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    Bladerunner Information Sheet

    This fact sheet contains basic information about the ITC Bladerunner,

    including basic specifications, running changes made in production, advice

    on how to trim, modify, and repair the Bladerunner. It is a summary of the

    postings on www.rcgroups.com. Complete information can be found on that

    site under the following heading:

    RC Groups Discussion > Airplanes - Electric > Indoor and Micro Models

    Please bear in mind that this list merely reports modifications made by

    others, and I cannot vouch for them. Also, remember that any changes to the

    Bladerunner will invalidate the warranty. The creators of this fact sheet, theforum from which the information was taken, and the site on which this

    sheet is stored assume no responsibility for the changes made as result of

    reading this fact sheet. However, they could be fun and helpful! Any

    suggestions and modifications are welcome. These can be sent to:

    [email protected]

    This sheet is updated regularly

    Last update: January 10, 2005

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    Table of Contents:Bladerunner Basic Components Page 3

    Running List of Improvements Page 3Setting Up the Bladerunner Page 4

    Trimming Page 4Balancing the Blades Page 4

    Seating the Brushes Page 4Rotor Adjustments Page 5Checking Center of Gravity Page 5

    Adjusting Center of Gravity Page 6

    Bladerunner Modifications Pages 6-8

    Cat Killer Mod Page 7Getting Rid of Ratcheting Throttle Page 7

    Lighten Bladerunner (incremental steps) Page 7

    Lighten Bladerunner (whole package) Page 7-8

    Longer Running Batteries Page 8Spacer Mod Page 9

    Shrinktube Spacer Mod I Page 9Shrinktube Spacer Mod II Page 10

    Shim Mod Page 10

    Bug Mod Page 10

    Carbon Brush Mod Page 10Tape on Rotors Page 10

    Vertical Support Mod Page 10

    Viagra Mod Page 10Convert Transmitter to Mode 2 Mod Pages 11-16

    Landing Gear Mod I Page 17Landing Gear Mod II: Page 17Landing Gear Mod III: Page 17

    Landing Gear Mod IV Page 17

    Landing Gear Mod V Page 18Boboche LED Mod Page 18

    Bladerunner Repair and Maintainence Pages 19-21

    Rotor Blades Page 18

    Replace Rotor Blades Page 18Lubricating Gears Page 18

    Motor Replacement Page 18-19

    Home-made Rotor Replacement Page 21Improving Gear Mesh Page 21

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    ITC BLADERUNNER INFORMATION

    (from RC Groups Thread)

    Bladerunner Basic Components:

    2 high quality very hot N20 type motors (1.7 ohm, 60% efficiency) 4mm pager motor (tail) 300mAh li-po cell (7C) light weight electronics (5 gram) with 3 ch. proportional control, rudder-throttle

    mixing

    2 ESC's for main motors and a bi-directional one for the tail. transmitter has a built in li-po charger with a cable and connector to the helicopter. The rotor diameter is 11.5 inches. The body is approx. 5.5" long x 2" tall x 1.5"

    wide.

    gear ratio is 1:13,5Running List of Improvements:

    new better rudder (yaw) trim on transmitter removed mechanical steps in the throttle stick new rotor blades (I believe that spare rotors can be ordered from ITC) new battery, high current 300mAh cell at 6-7 gram, both incl. fuse and low

    voltage cut-off.

    wires to the tail propeller molded into the CF tail rod weight reduced from 53 to 51 grams, larger ribs / stiffeners in main motor mount better material in the landing gear (that also doubles as the antenna). improved tail motor better production testing of the charging circuit bearings in the first batches are plastic (the frame itself). Ongoing production

    however, uses brass bearings for the inner shaft. No bearings for the outer hollowshaft.

    better weight control of the blister body rotors with the carbon wheel vs. glass white ones

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    Rotor adjustment Jig: (Swilson50)First, remove both rotors from the shaft I used 4 sets of 2 cassette tape casesarranged at 90 degrees. This gave enough height to prevent the center piece ofthe rotor from touching the work table. I placed the rotor ring on it with therotors between the jigs. I then measured the lower point of the inside of each rotor

    from the table. I also measured the pivot distance between the rotors (approx. 1/4inch). When I measured my rotors, I found that one had almost 1/4 inch more"pitch" than the others. Using the root of my 20 watt soldering iron, I applied alittle heat to the carbon rod and twisted out the excess pitch. I did the same thingwith the lower rotor and again, found that one rotor had about 1/4" more pitchthan the other three. Again, a light stroking by the soldering iron and twist out thepitch.This is harder to describe than it is to do.

