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mattharri

Loss of speed!

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Just built a Re RE Hotshot. Ball raced bearings, 4000mAh battery. After several runs with no issues the car has lost speed. I would guess its about half the speed from when first built. Any suggestions appreciated. Bit of a novice but am guessing motor or gear box ?.

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Just a couple of initial thoughts for a couple of quick checks.

Are the tyres slipping on the rims? Have they been glued?

Are the wheels/hubs/drive shafts all still seated correctly?

Worth checking the pinion on the motor is tight.

Could also be the range on the ESC has accidentally been changed.

J

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Since it doesn't appear to be pulling to one side then I'd assume wheel bearings/drivetrain at each corner is fine.

Is the battery FULLY charged ? Do you have another to try , or try this battery in another car ?

If you turn one wheel by hand does the opposite one spin the opposite direction ?

If you hold one rear wheel and turn the other by hand can you feel any restriction other than the motor turning in its magnets ?

Any noises when driving ?

Are the adjuster plates for the bottom motor mount screw set correctly for the pinion size you are using - if incorrect the gear mesh will either be too tight (causing very hot motor when running) or too loose leading to poor pinion/spur gear mesh which could give very rapid wear of the kit supplied aluminium pinion gear.

What motor are you running - if its a rebuildable one with replacment brushes are the brushes worn out ?

Can't tell much from the images as they are only thumbnail size.

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Thanks for your replies. I will check those things this afternoon and give a more detailed reply. The front wheels spin much more freely than the rear and Im using the standard motor supplied set at 15T. Only had about 2hrs run time. Battery fully charged too.

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Thanks for your replies. I will check those things this afternoon and give a more detailed reply. The front wheels spin much more freely than the rear and Im using the standard motor supplied set at 15T. Only had about 2hrs run time. Battery fully charged too.

the front will spin more freely since it doesn't have the drag of the motor couple to its gearbox.

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Hi again.

I have fully charged the battery again.Whilst waiting I removed the motor and wheels. The pinion seemed tight with no wear. One rear wheel was slipping whilst trying to remove. I have replaced rims with a new set that don't slip. Adjuster set plates are correct to manual.I have noticed if I turn one front wheel the opp side turns the other way which is correct.If I turn one rear wheel slowly all 4 wheels turn in the same direction but if I turn quickly it tries to turn in the opposite direction whilst the fronts turn the same way as the one I'm turning.Not sure if this is correct. I have since run car again and it seems better than before but still some way slower than first few runs.Was contemplating buying a sports motor but want to be sure I don't have any other problems. Could the motor be at fault after just a few hours run time. I tried to upload some images but kept saying file too big. Sorry

Cheers.

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When you say "One rear wheel was slipping whilst trying to remove", what exactly was slipping relative to what?

The behaviour of the rear wheels sounds a bit odd. The opposite rear wheel should turn more readily than the whole drivetrain when you turn a rear wheel by hand. Sounds to me like something is binding at the rear.

Are all the drive pins in place and properly located in their hexes? It sounds like one may be misaligned or missing entirely. Failing that, it could be an internal gearbox fault. I'd recommend getting to the bottom of it before running the car further, in case further running makes matters worse.

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Me again.

My son just ran his hotshot with a fully charged battery and after about 3-4 minutes it lost speed, but not only that when going full throttle it keeps stopping rapidly every couple of seconds. then takes a couple of seconds before it will go again. It is also very slow in reverse.

Driving me wappy now. Someone please help us! Im thinking ive done something wrong with the build but it was perfect in the beginning.Could it be the batteries in the radio? or something else silly.......

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Still could be any number of things tbh. Could be blown motor pulling too many amps and shutting esc down. Or blown esc or a major bind in the gear box. A tear down is in order I think.

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By slipping I mean the rim was spinning inside the tyre but from my last post I'm pretty confident something else is wrong.I'm hoping not for a full strip down! <_<

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Do you have the the trim settings on the transmitter set in the middle ? - the plastic sliders beneath the main control levers

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It is unlikely to be the radio batteries.

It could be a motor or ESC issue, but from the car's behaviour, it sounds like a major bind. The stop-start behaviour would be the ESC's way of saving itself from burning out. If there is a bind, the motor pulls far more power than it should. If allowed to continue, the ESC would burn out, so it shuts itself down to take a short breather, before trying again. A bind would also explain the slow reverse speed.

