Build Thread Chapin's build logs

[Chapinb]

Iv got a few builds planned and figured I would consolidate them all here. The first will be my primary rig.started life as a mega 4x4 senton. Added 4s kraton shocks (shortened by 10mm), max10 bl kit, buggy wheels, generic rear cvd, 10mm offset hexes, a chassis brace, 4s Mojave front bumper, and a generic 30kg servo. She's an ugly rig, but is very functional and to me coming from a revo platform, crazy durable.

I have 2 goals in mind for this build. Keep as much durability as possible but wanted it slightly wider then it currently is. To achieve this, I'm adding 4s kraton arms and supporting hardware.

Arms plus hubs are about 2.5" wider, minus my extension, should gain about 2" per side. More then I wanted, but I'm this far. Ain't stopping now.
Fun tidbit, all the arms and hubs are interchangeable. Want just 4s hubs on your granite? Will fit. **edit, see below. Not a direct fit**

Iv had a number of wheels spin off due to some part of the hex backing out. Got frustrated and it appears I went overboard on the loctite.

Added a metal rear diff with 45k fluid.
Side note, the 6s guys seemed to have gotten hosed on gear size. Guess what gear is 4s and 6s? Wow

Check out the potential ground clearance! The cvds unhappily go that far too.

I really like the pin and retaining screw on the hubs. But this is where sizes differ. The 4s hubs uses a thinner(?!) but slightly longer pin. I need to order that pin, so guess I'm done on the rear for now.

Iv a set of turnbuckles but not sure what one go where. Can anyone shed some light where the short/medium/long goes?

Now before anyone goes off asking why I didn't just get a 4s to start, I do have a good reason. I didn't know it existed. So there! But also I bought a few mega sentons during a sale so the family all ran the same rigs, same Batts, same spares, ect. I like to fiddle and it's been a good excuse to show the kids some engineering.
Enough for tonight, I'll start the front tomorrow and get some pins ordered for later.

 

[kratonwatch]

Cool build! I’m looking forward to the updates

 

[Chapinb]

Fun tidbit, all the arms and hubs are interchangeable. Want just 4s hubs on your granite? Will fit.

To clarify, this won't be a direct drop in due to the pin size. Hub will need to be drilled out and a longer pin would be needed. But the spacing on the arm is fine.

 

[Chapinb]

Finished most of the conversion, still missing hub pins, just some wire holding them in currently. Definitely wider then I wanted. Thinking mojave arms plus offset hex will put me where I wanted. Removed limiters in shocks, put stock kraton springs back on and filled with 40wt.

Tires look ridiculous but Im going to stick with them for now. Still on the lookout for taller, but narrow/light tires. Do have some 1/7 sct tire on the way but if the shipping weight means anything, they are heavy. Conversion was fairly straight forward and no special parts needed other then the hub pins.
Tie rods, hubs, axles, and hex.
Stock 3s senton on top for comparison.

Kraton 6s body looks more at home then the voltage body.

As far as the tie rods, longest went on rear, mids are front camber and shorties are steering links.
Hated the max10 fan whine. Printed a 30 to 40mm fan adapter in nylon and wired it into the stock fan harness. Polarity is reversed from the programming port beneath it. Pos in on the left.

Some other minor things in the works, but I'm waiting on parts for that.

In the meantime, im having difficulty finding extended hexes other then hotracing or the expensive m2c for the 4s axles. Do the 6s fit?

Side note, I opened 4 stock plastic diffs, a 6s diff and a 4s metal diff over the past week. 2 of the composite diffs had only a dab of ear wax colored grease inside, not even on the gears. 2 others were mostly filled with silicone oil but different weights. One had a lighter probably 10k-ish but one felt significanty heavier.
The 6s diff and the metal 4s diff were nicely filled with I'm assuming 10k. All 3/4s ring/pinions were basically dry. I could see a small amount of wear in the rear of mine because of that.

 

[Chapinb]

Ran the kraton arms/buggy wheels for awhile. Always fun to change it up. I did love how stable and smooth everything was but its time for next iteration.
Ordered mojave 4s arms/shafts/turns. Decided not to chop up the kraton shafts/turns to make them fit since I'll probably throw it in the kids at some point. I'm a bit of a hoarder of spare and random parts.
Never realized the front arms are significantly shorter then the rears, by about 3/4 inch each. The kratons are too, but its so much more noticable when they are this short. Front/rear seem to be interchangeable so it might make for some fun staggered stances. Maybe kraton rears on rear and mojave rears on the front?
From top to bottom - mojave rear w/o hubs, 4s mojave front, senton 3s front, senton rear. Not gaining any width with the mojave arms/hubs but they are sure beefier and have bigger axle carrier bearings. I feel better adding offset hexes on these.

