Mojave 8s Mojave EXB build

[calebgilmore]

@The_Otherside Wow. Just stunned at how the truck shrugs off anything you throw at it. Definitely harder then I plan to bash haha. I think it's a good call on just running a bigger pinion and dialling the power back. I'll probably get a 30-32 tooth. 1650kv is a little hot for 8s, and redlining at 100% full tilt. So it should be happy with 8s volts, but lower power output right?

@Jerold Yeah I've read a lot about people preaching their method, but they all seem pretty centered around the tape then goo, so that's what I went with. The flex seal spin was more for the factory finish look with the tape and goo underneath. I'll make sure to snag a seal spreader from work tonight too, good call on that one.

@calebgilmore I hear a lot of people using grp tires, and the 1/5 for the Mojave a bit too. But are they more for speed running? Or do you just need them for general street bashing on a larger scale with more power? Those 1/8s would look a little small haha. How long is the wear on them? I guess I could bite the bullet on a few pairs if they last longer then a couple sessions. My slash was 2wd so it wasn't so bad to just need rear tires most of the time.

I got my shocks rebuilt with the 1.4 pistons and 90wt on all four, as well as the stiffest springs arrma sells for the Mojave specifically and boots for the shafts. Took about half the 2oz bottle to do all four. Still need to install the stiffer sway bars, but I didn't really notice much difference in spring rate after reinstalling the shocks. How hard does your guy's chassis slap the ground when you land? I couldn't go over about 2 feet without slapping but I feel that's asking too much of the chassis, and even the parts holding the high dollar pieces, watching these videos jump 15-20 feet up. How far can you tune suspension to drive well but still take mild (3-5 foot high) running jumps?View attachment 202818

I'd guess you'd get a decent amount of life out of them. They are pretty thick. I don't expect the same for my infracton running that combo though hahahaha. I'd just guess with off road tires on road you'd end up with bald tires with a quickness.

 

[UPPERDECKER]

@calebgilmore I'm definitely keeping those grp 1/5's on my mind. I'm just having a hard time getting over the whole square adapter thing. I'd hate to turn up not liking them and then not having any use for the squares, and at those prices..

Shoe goo session went semi successful. Decided to put some more tape down before starting. Masked off the top of the body too, figured I'd need it later and it made doing the edges easier. Probably about 93% of the tape stayed in place while working it. Some was fixed, some came up, not sure how to handle it. Still have about a half a tube of goo. I'll try using the last of it to keep the rest of it down and throw excess where it'll fit. I'm assuming I can't go back to hot glue at this point, but if it gets too bad I'll just trim what's not staying down and the flex seal should leave a nice finish. Had an air purifier on blast next to me and didn't notice the fumes that much. Took about a tube and a half and about 3 hours starting with it taped.

 

[calebgilmore]

@calebgilmore I'm definitely keeping those grp 1/5's on my mind. I'm just having a hard time getting over the whole square adapter thing. I'd hate to turn up not liking them and then not having any use for the squares, and at those prices..

Shoe goo session went semi successful. Decided to put some more tape down before starting. Masked off the top of the body too, figured I'd need it later and it made doing the edges easier. Probably about 93% of the tape stayed in place while working it. Some was fixed, some came up, not sure how to handle it. Still have about a half a tube of goo. I'll try using the last of it to keep the rest of it down and throw excess where it'll fit. I'm assuming I can't go back to hot glue at this point, but if it gets too bad I'll just trim what's not staying down and the flex seal should leave a nice finish. Had an air purifier on blast next to me and didn't notice the fumes that much. Took about a tube and a half and about 3 hours starting with it taped.View attachment 202841View attachment 202842View attachment 202843

Yeah i actually pulled mine off this week and put some 1/6 hyrax on the build instead hahahaha. I don't remember what they cost now but i have 2 sets of 1/5 grp's and these adapters if you'd be interested. I have the big and little infractions now, and a 4s/6s lightning mcqueen builds, and an on road typhon so i won't be driving this beast on the road anymore. If these tires don't hold up it'll get 6s outcast tires.

