can someone explain gearing to me!?
08-22-2007, 07:19 AM
#1
can someone explain gearing to me!?
Ok, I've seen the gear charts, I know how to calculate roll out, FDR and pinion/spur. my question is how do you determine what FDR to shoot for? Is there a given range you want to stay in? I know with these brushless motors, you have to pay very close attention to your gearing or youre going to be buying new ESC's and motors very quickly if you get something wrong.
Is there a good rule of thumb when decided how you are going to gear your car?
Is there a good rule of thumb when decided how you are going to gear your car?
08-22-2007, 09:04 AM
#2
Depends on the track you are going to run on. Using the manufacturers Final Drive recommendations as a template, look at your set-up, type of cells and length of the straights and overall size of the track. If the track is small with a nice amount of turns, gear for torque and punch, higher FD. If the track is sizeable, nice length straights, gear for rpms, lower FD. Take a few pratice laps and monitor your temps. Make sure to have an adequate gear selection (several pinions and spurs) and do your math. With BL, 160-175 is the area that is the safe zone cut off (for Novak anyways). Anything higher than that, you are looking to thermal. Lets use the 3.5 by Novak. Safe zone FD is roughly 9.75 to 10.75, give or take. In my Pro4, I am running 100 spur/26 pinion, giving me a FD of 9.375. I am pushing the envelope, but am running an additional fan on the motor to keep the temps in check. To ensure I dont thermal, I am dropping a tooth, increasing my FD, but, lowering my temps. The downside is, lower top end. As long as you are happy with your top end and the temps stay in the safe zone, you have room to work with.
08-22-2007, 09:43 AM
#3
thanks bx! so there is a manufacturers recommendation? that explains alot.
08-22-2007, 09:45 AM
#4
I'm having trouble coming up with the man. rec. for a cyclone and a jrx-s. anyone know where i can find these or know what they are?
08-22-2007, 09:49 AM
#5
Tech Fanatic
Try gearchart.com for all your gearing needs!
08-22-2007, 09:56 AM
#6
You ever have a question about anything in particular, reach out to MarcosJ on this forum. He is probably one of the most informative and knowledgable dudes on rctech.net. I also give him props because he was in the Marines like me
Last edited by bxpitbull; 08-22-2007 at 03:54 PM.
08-22-2007, 11:47 AM
#7
08-22-2007, 12:27 PM
#8
lets see if this works....
FDR or Gear Ratio at the spur which ever u want...
1:1 is just that 1 turn of the pinion to 1 turn of the spur (applies to many different examples).
If I am looking for top end I want to be closer to a ratio of 1:1, if my memory serves me that's a tall ratio, 5.5:1. The closer you are to 1:1 the less torque u have.
A ratio further awat from 1:1 will give you more torque at the expense of speed, called a low ratio like 9:1 or 12:1
The key is to find a range that will not only suit your driving style but the track as well. If you have a tight twisty track you might want a lil bit more torque on the ground to help pull or push the car though the corners. If the track is loopy and has nice smooth corners then you might choose something that give less torque and more top end.
If your track is a blend then you need to experiment and find a happy spot for your driving.
Usually with stock motors I try and run 5-7:1 FDR, Mod I will try 8.5-11:1 all depending on the track. So lets say I have a mod 12T, I might start something like this (using a TC4 internal ratio is 2.5:1)
(spur / pinion)* Internal DR = FDR => (78/21)*2.5 ==> 3.714 * 2.5 ===>9.286 FDR
If you know your FDR (most manuals give this and so does gearchart.com) you can plus and choose your numbers to get the ratio you want. Just remember more speed move closer to 1:1 more torque move further away from 1:1
Brushless is a whole new creature and I'm still learning but the same principal applies
FDR or Gear Ratio at the spur which ever u want...
1:1 is just that 1 turn of the pinion to 1 turn of the spur (applies to many different examples).
If I am looking for top end I want to be closer to a ratio of 1:1, if my memory serves me that's a tall ratio, 5.5:1. The closer you are to 1:1 the less torque u have.
A ratio further awat from 1:1 will give you more torque at the expense of speed, called a low ratio like 9:1 or 12:1
The key is to find a range that will not only suit your driving style but the track as well. If you have a tight twisty track you might want a lil bit more torque on the ground to help pull or push the car though the corners. If the track is loopy and has nice smooth corners then you might choose something that give less torque and more top end.
If your track is a blend then you need to experiment and find a happy spot for your driving.
Usually with stock motors I try and run 5-7:1 FDR, Mod I will try 8.5-11:1 all depending on the track. So lets say I have a mod 12T, I might start something like this (using a TC4 internal ratio is 2.5:1)
(spur / pinion)* Internal DR = FDR => (78/21)*2.5 ==> 3.714 * 2.5 ===>9.286 FDR
If you know your FDR (most manuals give this and so does gearchart.com) you can plus and choose your numbers to get the ratio you want. Just remember more speed move closer to 1:1 more torque move further away from 1:1
Brushless is a whole new creature and I'm still learning but the same principal applies
08-22-2007, 06:02 PM
#9
lets see if this works....
FDR or Gear Ratio at the spur which ever u want...
1:1 is just that 1 turn of the pinion to 1 turn of the spur (applies to many different examples).
