12 replies to this topic

[Dave_12]

What would be the good starting point for gearing on a 6500KV GTP car racing   with a track power of 13 volts .?

[glueside]

What type track?

[Ramcatlarry]

try 8/38

[Dave_12]

I am going to try 9/39 

[vanges]

We have used 11/31  with 13 volts in Argentina and we are well.  We put a capacitor of 16v and 100μ that allows us to regulate the intermittent electrical problems in cars.

 Will you consult me if they brake well? They do a great job. 

 Are we crazy? maybe.  

[Wannabe80]

Bringing up an old thread.

 

I recently got a 6500kv RTR mid america gemini flexi.

 

It has the Trixie 2.0 board in it.

 

Within the first few laps the pinion came loose.

 

Replaced that with an 11 tooth to give it 11/36 gearing.

 

The car seems to stutter now down low speed and then just take off like a rocket, same using multiple controls.

 

From a google search seems it could be suffering from cogging due to the gearing, and the lack of low end emf feedback or something like that.

 

suggested changing the gears.

 

Current gears were 11/36 it suggested going to 11/42 i only had 11/39 does this seem right.

 

Track is 13.8v wooden unglued and about 130ft long total.

[stoo23]

Possibly or you could keep the 38 and put a 10 tooth pinion on

[Dave_12]

Stoo last tine i raced 6,500kv at Redline i was using 10/38  64p and found it to be good . 
Some were using a 11 tooth pinion but they   failed to finish the race .

[Wannabe80]

hrmm ok, so looks like i should be getting a 10T pinion.

 

Stoo last tine i raced 6,500kv at Redline i was using 10/38  64p and found it to be good . 
Some were using a 11 tooth pinion but they   failed to finish the race .

Why did they not finish the race, the ones with the 11T i mean.

 

I have the following spur gears in 64P

 

34,36,37,38,39 

 

Following pinions in 64P

 

8,11,12,14

[rmjlmartin]

I'll readily admit that my experience with brushless motors is mostly limited to the Mid America/Parma motors and Mid America Remora Ecoms, but there are a couple of things that I'd recommend keeping in mind.

 

First, as with brushed motors, the more aggressive the gearing (larger pinion, smaller spur), the greater the chance of letting out that magic smoke that keeps all electronics working from the motor or Ecom. I don't know where the limit is on a 6500kv brushless motor, and I'm not going to put words in David's mouth, but I'd be willing to bet that's why the cars with 11t pinions didn't finish the race. I'd also be willing to bet that the more aggressive gear ratio is what's causing the stuttering/cogging.

 

Second, you don't say what kind of track you're running on, other then the length, and no glue, but also remember that more aggressive gearing isn't necessarily always faster. We run a modified USRA Brushless Production class locally, with 6500kv motors, and, while the stock Mid America 8/36 (4.5:1) gear ratio works well on our King, at 13.6v, on the flat track, at 12v, the cars are much more driveable with a larger spur, and I believe I've ended up running 7/35 (5:1) on mine. The fastest straightaway speed might not necessarily equal the fastest lap times.

 

Personally, I'd recommend going back to the 8t pinion, and maybe even a larger spur, depending on the track.

 

That's my two cents' worth, any way. Hopefully it's useful.

[Wannabe80]

Hi,

 

I am not sure the name of the track but it is the one pictured in the attached image. if someone knows the name of it that would be great to know also for future reference.

 

The stock gearing that came with my car was 12/36, was changed to 11/36 when the pinion spun (edit i see you were referring to the OP)

 

I currently have 11/39 on it, yet to drive it will be giving it a go this Saturday. 

 

To see if going to the 39 from the 36 helps with the way it drives.

 

I do have other pinions i can use, however i do not have a puller/press as of yet to change them. I am looking at getting one soon.

 

Might look at getting some more gears and pinions when i get my puller.

 

I will give it a few laps if it will do them on Saturday and see how it goes.

 

I am only just getting back into and think that the 6500kv might be too fast for me for now until i get used to driving again haha.

 

Thank you all for your help.

 

 

 

[Dave_12]

Damian 6,500kv is way too much for that small track at Penrith . I have tried with a 9 tooth pinion   GTP body even then way way too much for that track.  
4,500kv with a GTP body is just controllable on that track at Penrith.  

[Wannabe80]

David, 

 

I thought it was just me being new to it as i too think the 6500 will be too much.

 

I like the 3000kv version i have been using past few months. 

 

I was gifted the brand new 6500kv for my birthday so wanna get it at least somewhat drivable on the track and get some use out of it.

 

I'm going to look at ordering some more pinions and gears and try a few different combinations.