    RESULTS: I still get rotor wobble, but the BR is MUCH MORE stable. It doesn'twander around in simple hover.(Oscillation in heli talk, I belive) I've also found

    that when moving forward and turning, the controls seem much smoother. Ofcourse trim is still required throughout the flight as the power curves of themotors change as you increase throttle and as the batteries drop. (seemingly aninherent part of helicopters).

    Seating the Brushes?: (Swilson 50)I kept banging the joystick until I got the tail rotor running and then I held it inplace and let the rotor run about 5 minutes, then I reversed it and ran about 5minutes...IT MUST HAVE NEEDED TO SEAT THE BRUSHES because itfunctions now. I also taped the heli to the table and ran the main rotor at about1/2 speed until it cut off. I would guess that it was 10 minutes or more. I could feelheat through the canopy. I let it cool about an hour and recharged it...MUCH

    BETTER POWER AND IT SEEMS MORE STABLE. I had noticed what I thoughtwas "cutting out" before. Perhaps the main motors needed seating too....and Iguess the battery needs deeeeeep cycling.

    o Checking Center of Gravity (CG): put a ball point pen under the LG (landing gear)as directed (a couple mm in front of the main rotor shaft) and see if it is near thebalance point. Report back where you find your CG at.

    o To get the CG back a bit you must move stuff back (be sure the battery isnot displaced forward a bit), or remove weight from the front (like thebody) or add weight to the back.

    o Of course adding weight is the least favorable option, but it should onlytake a tiny bit way out on the tail boom to make a noticeable change in CG.

    Maybe a couple bits of tape.o Another option: To check the C.G. just gently lift the helicopter by the top

    rotor and check that it tilts slightly (2-3 degrees) forward. The easiest way

    is probably just to hover it in a large open space (if you have it). Ifhelicopter drifts very slowly forward it is correct.

    o Adjusting Center of Gravityo Correcting Center of Gravity (Swilson 50)

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    I've also found that just a tad of clay on the front helps with forwardmotion. I don't really need to back it up. I just use reverse to stop forwardmotion. Be careful, though. As previously mentioned too much nose weightand it will start some weird oscillations...resulting in an "uncontrolledlanding)..polite term for CRASH.

    oMove Center of Gravity Forward: (CAed fingers) remove the tape holdingthe battery and simply slide it forward to adjust CG then put tape back on.

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    Bladerunner Modifications:

    Cat Killer: the tail propeller works better if you cut the guard off to increaserpm. (the 0,05W motor with the 0.5gram propeller is a hazard to eyes, so be

    careful! Please note that on newer models, many users have reported that doing

    this mod along with removing the canopy may result in a Bladerunner that is tooresponsive, causing rotor strikes. Best to go one step at a time! If you are getting

    too much power, GMRO suggests: a little tape on each tip of the tail motor propslowed down the rpms back there. With the ring gone the BR would work theboom down and up if left on the ground sitting on the landing gear and fullforward/backward was given at the transmitter. Now with the addition of scotchtape...just the normal clear 1/4" wide wrapped around each blade tip to allow thetape to extend off the tip approx 4mm but not wider than the prop itself slowed therpms down to allow for better control. I have the tape on the prop about 4mm too.Seems right. More or less tape could help tune for the feeling you want.

    Getting Rid of Ratcheting Throttle (early versions): for those with the earlyversion with ratcheting throttle, the ratchet indexer can be removed easily byopening up the TX case and removing 1 screw.