If I am looking for top end I want to be closer to a ratio of 1:1, if my memory serves me that's a tall ratio, 5.5:1. The closer you are to 1:1 the less torque u have.
A ratio further awat from 1:1 will give you more torque at the expense of speed, called a low ratio like 9:1 or 12:1
The key is to find a range that will not only suit your driving style but the track as well. If you have a tight twisty track you might want a lil bit more torque on the ground to help pull or push the car though the corners. If the track is loopy and has nice smooth corners then you might choose something that give less torque and more top end.
If your track is a blend then you need to experiment and find a happy spot for your driving.
Usually with stock motors I try and run 5-7:1 FDR, Mod I will try 8.5-11:1 all depending on the track. So lets say I have a mod 12T, I might start something like this (using a TC4 internal ratio is 2.5:1)
(spur / pinion)* Internal DR = FDR => (78/21)*2.5 ==> 3.714 * 2.5 ===>9.286 FDR
If you know your FDR (most manuals give this and so does gearchart.com) you can plus and choose your numbers to get the ratio you want. Just remember more speed move closer to 1:1 more torque move further away from 1:1
Brushless is a whole new creature and I'm still learning but the same principal applies
FDR or Gear Ratio at the spur which ever u want...
1:1 is just that 1 turn of the pinion to 1 turn of the spur (applies to many different examples).
If I am looking for top end I want to be closer to a ratio of 1:1, if my memory serves me that's a tall ratio, 5.5:1. The closer you are to 1:1 the less torque u have.
A ratio further awat from 1:1 will give you more torque at the expense of speed, called a low ratio like 9:1 or 12:1
The key is to find a range that will not only suit your driving style but the track as well. If you have a tight twisty track you might want a lil bit more torque on the ground to help pull or push the car though the corners. If the track is loopy and has nice smooth corners then you might choose something that give less torque and more top end.
If your track is a blend then you need to experiment and find a happy spot for your driving.
Usually with stock motors I try and run 5-7:1 FDR, Mod I will try 8.5-11:1 all depending on the track. So lets say I have a mod 12T, I might start something like this (using a TC4 internal ratio is 2.5:1)
(spur / pinion)* Internal DR = FDR => (78/21)*2.5 ==> 3.714 * 2.5 ===>9.286 FDR
If you know your FDR (most manuals give this and so does gearchart.com) you can plus and choose your numbers to get the ratio you want. Just remember more speed move closer to 1:1 more torque move further away from 1:1
Brushless is a whole new creature and I'm still learning but the same principal applies
That's the best explanation on gearing that I've heard yet. Good job brah!
08-23-2007, 05:48 AM
#10
No doubt. i wish we could get this pinned for newbies like myself.
thanks !
thanks !
08-23-2007, 05:52 AM
#11
that's a cool way of explaining things 
The only other simplistic thing that I would add for the newbies is, smaller pinion gear to gain acceleration, larger pinion to gain maximum speed if need be
The only other simplistic thing that I would add for the newbies is, smaller pinion gear to gain acceleration, larger pinion to gain maximum speed if need be
08-23-2007, 06:56 AM
#12
Ok, I've seen the gear charts, I know how to calculate roll out, FDR and pinion/spur. my question is how do you determine what FDR to shoot for? Is there a given range you want to stay in? I know with these brushless motors, you have to pay very close attention to your gearing or youre going to be buying new ESC's and motors very quickly if you get something wrong.
Is there a good rule of thumb when decided how you are going to gear your car?
Is there a good rule of thumb when decided how you are going to gear your car?
Works great.
And its simple.
08-23-2007, 03:32 PM
#13
Ok, I've seen the gear charts, I know how to calculate roll out, FDR and pinion/spur. my question is how do you determine what FDR to shoot for? Is there a given range you want to stay in? I know with these brushless motors, you have to pay very close attention to your gearing or youre going to be buying new ESC's and motors very quickly if you get something wrong.
Is there a good rule of thumb when decided how you are going to gear your car?
Is there a good rule of thumb when decided how you are going to gear your car?
Ask the guys at the track questions see what range they are using and watch them on the track, one thing I like to help other with is to LISTEN to the cars (and your car when you drive the infield and back straight) what do you hear? Is the motor screaming? Is the motor still pulling at the end of the track.... if it is then adjust 3-4 teeth on your pinion and try again.
Another thing I want to suggest if your running MOD, try this and you can get a nice feel gearing... Run a 15 - 16 turn with a stock gear ratio; say 6.0-6.5. That should get you enough motor to be competitive and yet slow enough that you dont over power your car through a track. I did a race this way, and it's great to see how other reacted when they ask what I was running. If your running brushless... well you & I are in the same boat, I'm still learning on that one.
Get out there and Hacktice Practice Practice...
Eventually you'll get a good feel of what works right for your style of driving & the tracks you attend.
08-24-2007, 05:37 AM
#14
Ok, I've seen the gear charts, I know how to calculate roll out, FDR and pinion/spur. my question is how do you determine what FDR to shoot for? Is there a given range you want to stay in? I know with these brushless motors, you have to pay very close attention to your gearing or youre going to be buying new ESC's and motors very quickly if you get something wrong.
Is there a good rule of thumb when decided how you are going to gear your car?
Is there a good rule of thumb when decided how you are going to gear your car?
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