At full droop, the shock spring retainer pushes into the arms. I shaved about a mm off in this area. When assembled, it still hits but gains me some extra travel. I'll limit it internally later if it's pushing the cvd too far.

The balls are much harder to put into place vs the senton and kraton, just a few thou wider. Putting a small Allen key thru let's the lips of the balls seat in before it gets sideways.
Kraton 6s body/wing fills out the large bumpers nicely. As is, it will rub front and rear. I have a pair of 13mm extensions en route that will let the rear clear, front probably will need a chunk of the fender flare cut off.

some new 1/7 shoes that I'll be trying. Generic buggy tires top left (4.5oz, 120mm), generic 1/7 sct tites in white (7.5oz, 138mm), 6s - 1/7th mojave in red (8oz, 139mm) and stock 3s senton (4.5oz, 110mm). 3s Granite/big rock are about 7 oz/130mm for reference. The 1/7 tires add about 15mm in width per side vs the narrow 40mm buggy tires. Between the slightly wider hexes and wider tires, ill be at my with goal that lead me down this path in the first place.


Waiting on cvd and hex extentions now before it gets driven again, but work has me tied up for the next week. Eventually like like to plop a sct body on it, iv got a fondness for watching the suspension tuck up into the wheel wells.

 

[Chapinb]

New hexes arrived. Used these guys
17mm 6s hex
They are for the 6s stuff but fits well. The 6s pin is larger (I think) but these come with both sizes. Means if you get some from Jenny's, it likely won't fit.
Rear spacing is spot on, no shims needed. For whatever reason the fronts needed a little over 1mm. Do I have an m8 washer? Of course not. Drilled a smaller one out and sanded till it was tights, about 1.3mm thick.

New 50mm motor fan went in. Fan mounts needed a little grinding to keep from rubbing on the shaft.

Button it back up, throw on the 6s mojave shoes and trim the front fenders for clearance. No running till tomorrow or Tues but it's ready!

 

[Chapinb]

While I had it apart, a rc4 transmitter came. Easy enough swap, but radiolink and spek have reversed throttle channels from each other. Added a jst for voltage telemetry, set steering and throttle endpoints, added some steering and throttle expo.

I can't say I'm happy with the fit and finish of this radio. It feels cheaper then the stock spek, the menu buttons arnt quality feeling. But for a cheap programmable radio with telemetry, it's still a bargain if it works.

She's sitting a bit higher then I'd like, but there's still preload spacers that can come out. They arnt the clip ins so that's getting saved for another day. Offhand, the spring rate feels about right.

In the meantime, one kids rig needs some esc upgrades and another is being rebuilt, or reborn might be a better term. A rock racer-ish build. Part arrma, part crawler. Sensored low kv motor, near locked diffs, granite tires and I'll see how much suspension travel I can get from it with parts on hand.

 

[Chapinb]

Well the crawler build kinda failed because I'm a big dumb animal and the sensored wire plug broke on the esc. I'm going to say it wasn't my fault since it was not secured but any sort of glue, just the data pins. Attempted fix and it runs but stutters way more then it should, and won't run at all uncensored. But hopfully the photos provide some glee to someone out there, or at least a visual schematic if someone needs it. It's a surpass 120a sensored esc with a rocket 540 sized motor.

Well, it was worth a shot.
The build is based on a badly used and abused 2wd mega granite. Adding front diff was easy, but the rear had different sized teeth vs what I had.

Ended rebuilding the origional diff since it has meatier teeth then the replacment. Front and rear have 100k fluid.
Can't say I'd reccomend the motor I choice for most. It's small 3650 but it's for a 30mph crawler thing, figured it would fit the bill and was cheap for the kid. The motor shaft is smaller needing a collar for my collection of pinions and the can isn't sealed - hence the tape. Fancy, I know.

The motor module was REALLY difficult to install. It's a new/usb blx case. I shaved the halves some so they meet smoothly and had to loosen up the bulkhead screws to slide it in. One of the rear screws was bent - how do you manage that?

