MrDGH111

Boomerang motors keep blowing !!!

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Hi Guys, i seem to have a problem, i have a 1986 Boomerang [completely original] that i bought back to life recently, it had been stored away at my Mums house for maybe 20+ years, all i did was buy a new battery (4400Nmh Overlander) and had about 2-3hrs of trouble free fun, then the motor blew, ok i thought just replace it and try again, i bought and fitted a Tamiya 540 Silver Can, it lasted a couple of hours tops and also blew, at this point i did think maybe i should try a different type of motor but it was suggested that maybe id picked up an object [maybe a small stone off my driveway] and it had caused the problem so rather than trying a different type of motor maybe just try another standard silver can [less than £10 so why not], well this time it didnt last an hour and i noticed smoke coming firstly from the MSC so i quickly disconnected the battery, i picked up the car and noticed that if i put the car in slow speed position no problems [forward or reverse] but when i put the car in to medium speed the smoke now started coming from the ceramic resistor [?] and when i went full speed the smoke started coming from the motor, i quickly found that this motor was now also blown. So obviously theres something wrong elsewhere, i pulled the MSC to pieces and could see nothing obvious [not even any evidence of burning but decided to upgrade to an ESC, oh and a third new standard tamiya silver can. Great the car seemed better than it ever has before, also upgraded to a steering wheel type transmitter too, mainly because the ESC didnt seem to be working right with the old stick controller [brake not working as supposed to], well ive run the car now 4 times [so not quite 2 hours} and the motors gone again ! No smoke this time, not even much of a burning smell but no power from the motor to turn the wheels. Ive tried 3 different batteries and ive turned the wheels by hand to seem if anything is tight, im not really sure how free they should feel but seem ok really. Where is my problem coming from ? It has to be from within the gearbox doesnt it ? theres been no reason to look in there since i built it back in 1986 and i dont really want to have to now but i guess if you guys are in agreement with me then ill have to, or maybe theres somebody out there whos experienced this and can give me a few pointers ?

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The wheels should turn very freely. Did you try turning just one or two at the same time ? You need to spin the two rears at the same time to feel the running gear otherwise you ll just feel the differential. Check that then check each wheel individually to make sure nothing is binding on the wheel axles (grass or string sometimes gets woven around the axel and causes binding). If no luck you ll have to open the gearbox to see what’s happening inside. 

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Thanks for reply.

Ive spun each wheel individually and they all seems fine, ive also then spun both rear wheels together followed by both front wheels together, sure theres a little more resistance [which is to be expected] but not really anything that id say was definately going to cause any problems but i should say im very new to this, i dont have another car to compare it to so dont really know what i should be feeling here. I held the car against the inside of my garage internal door and quickly pulled down wards, after lifting the car away from the door the wheels spun for a couple of seconds longer [bear in mind there is the latest burnt out motor still fitted] ???

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17 minutes ago, t3garett said:

The wheels should turn very freely. Did you try turning just one or two at the same time ? You need to spin the two rears at the same time to feel the running gear otherwise you ll just feel the differential. Check that then check each wheel individually to make sure nothing is binding on the wheel axles (grass or string sometimes gets woven around the axel and causes binding). If no luck you ll have to open the gearbox to see what’s happening inside. 

Thanks for reply.

Ive spun each wheel individually and they all seems fine, ive also then spun both rear wheels together followed by both front wheels together, sure theres a little more resistance [which is to be expected] but not really anything that id say was definately going to cause any problems but i should say im very new to this, i dont have another car to compare it to so dont really know what i should be feeling here. I held the car against the inside of my garage internal door and quickly pulled down wards, after lifting the car away from the door the wheels spun for a couple of seconds longer [bear in mind there is the latest burnt out motor still fitted] ???

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Does the burnt motor still work ? If so try running the car with the wheels off the ground to see if it runs freely and accelerates / revs ok with your throttle imput. I really think you should open up the gear box and take a look. There might be something loose inside that gets jammed in the gears and make the motor overheat. Your problem is defiantly mechanical and not electrical since you changed from msc to esc to no avail. Good luck and keep us posted. And don t despair !

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2 minutes ago, t3garett said:

Does the burnt motor still work ? If so try running the car with the wheels off the ground to see if it runs freely and accelerates / revs ok with your throttle imput. I really think you should open up the gear box and take a look. There might be something loose inside that gets jammed in the gears and make the motor overheat. Your problem is defiantly mechanical and not electrical since you changed from msc to esc to no avail. Good luck and keep us posted. And don t despair !

Motor doesnt work at all now.

Looks like i have to go look into the gearbox then, i really didnt want to do this especially as its so old, im almost certain to have issues and break something thats difficult to obtain, so if there is somebody else out there with any other ideas please let me know before i 'put it under the knife', thanks for you help though and i do think youre right, ill keep you posted.

