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Bugged out

Keep burning out motors!

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Hi all.

Need some advice.

Bought a Blitzer beetle and built it with my son a year or so ago.

I bought the car,ESC (Hobbywing quickrun1060) and batteries separately online.

After a few runs we toasted the stock motor.so after some reading I thought it was the ESC.

So purchased a new ESC and a quicker motor (15t) which the ESC is rated down to.

That motor ran twice and started smoking! Looked cool going along but ultimately an expensive special affect!

I have since been through 2 more motors they run once or twice and then the ESC won't even register the motor when it is switched on.

Please can I have your help and thoughts as my son has been very patient helping to repeatedly strip down and rebuild the blitzer beetle.

But ultimately we want good fast paced reliability.

These are the specs;

Batteries are;

 Floureon 7.4v  30C 4000mAh

We have 2 of these and usually run one after the other.

Etronix ProbeWP ESC 

Motor limit brushed 15t and up (7.2v) 17t (8.4)

Max instantaneous current 200A Fwd

100A Rev.

Brake current 150A.

ESC is set to Lipo and with braking.

The motor is Etronix 15t brushed.

My son runs the car hard on dirt and short grass down the park.

Sorry this is a long post but trying to give you all as much info as possible so you can solve my problem.

Many thanks !!

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The only reason I could think of is, either,

 

too high gearing putting stress on the motor! 

Something in the gearbox is wrong, does the car have ball bearings

And the last what I could think of is... brushes in the motor.

 

Since a 15T motor is capable of high revs, the gearing or this motor should be higher. 

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1 hour ago, Fabia130vRS said:

The only reason I could think of is, either,

 

too high gearing putting stress on the motor! 

Something in the gearbox is wrong, does the car have ball bearings

And the last what I could think of is... brushes in the motor.

 

Since a 15T motor is capable of high revs, the gearing or this motor should be higher. 

I replaced the stock pinion for a steel like for like (I think 19t 32dp)

I have taken the stock gearbox apart and cleaned re-greased everything with silicone grease. twice now in the last few weeks.

From reading on forums it is supposed to be a bulletproof transmission?

I have reinstated the dogbones( backfrom CVD) lubed ends with moly grease and uprated to hardened diff cups (as the stock ones were wearing)

lubed with silicone grease on the splines as per blitzer beetle manual.

The only other thing I can think of is switch to brushless ESC and motor?

Absolutely stumped but I am still of limited knowledge but I am keen to learn as my son loves it and what we have done with it.

 

 

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3 hours ago, Bugged out said:

We have 2 of these and usually rum one after the other.

Last time I ran packs back to back I burnt out a silver can, it was on 3s though.

I agree the gearing maybe on the tall side, depending on what you class as short grass, bowling green or football pitch length? 

Presuming it's fully ballraced? 

With the motor out, do the wheels turn freely and not binding anywhere? 

Do the battery connectors and cables get hot?

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It's fully ballraced with metal bearings although some of these could now be 2nd hand as I bought up a couple of chassis from eBay as spares (had a few "big crashes")and they may be mixed up a little.

Are the rubber sealed ones better?

Short grass as in just been mown or Tarmac. 

How could I shorten the gearing? Would it be a different pinion perhaps?

I can't seem to find alternative nylon spurs/gears anywhere.

The battery connectors are the yellow XT60 type(put on by local RC shop) as the tamiya type got too hot.

I haven't noticed the wiring/connectors getting hot but the can has been very hot and melted a 14t we put on 2 motors ago.

Hot enough to burn you if you're unlucky enough to accidently touch it!

Would a heat sink help this?

The chassis rolls freely back and forth but seems stiffer /like it chugs with the motor installed.

I hope this info helps any theories.

I've bought suspension hop ups and steering mods as seen on this forum so don't really want to give up on this cool basher.

 

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I have a spare Etronix 17t  motor I am willing to put in but not if it is only going to Last 1 run! At 20quid a pop that's an expensive expendable part!

Are we trying to run too hot a motor perhaps? 

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3 hours ago, Bugged out said:

I replaced the stock pinion for a steel like for like (I think 19t 32dp)

With a faster motor, you shouldn't go for a larger pinion at all. Also, your 32dp pinion is not the required metric m0,8. They are close, but probably not close enough

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56 minutes ago, bsy2010 said:

Also, your 32dp pinion is not the required metric m0,8. 

I can't remember exactly the card of the blister I got from the local shop but I think it was 0.8  32dp ?

It is actually a 13t not 19t my memory isn't the best with numbers and stats and I couldn't remember how many teeth without looking.

The last time we ran it...

It was excellent then when we put the 2nd battery on it died straight away. At the time I thought it was a duff battery. But now it may be we are just overheating the motor by running it for 25mins plus each battery at full tilt.

Is the solution to cut run time?

Install a heat sink?

Switch to brushless?

Any or all of the above? 

Thanks for your comments so far it's all a learning curve! 

 

 

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How tall are the rear tires?

The stock tires are a relatively low-profile diameter of 99mm. Taller aftermarket tires will have a significant impact on your final gear ratio, and not in a good way. The Blitzer Beetle transmission was originally designed with much smaller wheels in mind, so even the smallest pinion option (13T) is still a bit tall. I've tried a bunch of different 2.2 tires on my own Blitzer, but the OEMs are going to be a better bet if you want to put anything hotter than a stock motor in there.