Since the esc was toast, I threw an 80 amp uncensored that I uad laying around to get it up amd running. Not much of an exciting build, but it sure have me plenty of problems.

 

[Chapinb]

Next on the healing bench is a redcat ascent 18 crawler. The lil guy has become our tag along for hikes or camping. The redcat seems pretty durable so far, nothing broke and its seen a bunch of abuse from kids and adults alike. I won't be doing anything usual to this guy, just the basic reccomended upgrades. Moved the electronics around and brought the rear shocks inboard

Injora 1.3 beadlocks carrying swampers. Little bigger, meaner and softer. Extended brass hex and brass front portals. Have a servo on standby if the stocker can't cut it. Unlike most reviews iv seen, my stock portals did have some black grease coating the inside. I removed that and stuffed it full of new stuff.

The little bead locks sure are a fussy item, but well made. Body will need to be trimmed up front a good bit, rear might be ok. Wanted to run it with just front beads for the time being to play with a redneck overdrive system. When doing the right side portal, a bearing failed during removal. Look at the balls at the end of the 2mm hex! Not even going to attempt fixing that guy.

Bearings ordered so project done for now.

 

[Chapinb]

Portals, hexes, wheels and sweet new body all on. I have a mini course in the basement (couch and cushions) that he mod make much easier. Can do reverse wheelies now!
It really, really could benefit from throttle expo, esp with the kids. But since it has a 2in1 esc, that involves replacing more then I want to right now. Awesome lil rig that's pretty cheap to experiment with or upgrade.

 

[Chapinb]

Went for a bash today and one kid was a little sour about the abilities of the stock senton tires in the rough dirt. Showed him all the tires I had, and to my surprise he chose typhoon over granite tires. His innards got CAKED with mud, so he asked for a new body too. From the selection, he wanted the kraton 6s, maybe to patch his dad's stellar looking truck. Took a fair amount of trimming to get to fit. He currently has a quicrun 120a esc with a 2600kv 3660 motor. Lower kv to keep speeds in check. Both kids will be moved to 3s in a month or so so we all run the same batteries so they both got lower kv motors to prevent broken ankles.

Have had enough time to play with the rc4. Mixed feelings on it. I love the voltage telemtry but setting when the alarm goes off is challenging. It's sample rate is fairly high so it dings if you punch the throttle. I'll find the sweet spot soon enough. I think I lost signal a few times where I shouldn't. Might be because one antenna is stuffed into the receiver box while the other is flying high as expected, but that shouldnt cause a brown out. Will experiment later...
The 7 year olds granite started as a rocky project but runs pretty well. He's mastered bucket backflips already.

 

[Chapinb]

Thought this was a fun failmode. Hbx 16890a on 3s, extended hex and bigger tires, otherwose stock. Made a new ramp yesterday and was sending it this morning. After 3 packs on the ramp with 6' on air, some terrible crashes and laughs, it finally broke. Any arm? A shock? No.

It broke a receiver. Never ever have a broke a receiver. Even back in the crystal days and massive plane crashes. If yoi don't have one of these things, go get one.

 

[Chapinb]

My arrma collection is quickly growing, up to 5 fully functional 3s rigs. It's grabbed the attention of some of the younger kids and wanted something for them to try that wouldn't break an ankle. Just turning down the remote makes for a ton of cogging in grass, so that wasn't an option. And I'm not about to drop another pound of flesh on a sensored kit for them.
I have an abundence of parts as well as a mega 4x2 granite i snagged for extras. I had an idea to try 3s on a 21t, 4s rated brushed moter with a mega esc. May I present #6 to the 3s collection!

Was a stock granite mega 4x2 with a 2in1 esc. Replaced with a regular mega esc since it's physically bigger and I had hoped it handles the power better.

Metal 91t spur, stock (13?) pinion, 21t brushed motor, after braking in.

Plugged it in (on cam just in case) and it recognized 3s with the familiar 3 beeps.