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Depending on the kinds of grease and oil used, after 20+ years it all can get quite sticky and make the motor work to hard.

Do a full service on the gears and get ball bearings while you are at it.

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1 hour ago, MrDGH111 said:

Motor doesnt work at all now.

Looks like i have to go look into the gearbox then, i really didnt want to do this especially as its so old, im almost certain to have issues and break something thats difficult to obtain, so if there is somebody else out there with any other ideas please let me know before i 'put it under the knife', thanks for you help though and i do think youre right, ill keep you posted.

You shouldn't have any problems with parts as the Boomerang was rereleased last year so there are plenty around still.  You could always turn the original into a shelf queen and buy a rerelease to run if there is sentimental value in the old one.

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3 hours ago, MrDGH111 said:

well ive run the car now 4 times [so not quite 2 hours} 

Just a quick Math check and that is aprox 30min a hit. 

Way too long no matter what motor. Its 4wd so its even harder on the motors with the drive train lag and added grip of a 4wd. Try running it for 10 min at a time and it should hold together just fine with a cool down between runs  The heat will kill any motor . ( Brushes and comm will glaze up, or winding's will short out or brushes will drop off or brush springs will get really soft. Maybe ALL of those RIP death sentences at once)

I run my brushless and brushed cars to a heat value not a min value. Some times 10 min or 5 min depending on weather, Track, Car type and how much performance I'm chasing out of it....

 

Just my Thoughts!!!!!!!

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What pinion is on the motor?

&

Are you aware of the Hotshot gearbox's pinion meshing system with the 4 stick plates works...?

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Personally, I would disassemble the car, clean any old grease out of the gearboxes and off the gears, and then reassemble the car as per the manual... I would also replace any bushings with ball bearings to help reduce friction in the drive train.. (bearings are quite inexpensive to buy now)

Back in the day, you probably used a 1200mAh battery in your Boomer.. Now your using a 4400mAh battery that is more than 3.5 time the capacity and runtime of what you had BITD.. All that extra runtime means more heat is being built up in the motor.. Consider doing what MadRacer suggested, and run it for 10-15 mins and then give it some time to cool down before running it again..

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3 minutes ago, Backlash said:

Personally, I would disassemble the car, clean any old grease out of the gearboxes and off the gears, and then reassemble the car as per the manual... I would also replace any bushings with ball bearings to help reduce friction in the drive train.. (bearings are quite inexpensive to buy now)

Back in the day, you probably used a 1200mAh battery in your Boomer.. Now your using a 4400mAh battery that is more than 3.5 time the capacity and runtime of what you had BITD.. All that extra runtime means more heat is being built up in the motor.. Consider doing what MadRacer suggested, and run it for 10-15 mins and then give it some time to cool down before running it again..

I run my bashers for around 30minutes a time with TBLE-02S and silvercan or torque tuned and haven't had any problems.  These are generally TT02B and Monster Beetle, but I have run my rere Boomerang for that long and a Novafox as well.

These are new though, well less than 18months old and have bearings and a bit of maintenance.

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Also depends where you're running... if it's a small area (like smaller than half a tennis court) AND you're running the LARGEST possible pinion gear (="highest" gearing) then you'll be forever accelerating & yeah it's not hard to cook even a silvercan.

Use lower gear (smaller pinion) for tight areas, largest (think its 17?) for wide area speed runs. 

Lower gear = more torque, car might feel less sluggish on pickup too.

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I recently had to do some maintenance on my re-release hotshot which is only 10 years old, and the grease has gone 'sticky' in that already. As other suggest, strip and degrease, then re-grease, re-bearing, and re-assemble. Also another quick check you can make is to take off the wheels and triangular drive hubs and make sure there is no grass or other obstruction wound round the axles. Running on grass will also heat up a motor a lot faster than running on a hard surface such tarmac or hard dirt.

 

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I burt out a silver can with my boomerang, so, stripped, cleaned,regreased and fully ballraced it.

I'm now running a 15t firebolt,1060 esc ,with 2s lipo in both the boomerang and a novafox, and the novafox will run rings around it, ive ordered smaller pinions to see if that helps things.

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1 hour ago, Wooders28 said:

I burt out a silver can with my boomerang, so, stripped, cleaned,regreased and fully ballraced it.

I'm now running a 15t firebolt,1060 esc ,with 2s lipo in both the boomerang and a novafox, and the novafox will run rings around it, ive ordered smaller pinions to see if that helps things.

My Novafox is the fastest of my Tamiya buggies by far when stock so I'm not surprised to hear that.  And it has a silvercan vs the torque tunued in the TT02B. 

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On 11/03/2018 at 10:35 PM, waterbok said:

Depending on the kinds of grease and oil used, after 20+ years it all can get quite sticky and make the motor work to hard.

Do a full service on the gears and get ball bearings while you are at it.