    Lighten Bladerunner (step by step):o blister body is about 5 grams (10%) and is what you need to remove to

    really increase flight times.

    to Remove the canopy just cut the plastic tabs off at the bottom andslit with a Exacto Blade (need to watch the antenna wireitshooked on to the back of the landing gear..)

    add about 1 gram of weight in the front to restore the C.Go replace the 2mm CF tail with a 1 or 1.5mm rod

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    o remove the guard from the tail propeller (see Cat Killer, above)o start to trim down on gears and plastic partso maybe try a 340mAh Kokam cell (more suggestions below for batteries)o The weight of the landing gears (and antenna) is less than 1 gram so not

    easy to save a lot there, but it is possible to take a little.

    Lighten Bladerunner (whole package) (pjottr):Managed to get the weight down to 48 grams using a single (9,5 gr.) Kokam360 HD, modded the undercarriage to carbon, used AWG 32 wire (same wireas the original from print to lipo) for antenna (19 cm long) and battery leadsand some micro connectors from Bob Selman....Lipo is taped on (seems to bethe lightest option)

    [Whatever you do maintain C.G. 1-2mm in front of the main shaft]

    Longer Running Battery?:The fuse and the low voltage cut-off is in/on theexisting battery itself so if you replace it with a new battery be careful. I would

    suggest the 360mAh high current Kokam or similar battery. (Petter) Here areother suggestions:

    o Overview: Two different li-pos have been used. The first one is about 9grams, around 300mAh, 5C the other one 7 grams 300mAh 7C. Any high

    current (10C) 300-320 mAh cell below 8-9 grams should do. The mostimportant thing is to get the weight below 50 grams (also from Petter)

    o I'm running two Etec-250's in parallel and that works very nicely. It evencharges with the existing charger, takes almost an hour though. My

    original battery weighed 8.5gr, the 2 E-tec 250's together without all thewires weighs on 10.5 gr. (thopter)

    o the Kokam 340 HD seems to be the best choice for now After using theinbuilt charger check your Volts, if it's only 4.1 V or less you can use a

    lipo charger to charge to 4.2 V for a minute or so more flight time...(pjottr)

    I have two Kokams with tiny BSD connectors, I just tape them inwith the +/-solder tips of the lipo facing downwards in the frontpart of the frame of the original lipo to maintain CG..

    After the 4 minute flight I switch battery, check rotors - the motorscan cool down- and I'm flying again

    Taking out the original lipo with the cut-off board is easyenough, you don't need the cut-off because you need >3,9 V to fly

    at all... (pjottr)A little warning. (Petter)If you optimize everything you will probably be able to fly for almost 10minutes. After a while this could burn up the brushes in the motors. Themotors have not carbon brushes and while testing some 300mAh 7C batteriesIhave had flight times of 10 to 15 minutes. This burns the brushes quite fast !

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    Spacer Mod: (66tbird) I took them off and balanced the blades like a prop, the re-installed then with the 10mm "spacer" mod. It works even better. While I had the

    blades off I took a little pitch off them to increase the rotor speed. Motors run

    cooler now also.

    Shrinktube Spacer Mod I: (GMRO) Get a piece of shrink tubing. (I matched thesize from my Radio Shack bundle pack). I've found I could use close to 12mm as

    far as the length of this new piece is concerned. I removed the top silicon stopper

    on the top of the BR's mast and removed the top rotor. Then I went about waydown and removed the stock spacers. I put the new piece of shrinktubing on the

    mast and replaced the stock spacers and the top rotor. My silicon stopper is just

    flush with the top area of the mast. I'd say it is on there about 4mm or so. Plenty

    IMO to keep all on the mast. Now the 2rotors are further apart and I don't notice

    any bad tendencies but the clashing of the rotors is greatly reduced. I get a much

    faster forward speed now without clashing of the rotors.REMEMBER: DONT APPLY HEAT: USE SHRINKTUBE AS IS

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    Shrinktube Spacer Mod II: (prevent rotor strikes) (jpottr)I did put a piece of 10 mm shrinktube between the rotors on the shaft to increasethe distance between them...Flying seems to be as good as always, but less chancefor rotors hitting each other.