Used a 6200mah lipo, first half was easy driving on the road to ease into it. Esc very cool, motor a little warm. 2nd half was mostly full throttle on grass and jumps. Esc stayed super cool, motor just passed the 5 sec finger test after the run. Speed is faster then stock 2s as expected based on kv and voltage changes. Torque was better too, it even (barely) wheelies. Not sure the lvc works since the lipo was at 3.6v per cell when I stopped. If it were in a 4x4, it would be too hot, would need a higher turn motor since there isn't any more room to gear down.
Over all, success! Will it keep working? I dunno, but some kids and I intend to find out.
Paired it with a new Hotrc ct6a transmitter because it has an adjustable and lockable max throttle knob, from 0-100%. Really like this transmitter so far, will report after more use. Got a ct8a as well, but can't reccomend it simply because it HAS NO EXTERNAL TRIM BUTTONS! It's all done by programming menus. Seriously? Why?
Both versions take usb, 2s lipo, 4 aa batteries or a 18650 cell. Or a combination of 3. The 18650 holder was designed by a child though. Its positive terminal dosent reach the cell and its positive down. Every other thing iv used with a single 18650 has neg down. A blob of solder fixes the spacing issue. Please don't solder an 18650 yourself unless you know what your doing, they do not take heat well at all.

The usb port charges the 18650 to about 4v, the same voltage it registers when only plugged into usb. It will not charge the 2s port. It has telemetry! Rssi and car voltage. It does have a multi model memory but does not save trims specific to each one, so that's a pain in the rear. The ct8a does remember trims. So close, yet so far to being 2 cheap, great remotes... Hope I like them because I have 2 more ct6a coming, I certinally prefer them over the stock spektrum and it feels better in my hand then the rc4.

 

[Chapinb]

Had a big day yesterday, running all the rigs pretty much all day. Some new kids, some familiar. Only had a few brakages, granted most rigs are neutered for youngins. Broke some ebay special shocks shafts, a wing ripped out of plastic and one animal of a child broke the limiting plastic for steering on a hotrc remote, so the wheel just spins all way around. Easy fix, but jeeze...
Iv been using these slippers is almost every rig, and they all failed. We have 2 brand arrma slippers that have not yet, but did need adjusting after settling in. The knockoffs had been decent up till this point, not sure if its because I gave a bit more power to the kids or some dew got in there. Had 4 fail in the same way almost back to back. The screw (no spring in these) started to stretch the pot metal threads, loosing the slippers. Not the screw backing out. I spent waaay to much time rebuilding, cleaning and reinstalling these things before figuring out why they were failng after 1 pack.. The screw is only a m2 so cant get much pressure to start with, but its enough to stretch the slipper threads and cause it to loosen up. Iv glued a few, 2 with super glue and 1 with JB weld and they all held up so far but obviously don't slip anymore. Will be replaced eventually. Now looking for budget alternatives. Have a few other styles coming to test and some Jenny stock arrma ones in the meantime. Buyer beware, skip these, even on 2s. The gear itself is decent and true if you just need that however.

Had 1 motor cap come unscrewed. Normally these are thread locked or have a grub screw screw holding it. This had neither. Lil red locker amd tightened back up, good to go.

The 3s brushed granite is still running well. Still not sure if its has lvc for 3s but ran a 3s pack down to 3.4v so guessing not... Will probably change the motor out for a 35t at some point. don't need speed for this rig, but slow and powerful.
Fun fact - a 775 will fit with a little a few mm taken from the chassis and new mounting holes. That might be a future project just for kicks.

 

[Chapinb]

Glued slippers are holding up thus far. It was supost to be a "temp" fix, but iv got little motivation to fix it if it's working.
New, and probably last for awhile, rig came into my hands. A infraction mega, sans esc and motor. Tx/rx included but after 30 min of frustrating binging, one was bad - likely the reason I found it cheap. Threw on some 100mm buggy-ish tires and a brushless kit, and went for a hoon. Drifts super nice but can't handle grass. Dosent jump worth a damn due to the front shovel bumper.

I have a rally build in mind for this. Threw on some random 80mm shocks but realized it didn't gain any clearance. The front hubs and the rear arms/drive shafts prevent it. Do a little dremel work, and fixed! Stock max vs current.

Right side picked up about 3/8" and rear near 1/2".
Since I'm ditching front bumper, I lost my body posts. Changed to regular 3s bulk to get them back, but that means the shocks are too short. Will get regular 3s shocks to replace. f/r Mojave skids and bumpers to keep the sway bars and give some protection. Some sct tires added for some extra clearance, they are about 110mm with a bit off offset, not positive I'll keep them.
Not sure what body to go with, I wanna keep closed wheels but don't want to buy an expensive body. Not even sure what would fit the narrow platform.

