Noob gearing/motor question

[CertifiedMike]

Roll out is the relationship (ratio) of rotation between your motor and your tires. All things are considered in this calculation such as tire height, spur and pinion and the transmission ratio itself.
Its a great way to help you figure out how any one if those items, when changed, will effect your rc.
Small changes in the ratio equate to big changes on your rc so I shoot for 1:1. As a baseline.

My car has a 23 tooth pinion, 84 tootj spur, 2.64 ratio trans and 78mm tires.
Thats 1.001 I think. Pretty happy with that to start
I have a pinion tooth or 2 up and down, spurs too to experiment with as well.

 

[CertifiedMike]

Motor kv was 4100 on 2s btw.

 

[skunknuggit]

Roll out is the relationship (ratio) of rotation between your motor and your tires. All things are considered in this calculation such as tire height, spur and pinion and the transmission ratio itself.
Its a great way to help you figure out how any one if those items, when changed, will effect your rc.
Small changes in the ratio equate to big changes on your rc so I shoot for 1:1. As a baseline.

My car has a 23 tooth pinion, 84 tootj spur, 2.64 ratio trans and 78mm tires.
Thats 1.001 I think. Pretty happy with that to start
I have a pinion tooth or 2 up and down, spurs too to experiment with as well.

Ok i have a t4 with 22/81 and a 4000/8.5t motor and that thing rips pretty good. But I think I killed the esc. I ran it on 2 and 3.

 

[skunknuggit]

Roll out is the relationship (ratio) of rotation between your motor and your tires. All things are considered in this calculation such as tire height, spur and pinion and the transmission ratio itself.
Its a great way to help you figure out how any one if those items, when changed, will effect your rc.
Small changes in the ratio equate to big changes on your rc so I shoot for 1:1. As a baseline.

My car has a 23 tooth pinion, 84 tootj spur, 2.64 ratio trans and 78mm tires.
Thats 1.001 I think. Pretty happy with that to start
I have a pinion tooth or 2 up and down, spurs too to experiment with as well.

Transmission is 2.6 as well but my tires are closer to 100mm

 

[CertifiedMike]

Ok i have a t4 with 22/81 and a 4000/8.5t motor and that thing rips pretty good. But I think I killed the esc. I ran it on 2 and 3.

Some escs can handle that load all day long. I wouldn't jump to conclusions just yet.
17 toorh pinion will put you right where I'd start anyway. It should be ok on 2 or 3s there.

 

[skunknuggit]

Keep the 81 spur?

 

[CertifiedMike]

I think it will work ok.
Its a fair starting point
You absolutely still neef to monitor your motor, esc and even battery temps just to be sure 'some guy on the internet' was wrong when he tired to help you!
Plug some numbers in to that calculator link and double check my work but I think you're ok.

 

[skunknuggit]

Ok thanks ill try it out. I think I have the stock pinion still and it's an 18 stock i believe. If not they're cheap enough I can buy a few

 

[CertifiedMike]

Ok thanks ill try it out. I think I have the stock pinion still and it's an 18 stock i believe. If not they're cheap enough I can buy a few

Robinson Racing Products makes fantastic pinion gears at very rasonable prices. I use them whenever possible.

 

[skunknuggit]

View attachment 231473
Robinson Racing Products makes fantastic pinion gears at very rasonable prices. I use them whenever possible.

Good to know... I got their all metal diff gears in right now cause I already tore up the idler. What kind of lube do you use in the transmission? Not the diff itself but inside the case where the idler and the shaft the spur is on and the diff

 

[CertifiedMike]

Good to know... I got their all metal diff gears in right now cause I already tore up the idler. What kind of lube do you use in the transmission? Not the diff itself but inside the case where the idler and the shaft the spur is on and the diff

In my car, the trans is dry. My car is belt drive. Always pulling debis into the trans even as sealed as I can get the drive, I need to think that way.
Also, any lube that gets on the belt and pulleys is no good.
I use Superlube on gears like that usually. A thin coat sticks forever. It works great but is sticky.
Another popular choice is Mobile1 synthetic red lube.
Avoid lithium due to petroleum content. Thats important in all your lubes, products... petroleum is no good for plastic and rubber parts.
Synthetic is the way.

 

[CertifiedMike]

I wanted to clear up the roll out.
The actual definition is:
Roll Out is defined as the distance a vehicle moves forward per revolution of the motor according to competition X.
That is why there is an inch and mm involved in the ratios.
I felt like I dropped the ball a bit there.

 

[skunknuggit]

Thanks for clearing it up a little bit. I bought some different gears today so ill try them out tomorrow hopefully

 

[CertifiedMike]

Good luck with the changes. Don't forget to monitor your temps.

 

[skunknuggit]

Got a temp gun too lol

 

[CertifiedMike]

Got a temp gun too lol

Excellent!!! You could write your temps down so you can compare runs, changes etc too. Creating your own data and getting a baseline temp so you can better understand the changes you make is easy and a good idea.
Watch the ambient temps too.
Its a lot different driving on 30° pavement and 130° pavement!

 

[Greywolf74]

either use a lower kv motor or a smaller pinion. I personally don't like to see more than 160F on my ESC and motor.

 

[RustyUs]

Hey all I'm still kinda new to the hobby. I did some research and I'm still not 100 percent sure about some thing. I have a associated t4 and a trophy rat. The t4 has a hobbywing 8.5t/4000 kv motor and a 22/81 gear setup. The t/r has a castle 5700kv and 32/74 gear setup. And it gets too hot and goes into limp mode. I also have a castle motor that is a little smaller and a reedy 3300 that I guess came with the t/r. My question is should I use one of the other motors for the mor torque from the lower kv or is that not how it works. Or should I upgrade my esc. I'm currently only running on 3s

I was waiting for someone to mention one of those speed calcs. I always go conservative on the voltage...

That's the reason for my reaction in your original post.

 

[skunknuggit]

I was waiting for someone to mention one of those speed calcs. I always go conservative on the voltage...
View attachment 231643
That's the reason for my reaction in your original post.

Ya thats insane the speed calculator i used said around 70 but I haven't been anywhere near that yet... maybe 40... not sure but I need to get a gps because I'm not strapping my phone to it. Was running it on 2s earlier and the cheapo battery plug melted but the motor and esc were just above 100... I have some gears and new plugs coming tomorrow so I'll update you then

 

[skunknuggit]

I was waiting for someone to mention one of those speed calcs. I always go conservative on the voltage...
View attachment 231643
That's the reason for my reaction in your original post.

Also I got cheapo batteries they say 11.1 volts... I havnt actually tested them and I also have probably the cheapest balance charger from Amazon so I'm probably not putting out as much power on my setup