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Old 03-23-2006, 08:49 AM   #4111
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Originally Posted by R/C Anonymous
Is that the temperautre of the can, endbell, or armature?
I take it by pointing the temp gun inside the can side slots and onto the armature itself ('arm' temp) and also take multiple readings through each of the slots, using the highest reading.

A side note: A good thing to do is to point it at the end of the armature rod sticking out of the endbell ('comm' temp). If the temp reading here is higher than the arm temp, then either the brush spring tensions are too tight, or the brush combo isn't a good one. You'll probably want to fix that before using the arm temp for gearing.
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Old 03-23-2006, 09:09 AM   #4112
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Originally Posted by teamgp
A good thing to do is to point it at the end of the armature rod sticking out of the endbell ('comm' temp). If the temp reading here is higher than the arm temp, then either the brush spring tensions are too tight, or the brush combo isn't a good one. You'll probably want to fix that before using the arm temp for gearing.

Or it could just be the friction between the bushing and the arm shaft creates a higher temp here because it has nowhere to transfer heat for cooling... for example... the pinion side has the pinion to transfer heat to.
Brush face/commutator condition after a run is the best indicator for brush and spring choice.
Motor temp is a general rule, and will even change from like motor to like motor. I have run motors in the 220 region, and they were fine. It just depends on the environment and the motor itself. On the track performance IS the best rule for gear selection, and unfortunately, it is a crap shoot to get it just right. Starting low on gear, as GP said, and working your way up is the only way... as frustrating as it can be. Asking others CAN make matters worse sometimes, there are way too many variables to rely ONLY on someone elses suggestions. Thats why it is important to keep records of motor type, brush type, spring choice, gear, tire type and tire size, ambient air temp, and race surface temp, to name a few. This will help you in the long run make faster and wiser choices for a better setup.
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Old 03-23-2006, 02:39 PM   #4113
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Originally Posted by VenomWorldOrder
i told him it came with a 84 tooth spur, but i also told him heaps of other info (ie to get a 87 spur)...and he probably got confused
LOL. I got a motor master and hudy lathe sitting in front of me and I would not have a clue what to do with them

Ok, so 84 spur is standard
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Old 03-23-2006, 03:51 PM   #4114
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went from a 22 to a 20 pinion on a 84 spur , now im running cool ? also get a winding sound after i let of the throttle now ??
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Old 03-23-2006, 06:21 PM   #4115
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Originally Posted by Novarossi
LOL. I got a motor master and hudy lathe sitting in front of me and I would not have a clue what to do with them

Ok, so 84 spur is standard
lol! i told ya man, don't bother with the motor master.
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Old 03-23-2006, 07:27 PM   #4116
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Originally Posted by benroc
went from a 22 to a 20 pinion on a 84 spur , now im running cool ? also get a winding sound after i let of the throttle now ??
Hi Benroc

I would try the 21T pinion with 58mm tires. Keep track of the rollout on your chart so that you can change the pinion and spur gear as the tires get smaller. If you are a newbie, make sure you check your ride hight as the tires get smaller. At your local track, find a fast, nice, racer and ask for some tips on setup. Most people are happy to help and most Xray people are good people!
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Old 03-23-2006, 07:51 PM   #4117
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nobody helps !!! , everyone says look at rollout chart but theres no reference , there is just numbers , how do you know what range you should be in ?
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Old 03-23-2006, 08:08 PM   #4118
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Originally Posted by benroc
nobody helps !!! , everyone says look at rollout chart but theres no reference , there is just numbers , how do you know what range you should be in ?
What type of stock (or base)are you using? Monster? Co27? I can get you in the ball park if you let me know! When I get home from work (Yes I'm doing this at work, don't tell! ) I will get you a rough pinion selection for some different tire sizes, but I need to know what base stock motor you are using!
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Old 03-23-2006, 08:09 PM   #4119
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Originally Posted by benroc
nobody helps !!! , everyone says look at rollout chart but theres no reference , there is just numbers , how do you know what range you should be in ?

