Wltoys 12428b (part 13: hunting drivetrain vibration)

Since i put the front diff back in the car really felt as though it was running with the brakes on.  Even on the bench, it seemed to take more throttle to just get the wheels moving.  Looking at the drive-train rotating, there was clearly some oscillation there that wasn't ideal.  It was evident most on the central shaft behind the front diff.

So .. started pulling it all apart again. Because it was easy, I tested with the rear diff removed and it was clear the problem wasn't there.  Then I thought it was my front diff fix (upgrade 12T driving gear and Then Cup to accept M3).  And although my drilling wasn't perfectly straight, it shouldn't have caused the driving gear to rotate out of true of the bearing:

This to remind me which way the front dif goes.. ;)

..but with the front diff removed and the center shaft flapping in the air, still the noises.  So i very carefully ran the car with the large center reduction gear exposed:

Note screwdrivers to stop shafts flying around the place..

And even at that point it was evident that there was oscillation.  No issue with the motor and reduction gears or the little silver bearings, but the shaft the reduction gear sits on (reduction pinion (0084)) isn't true.

Reduction gear with universal joints, front (left) and rear (right).

So I have two issues here.   0084 may be bent(?). And with everything open it became clear that both the universal joints are noisy, especially the rear one which has slop in just about every direction.

So what to do..?  I pulled the springs and pins etc out of the universal joins (how intricate and amazing are they?!) and filleditfullofgreaseandputitbacktogether.  What?  yes.  I may have just made a dirty greasy muck trap for later on, but for right now .. it's quiet.  Which helps finding where other noises are coming from.  Not that there's anywhere left really..

..put back together, pulled it apart.  Not a nice set of noises.  I'm getting a metal vs plastic grinding.  Current guess is a bent 0084. PS: I didn't do anything on the 0084 theory because.. 

UPDATE: for reasons i had the rear of the car apart again and i found something very significant!  If i "over" tighten the 4 screws holding the rear diff on then they compress the housing and it causes the diff to bind and make a not very nice noises.  I ended up adding thin washers between the two halves of the diff and when tightened up it ran smooth.  Gaps in the housing i sealed up with silicone.

NOTE TO SELF, INSERT PICTURE HERE

UPDATE 2: Same same in the front!!! Ended up making a thin cardboard gasket between the front and rear halves of the front diff housing and again that fixed the issue there in that it's much quieter now, for now.. :)

NOTE TO SELF, INSERT PICTURE HERE

Wltoys 12428b (part 12: shopping for parts online)

I am sure there's an art to this and I'm not quite sure if i have it down pat as yet.  Have been shopping online a bit lately and have had instances of each of the following scenarios:

1. Item delivered on time, all good.
2. Item delivered on time, but found to be faulty.  Refund issued.
3. Wrong item delivered.
4. Item not delivered (not sure if that relates to the wrong item above).
5. Waiting a long time so you're not sure what you're waiting on.. 
6. Item not actually available, sorry it's on backorder :/

Mind you, i did just do a bit of choose the lowest price + postage in AU, so maybe i deserve what i get.  That being said, while i wait for my "Then Cups", i wanted to collate a list of my mistakes thus far.  So, my amateur insight polished up as a cheap pro tips:

1. Get the actual proper part number, in this case it's wl12428-0081
2. Do a search on that, not some other weird description like "Then Cup"
3. From the set of returns exclude any not in AU (use site:au at the end of the query)
4. Evaluate their professionalism by some vague indeterminate metrics.
5. Roll the die..

And thusly a list of suppliers of the wl12428-0081 part, ranked by um, yeah:

1. http://www.worldhobbies.com.au/front-diff-outdrive-cup-then-cup
2. https://www.alburyrcmodels.com.au/front-diff-outdrive-cup-then-cup
3. http://www.modelengines.com.au/front-diff-outdrive-cup-then-cup
4. https://www.supercheaphobbies.com.au/store/front-diff-outdrive-then-p-24100.html
5. http://www.acehobbyaustralia.com.au/ which is reporting "503: Service Unavailable" so guess who's last.

So getting meta for a moment, isn't it curious how most of these sites use EXACTLY the same url, it's like they're not only using the same site, but the same data feed as well.

