Steve Weiss

Chris,

It honestly depends on a number of factors, but generally I start people out much lower than that, around 5.4 and go up from there.

I would say that most will probably end up around 4.8-5.0

Chris08527

iTrader: (16)

thanks steve that is what i was looking for, i understand it depends on many things but i was just looking for a ballpark # to start from.

SSS Racing

iTrader: (6)

Hi Steve,

Just want to check something re my GTB SS speedy.

I've just started running lipo packs with the speedy, and have noticed that if the low voltage cutoff point is reached, its the RED and GREEN leds that flash to indicate the cutoff has cut in. Not RED and AMBER leds as per the instructions..?

Thanks,
Ryan

Steve Weiss

Ryan,

I just looked over the addendum that is included with the GTB and you are correct in taht there is a mistake there.

When the cut off has activated the red and green LEDs will blink alternately.

J.Filipow

iTrader: (15)

HEY STEVE TYPE!!! How's your foot?

Steve Weiss

Still uncomfortable... hurting less though... thanks for asking!

jarmuth

I have a Novak 8.5 brushless motor in my B4 Chassis with a late model body. I am using a GTB esc and using a 3600 lipo battery. I was running an 81 tooth spur with a 24 tooth pinion.

About 3-4 minutes into the race, it stopped running. It seemed very hot and started up again after sitting for a couple minutes. I assumed that I was using too big a pinion and starting using smaller pionions.

I went down the list and am now down to using a 19 tooth pinion with the same spur gear. Last night I did a practice run using the 19 tooth pinion. It still quit running after about 4 minutes. I checked the temp and it read 170-185 degrees. I am assuming that earlier it may have been even hotter. The ESC was at about 90 degrees.

According to the Novak website, I should be using a fdr of 9 with a 2 wheel drive buggy. As near as I can figure, I should have been right there with the 23 tooth pionion and a lot higher with the 19 tooth. Have I ruined the motor, or is there something else I can check. I cleaned all the dirt off of it before my latest run.

Thanks in advance for your help.

Steve Weiss

Jarmuth,

The gearing recomendations are good places to start, but as we note the motor temperature should always be the first peice of information used to figure out if the gearing is correct.

Does your 8.5 have a sintered or a bonded rotor in it...?

If it has a bonded rotor in it, the gearing will need to be lower...and as such the higher gearing that you started out with might have over-stressed it and caused it to demagnetize.

Once a rotor begins to demagnetize it causes everything to run hotter.

I would check your rotor and possibly try replacing it with a new sintered rotor.

Let me know if you have any other questions!

stitchy

iTrader: (13)

Sorry if this has been asked before, but can lipo cutoff be activated in profile 5 on the GTB? [edited for clarity]

Per the instructions, profile 5 is the only one that is not programable. Why is that? Thanks for your time!

Steve Weiss

The lipo cut off should be available in any of the profiles on the GTB.

The 5th profile was made "unprogrammable" to make it an easy profile for boat useage.

stitchy

iTrader: (13)

Oh I see. So for cars, if we want reverse, we should use profile 2? Thanks for the answers Steve!

Steve Weiss

Yep, profile 2 will have reverse and all the adjustment you will need!

kavadni

iTrader: (1)

Steve,

I love this thread.

Can you point me at, or produce of the top of your head, a guide to brushes and compounds, to help me decide which ones to try. I race 27t at the moment.

Kevin

kn7671

iTrader: (16)

Steve,

Regarding 1/12 scale 17.5 Rollout on NON-Oval Carpet Racing, the Novak website recommends a rollout of 65mm with a 17.5 motor, but everyone at my track is running around a 79-82mm rollout, which is closer to the rollout suggested for Oval 1/12 racing using a 17.5. Our track is about 60'x90' with only one straight, the rest is all twisty's.

Any reason for the huge difference is what is suggested compared to what we are running? It does not seem that we are over geared, temps are in the 150-160F range after 8-minutes.

Steve Weiss

Thanks Kevin!

IT's been a while since I did the stock motor thing, but I will let ya know about what I know and remember

In most instances I always tried to run Trinity 4499s... they always seemed to give me the best power, but they were finicky... if they got too hot they'd burn up FAST.... so if it's really hot out these might not be the best brush for you. Also, these brushes seemed to varry from batch to batch...so sometimes brushes were good, sometimes they weren't... it's sort of a roll of the dice with them...but if you find a batch that are good, you're in luck!

Next in line was the Reedy 767...which is a good brush that I used when temperatures were a problem... I never felt like they produced the same overall power as the 4499... but they were easier on the motor and less sensitive to high temperatures...they seemed pretty consistant from batch to batch as well.

The "F" brush came around after I really got out of stock racing, so I don't really have too much experience with it... but even when I tried them back to back against good 4499's I prefered the 4499's... but in my estimation they sort of fall "in between" the 4499 and the 767 when it comes to performance.

You pretty much always want a serrated brush... you just want to break the brush in for a little bit at low current... maybe 300 seconds at 2 volts or something like that...

As far as cuts on the brush go... a vertical slot in the center helps keep the brush aligned properly and generally keeps the comm cleaner and cooler ... it reduces power a little bit but not too much.

A hole in the center of the brush reduces power and keeps the brush a bit cooler too.

Cutting the edges of the brushes can effectively change the timing the in motor slightly... some motors respond well to this, others don't... but generally more timing increases motor heat in most instances.

Hope all this helps!



The reason there is probably a big difference is that we are conservative in our gearing recommendations due to the fact that most people will continue to run their vehicle on the track until the battery dies out... and with a 17.5 this can be a very long time.

Race gearing for 5 or 8 minute applications will vary with driver, traction, track size, and ambient temperatures.

Hope this helps!