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Old 02-19-2008, 12:00 AM   #1
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Default 27T ROAR stock motors

Ive been racing with these motors for a while and when going to nationals i see guys that are in a totally different league with these motors.
How do the guys tune these motors for 33000 + rpm.
Ive played with brushes and springs and bedded in bushes, shimmed etc... and on a dozen or so motors are lucky to get around 30000rpm.
Ive seen one guys motor do 37000rpm !!!
Surely the quality control on these motors should have a smaller performance difference from one motor to the other.
Ive been through Big Jims motor book and while its great info there it makes me question the legality of some of the top guys motors.
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Old 02-19-2008, 03:17 AM   #2
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I am done with tuning stock motors, i'll just run xxx hard brushes and skim it over once a meeting.

Anything to give it that extra rpm, 1 run uber soft brushes, how they are serrated/drilled, some are put in/baked in various liquids, not only that but factory guys probably get slightly better motors too, the best of the best. Probably not much better (if at all) but it all helps. Not forgetting the best voltage cells too.
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Old 02-19-2008, 04:35 AM   #3
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A good motor?
First the Factory guys get to start with a strong magnetic field can picked through no doubt. Then pick and arm with nice tight wraps and low resistance pole to pole. These are the luck items for the rest of us.

Second polish & hone the bushings and set the shims so the arm is centered in the magnetic field.

Third select the right brush, this is preference and track based.

Forth & Fifth a good break-in and the right spring, this is tricky because the tolerance here is horrible. There are greens heavier than the average red and reds lighter than the average green, the true values are all over the place, you need a lot of patience and a good feel for tension, then keep swapping and re-dyno because every motor has a prefered sweet spot.

Lastly keep dynoing it because it will vary and finally drop of and need new brushes and fresh cut.

Be leary of those running older motors since some of the older can/arms are easier to crank the timing than the new.
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Old 02-19-2008, 04:35 AM   #4
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duplicate post
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Old 02-19-2008, 06:48 AM   #5
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Just let go Ken, just let go.

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Old 02-19-2008, 06:57 AM   #6
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RPM doesn't mean squat. When you have an efficient motor with a high power out put and torque then you can gear it to be fast. Secondly, car corner speed is going to make or break you. If the car doesn't handle your lap times will be slow. It's not all about RPM.
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Old 02-19-2008, 09:23 AM   #7
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^+1

If youre going to be running stock, its most likely because it has tons of torque, and not too much speed, thats its purpose, no matter how much someone tunes a stocker, it wont do too much in RPM
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Old 02-19-2008, 12:38 PM   #8
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All reasonable answers but i am not a below average racer and drive fairly well.
Why i ask is when we run the top boys are definately faster speed wise down the straight.
I have looked at gearing the CO27 motors up to 31mm rollout but they get flat on the bottom and get very hot.
Does the charging of batteries at high amps give them the advantage ???
Between myself and a few other racers we have sat with different brushes, springs and tuned motors but do not see this kind of performance.
Last years lap times are closer to the pace of the 19T class.
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Old 02-19-2008, 01:47 PM   #9
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Power going in is power going out so they say, so yes to a degree charge rates will effect what is being delivered to the motor, but I cant see charging at anymore than 6amps is going to help, all it will do is ruin the cells quicker.

This is going to sound obvious, merging on stupid to mentioning it, but you need to visually see for yourself what the pro's are doing that you're not.

Look at the lines they take on the track, see what charge rates/equipment they use and how its used (esc settings etc) to get the full picture.

Your transmission needs to be butter smooth too, so check for anything unusual on their cars, its been known for people to cut 1 of every 2 teeth off the pulleys to decrease resistance in the transmission, remove the inner sheild of the bearings etc, stuff like that just helps things spool up that little bit quicker, over the course of a lap and the race duration it all adds up....
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Old 02-19-2008, 02:16 PM   #10
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batteries/chargers/esc/driving lines all make a difference, but supposing that you are a decent driver, and probably have good equipment, i doubt all those are reasons. What esc are you using? the FETS might be wrong for stock. You mentioned last years stock is close to 19t of this year? i doubt that, but i dont see why they should be getting slower this year.
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Old 02-19-2008, 02:27 PM   #11
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1st national of the season is this coming weekend.

Im using a Tekin G11 Pro and its plenty for stock.
My equipment is all fairly new with exception of my Tekin esc.
Ice and Checkpoint chargers with IB4200 packs in the 1.24V range
CO27 motors are prefered motor by most racers if not all.
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Old 02-19-2008, 03:45 PM   #12
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If your motor is slowing up towards the end of a run it may be because of your current limiter, it doesnt always pay to run it on max, try 90% instead and this may reduce brush burn, and you will not notice any lack of punch.

Sometimes all that is happening is the wasted energy is turning into heat and killing your motor and its brushes.
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Old 02-19-2008, 05:54 PM   #13
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It would be good for those that are reading this thread to list there make of car, rubbers or foams, type of motor, pinions spurs roll out or final drive so every one can see where evryone is running and can compare there specs to each other this might help a lot of people.
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Old 02-20-2008, 02:08 AM   #14
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Quote:
Originally Posted by 16skyline View Post
It would be good for those that are reading this thread to list there make of car, rubbers or foams, type of motor, pinions spurs roll out or final drive so every one can see where evryone is running and can compare there specs to each other this might help a lot of people.
That would be great
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Old 02-20-2008, 07:01 AM   #15
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Quote:
Originally Posted by razzor View Post
Ive seen one guys motor do 37000rpm !!!
Tooooo much timing, some rotors are advanced more than others. Some cheaters also move the comm, bad idea. You can also advance the magnetic timing with a Zapper. If you are running touring car this will not really help you as you are looking for torque in most cases. You can have torque or RPM but not both. With the lighter 12 scale or on a large track RPM is good but RPM also creats friction which creates heat and eats up the small amount of remaining torque. If you clean, oil and properly break in you motor you are probably 95% to where you want to be. If you have a dozen or so rotors you can look them over and see some had to be balanced less, these ones also will probably be wound neater too. You can also see where the parting lines on the comms are advanced or retarded vs the stack. Out of 12 rotors 1 will be better, this is where the team guys have slightly better motors.
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