Quick review of Lipo Battery Low Voltage Alarm

These little RC Lipo Battery Low Voltage Alarm 1-8S Buzzer Indicator Checker Tester LED AZ nifties are pretty awesome.  I can't say this is an original discovery; i saw them on ebay.  The idea is you attach them somewhere on your
RC device, i zip tied mine to the battery hold down arm:

..and they'll give you a constant readout cycling between each cell voltage and a total voltage.  The bonus is you can set an alarm to beep at you when it falls below a set voltage, note; it's REALLY loud.

It's not without it's annoyances, in the end i disabled the alarm and just kept an eye on the display.  I think they could go one up on this device and also add a temperature monitor and probe; but still, i think it's awesome for AU$4.

Wltoys 12428b (part 11: fixing rear diff failure)

So we have two of these cars.  Up until now I'd been writing about the first car, which is now in the process of being painted white.  The second car came out of the box the other day, and taking both batteries we went and ran it just now.  Such fun!! Reuben had a great time, which after all, what this all about; having fun.

..but on the way home, both batteries near dead, having bounced it all over the place and tumbled here and there and generally had an awesome time, we're literally rolling downhill on the way home and i was thinking it was making a bit of a strange noise.. Suddenly the tail shaft just drops right out on the footpath, nice as you like..

Pan head broke off inside the

Upon inspection i can immediately see it's the same bolt that broke in the front on the white car.. The now infamous 0109 "Pan Head (m2x8)", which this time now broke inside the 0085 "Active rear axle pinion" at the rear:

Pan head bolts.. why do you keep breaking?

The thing is, i can't see how these parts are loaded, moreover I don't think we were abusing the car.. It's not like we were doing jumps or whatever..  So I've now gone and ordered the 0085 "Active rear axle pinion" and some extra m2x8 bolts from Super Cheap Hobbies.

However I'm in the mind to drill these out to m3 and put a proper bolt in there..

 ..some days later i got tired of waiting for parts and I did exactly that.  First I had to drill out the grub screws to release the 0085 from the sub-assembly.  Then on the drill press I drilled out the old bolt with a 2.5mm bit, then tapped it out to M3.

0085 in the bench vice ready for tapping to M3

Then test re-assembled everything using an M3x8 hex head bolt, all good. 

The remnants of a grub screw next to the repaired assembly.

Finally all the bolts and grub screws were lock-tighted back in after final assembly.  Works a treat! and now i can await the delivery of the parts i don't need.

Wltoys 12428b (part 10: painting)

So now the car is out for awhile I'll take the opportunity to paint it.  There are many screws holding the various body panels to the body frame, and after awhile with the electric screwdriver, the parts are in a pile.  Same same taking the bead locks of the wheels:

I decided to leave a black patch on the bonnet because it's racy ;) I just used some painters masking tape to leave the standard faux-carbon panel there.

.. when it's nice outside I'll paint it up I painted it, but it's like 3 degrees C out, so now the study smells like paint.  Still.. it's somehow awesome anyway ;)

Pro Tip: Using the car's packaging as a spray booth ;)

I ended up doing the wheels as well.  All back together and I think it looks awesome! :) really goes well with that blue anodizing.

POSTSCRIPT: In heindsight i scrimped on the surface preparation.  I didn't sand or even prepsol the surface at all.  So when after a few runs the paint started coming off in flakes, I only had myself to blame:

The result is a function of the preparation.. or however it goes..

So! I wire brushed it all off, then sanded it etc etc..

Effort makes the world go around..?

And currently it's looking good.. :)

Wltoys 12428b (part 9: lubricating differentials)

I read somewhere that the metal differentials on these cars come a little dry, and it's true.  It's not a big deal to pull out the various screws to be able to access the rear diff and to apply some machine grease.  It's all shown in the exploded parts diagram for the diff and comes apart easily enough: 

Exploded diagrams are goooood.  It's SO nice having a proper car..

Ensure you also lubricate the gears inside the differential, there's another four screws to access those.

Rear diff in carrier, ready for reinstall.

NOTE: When reinstalling Be sure to orient the diff the correct way in the carrier lest your rear wheels will drive in the wrong direction.  I did that .. ;) also note that you align the bearings on the axle with their housings within the diff carrier.  It's pretty straight forward.

