Motor heat issues.

[Waitwhatsthat?]

I have a pieced together wraith that I'm having trouble we with keeping the motor temps down on. Short back story here. I took an ax10 deadbolt and swapped everything over to a wraith cage and chassis. So the original setup was 87/20 gearing with a 55t motor on 3s. It worked fine in the deadbolt and was ok in the wraith. I wanted a little more wheelspeed and the cheap motor was getting tired, so I swapped in a 45t motor, with 87/18 gearing. The first run it was good. The next run it overheated and smoked. I found that I had overtightened the wheels, and attributed this to the overheating issue. So last night I installed a 35t motor that I had laying around. Dropped the gearing again, 87/16. I made sure that the transmission and drivetrain spun freely while I had the motor out. This combo felt good as I tested it out around the house. After about 20 minutes I checked the motor temps. I could feel the heat through the skid plate, and temp readings in the can were right in the 160 range. Seams a little hot for some very mild running for a short amount of time.

I followed the the motor and gearing guide, but it's not perfect, as it doesn't take into account rig weight, tire height, and various other factors. That's ok as I understand it just gives a good starting point. Ive got a 12t pinion on order which will bring the creation down to 7.25:1. Which is much lower than the recommended gearing ratio. Until then im trying to figure out any other causes of this heat. I did notice that there was a small amount of up and down play at the spur gear shaft. Not enough for the gear teeth to become out of contact, but enough to notice. I'm thinking of opening the trans and changing the bearings out. Could this be causing the problem?

Thanks in advance for actually reading through all of this.

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[PileDriver]

If the drivetrain is free then it should be good. When I run brushed motors on 3s my gearing is 88 or 90 spur and 9 or 10 on the pinion 48p.

You should be able to fully tighten your wheels without the drivetrain binding up. I use a electric screw driver with a light torque setting.

[TacoCrawler]

I run an 87/14 on 3S
and the motor becomes just warm.
Granted... I don't go any faster then may 6mph.

Besides gearing...
I would be making sure the drive train rolls free.

I have had ball bearings seize up (axles/hubs specifically)...
and ya don't really know they don't roll smoothly
until ya remove them and attempt to spin them by hand.

The torque from my motor, even with a seized bearing...
just rolls on regardless.
But a seized bearing will reduce your run time...
and create more heat for both the motor and ESC.

I never drive in mud or water.
So a seized bearing can happen just from driving in dirt/dust.

[Waitwhatsthat?]

I can fully tighten the wheels without causing a bind but in this case I had overtightened them. I have a bad habit of really cranking down on wheel nuts after I had some come loose and strip out the hexes.

I tore down the transmission and inspected everything. Nothing was froze up and all seamed to be in good condition for a trans that hadn't been apart in two years. I did replace the bearings anyhow since I had plenty of extras. This took care of the play in the spur gear shaft. Did quick run around the house and the temps were barely over 115. I think that the play in the shaft was causing the spur gear to be pushed closer to the pinion and creating a tight gear mesh, causing the motor to run hot. At least that's the only thing I can come up with. I'm going to run it on some trails tomorrow and really test it out and monitor the temps. If it gets hot I'll go to the 87/12 gearing.

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[PileDriver]

Good stuff man glad u fixed the problem.

[Waitwhatsthat?]

Well after a good run yesterday it started to hot again. Didn't smoke like the previous motor at least. Also have a nice clicking noise coming from the trans. Guess I drop the pinion down to the 12t and figure out what's causing the clicking noise.

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[TacoCrawler]

87/12 is geared purdy low IMO...
definately not a top end speedster...
but low speed wheel spin might be hampered some.

a brushed 55 T motor shouldn't run too warm with 87/20
tho' I usually ran my 55 T at 87/18
an 87/16 should do acceptably with a 45 T motor.
87/14 for a 35 T motor
and 87/12 for a 27 T motor.

is your system a brushed or brushless motor set up ?

I run brushed 87/14 with a 1:6 scale hard jeep tj body atop my wraith.
Probably weighs in at 12 ^ lbs with the chassis.
Along with 2.2 PL TSL XL tires (5.80")
Runs between 140* - 150*
Maybe a little higher if I'm on the throttle 100% of the time.

If your motor is still becoming too warm... something else must be amiss.
But I'm not so sure it's your gearing.

What tire height ?
don't say 7 + inches tall. Lol

160* motor temps aren't exessively hot IMO
tho' 140* would be better.
I've seen folk running 180 without failure.
Tho' IMO... cooler is always better.

Maybe it's just that the motor isn't efficient
and runs hotter then others might ?

Hope it's not a budget Axial, integy or RC4WD motor...
'cuz those can be subpar and easy to blame.

Higher end rebuildable motors are generally more efficient
and run cooler then most all of the budget motors offered.

I run a Holmes Hobbies Torque Master 35 T / HH's BR/XL ESC
runs way better and cooler then did my prior attempts at running
the Axial, RC4WD, integy and other non-rebuildable budget type motors.

After running my HH's 35 T TM
I regret ever wasting my coin on budget motors.

I'd only use a budget motor again if I were fording/splashing thru mud puddles or driving in a mudpit.
I'd probaly just toss it in the trash after that abuse.

What temp is the ESC reaching ?

--------------

Far as clicking inside the trans...
unless a bearing has exploded...
it could be the idler gear has sheared or flattened a tooth.
common deal for the idler gear to fail if still utilizing the plastic trans gears.

If metal gears are in the trans...
I might possibly suspect the screws sandwiching the outdrive halves
are backing out and hitting the case internally.

use Blue Locktite on them screws if they're backing out.

[Brake Weight]

Something isn't fitting correctly if the wheels are binding. When you snug up the m4 nut by hand it shouldn't be more than maybe a 1/3-2/3 more and it's tight. Invest in some poly lock nuts. Technically after one use they're not good any more.

How do you set he gear mesh? Some do it by feel, others with a piece of paper. I like to use the Axial plastic bags and then push the gears together firmly.

Pics?

[Waitwhatsthat?]

OK Taco, lots of info there. It is a brushed 35t cheap rc4wd motor. I pulled the motor out of my scx10.2 which is now running a Holmes motor, and yes the difference is amazing. Even though it's a cheap motor Ive taken good care of it. It gets washed, cleaned and re oiled after every run. I'm not sure what the exact temp was during the last run. The batteries died on my temp gun. (FML). I haven't opened it back up yet to see what the noise was, but I'm running steel gears in the trans, and the screws are loctited in.

Brake, the wheels are no longer an issue. I'm fairly certain they are what killed the 45t motor though. I had over tightened them and I blame myself completely. I have strong hands and can really crank down on the nuts, so lesson learned, and I'll be more careful in the future. I set gear mesh by feel. I've tried the paper method but it never comes out right, so over the years I've gotten a good feel on how mesh is supposed to be. I'll get some pictures when I open it back up. Might be a couple of days.

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[Waitwhatsthat?]

Well I got some motivation and decided to check it out real quick. I immediately noticed something off with the gear mesh. Turns out the motor bushing was worn out and the motor had tons of play in it. I guess it's time to start over with a fresh motor, and this time with a good one. Btw I forgot to mention, it's around an 10lbs rig. Tires are proline tsl xl's. Took the motor apart, brushes were pretty much gone too.


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[allanon1965]

I do think you have found your problem

[Waitwhatsthat?]

I hope so. As for now that makes rc #3 down for repairs. Hopefully the holiday season will be kind to me, and I can get them up and running again.

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