Man, your track must blow if no one will help you get in a ball-park. The people here have gave you ideas, running foams you really should be using roll-out charts, where is your car compared to speed with the fast cars? It's not magic, just requires a-little experimenting to get it right. With a monster I was around 26-27mmm roll-out.
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Old 03-23-2006, 08:37 PM   #4120
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Originally Posted by benroc
nobody helps !!! , everyone says look at rollout chart but theres no reference , there is just numbers , how do you know what range you should be in ?
Roll out charts help once you know where to start. For the Monster Stock, I used between 26 and 27. For the CO27, I'm using around 30. Each motor will be different. Once you find a good temp on your motor or a good power range (performance on the track), check your roll out. Then as the tires wear down, change your gearing to maintain that roll out.
Getting setup advice on here from people who don't know your driving style or ability is kind of useless. You can put Ralph Burch's National's setup on your car, but if you're not driving under the same conditions, with the same traction and similar radio settings, it really doesn't matter. That's why people keep telling you to ask the locals. Even then, different driving styles will require different settings. Using someone else's setup should just get you in the ball park. Then you have to adjust the car so that it feels good to YOU.
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Old 03-24-2006, 06:07 AM   #4121
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27 ea motorports epic modified stock 84/22 gears
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Old 03-24-2006, 06:44 AM   #4122
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benroc I found this info very helpful when I was fisrt learning about roll out and gearing. There is a complete article at rc car action's website but this is the good stuff....

ROLLOUT = TIRE DIAMETER x 3.14 ÷ GEAR RATIO. A tire rollout number tells how far a car rolls with one revolution of the engine. Knowing gear ratios is important and an essential element in the following equations, but only rollout takes into account the size of your tires and your gear ratio. Why is this important? Changing to tires of a different diameter will result in a higher load on the engine, and that will cause a loss of acceleration, and it could possibly increase top speed—much like installing a larger clutch bell. You may want these changes, but you may not. A rollout number quantifies exactly the effect of gear ratio and tire-diameter changes. Higher rollout numbers mean an increased load on the engine, which results in slower acceleration and faster top speed. Conversely, lower rollout numbers result in quicker acceleration and lower top speed.

You'll need to know your tire circumference; calculate this by multiplying its outside diameter by pi—3.14. Measure the tires with calipers if you can, or use a ruler. You only need to measure one tire except when the front and rear tires are of different sizes, which is typical of many nitro on-road racers. In such a case, you'll need to measure the front and rear tires. Then calculate rollout using this formula:
tire diameter x 3.14 ÷ gear ratio = rollout
Once you've calculated rollout, here's an example of where it's useful:
You're changing to a larger tire, but you want performance to stay exactly the same. Before you make any changes, you should calculate rollout to have a baseline number, and then run the numbers again with the new tire diameter plugged into the equation. Knowing you want to keep performance the same with the new tires, you'd want to determine the ratio change required to maintain that performance.
Using the MP7.5 as an example, calculate the rollout with the existing equipment:
(4 inch diameter x 3.14) ÷ 11.7
(final drive ratio) = 1.074 rollout
This tells me that for every engine revolution, the car travels 1.074 inches. If I use 4.6 inch-diameter tires instead of the 4-inch tires I currently run, which gear ratio will I need to make the car run as it did with 4-inch tires?
Step 1. First, calculate the circumference of the 4.6-inch tires.
(4.6 x 3.14) = 14.45.
Step 2. Put the new tire circumference into the equation. We don't know what the final drive ratio needs to be yet, so put an “X” in place of the ratio for now.
14.45 ÷ X = 1.074 (original rollout figure)
Step 3. Multiply both sides by X ÷ 1 to move the “X” to the right side. You now have:
14.45 = 1.074X
Step 4. Divide the tire circumference by 1.074: 14.45 ÷ 1.074 = 13.45 (rounded).

This tells us that the final drive ratio needed to maintain performance with the larger tires is 13.45:1. Examine the available clutch- and spur-gear sizes to see which combination will get a final drive ratio as close to 13.45:1 as you can get it. In this case, a 12-tooth clutch bell and a 48-tooth spur gear would be the closest possible combination (use the drivetrain ratio calculations from earlier to refigure the gear sizes for the proper ratio).
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Old 03-24-2006, 07:09 AM   #4123
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Originally Posted by benroc
27 ea motorports epic modified stock 84/22 gears
benroc, YGPM.
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Old 03-24-2006, 07:12 AM   #4124
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i know that but how do you know what rollout you nedd theres 100 of them ,
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Old 03-24-2006, 07:38 AM   #4125
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so is rollout is based on the motor not the track? because the motor will run good with a certain spur and pinion but if you run on a bigger track and use a larger pinion because it has a longer straight won't the motor heat up. such as my 19 turn runs good with a 120 spur and a 33 pinion with 57mm tires which is a rollout of 29. so what i'm asking is 29 the rollout i should use at all tracks?
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