And there is still the issue of the odd behaviour when turning one rear wheel by hand. This strongly suggests a bind at the rear. Before pulling your gearbox apart, perhaps check the rear hubs? If one is binding, the car would probably pull to one side, but if both are binding, it would go straight, but not very well...

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The trim slider for the throttle was set towards the top end.When lifting the car up and powering the throttle the wheels spin freely but stop quickly when releasing the throttle. It doesn't stop/start when holding in the air, only when on the ground. Sounding like a resistance issue to me now. Am really appreciating your help by the way.

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Your throttle trim should be in the centre of the slider range - and then programme the ESC as per the instructions.

I do agree though there may be some resistance at the rear gearbox though - if anything the hotshot gearboxes tend to be a little tight on the first few runs, due to the flashing on the drive gears, but once bedded in they run smooth.

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I'd have the rear end apart and give it a good check over. I think XV Pilot is likely right.

J

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Seems strange to me that it starts off ok but within a few minutes all starts to go wrong. think I will re-centralize / programme the esc and have another go. Failing that from the advice i'm getting on here I may be whipping that gearbox out tomorrow. Would too much or the wrong type of grease cause any issues?

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hi,

it could just be a duff battery , have you tried other batteries with the same result?

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How hot is your ESC? That is one thing about Hotshots, the electronics get toasty!

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I don't have another battery to try so I'm a bit stuck with that one.Haven't checked the esc for temp. its a TEU-101BK. As I have mentioned I'm very much a novice. Its a pity I don't have a collection of spares so as to eliminate different things. I think all I can do is reset the esc tomorow and then maybe check the gearbox out. If all seems ok then will maybe have to bite the bullet and get the wallet out AGAIN for some new parts. battery, esc, motor perhaps.Unless anyone has a magic wand!

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Mine did the same thing with the TEU-101BK with a Tamiya SuperStock RZ motor (23T). The way the Hotshot has no ventilation for the ESC and that warm of a motor would heat up the ESC and it would cut off in no time. I had to upgrade the ESC to run mine for any amount of time.

Honestly now my Hotshot collects dust more than anything. If I want nostalgia I run a Frog, modern I run my DB01. The Hotshot is definitely in-between and not as fun to drive.

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Morning.

I have reprogrammed the esc. (never programmed it from new!) told you I was a novice. Problem still persists. Reading the esc booklet it appears I have a overheating problem which causes loss of power and also causes the motor to be stopped automatically. Am now looking for a new esc. Can anyone recommend one for me. Ideally from modelsport which is where i bought the kit from. If you can re-assure me that this is the problem that would be good also. Feel better for knowing what the problem is now. Would it be my fault for not programming it from new? cheers guys.

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hi Mattharri,

the stopping starting is also indicative of a dead battery so a little more investigation is required here i feel, if its thermal related it usually takes a while to cool to usable levels , and also requires switching off and on again ,to check the thermal issue ,run the car until it begins the cutting out thing and feel the esc , if its hot and not just warm then it could be thermal cut out, if the start stop is lasting a second or two and the esc is just warm then its most likely low battery warning, given that you have recharged the battery and its quite a high capacity item then a new battery would be worth a go first ,

the worst outcome from buying a new battery when the other turns out to be fine is that you will have two batteries for more play time , you will still need a new esc of course,if the esc is the issue, but, if the esc is fine and you buy another you will be left with a redundant esc and still need a new battery .

if you have a local hobby shop you could pop in and ask if they can check the battery ,

hope this helps a bit,

;)

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Thanks alfagta.

I have put the battery back on charge and within no time it was saying fully charged? On further inspection I noticed one of the cables coming out of the battery was split/torn where it must have dragged on the floor. I have taped this up and have put back on charge and is still charging now. Could i test this with a voltmeter? Good idea about buying battery first. I was going to get a spare at some point anyway. I will see how it charges and try again and post again this afternoon.I'm using a Vector NX85 and set it at 1.0A. As I type this it has come up as fully charged. Will give it a quick try and let you know.

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Just tested car and within about a minute it was stop/starting and beeping from the esc which then reset itself after about 5-10 seconds. I will try and get battery tested or may have to wait till Monday till I get back to work.I remember on one particular charge a week or so ago that the battery got red hot whilst on charge but has been ok since. It just seems to charge too fast.Maybe it is just the battery?

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