Lubricating the front: getting access to the front diff is pretty straight forward.  After removing the body, invert the car and remove the bash plate, front bumper and the long bolts holding on the lower control arms.  After that it all drops away and you can remove the front diff cover:

Note the orientation of the diff, don't put it in backwards!

Wltoys 12428b (part 8: fixing the front drive)

So I didn't enter this RC thing with my eyes entirely closed.  I understood that things break, and i was willing and able to fix them when it happened.  Yet when this broke i was scared that I'd made a mistake.  As i sit here, i have started tearing down the front end and i breathed a sigh of calm and added Jazz (Thelonious Monk - Straight, No Chaser (thinking of you @hobbit!)):

1. I do like fixing things
2. Parts are available although they might take awhile to get here.
3. I bought two identical cars in case one broke.. ;)

So now i get to see deep inside my car, albeit somewhat earlier than i thought.  I'm not really sure what's the fastest path to the front diff, so I'm just diving in, live and learn and all that.  Somewhere i got these really nice and small ziplock backs, so I'm just popping each "group" in a new bag as i go.

..fast forward a bit .. so anyhow, looks like the front diff and pinion are all intact (not that there's much in the way of grease..):

The front differential.  All good there (but needs lube)

  (BTW I'm still blowing out about how much fun this car was to drive.  And the more I sit here looking at it's insides, the calmer i feel.  It's bizarre i know.)

.. add time .. ok, so found it.  There is a very small bolt holding the "Then Cup" (don't ask me, that's what it says on the parts list! ;)) to the front pinion gear.  The cup and pinion interlock and the screw holds them together.  The screw shouldn't have been loaded rotationally and only under a static load longitudinally, so i can't see how it could shear, yet it has.  This pic shows the rear of the front pinion and if you look inside you can see the back of the head of the bolt:

Left: The "Then Cup" and right: rear side of 12t pinion gear.

.. fast forward .. i found the part numbers in the manual (I do like that this car has nice exploded parts diagrams).  The name of the broken item is the 0109 "Pan head screw" and it's sheared off inside the 0081 "Then cup".

Appropriate page in the manual..

So now, how to fix it? I guess i could go see my friend Randall and try to drill them both out and tap the cup with a larger bolt.  And/or order replacement parts.  On that front I was VERY pleased when i found multiple stockists in Australia, Albury Models and Super Cheaper Hobbies.

PS: It seems like I'm not the only one who's had issues with this particular bolt.

..fast forward a few days.. parts delayed, bored.. stuff it, I'm going to fix it myself.  I drilled out the screw head from the driving gear easily enough (with a drill press).  Next i tried to drill out the remainder of the bolt from the then cup, which went amazingly well.  I happened to have an M3 tap so i drilled it out to 2.5mm and tapped it from there, which also went amazingly well:

Tapping Then Cup 0081 out to M3.  Tape indicates 8mm depth.

So all that was left to do was to find a suitable M3 bolt, which i didn't really have, but found an M3 threaded screw with a nice solid Phillips head (I think it came from an old printer or something).  The driving gear hold needed a bit of relief for the screw, easy:

I used the longer M3 screw at the rear, cut to length.

And finally here it all is back inside the car.  White paper is to save the desk from the grease a bit:

Now putting the rest of the car back together, fingers crossed! :)

Wltoys 12428b (part 7; 0.7c charging and rwd conversion..)

It occurred to me that i could be using the iMax to do discharge profiling on the standard 12428b batteries (2s 1500mah LiIon); that would be much more efficient than this weird play time discharge testing.  Except that's very boring .. ;) maybe later.  For now here's the charge graph, noting it accepted 1297mah this time (at 0.7c or 1 amp).  Also note that at the end of the last play the batteries were quite out of balance:

..fast forward to some time later.  Well.. The second half of this post was supposed to be about how the car performed on that charge, and well.. it was AWESOME!! I went to a new as yet empty subdivision near my house and the thing went off!

1. Awesome power in a straight line (now that i can control it)
2. Steering track doesn't seem to be so bad (now i've fixed the steering)
3. Great looks, handling.. I LOVE this thing.

