock, brand new, running in kyosho stock class. the motor was box stock, brand new.

i changed pinions, no change.
i went to a lesser tooth pinion, no change
i changed to another stock motor, no change.

there is something about my stock chassis that is making motors go thermal nuclear.

egonzalez
2011.10.10, 01:00 PM
Hi Mike,

You may try the following:

Electrical:
-replace your motor wire
-solder your motor wire to the board (click here (http://fastpaceracing.com/content/how-solder-motor-wires-board))
-make sure the connection between the +/- board wire to the battery tabs are tight, not loose (mine is not solder btw, but I always check them. Soldering them would be best).
-I'm sure you've tried replacing your motor with new ones but, have you tried borrowing someone else's motor that works? Maybe try that also. It's possible to get bad motor from the same batch.

Mechanical:
-make sure rear tires are not rubbing on the body.
-remove pinion and check if your rear diff can move freely if you spin it by hand.
-make sure the motor screws are not too long
-some motors, when tightened on the motor screws tends to bind inside. I dont know why but I'm thinking its the bushing or the screw holes are off center but anyhow, check on that also.
-check the rear pod bearing cups and make sure you're using the same and in the same position. OFF center shaft can also cause resistance=over heating motor.

Good luck!

Hey Mike,

The motor screws the hold the motor in place can cause binding against the armature. I have had the same exact symptoms and that was the culprit. Not all motors have the same amount of spacing from the can to armature…

arch2b
2011.11.06, 12:03 AM
anyone else had any success in fixing this problem? i'm thinking about emailing kyosho support to see if they have a solution.

johndo
2012.06.19, 06:01 AM
We also having motor overheating issues with brand new MR03 and Life batteries. We changed gearing, aluminium motor case but problem exists. After 7-9 minutes cuttoff and only steering is working.

We remove motor capacitor and the problem dissapears. We don't want to do that because affects motor lifetime.

Any suggestions?(We don't want to change FET because the board can handle 7.2V ov Life.

refsiul22
2016.08.10, 04:24 PM
Old thread.... but still interesting!

I have been racing a Stock (PN 70T motor fixed gear ratio 13 Pinion 53Spur) category for a few weeks in our club. Car has been great and competitive but have noticed that my motor temperature has been too high (forgot to bring a temperature gun to the track, but to give you a reference, you can’t touch the motor after a few minutes of racing..)

I’m running a PN chassis with a Kyosho ASF board, PN 70T motor, 13 Pinion 53 Spur on a 94mm Lexus car. I have compared to other racers and their motor temps were much lower and OK compared to mine. I have cleaned and lubricated the motor, checked the brushes, diff, bearings, etc. everything smooth.

Car works great, and have won several Mains recently but I’m kind of confused at what’s causing the overheating.. I will try to cover all suggestions above... but do you have any updated suggestions or similar experiences/solutions?

In the following weeks, I will try to update the temp that my motor is reaching.

***
PD. Forgot to mention that (as far as I know) I'm the only one using gear diff

mleemor60
2016.08.10, 05:54 PM
Look for any kind of binding first. Anything. I have seen the pinion work it's way out the motor shaft until the base of the teeth comes in contact with the spur. Almost not noticeable unless under load. Maybe a little change in motor pitch but little other warning. You may find a piece of hair wrapped around the axle at one or both hubs. Check solder joints for weakening connection which can cause excessive current draw. What condition are the brushes in? How is the tension. Using "comm" drops? Things like that. Heat means it is being overworked either electrically or mechanically. For the motor to be "on pipe" you should be able to use the lip test. If you can hold the motor to your bottom lip for a second or two without raising a blister you are where you need to be gear wise. Any hotter and you need less gear. Any colder and you need more gear. At 13/53 or 4.07:1 I would say you are geared way to high unless you are running the Bonneville Salt Flats. You said that was a "spec" ratio. I would like to be the one selling motors with that ratio. Just for sh1ts and giggles try an 11T pinion with no other changes and see if the motor cools down along with quicker lap times. If it does I would lobby for a different required ratio.

arch2b
2016.08.11, 06:43 AM
if others are running the same ratio and do not have the same issue, hard to point to the ratio in this case... if it were so, all would have the problem. in the end, it could be he just got the bum motor, it happens.

have you tried another of the same motor? just one thing to add to checklist of things to run down.:p

refsiul22
2016.09.12, 01:43 PM
tried a backup 70T motor and had the same problem..

some findings/updates:
-temp after a few minutes of racing reaches 130F
-motor were cleaned and lubricated prior to racing.
-peer racers (same ratio and track conditions) reach 95-100F
-changed from gear to ball differential to see if it made a difference. Temp was slightly lower, but still way above peers.

will try 70Ts motor on second car and solder some 50T, 39T motor to racing car for tests.

EMU
2016.10.21, 01:17 PM
tried a backup 70T motor and had the same problem..

some findings/updates:
-temp after a few minutes of racing reaches 130F
-motor were cleaned and lubricated prior to racing.
-peer racers (same ratio and track conditions) reach 95-100F
-changed from gear to ball differential to see if it made a difference. Temp was slightly lower, but still way above peers.

will try 70Ts motor on second car and solder some 50T, 39T motor to racing car for tests.
Have you made any ICS adjustments for power delivery? Are you aggressive with throttle/brake? How low is your motor, depending on mounts, some can rub the track when in the lowest positions increasing heat.

How new is the motor? Do you have an OLD motor you could try, or borrow from someone that you know does not get hot over a battery pack.

I have had some electronics that made the motors get a little hotter, and they were always a little faster than others (they would be used for stock classes). The difference was not 30f though, maybe 5-10f at most.

TheSteve
2016.10.21, 03:07 PM
Swap cars with a friend for a race, see what the temps are like.