Love stock but fenders will need to be hacked some and the sct tires won't tuck in well. Not positive how front bumper will clear either.

There's always the senton body, but I dislike the body in general. I'd narrow the body by 15-25mm if I go this route.

And for fun. Actually like this more then expected.

 

[Chapinb]

In my search for the right wheel, I snagged some copperhead 2 lp. Dropped pinion to 13t on the 3200kv max10. Cut up kraton body was much too wide and rubbed everywhere. Threw on a granite type shell and off to the park!

One of, if not the only mojave width, copperhead running trucks. Clearance is tight tight when under full lock but clears. It's definitely a different animal now. But feels numb, slow. Crazy grip, great wheelies. If I was on a med chassis, would feel like like a larger Granite. I'll keep em on for a bit, but they wont stay on long. Im already missing the nimble, overpowered truck from when I had buggy wheels on. Trying the Tracer truggy wheels (143x60mm but 8oz and very LP) when they arrive to get the feel back while keeping the ground clearance. The esc will thermal if I'm not careful with the coppeheads. Guess it's a good excuse to drop in a proper 4s size/kv motor for better gearing options since I'm bottomed out on pinion size.
Used graphite to lube the rear cvds. Never using this stuff again on them. Huge mess on my bench, on my hands, pants and coated the body while running.

Because I'm cheap and/or lazy in strange ways, Iv reused some of the arrma 23t servo savers on 25t servos. They pressure fit fairly well. Out of the 4 rigs running stock saver/aftermarket servo, all are holding up till today. One has started to strip on a buggy. This one had to be pulled off and reseat, so that might be a partial reason it failed earlier then the others. Has maybe 15 packs before going. Works in a pinch, but guess I gotta stock a handful of Kimbrough savers now.

The 3s mega is still running! About 10 or 12 packs through it thus far. It really is more fun then it has any right to be.

 

[BruceRC]

Awesome thread, man.

 

[Chapinb]

The ex-infraction mega is now officially a rally car. Finished it up and just took it out for a maiden. It's dark, so can only do so much, but initial impressions will be it's a good addition to the stable. Fast, nimble, much more so then anything else iv got.
Used 3s typhon shocks all around, all spacers removed, and she sits level. Rates appear to be in the ballpark, maybe need a tick stiffer. All shocks are a little long, but fully serviceable.
110mm rally tires from ali, soft and I like the tread. Too early to say longevity or dirt grip, but road grip as acceptable.
I wish the body fit better, but the rally is now a strange size, it fits but wish it was lower. 4s Mojave front and rear (trimmed) bumpers. 3670 motor, 2600kv. More testing tomorrow!

Onroad and offroad bulkheads, at least on the front, have different mounting positions. I ziptied it on, shhhh don't tell anyone!

 

[Chapinb]

This mornings project, making a less jankey external resistive discharger for lipos. The current one can be standalone amd has adjustable lvc or with my charger, but its been through so many changes over the years, I thought it time for an update.
The og that has served me for near a decade discharging everything from 1s to 20s.

New version is a bit simpler. Some resistors, a fan and a heatsink. 4x 2ohm resistors in paralell for 0.5ohm load.

Is stable at 100w discharge, probably 125w but gets hotter then I'd like.
For giggles, I also tried a 12v car window defroster. The charger limits it to 130w, but it should be stable at 150w at least. Guessing the charger does some math and limits it based on resistance? In any case, it makes for a nice plug and play option for thoes who don't wanna make their own.

In any case, iv got almost 400w of discharge ability between the 3 dischargers when used on both channels of the charger.
What I don't understand is that if I connect all 3 to a single port, the charger limits it to about 100 watts. The manual does reccomend 1ohm for the resistor load and the 3 together are about 0.2ohm.

 

[Chapinb]

Built a ramp a lil bit ago, great kick. But its heavy, large, hard to store or transport. It's literally strong enough to support a car - I used mine to bend the ply into shape.

Saw a folding ramp somewhere on the forum and decided to try my hand. Started with 2 sheets of 5.5mm 2x2' squares and shaped them into a ramp shape with water and ratchet straps. Let dry, and they hold their shape.

Glued and screwed together till the glue was dry, then got to work on the supports.
Folded, lowest position, highest position and underside. Can go anywhere in between as well. I ain't no finish carpenter, so she not that pretty. But functional and allows the ugly old ramp to be removed from the front yard as per better halfs requirement.