 

[UPPERDECKER]

@calebgilmore Oh wow that might be my ticket into grp's haha. How used are they? Still early in the build to be pulling that trigger though. If these bandito 2.8s don't work out I'll probably hit you up. Shoot me a message so I can come back after this rig can breathe. Let me know how those hyrax hold up too, I see crawlers with them on 2.2's so it feels weird to me seeing them in 1/6 haha.

 

[calebgilmore]

@calebgilmore Oh wow that might be my ticket into grp's haha. How used are they? Still early in the build to be pulling that trigger though. If these bandito 2.8s don't work out I'll probably hit you up. Shoot me a message so I can come back after this rig can breathe. Let me know how those hyrax hold up too, I see crawlers with them on 2.2's so it feels weird to me seeing them in 1/6 haha.

Yeah i run them on my mojaves and udrs so we'll see how these bigger ones do. They are for the Super Rock Rey and it's 8s but not geared this absurd. Ordered an 8s kraton wing to put on the back because i know this wing will get shredded when they balloon. You can see the ones in the pics above that i used and the others are brand new. I'll add a pic to this.

 

[UPPERDECKER]

Okay guys, wow lots to unpack on this one.
Just finished putting the diffs back together. Part of me wanted to run it as is, but I knew that I would just be beating myself for not tuning it before hand.
Started with the center diff, knowing that was going to be the slowest at 500k. I gave that time to settle between steps while doing the other 2 at 30k, like water compared to 500k haha. Factory setting was LSDx3, and this was the fluid level before the rebuild. (seems low?)

Moving on with the front diff, the diff had about the same amount of fluid as the center, but it did have adequate ring/pinion grease (smeared the excess for better coverage). Again LSDx3 up here.

Now finally the rear. After taking it out this was the fluid level.

And this is where things get weird. Taking it apart to clean out like the other two diffs (NAPHTHA for the win?), I noticed there was one of the three LSD plates missing, the circular one, from both sides behind each sun gear. Having some forward thinking I had purchased some spare LSD plates and gaskets with the notion that those are going to be the wear parts over the gears themselves, barring catastrophic failure.

Well after putting in the circular plates that were missing and putting it all back together, it was incredibly hard to turn, severely notchy when turning with drivers. Rebuilt it twice with same results. Turned to the internet for answers (mostly Arrma forum), and it sounds like its a common scenario with the EXB models. I wasn't quite sure how to tackle the problem, If I shimmed the interior gears, it would only promote less tolerance/more notch. I decided to call it a night at 3 am, but not without looking for more answers.

I got up this morning determined. I could not let this go to waste. Got back downstairs headfirst.
Couple more rebuilds and making doubly sure the plates were oriented in the right direction, same results.
Que brainstorm math formula gif.
What seemed to be happening was that when I ran down the four bolts holding the ring gear to the diff case, it was compressing the sun gears into the other gears and ruining the mesh. After backing them out until mesh was well enough, the bearings would then not fit into the diff housing, even with no shims. This led to the thought, how do I shim behind the sun gear without effecting the mesh, and allow proper torque of the ring gear bolts? I guess it took a nights rest for a more clear mind. Came to the conclusion, you could put another gasket in. Now I'm not sure how stacking gaskets will affect performance or longevity, but the mesh is spot on now. Anyone have any thoughts on this?

Diffs going back together.

The completed diffs, all LSDx3, and showing the circular LSD plate that was missing. (from spares)

 

[The_Otherside]

Yeah man... had aaaallll those same issues.... lol.

I know exactly what you're going through.

 

[UPPERDECKER]

Alright I've been away from the truck for a little bit. Had some time to put down some coats of flex seal on the body though so that's almost ready for trimming. The flex seal is a lot softer then I had anticipated, so it will likely rub off in the wheel wheels, along with anywhere else it's making contact. Oh well, I like the look a lot better then seeing the tape everywhere haha.