But.. ..i broke it :(

It's now running rear wheel drive only, the front drive shaft (?) has come out of the front diff.  At one point I'd thought it might be cool to have a rear wheel drive car, but with this power and these tyres there was very little traction off road. 

Wltoys 12428b (part 7; more play time, early cutouts)

OK, so that was fun!! :) i probably should have timed it, but the upshot is that i ran for awhile, and then it cut out.  If i switched the car off and on again it worked, only to cutout again, albeit sooner than before.  The cycle repeated 4 or 5 times until i decided to call it quits. Giggles were had.

re: cutting out, I can only assume that this is what happens when the battery is running out of charge, I don't have a battery monitor (they're on order from ebay) so i don't really know.  The standard battery did only ingest 1133mah at 1c (see part 6 for the charge graph). Next time I'll time try a slower charge rate, or get better batteries.. ;)

At any rate, please enjoy me terrorizing the cat! (top left).

PS: No cats were actually harmed in the making of this production.. ;)

Wltoys 12428b (part 6; voltage protections and standard battery charging)

So after i fixed the steering, i took the car out and was able to have a play.  When the car eventually stopped, i was pleased to see that it obviously had a voltage protection circuit (as in didn't run the battery flat) and when i checked the battery (2S LiIon) it showed 7 volts remaining (or 3.5v per cell).  I'm not sure if that's a sensible rating or not.  Note to self, look at that later.

So then set the battery to charge on my b6acv2 charger using the 2s LiIon charge setting*.  The standard battery is 1500mah so if we assume a safe charging rate is 1C then that means i set my charger to charge at 1.5A.  I then set DataExplorer to monitor the charge and this is what i found:

Forgive me the weird colors, i run my computer
with colors inverted; it looks great to me ;)

Compare this then to the nominal charge provile of a LiIon battery from Battery University, they do appear somewhat simiar, which is cool :)

 ..right enough chat.. lets play!!

* I did stuff up the other day and set the charger to use the LiPo setting, which uses a terminal voltage per cell of 4.2v.  That meant the 2s ended up with a total voltage of 8.4v and i was initially shocked then pleased that the 12428b refused to run.  After i discharged the battery a bit it ran fine.

Mucking around with a Rigol ds1102e (part 1)

Until yesterday i had never used an oscilloscope.  They're AWESOME.  It took me a little while to get used to using it, but already I'm learning things.  Like check this out, this is me turning on a switch, it's not just OFF and then ON is it?  apparently this is called switch bounce and i want to know more about it!

I was able to get this neat screenshot using the USB export feature, but i was able to capture it using a single shot capture on the rising edge.  Which is where the device quietly records everything, but waits until the voltage rises above a trigger voltage, and then stops recording.  You can do it over and over, and get all kinds of behaviors.  If i try and let the switch kinda close itself it effect is really obvious.  Who'd have thought a switch could be so interesting?

Makes me really appreciate how clever people must be in our world surrounded by electronics. Thank you everyone for the awesome stuff you do!

Wltoys 12428b (part 5; play time!!)

Well that was fun!! just spent 10 mins or so wheeling around my backyard, bits of tufty grass here and there, getting used to things:

1. Heaps of power, but the throttle trim can tame that right down if you like. 
2. It tends to track a little on sealed surfaces, you can tune it out with the steering trim but then it will track in the other direction.  The toe is fairly obviously out (the wheels aren't parallel) so i'll have a look at that.
3. Towards the end there was a bit of full throttle hardcore rc-action, fast bits and powering over tufts of grass etc (ehehehe), ultimately it shut itself down; the motor was too hot to touch.  I let it cool off and it was ready to go again.
4. Still love the headlights ;)
5. Need an action pic here don't I.

UPDATE: It appears that the steering arms aren't adjustable.  But now that i think about it i saw a fellow who had bent his with heat; imho it would work but would make them act as variable length.

Wltoys 12428b (part 4; fixing steering)

Note there's a deal of thinking out loud here, I'm no expert on any of this.  So I pulled the transmitter apart again.  There are 3 wires coming from the steering or "wheel";  Red, Black and White (see below). 