    Shim Mod: (GMRO)I did reshim my motors on the BR to better fit the gears (the motor to pick up gear)My motors seemed to be a bit far apart for my liking. SO, a little exacto knifing,(and I mean a little) and I got a nice mesh. My concern was if the BR touched awall or ground sideways the motors could strip out the gear since mine seemedloose. Now all functions better, at least I think, and I don't worry about stripping.

    Bug Mod: cut out the canopy of the body and glue it onto the front of the frame,gives it kind of a bug look

    Tape on Rotors: (msburko)I wrapped 3/4" clear tape (NOT transparent tape, to brittle) around theblade tips. Too many rotor on rotor strikes took chucks out of the tips. Thetape is keeping the rotor from cracking all the way through.

    Vertical Support Mod: (thopter)I found on my two BR's that the gears would slip on the upper rotoroccasionally when I started up. It appeared that the backlash was toogreat between the gears. After looking into the loose shaft as being theproblem I came up with a simple mod that fixes it perfectly. If you add asmall piece of foam between the upper rotor motor case and the battery itapplies a little force to push the motor outward. This corrects the problem.Petter you may want to consider a small support built into the plastic

    fuselage that accommodates vertical motor support in future models tocorrect this. For now foam works well as a vertical support mo

    Viagra Mod:(66tbird)Removed the canopy, and the lipo. Replaced it with a 250 on a connectorso I can use my own charger. The AUW is 45 grams and it stays up a LOT

    LONGER, Sorry, I've got to do it, it's the "Viagra" mod.

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    Transmitter Mode 2 Mod:(msburko)Before you do any of this take the 9V battery out of the TX.

    o The End Result: I'll start with the results. Have a look at the modified TX.First of all it is now up-side-down. The wire coming out of what is now

    the top is the new antenna. The wire is the same length as the original

    extended antenna. Leaving the antenna at the bottom was not going towork. It was poking me in the stomach. Flight testing has been 2 flights. It

    works. I have to check if I am getting full throttle. If not the pot on thethrottle axis can be adjusted.

    o Step 1: Gimble ModsThe Centering Mechanism (CM) must be moved from the original pitch

    (fwd/rev) stick to the original throttle stick. Later we will swap the wires

    so the stick functions swap. Photo 1 shows the 2 axis stick with the CMremoved. Loosen the 2 silver screws and wiggle it out. The 1 axis stick has

    almost the same piece. It too needs to be removed. The 1 axis piece is just

    a gimble support for the axle of the gimble. It does not have the spring,

    screw or extra plastic piece. Get the gimble support installed on the 2 axis

    stick and you are done with that side

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    o Step 2: Inserting the Centering Mechanism.Photo 2 shows the CM inserted in the 1 axis stick's frame. Unfortunatelythe Frame is different and blocks the movable piece of the CM (CM-

    arm).The metal detent thingy was also removed. The new throttle stick

    does not have the ridged part for a detent so the metal part is surplus.

    o Step 3: Shaving the FramePhoto 3 shows the frame shaved to allow the CM to work properly. I used

    an Xacto knife. I cheated and also shaved about 1mm off the CM-arm. I

    decided to unscrew the frame to make the shaving easier.

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    That shiny thing under the frame is a CPU heat sink I used to support theframe during cutting. To unscrew the frame there are 4 black screws. One

    of them is under the TX board. Be careful, the wires break easily. Photo 4

    shows the CM has full travel after all that adjusting.

    Get the gimbles back together and the hard part is over. It took me about 3hours, with interruptions, To do this part. I consider myself slow at this. I

    reassembled the TX and made sure it would still control the BR. I

    recommend you do that too. I held the case together with tape for that

    brief test.

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    o Step 4: Rewiring the TXThere are 3 pairs of wires to swap. Desolder and resolder as follows:

    1) Brown and Black wires to the outer terminals of the two middle pots.