I've been looking at a few other builds around here, I forgot who's it was, but I noticed the battery tray can be relocated rearward. This allowed enough room to mount the xlx2 right in front of the battery. It's tight but totally fits and leaves plenty of room to swap spots with the receiver box. This also left me just shy of clearing the chassis side gaurds with the battery. I only needed to take out a little bit to make the battery sit flush so I had no problem deciding to make the cut.

So finally having a safe spot for everything gave me a pretty good feeling to drive on with the power train. I had to cut some bolts to mount the motor, castle states not to exceed 5mm into the motor so I cut just short at about ~4mm passed the mount plate. Looking at the range on the mesh slider, I won't be able to go over 24 or so teeth on the pinion. I threw in the largest of the pinion set I have at 22 teeth, should be plenty for easing into it, especially on 8s, though I'll probably have the power dialed down on the aux channel untill the whole truck checks out.

Also decided to throw the motor fans on since the motor is now permanent installed. I really like these but I'm not into the gold so I'll probably change out to normal silver bolts or order some black ones.

M2c +2mm hexes we're a quick and easy install too. The double nut sticks out quite a bit but that's fine for the added security. Kind of bummed to find arrma updated the hexes when they updated the wheel design, so now these are only +1mm, and at that price, oof. I'll include these measurements if anyone's looking

I still have a lot of work to do. I'm really excited to get the xlx2 mounted though and fire it up.

 

[The_Otherside]

Sucks I know, but you absolutely need those hexes.

 

[MambaSenton]

Coming along!

 

[UPPERDECKER]

@The_Otherside yeah, I definitely see the hexes as a must have insurance, even the cost of the hexes was less then that of a new pair of tires/wheels. The double nut is just full coverage.

I stayed up a little late last night and did a little soldering. I really like working with these ec8 plugs. I just use a torch to heat up the terminal enough to melt the solder when it contacts the metal, and fill untill it comes out with the wire, top it off with dielectric, and heat the shrink. It was a little tight with the bec leads in with the esc, but super solid connection with a factory finish.

This is my solder station. It ain't pretty but it does the job.

One of the obstacles was finding a way to secure the esc flush with the chassis. It fits in the pocket on the chassis but rides on one of the bolts fastening the side gaurds. I always just use double sided tape for securing esc's and rx boxes, so I just stacked 6 strips. This stuff is incredibly strong, very stretchy and super easy to work with. https://www.amazon.com/dp/B08JTYFFN...t_i_E73H6V8KQ0E8G66RZ31A?_encoding=UTF8&psc=1

I did a bunch of wiring after mounting the esc, bec, and rx box before work today. Feeling pretty good about the chassis layout. I'm a little worried about the center front driveshaft contacting any wires going into the rx box, but I haven't fastened any of them yet. Don't mind the spaghetti.

Also had to change the blue motor wires to red, it just wasn't right. Before and after.

Hooked up the esc and bec to the b link and got the power settings dialed in. It moves under its own power now.
One thing that came up was that the castle sensor wire wasn't long enough. I was already using the longest one they have at 300mm and it doesn't look like there's any way to extend it. Not any way to plug n play at least. I'll end up making one later after a few test runs. It doesn't cog too bad without it, it seems.

 

[UPPERDECKER]

Alright, after multiple days and multiple coats, the body is 'done'. I mostly just don't want to deal with it anymore. I'll see how the flex seal holds up and I'll probably go over it again later down the road to completely hide the tape. Trimming wasn't too bad but the windows put up a decent fight.

This was after 3 coats/2 cans of flex seal. It really got a bit more durable after it fully cured. It felt like I was cutting leather.

I put the body trim on right after cutting all the excess off. It's really helping keeping the added protection from peeling off the edges too. I'm loving it. I'm a sucker for fender flares too so I was sold.

I used a 10 foot roll and ended up with a little over a foot left. Even managed to get a near perfect join right in the middle on the back.

