Yes, another gearing question (involved!)
06-24-2008, 10:55 PM
#1
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Yes, another gearing question (involved!)
Just for info when I write DT = Losis Desert Truck.
I was thinking and came up with something. The stock pinion/ spur in the DT is 16 tooth pinion/ 88 tooth spur X 2.43 final drive ratio = 13.365 gear ratio. Everyone suggests hoing lower on the pinion when switiching to a brushless system. Now, Traxxas has a high gear ratio as well, lets take the Rustler (similar to size and weight of the DT)for example: Rustler stock spur: 83 tooth, stock pinion 25 tooth and comes with a 28 also. So take the Rustlers final of 2.72 and multiply the spur and pinion and you get a 9.03 gear ratio. If you use the optional included 28 tooth pinion you get 8.06 which is a lower final drive ratio?? This confuses me, maybe the pros can answer thos one. Any time you are going to run a hotter motor than stock its always wise to go down a few teeth on the pinion. And I know what this does, it increases acceleration, lowers top speed, and runs cooler. But according to the gear charts going down on the pinion raises overall gear ratio. And in Losi manual it states: when using higher gear ratios, it is extrememly important to monitor the temp of the batteries and motor. Do you guys see where my confusion is here? Going higher on the pinion lowers the gear ratio, but makes it run hotter. But Losi and everywhere else I read says higher gear ratio = hotter. Or do they only mean when concerning the spur gear. Higher on the spur raises the total gear ratio. Anyway I did all this trying to determine an overall good ratio to run my DT with the VXL system in it, using info collected from traxxas and Losi manuals. And according to a Traxxas chart I read the lowest (hottest?) final drive ratio they suggest is 9.36 - 9.79. To get that range in my DT I could keep the stock 88 tooth spur and use a 24 tooth pinion? Now thats way higher than anyone has suggested, but falls right into line with the traxxas chart. Or if I stuck to the rustlers stock overall it was 9.03. So in the DT that would be a 23 tooth. This would almost match Rustlers stock settings in their Rustler VXL. And its well in the green area of the chart showing "ok to run" If all this is true, why is it necessary to go down to a 15 tooth pinion in the DT when switiching to Brushless? Anyway if theres something Im overlooking please let me know, and if you read this whole thing thanks for your patience.
I was thinking and came up with something. The stock pinion/ spur in the DT is 16 tooth pinion/ 88 tooth spur X 2.43 final drive ratio = 13.365 gear ratio. Everyone suggests hoing lower on the pinion when switiching to a brushless system. Now, Traxxas has a high gear ratio as well, lets take the Rustler (similar to size and weight of the DT)for example: Rustler stock spur: 83 tooth, stock pinion 25 tooth and comes with a 28 also. So take the Rustlers final of 2.72 and multiply the spur and pinion and you get a 9.03 gear ratio. If you use the optional included 28 tooth pinion you get 8.06 which is a lower final drive ratio?? This confuses me, maybe the pros can answer thos one. Any time you are going to run a hotter motor than stock its always wise to go down a few teeth on the pinion. And I know what this does, it increases acceleration, lowers top speed, and runs cooler. But according to the gear charts going down on the pinion raises overall gear ratio. And in Losi manual it states: when using higher gear ratios, it is extrememly important to monitor the temp of the batteries and motor. Do you guys see where my confusion is here? Going higher on the pinion lowers the gear ratio, but makes it run hotter. But Losi and everywhere else I read says higher gear ratio = hotter. Or do they only mean when concerning the spur gear. Higher on the spur raises the total gear ratio. Anyway I did all this trying to determine an overall good ratio to run my DT with the VXL system in it, using info collected from traxxas and Losi manuals. And according to a Traxxas chart I read the lowest (hottest?) final drive ratio they suggest is 9.36 - 9.79. To get that range in my DT I could keep the stock 88 tooth spur and use a 24 tooth pinion? Now thats way higher than anyone has suggested, but falls right into line with the traxxas chart. Or if I stuck to the rustlers stock overall it was 9.03. So in the DT that would be a 23 tooth. This would almost match Rustlers stock settings in their Rustler VXL. And its well in the green area of the chart showing "ok to run" If all this is true, why is it necessary to go down to a 15 tooth pinion in the DT when switiching to Brushless? Anyway if theres something Im overlooking please let me know, and if you read this whole thing thanks for your patience.
06-24-2008, 11:02 PM
#2
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RE: Yes, another gearing question (involved!)
I think I got it. I did some more reading and found that a higher gear ratio is actually numerically lower. So it goes against what common sense might lead you to think. The 9.03 ratio being low on the chart is actually a higher gear ratio than the 13 of the Desert truck. It makes more sense now. But I still dont get this part: im trying to basically match the final drive ratio of the Traxxas gear chart showing what they consider ok to run for all puposes in the Rustler. And to do so Id have to go wayy up to over 20 teeth on the pinion to match that ratio. But from what everyones suggesting they say go down on the pinion (which is stock 16) on the DT for overall safe and cool driving (not to mention not frying the diff which some have already done when going to brushless.
06-25-2008, 10:07 AM
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RE: Yes, another gearing question (involved!)
ORIGINAL: Custnam
Just for info when I write DT = Losis Desert Truck.