With the device powered off, i disconnected the wheel from the PCB using the connector.  Then I inserted thin jumper leads into the (female) wheel side of the connector, variously attached them to my multi-meter and applied steering inputs as follows:

1. Connected to Red and Black, resistance decreases as steering is applied counter clockwise.  No change to resistance as steering is applied clockwise.
2. Connected to White and Black, resistance decreases as steering is applied clockwise.  No change to resistance as steering is applied clockwise.

My guess is that Black is Vcc and the wheel itself turns a potentiometer.  So my theory is that i should be able to swap the Red and White cables over and we're good to go...fast forward an hour or so, and YES!!!  

It turns out you can remove the potentiometer from the transmitter and it makes it much easier to work on.  Just unscrew the nearby mount for the trigger in order to access all the screws.  At any rate, with the pot out on the bench, it's pretty easy to see what has to happen.  I noted the OEM setup in case i needed to revert it

PS: Thanks to tk on #taslug for the tips and Tribesmanjohn for the Oscilliscope which it turned out i didn't need ;) but it's been much fun playing with it anyhow.

PPS: We have two of these cars and on the 2nd one the remote was fine.. go figure!

Wltoys 12428b (part 3; steering reversed)

From my previous post, the steering on our new Wltoys 12428b RC car is reversed..

This is bugging me now.  Part of me i am sure is quite happy to have a problem to fix.. at any rate, a quick google netted me the following pieces of advice, in no particular order:

1. old4570 says "..The Tx has no reversing , so you will need to flip the Steering servo.."
2. SOUL FORCE QUADS offered "..I'm just guessing here...) WITH CAR & TRANSMITTER TURNED OFF - Press & hold the "mode" button on the transmitter... then turn on transmitter and release mode button. Power on car, turn wheel to see what happens. Repeat up to 4 times if necessary... Good luck!!!
3. Some reviews on a replacement steering servo on bangood, warning "..Compared to original WlToys 12428 - this one is inverted! Designed good, works great but I had to replace 2 wires in remote to get it working correct (my RX doesn't have inversion button)..."

Meanwhile i had already pulled the remote apart and i can see 3 wires (red, blak and white) going from the PCB to the steering wheel.  I can't be sure if reversing the polarity of the wires will help, and as yet i have no oscilloscope.. (hehe).  I also can definitively say there is no hidden servo reverse switch there..

So I put the remote back together and tested it functions as normal, ok, i didn't make it any worse :) Then tested the 2nd option, but no go, even tried an extra time!  So now I'll read up on "flipping steering servo".

1. Someone else said i should by a servo reversing cable..
2. Others have suggested re-soldering the servo connections internally.

.. but i really need to go to bed now .. ;)

PS: We bought two of these cars, the second one didn't have the same issue.. I had to check it several times to be sure i wasn't going insane.. weird.

Wltoys 12428b (part 2; it arrived!)

 My somewhat ignorant review so far (1 day..), first the awesome stuff:

1. The headlight and tail lights are awesome ;)
2. It's sufficiently heavy, the build quality is very good.
3. My boy loved the way the rear suspension worked.  Smooth and powerful.
4. It goes slow well and can be used indoors if you're careful.
5. The steering servo seems powerful, if a little fast at speed.
6. I like the look, but i can't wait to spray paint it all orange or something.

Then the stuff I've fixed:

1. The front suspension didn't rebound, but it was adjustable.
2. The rear diff is metal but it didn't have much grease in it.
3. I set my imax b6ac v2 charger to liPo instead of liIon which overcharged the battery by 0.2v, enough for the car not to start the first time.  I fixed me being shite .. ;)
4. There was a squeaking noise coming from somewhere, i thought it was the rear diff but not that, so i sprayed some silicone lubricant on the drive shaft at each universal joint, but the culprit was right where it exits the transfer case (near the centre of the car).