Ooooooookaaaaaaay, i really didnt want to have to do this [worried about breaking irreplaceable parts] but it does sound like there's a strong possibility that this maybe is contributing to [or causing entirely] my problem, thanks for the advise.

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On 11/03/2018 at 10:35 PM, waterbok said:

Do a full service on the gears and get ball bearings while you are at it.

By 'get ball bearings' do you mean for the wheels ? there aren't bearings available for within the gearbox are there ???

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On 12/03/2018 at 12:13 AM, MAD RACER said:

Just a quick Math check and that is aprox 30min a hit. 

Way too long no matter what motor. Its 4wd so its even harder on the motors with the drive train lag and added grip of a 4wd. Try running it for 10 min at a time and it should hold together just fine with a cool down between runs  The heat will kill any motor . ( Brushes and comm will glaze up, or winding's will short out or brushes will drop off or brush springs will get really soft. Maybe ALL of those RIP death sentences at once)

I run my brushless and brushed cars to a heat value not a min value. Some times 10 min or 5 min depending on weather, Track, Car type and how much performance I'm chasing out of it....

 

Just my Thoughts!!!!!!!

Most ive got out of the Boomerang [using the 4400mah battery] is 30mins, sometimes as little as just under 20mins, sometimes on a tarmac driveway, sometimes on the grass field next to my house but i did buy a second battery and when the first goes flat we slip in the second one.

Have we really only gotta have 10-15mins of fun at a time ? Its mainly my 6 year old son who is absolutely loving his new found pastime, if i tell him hes got sit and watch it cool down for 30mins hes not gonna be happy, probably shoot off on his pushbike somewhere, lol. 

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On 12/03/2018 at 12:45 AM, WillyChang said:

What pinion is on the motor?

&

Are you aware of the Hotshot gearbox's pinion meshing system with the 4 stick plates works...?

Sorry i dont have a clue about the pinion ? whatever came as standard back in 1986. This car is [was*] all completely factory standard.

*now fitted with 4400mah NiMh and a ESC

No im not aware of 'Hotshot gearbox's pinion meshing system with the 4 stick plates' or how it work ?

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12 minutes ago, MrDGH111 said:

By 'get ball bearings' do you mean for the wheels ? there aren't bearings available for within the gearbox are there ???

Just gone thru the manual, thats  17x 1150, 5x 850 and 2x 1150 trust bearings, if these are dried out (oil can get very sticky like a laquer)

thats a lot of resistance.

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4 minutes ago, MrDGH111 said:

Sorry i dont have a clue about the pinion ? whatever came as standard back in 1986. This car is [was*] all completely factory standard.

*now fitted with 4400mah NiMh and a ESC

No im not aware of 'Hotshot gearbox's pinion meshing system with the 4 stick plates' or how it work ?

first rtfm ;) its on page five step 5

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2 hours ago, MrDGH111 said:

By 'get ball bearings' do you mean for the wheels ? there aren't bearings available for within the gearbox are there ???

I just checked the Boomerang manual, and it appears that the Boomerang has plastic or metal bushings on all of its rotating parts like axles and gears.. These bushings can create a lot of resistance in the drive train, and can put more load on the motor which could be part of the reason why the motor is over heating..

As said previously, 30 year old grease can dry up and also put excessive loads on the motor as well..

Bearings are cheap to buy now, and you could probably ball race the whole car for not much more than the cost of a new motor.. It would only take 10-15 minutes to replace the bushings in the wheel axles with bearings, but to do the gearboxes, you will basically have to disassemble the whole car.. If you are going to have the gearboxes apart, then you may as well clean the old grease from the gears and re-grease them at the same time..  

Did you build the car originally??  I'm getting the feeling that you are a little reluctant to disassemble the car and do the maintenance that the members have suggested like cleaning and re-greasing the gearboxes, and fitting ball races... If you are able to do this work yourself, take it as an opportunity to do the rebuild with your son, and show him how the car works..

If you don't have a manual, you can find one on the main site here ..  https://www.tamiyaclub.com/manuals.asp?cm=369

Also, running the car on grass (or sand) can cause excessive load on the motor.. A large concrete or asphalt area like a netball court, or unused carpark would be better area to run the car.. Likewise, a hard packed dirt area like a BMX track, or bush land would also be suitable..

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15 hours ago, MrDGH111 said:

By 'get ball bearings' do you mean for the wheels ? there aren't bearings available for within the gearbox are there ???

Fully ballracing, gearbox and axles, i consider a must on all my cars (although ive not checked the bullhead yet! 🤔), as it increases battery life, aswell as speed, and reduces the chance of motor damage etc.

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On 11/03/2018 at 10:35 PM, waterbok said:

Depending on the kinds of grease and oil used, after 20+ years it all can get quite sticky and make the motor work to hard.

Do a full service on the gears and get ball bearings while you are at it.

Thanks for the advise

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