    2) White and Gray wires on the center terminals of the two middle pots.3) Brown and black wires to the outer terminals of the single pot.

    Cut a length of wire about 2 inches (5cm) longer than the extendedantenna. I use a twisted pair and the 2nd conductor is a grounded shield

    (of sorts) for the portion of the wire inside the case. I doubt this is

    necessary.

    Drill a hold in the case to feed the new antenna out. My shield wire is cut

    off so it does not leave the case. Be sure the wire will clear the battery

    holder on the insie of case's back cover.

    Desolder the white antenna wire from the PCB. Move it to a safe place in

    the case or just cut it off.

    4) Solder the new antenna wire to the PCB.

    Look for any broken wires and repair them. Put the TX back together.

    Now when you hold the TX the 2 axis stick, with the trim adjust should be

    on the left. The LED should be down (6 O'clock position).

    The last part of this mod is to re-label the case. The photo in the first partshows what I did. To write it up seems like overkill. The photos on the

    next page show the before and after

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    o Landing Gear Mod I: For landing gear replacement you can use wire or 0.7mm CFrod or similar and just glue them in at the front and rear as 4 legs. If you don't have

    these materials; I have used Q-tips (the thing you put in your ears) on someprototypes. Cut of one end and glue them like legs to the plastic frame. If one later

    breaks or come loose, remove the old glue and glue in a new one.o Landing Gear Mod II: Replaced it with carbon sticks and glue, used some thin AWG

    32 wire for the antenna

    o Landing Gear Mod III: (msburko)had broken the front end of the non-Antenna landing gear (LG). I had alreadyadded an aluminum tube to fit the now shortened LG into. I added 15mm of sqtoothpick to both front and rear LG mounts. That keeps the LG from goingcompletely flat during a hard landing (crash). The toothpicks were glued withGOOP. CA and a wrap of Spiderwire Braid would probably be a bit lighter. TheGOOP was faster and easier. It's holding up quite well. I put the toothpicks to theinside so the frame would back up the toothpick and take the impact.

    o Landing Gear Mod IV: (spudandretti)One leg in the front straight down and two in the back spread eagled using 1mmcarbon rod.

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    Landing Gear Mod V: (schoey)Put a curve in the LG, which works alot better and no added weight.

    o Boboche LED Mod: (Boboche)This mod is for the people who don't want to kill their battery while letting thedevice on, or for people that love bright leds, or simply for people who like taking

    pictures with lensflares

    o I bought a bunch of 20+ candela white LEDs off Ebayo I'm taking the power straight from the switch when it's turned on, and the

    ground straight off the battery's ground. This adds a cool factor and also a

    light to tell you that your switch is in the on position.

    o I've limited the current to about 17mA (I didn't remember if the diodetook 20 or 25mA, but is bright enough as-is anyways).

    o The only concern I'd see with this mod is the chance of the bladerunnerstopping before reaching the threshold where the battery could bedamaged, and still draining current to power the LED. I wouldn't worry

    too much about it as LEDs consume a fraction of what the motors are

    eating. Plus, if you pick it up and turn it off like you do usually, it's not +/-

    1 minute that will make much of a difference.

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    Bladerunner Repair and Maintainence:

    o Rotor Blades: To repair the blades, either to "restore" the leading edge or to fix abroken blade I normally use a piece of tape wrapped around the leading edge. It is

    also possible to glue in a small piece of blister material i.e. from a coffee cup,however the blades then tends loose some flexibility and may break easier again.

    o Replace Rotor Blades:o destroyed my blades long ago....a large plastic party cup/barbeque cup Is all

    you really need. Just copy the same pattern, or make your own..