And finally the broken stuff:

1.  The steering is reversed.  Maybe my brain is backwards so i didn't say anything, but my boy is the same.  Can't find a switch anywhere to reverse it and so short of replacing stuff* I can't find any way to fix it :/

* in addition to replacing the transmitter as best i can tell the receiver is part of the ESC and from what i've read the servo is an incompatible 3 wire type which doesn't work with most hobby grade stuff.

iMAX b6acv2 battery charger (part 1: logging and graphing)

I purchased a iMAX B6AC V2 multi-chemistry battery charger for use with RC cars, and immediately installed the official application under Windows.  It allowed me to control various functions as per the display and buttons on the actual device, and in addition offered realtime graphs.  They worked!  however, it was immediately obvious that this would never do.  I couldn't save the graphs, nor could i access the raw data, and starting a new charge/discharge resulted in the previous data being destroyed.  wtf!!

I went on a bit of a hunt and found Logview and a reboot called Logview Studio.  I installed both on Windows.  Logview didn't recognize the charger at all.  Logview Studio did, however when it came to recording data nothing actually appeared.  More concerning was that it seems development stopped with the most recent versions for both being released around September 2014.

So then went to my old faithful, why did i ever doubt you, the open source community.  Pretty quickly i found GNU DataExplorer and being a Java app it ran ok on Windows.  On OSX i need to do some rubbish to allow me to access the device via USB, so i shelved that.  Under Linux (Ubuntu 18.04) it's sufficient to be root, although with the correct permissions i shouldn't need to sudo.

Here's a pic of me proving to an ebay vendor that their 1800mah battery really isn't.  Leave positive feedback they said..!

Wltoys 12428b (part 1: how we chose)

So after playing with a toy grade RC car that my boy was given, I decided I'd like to get into the hobby some more.  If you've been here you know how hard it can be to choose, so maybe this might help someone.  My decision was based on a few criteria:

1. Had to be initially cheap (we paid ~$120AUD delivered), I wasn't sure we were going to stick with this hobby.
2. It had to be able to be fixed and have parts readily available.
3. It has to have an active modding community, from which i can pick an upgrade/mod path if required.
4. Has to be fun to play with outside but not be ultra fast because we're just going to crash it otherwise.
5. Generally look tough and not like a toy.. yeah.. ;)

After much consideration i decided to purchase a pair of Wltoys 12428b 1/12 4WD RC buggies, one for me and one for my boy.   It's the successor to what seems to have been a wildly popular RC car the 12428.  I think this model looks better and has more metal parts as well.

Seems blogger still works..

w00t.

Easy blog code formatting codeformatter

 $ sestatus  
 SELinux status:         enabled  
 SELinuxfs mount:        /selinux  
 Current mode:          enforcing  
 Mode from config file:     enforcing  
 Policy version:         24  
 Policy from config file:    targeted  

To get code looking like this ^^^;

1. visit http://codeformatter.blogspot.com.au/
2. paste in your source code
3. copy out the html
4. switch your blog to html input
5. paste in the html block
6. switch back to compose or preview etc.

Thankyou codeformatter!

X forwarding firefox in OSX yosemite

 hoolio@macbook:~$ ssh -Y server  
 Warning: No xauth data; using fake authentication data for X11 forwarding.  
 Last login: Thu May 14 11:03:26 2015 from xxx  
 $ firefox &;  
 [1] 18949  
 $ connect localhost port 6000: Connection refused  
 connect localhost port 6000: Connection refused  
 connect localhost port 6000: Connection refused  
 Error: cannot open display: localhost:0.1  
 ^C  
 [1]+ Exit 1         firefox  

Apparently X is no longer a part of OSX, and you have to install xquartz to get x forwarding again.

 hoolio@macbook:~$ ssh -Y server  
 /opt/X11/bin/xauth: file /Users/hoolio/.Xauthority does not exist  
                                  Last login: Thu May 14 11:39:05 2015 from xxx
 $ firefox &  
 [1] 20620  
console.error:  
  [CustomizableUI]  
  Custom widget with id loop-button does not return a valid node  
 console.error:  
  [CustomizableUI]  
  Custom widget with id loop-button does not return a valid node  
 SystemMessageCache: init  

and up pops a firefox window, hooray :)  now it's just working out why its .. so.. slooow....

EDIT: i discovered it's to do with the ssh encryption type.  try this;

 hoolio@macbook:~$ ssh -Y -C -o CompressionLevel=9 -c arcfour,blowfish-cbc server firefox -no-remote  

and DON'T do it over wifi; the double encryption plus inherent X latency make it terribly slow.