Gearing question ...

[harald-hans]

Hello,

as some of you know I build a new truck with the HV-Maxx-System from novak ( www.never2mu.ch ) .

Until yet everything works pretty good.

I have the gearing just like Novak write it in the instruction/manual with 70 on the spur gear and 12 on the pinion gear.

Now my question is: because the car has much/enough starting torque - if I change the pinion gear to 14 the car must be a bit faster in the high speed but a little bit slower in acceleration - is that correct ?

And if yes - is there any possibility that something can go wrong or be damaged by using this "gear setup" ?

Does the motor heat go down with a change of a gear ratio ?

Question about question. :C: :C: :C:

Sorry for that stupid question but I do not have any experience until yet with playing with the gear ratio and the truck/brushless system is to expensive to make stupid experiments.

So for that reason it is better to ask first, especially here where are so many people with much more expereince than me.

Thanks in forward and with greetings from Germany

harald-hans

P.S. if you konw any other or better gear ratio than please told me - the 70/14 combination is no "must have" for me !!!

[Dafni]

I never owned a Novak HV, but I heard many stories about thermal problems with this setup. So I think it is wise to stick to the recomended gearing fro the manufacturer. (stock wheels assumed)
One or two teeth more on the pinion will not kill your motor, I guess. But keep an eye on the temps.

Here's a quick gearing guideline:

Smaller pinion has the same effect as bigger spur.
Smaller pinion (or bigger spur) gives you more reduction.
Bigger pinion (or smaller spur) gives you less reduction

(reduction = ratio from motor turns to wheel turns)

Less reduction means more top speed (rpm at wheel) and less torque.
More reduction means less top speed, but more torque (power at take-off, if you want to put it like that)

Hope this helps

[coolhandcountry]

If you go to a taller gear ration 12 70 to 14 70 (lower ratio) it may make the motor run a little hotter. Gearing up(higher ratio) don't mean always that you ger more speed. How much does you truck weigh? The height of tires make a difference to. Taller tire is like running a higher gear ratio. I don't want to tell you yes or no on question until I know more. The novak Hv maxx seems to like a High ratio gear. Greetings back to you from USA

[Serum]

Hi!

Have you got a tempgun? www.hpi-shop.com sells them for a rather nice price, though if you don't have got much thermal shutdowns, you might consider gearing it up a bit.

How many cells does your HVmaxx take at this moment?

[captain harlock]

Well, lets see, your first question should be given the answer yes. If the truck makes wheelies and then go from a current gear ratio to higher one, the higher one will decrease torque and as a result your truck will do less wheelies, but perhaps in most cases more speed. If your motor is a torqy motor then you can gear way higher than stock gearing, but when you are using a mild truck brushless system such as the HV-Maxx which produces arond 370-400 watts considered pretty low and weak to the wild ones like the Feigao 9l that gives around 1100-1200 watts, you must not exceed the usage of more than 1-2 teeth. I bet your E-Maxx is stock chassis, tires, etc..so you can use 1 or two additional teeth in your pinion gear or decrease 3-6 teeth from your spur gear. This will not heat up your controller to an extreme point, but it will be hot to the point where it will not thermal, however, if it thermals, then you should deduct some teeth from your pinion or induct more gears to your spur. Doing so you will gain the motor more effeciency which means less heat. If you are going to use 14 teeht pinion then there is not any real problem, just make sure that the controller does not thermal and if it does, just forget about the 14t and get back to the 12t.

[harald-hans]

Oh thanks - so many answers and informations.

Yes I have a tempgun and I will check the temperature as soon as possible and post it.

The truck weight is about 5,3 Kg and it is not stock (see pictures at www.never2mu.ch ).

Until yet I have only one thermal shutdown, but I have to say it was a very hot day with outside temperature around 30 degrees celcius and I bash that beast so hard - first with a set of 14 cells GP3700 and then without any pause with a set of 14 cells IB3800 - every set holds only arund six to eight minutes - so you can image the drivestyle.

When I drive "regular" there is no shutdown - runtime something between 10 and 15 minutes.

So the best would be to check the temperature with the tempgun and make a try with changing the pinion gear to 14.

I will post my experience as soon as possible.

Thanks again and with greetings from Germany

harald-hans

[captain harlock]

NO, the fourteen t. pinion will make the situation even worse. Go for the 11t pinion instead of 12 and check the temp of your controller and motor.

[captain harlock]

14 cells are pushing your motor to its limit and that is why I recommend you to use 11 or even 10t pinion to tolerate the high load the motor is under.

[harald-hans]

Originally posted by captain harlock
14 cells are pushing your motor to its limit and that is why I recommend you to use 11 or even 10t pinion to tolerate the high load the motor is under.

Thanks - I will try that !!!

Greetings,

harald-hans

[harald-hans]

Hello,

today I make a test just as I promised - configuration as known - outside temperature around 25 degrees celcius and I run my truck with a set of 14 cells IB3800 within 8 minutes - after that I took my tempgun and the temperature on the heat sink and on the motor of the HV-Maxx was around 50 degrees celcius.

The ESC is "handcold", the fan on it seems to work very efficient.

In my opinion a really good system setup !

Greetings from Germany

harald-hans


P.S. I forgot to told you that I cut out the original EMAXX-body in the area of the windshield and in the area of rear window - so the airflow seems to make the whole system work better.

[captain harlock]

Great news. Have fun and fasten your seat belt.