The gears are definitely 0.8 module, so 32dp may fit, but likely to cause premature wear to your spur gear.

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The new tire are Proline Trencher

(I think).

They measure 105mm diameter on the wheel.

They do balloon a bit when he's nailing it which increases the circumference further still!

So OCD. would you recommend getting a fresh set of stock spikes for the rears and keep them for grass?

We're going out now to run it with the 17t.

I'll let you know how we get on 😉

15315024658718706717565722343249.jpg

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13T Should be ok, but I definetly would go 17,5T brushless with the 13T pinion.

 

in what condition are the brushes of the motor?

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On 7/13/2018 at 10:22 AM, Bugged out said:

The new tire are Proline dirt hawgs

(I think).

They measure 105mm diameter on the wheel.

They do balloon a bit when he's nailing it which increases the circumference further still!

So OCD. would you recommend getting a fresh set of stock spikes for the rears and keep them for grass?

We're going out now to run it with the 17t.

I'll let you know how we get on 😉

 

I think that may be your main issue; you've added more than 10% to your tire diameter. These came stock with a 27t motor. I don't think you're ever going to find the correct gearing for that combo if you want run times that 4000mah is going to offer. When the Blitzer was a new design, 1700mah was the upper limits of capacity, so you are expecting a whole lot out of a motor that wasn't designed for this kind of abuse.

Have you considered going back to a stock motor to see if this corrects the issue?

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I used to run a 13t pinion on a 13 turn motor (tamiya touring car motor) on the beach with the stock tyres, with a motor heatsink and that got hot. You will need to go brushless if you want to go fast.

I would go with something like a castle 3800kv combo.

 

 

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We have switched back to stock (worn) tires on OCD's advice and the motor ran much cooler.

We stopped after 15 mins to let the motor cool and then ran again for 15 mins and so on till both batteries were out.

I believe the issue could have been solved! We have steering and suspension mods to add tomorrow and we will run again to test.

Thanks to everyone's input!

I wouldn't have even guessed it would have anything to do with the tires but makes sense now with the larger tire and foam which makes them heavier still!.

Does anyone want to buy any Trenchers ???

20180713_200658_099.jpg

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1 hour ago, berman said:

I used to run a 13t pinion on a 13 turn motor (tamiya touring car motor) on the beach with the stock tyres, with a motor heatsink and that got hot. You will need to go brushless if you want to go fast.

I would go with something like a castle 3800kv combo.

 

 

That chassis is wicked fast!

Perhaps in the future but I think we are hopefully getting to a happy consistent level.(early days)

Thanks for the tip on the brushless combo and sharing your excellent vid.

What beach was that on? 

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3 hours ago, Fabia130vRS said:

13T Should be ok, but I definetly would go 17,5T brushless with the 13T pinion.

 

in what condition are the brushes of the motor?

I haven't stripped the motor yet

(a bit scared)

But I have a couple to practice on now😳

 I will have a look and see what we did to what.

Thanks for your info and knowledge.

I might save that combo for a future re re kit... 

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Seems to be solved! Run a few times now even in this hot sunshine and so far so good.

The steering mod and turnbuckle upgrades have made all the difference as well...! 

20180714_193002.jpg

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On 7/14/2018 at 9:47 AM, Bugged out said:

That chassis is wicked fast!

Perhaps in the future but I think we are hopefully getting to a happy consistent level.(early days)

Thanks for the tip on the brushless combo and sharing your excellent vid.

What beach was that on? 

Yeah it went alright. That was Waihi Beach in NZ, me and another TCer used to frequent there.

Glad you got it sorted! Maybe keep a set of new factory tyres for grass etc? Or measure the diameter and see if proline or jconcepts offer something similar diameter with a more versatile tread pattern?

Heh, now I want another Blitzer...

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On 7/13/2018 at 6:22 PM, Bugged out said:

 

15315024658718706717565722343249.jpg

Glad you got it all sorted. :) what body shell is that? I’ve not had a great time with the poly repo shells I’ve tried, this one looks a bit better?

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19 hours ago, jupitertwo said:

Glad you got it all sorted. :) what body shell is that? I’ve not had a great time with the poly repo shells I’ve tried, this one looks a bit better?

I've racked my brain and tried to remember.

I reckon I got it off eBay but I am uncertain if it may have been from USA to UK for about £40 (including postage)

The one I had came with a blue spray film?

So don't know if the one on ebay above is a bit too cheap and cheerful?

but £10 plus paint is worth a punt.!

Screenshot_20180720-185220_eBay.jpg

20160509_165509.jpg

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On 7/19/2018 at 7:17 AM, berman said:

Yeah it went alright. That was Waihi Beach in NZ, me and another TCer used to frequent there.

Glad you got it sorted! Maybe keep a set of new factory tyres for grass etc? Or measure the diameter and see if proline or jconcepts offer something similar diameter with a more versatile tread pattern?

Heh, now I want another Blitzer...

What a beach! Good advice on the tires mate ! I may well do that and try and source better wearing tires but looking at a grass set of stock spikes as we have 2 sets of wheels for each car now (I had to get one as well built from eBay scrap cars and parts) 

20180720_153928.jpg

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