    o nail polish remover put on both sides It will eat the CA glue away and you cansave your rods. .For pulling them out of the hubs you can do the same....Butyou have to pull it straight with a little turn......or your rods will get stuck in

    the plastic hubs and you will have to drill them out... o Lubricating the Gears:

    o Silicon Lube: (Steve S63)I have used Silicon Lube in a tube. I purchased it some years ago for plasticgears as it is a plastic friendly lube unlike most petroleum lubes. It's not cheapbut it lasts a long time and I did notice in improvement in rotor speedafterwards. I used a Q-tip to apply it on the faces of the two main gears wherethey touch & on all gear teeth. I also lubed the shaft up to the reduction forthe top rotor. I also got the bottom of the shaft below the bottom gear. Makesure not to get it too low or the bottom retaining tube might come off in flight

    o Super Lube: (GMRO)I've used Super Lube, it's in a gray tube and it looks like clear toothpaste,once in a while on plastics that have larger gears in them as it has no

    petrolum distillates in it. Those will destroy and weaken plastics.o Motor Replacement: pull the axle for the gear to get to the screw. Just use a knife or

    something sharp to get under the "head" of the shaft and pull it up.

    o Any N20 type of motor with windings between 1.5 ohm and 2.2 ohm will do.(I have used the standard N20 type motor from GWS with 6.5 ohm windings)

    The flight times will probably be a little shorter than with new original motorsbut it will work. (Petter)

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    o Goldmine N-20 (inexpensive) motors: for those of you who ordered the goldmine motors all you have to do is separate the black cap that contains the

    brushes from the goldmine motors and epoxy that black cap onto the stock

    motor can and voila!-- new brushes for your bladerunner N20 motors.....this isa good temporary fix (until stock motors are available because it is 75 cents a

    motor, a cheap fix....(MeBluEyz99) STEP 1

    Must have motors to do the brush swap. I used these motors and

    bought a few for spare brushes......here is the link...

    http://www.goldmine-elec-products.c...aitem=3&mitem=3

    STEP 2Carefully remove the motor from the BR.Remember the orientation of

    the stock motor can by using the number markings on the side of the

    motor can so you can place it back correctly. You may have to removegears and rotors as well as other small parts to make the screws

    accessible that hold the motor to the BR frame.

    STEP 3Please note the polarity markings on the stock motor can and the

    replacement motor can. It is very important use markings like (-)

    Negative and (+) Positive. Take very detailed pictures of the wires and

    motors and markings before dissassembly so you know howeverything goes back together.

    STEP 4Separate the black plastic end caps off of both motor cans whichcontain the brushes and remember not to mix them up. To remove the

    black plastic caps you may need to use small needle type tools(soldering tools) or even jewelers screwdrivers, but be careful not to

    break your tools.

    STEP 5Take the black plastic cap (the good new brushes) and apply very

    small amounts (SMALL AMOUNTS NOT TWO GALLONS) of 2

    part epoxy on the inner sleeve of the new cap that contains the newbrushes for your stock motor can.

    STEP 6Allow time for the epoxy to set.

    STEP 7Solder the motor leads back to the stock motor can, making sure the

    proper polarity has been observed and put your BR back together

    slowly and carefully, with great caution because it is toy quality it maybe fragile.

    o Replacing Motors with Carbon Brushes: (Swilson50)One of my motors gave out. When I opened it, the three fingers were just aboutamputated. The commutator is also very badly scored from the fingers. I had a coupleGWS EDP-20 motors, so I thought that I would try them. They have CARBONBRUSHES and they are rated 7.2 V. I put them in and it wouldn't lift with the 340lipoly, so I switched to 2 140 lipolies in series. Wow, did it lift off, but the batteries

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    got very hot very quickly. So, I switched the caps to use the carbon brushes on the BRfactory case and arm. Just be very careful when re-inserting the com between thecarbon brushes. NOTE: you will have to reverse the motor wires. The carbon brushesare bent in reverse from the finger brushes. (guess how I know.) This looks like aLONG TERM FIX.