I was thinking and came up with something. The stock pinion/ spur in the DT is 16 tooth pinion/ 88 tooth spur X 2.43 final drive ratio = 13.365 gear ratio. Everyone suggests hoing lower on the pinion when switiching to a brushless system. Now, Traxxas has a high gear ratio as well, lets take the Rustler (similar to size and weight of the DT)for example: Rustler stock spur: 83 tooth, stock pinion 25 tooth and comes with a 28 also. So take the Rustlers final of 2.72 and multiply the spur and pinion and you get a 9.03 gear ratio. If you use the optional included 28 tooth pinion you get 8.06 which is a lower final drive ratio?? This confuses me, maybe the pros can answer thos one. Any time you are going to run a hotter motor than stock its always wise to go down a few teeth on the pinion. And I know what this does, it increases acceleration, lowers top speed, and runs cooler. But according to the gear charts going down on the pinion raises overall gear ratio. And in Losi manual it states: when using higher gear ratios, it is extrememly important to monitor the temp of the batteries and motor. Do you guys see where my confusion is here? Going higher on the pinion lowers the gear ratio, but makes it run hotter. But Losi and everywhere else I read says higher gear ratio = hotter. Or do they only mean when concerning the spur gear. Higher on the spur raises the total gear ratio. Anyway I did all this trying to determine an overall good ratio to run my DT with the VXL system in it, using info collected from traxxas and Losi manuals. And according to a Traxxas chart I read the lowest (hottest?) final drive ratio they suggest is 9.36 - 9.79. To get that range in my DT I could keep the stock 88 tooth spur and use a 24 tooth pinion? Now thats way higher than anyone has suggested, but falls right into line with the traxxas chart. Or if I stuck to the rustlers stock overall it was 9.03. So in the DT that would be a 23 tooth. This would almost match Rustlers stock settings in their Rustler VXL. And its well in the green area of the chart showing "ok to run" If all this is true, why is it necessary to go down to a 15 tooth pinion in the DT when switiching to Brushless? Anyway if theres something Im overlooking please let me know, and if you read this whole thing thanks for your patience.
Just for info when I write DT = Losis Desert Truck.
I was thinking and came up with something. The stock pinion/ spur in the DT is 16 tooth pinion/ 88 tooth spur X 2.43 final drive ratio = 13.365 gear ratio. Everyone suggests hoing lower on the pinion when switiching to a brushless system. Now, Traxxas has a high gear ratio as well, lets take the Rustler (similar to size and weight of the DT)for example: Rustler stock spur: 83 tooth, stock pinion 25 tooth and comes with a 28 also. So take the Rustlers final of 2.72 and multiply the spur and pinion and you get a 9.03 gear ratio. If you use the optional included 28 tooth pinion you get 8.06 which is a lower final drive ratio?? This confuses me, maybe the pros can answer thos one. Any time you are going to run a hotter motor than stock its always wise to go down a few teeth on the pinion. And I know what this does, it increases acceleration, lowers top speed, and runs cooler. But according to the gear charts going down on the pinion raises overall gear ratio. And in Losi manual it states: when using higher gear ratios, it is extrememly important to monitor the temp of the batteries and motor. Do you guys see where my confusion is here? Going higher on the pinion lowers the gear ratio, but makes it run hotter. But Losi and everywhere else I read says higher gear ratio = hotter. Or do they only mean when concerning the spur gear. Higher on the spur raises the total gear ratio. Anyway I did all this trying to determine an overall good ratio to run my DT with the VXL system in it, using info collected from traxxas and Losi manuals. And according to a Traxxas chart I read the lowest (hottest?) final drive ratio they suggest is 9.36 - 9.79. To get that range in my DT I could keep the stock 88 tooth spur and use a 24 tooth pinion? Now thats way higher than anyone has suggested, but falls right into line with the traxxas chart. Or if I stuck to the rustlers stock overall it was 9.03. So in the DT that would be a 23 tooth. This would almost match Rustlers stock settings in their Rustler VXL. And its well in the green area of the chart showing "ok to run" If all this is true, why is it necessary to go down to a 15 tooth pinion in the DT when switiching to Brushless? Anyway if theres something Im overlooking please let me know, and if you read this whole thing thanks for your patience.
Well, first you have to remember they are two deferent trucks, with two deferent motors one is a 550 12T, the other is some unknown 27T 540 motor. Now the 550 will make more torque the the 540 hence the fact that it can handle a bigger pinion. Now that said for every one tooth added to the pinion, that would be like taking three teeth off the spur. But other than those, I think you have every thing right. (But I am by no means an expert on these.)
(P.S. I am using the Titan motor for the Rustler, not the the VXL system)
Hope I helped
Warheadforever
06-25-2008, 05:25 PM
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RE: Yes, another gearing question (involved!)
It just depends on what motors and batteries your using, you have to find the right ratio based on that really. Brushed and brushless can be way different in gearing, the brushless gearing will depend on the kv of the motor and again the voltage your using to run it plus the vehicle involved will also be a major factor. Higher kv motors need to run at higher rpm so the gearing is lower (large spur/small pinion.) and lower turn brushed motors are the same way. The VXL motor is lower kv vs say the Mambas so unless your running higher voltage through the VXL it will be slow unless you raise the gear ratio vs a Mamba at the same voltage....