    You can get the motors GWS EDP-20 from serveral places including Balsa Products(www.balsapr.com). They're a bit pricy at about $10.50 each.Please note that Swilson 50 was not using the stock battery with these

    brushes

    Step By Step Installation of Carbon Brushes:

    1. Remove the BR rotors, remove the rotor shaft (the bottom retainer is a finger-tight fit). The gears will come with the shaft. Watch for the little teflon spacers

    and note their location. Unsolder the wires from the receiver to the motors. (I

    use a 15 watt/grounded soldering iron). Note which wire is in front and back.Note which side of the motor is outside. Push the pins out of the idler gears.

    This is tight on some, and loose on others. Note the tiny teflon washers.

    Remove the gears. With a tiny screwdriver, remove the screws holding themotors. BE VERY CAREFUL NOT TO LOSE THEM..After removing the

    motor, press the pinion off the shaft, but note how far down on the shaft it

    goes. It's a tight, but unglued fit.

    2. With a small screwdriver pry the two bend-over tabs from the "new" motor.This will give you a feel of how to do it. Then push the arm out which will lift

    the endcap. Then gently pull the endcap from the arm. Take a look at the

    carbon brushes.

    3. Do the same with your "old" BR motor. Again, carefully remove the old endcap from the arm. You might need to take a q-tip with alcohol to clean thedebris from the arm. You want to keep the BR can and arm. You will need to

    completely remove the arm which makes it easier insert it into the new end

    cap. I place the end cap in a vise and gently spread the brushes with tweezers(small pointy type). Place the arm into the end cap and gently twist it to be

    sure it's seated between the brushes.4. Here's the tricky part. Take the end cap/arm combo and slide it back into the

    old BR can. You may have to "jiggle" it a bit to get the arm shaft into the

    bearing. Hold your finger under the bearing so it doesn't jump in and pull

    itself out of the end cap. The end cap and can have a notch, so you won't have

    trouble matching them up.5. Carefully bend the tabs back. It doesn't have to be a "hammer tight" fit. 6. FINAL RE-ASSEMBLY. Reverse the disassembly. NOTE: You will need to

    reverse the wires because the GWS encap has the brushes in reverse order. (Itis easier to place the motors back in with what was the outside "inside"

    because the wires from the receiver to the motors are so short.7. GEARMESH...Check that the pinion is the right height to match the idler

    gears and that the idler gears are the right height for the spur gears. If not, you

    probably lost one of the teflon spacers (or put it in the wrong place).

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    Addition to Motor Replacement:The intermediate gear is pretty easy to remove.Those "rivits" are actually small axles with heads. They just press into the lower

    black frame. I was able to use 2 dull blades, like utility knife types, to pry under

    the head of the the rivit against the top of the intermediate gear and lift. The axles

    will come out if you pull upwards. Once I got them up about 2 mm I was able to

    get pair of hemostats or small plyers on them and pull them out the rest of the way.

    There is a small washer under the intermediate gear so be careful not too loose it.AND when you press the axle back in don't bottom it out. There should be some

    space and play between the gear and the head of the axle. Try and check how

    much play there is before you diss-assemble it. I used needle nose plyers to pressthe axle back in by lightly squeezing the head of the axle and the bottom of the

    black plastic plate it presses into.

    Homemade Rotor Replacements: (Kwok Yu): The plastic from 2 liter coke bottlesare good for making propellers. Here is a photo from

    Improving Gear Mesh: (pgoelz)I've had a couple instances where the BR dropped abruptly. Turns out thatthe gear set for (in my case) the right hand motor was very loose... loose

    enough that the gears could slip from time to time. The two culprits were thevery loose fit of the intermediate gear on the shaft and the slightly sloppy fit

    of the mainshaft. I was unable to figure out how to tighten the intermediate

    gear on its shaft, so I compromised and moved the motor slightly closer tothe gear. I did that by slightly elongating the mounting holes. Then, I rooted

    around in my scrap bin for some 2mm CF rod and found a piece that wasslightly larger than the stock 2mm mainshaft..... just larger enough to be a

    nice clean fit in the frame. I ground a flat on the top of the shaft to accept theupper rotor, pressed the gear and lower retainer back on, and voila.... no

    more gear mesh issues. And the BR has not dropped since, either.