 

[UPPERDECKER]

Okay so this will be my last update, everything on the spec sheet is checked off except the windshield and horn, not doing any weights, but I'll work those out in the summer time. I'm calling this build complete. The truck is a little over 16 lbs loaded rtr.
So all that's left was the lighting. I couldn't find anything that would look nice enough, and not well over a hundred bucks. All the light kits that came with taillights were incredibly overpriced or not for larger then 1/10 scale, so I decided to just forgo rear lights and build custom.

I knew I wanted bright so I was looking for more than 6v. This light bar claims up to 8.4v but came with a button switch module in line with the power lead. I already have a power switch so I cut that one off and soldered on a regular rx lead so I can daisy into my other lights before the switch. https://www.amazon.com/dp/B089MB2BT..._dl_EJD4WK9YVKG807A5W5S9?_encoding=UTF8&psc=1

Then I threw some cannons on the roll cage and some red inside the interior. I was going for more red under the car but couldn't get it passed the fenders. I'm still really happy with it though. They all run off the rx with the fans at 7.5v

All the wiring stays clean bundled together under the body, all goes to one line to a switch in the rx box and made it a quick disconnect to reach through the windshield

I took it for a run at the park today. Wow. What a savage animal. It really throws the weight around which I love to work with. It lays down rubber tracks at half power output and it swings corners like a dream. I don't plan to send it off any jumps, that's not what I built it for anyway, so I don't see any breakage in the future. I get plenty more satisfaction just from using the suspension and traction to push the limit on precision handling. The weight really adds to that, and the power is seemingly unlimited.
Thank you all for reading along, and with all the helpful tips and advice. I'll try to get some video soon.

 

[UPPERDECKER]

Alright I think the build is now truly complete, and the only thing I see changing going forward from here is just springs, droop, and tires, from off road setting to on road setting. I have it set up for on road now, and probably will for awhile after drifting this thing around.

This was the aftermath of the final shakedown. The Mojave was tested that day. It made it's way home under its own power but not without some odd sounds. Sounded like a purr that was rotating, if that makes sense(later upon teardown, come to find my pinion screw took a hike).

And this was after only one round of simple green. Honestly I can not recommend this stuff enough for cleaning. Spray on, sit for 3ish minutes, hose off. Normal all purpose stuff, nothing fancy.

This is the face I cut out of the mesh for the fans. It has completed eliminated any potential heat staying inside the mesh, and the motor quickly cools even after pushing it hard with the drifting, without having to take the body off and open it up.

I was having some issues keeping the center diff in check. I would always hear an unpleasant misalignment of gears under heavy throttle. It took awhile to completely solve it but after isolating the diff in rigid aluminum, no noise or shavings to be found anywhere.

On a quest to get rid of steering slop I went looking for Mojave steering arms and found nothing aluminum. Tried some for the Kraton, but were too long so I ended up using them for rear camber arms. Also during teardown I found that my sway bar links popped the plastic in half, rendering it useless. So next on the list was some aluminum sway bar links. Was really getting into the red color scheme at this point.

Still on the quest against slop, I opted for some Felony steering arms this time. Although shorter than the stock Mojave arms, they have enough threads to grab securely. Threw on some loctite just for good measure.
While I was at it I got the steering rod for the servo. Cheap, aluminum, red, throw it in the cart.

While doing some reading to rid the slop, and having my bellcrank already apart, I came across a thread about converting the bellcrank bushings to bearings. Took me awhile to understand what they were going on about, but I knew that bushings would wear out eventually, so I was on the case. Fortunately they had pictures provided for help, and these are what came out of mine. Bearings now installed in place and steering is butter smooth, and the servo returns to true center position every time.

One more with the top down.

I just really like this angle for some reason. After changing front and rear diffs to 100k, putting 38lbs/in springs all the way around, swapping shock pistons to 1.2, setting proper droop, (my springs aren't preloaded, they are resting at the collars under max unload) and lowering the body, I am EXTREMELY happy with the way this thing turned out. It's an absolute powerhouse, and nails drifts like it's on tv.

All buttoned (zipped) up ready for charge.

Here's my revised spec sheet if anyone's curious.

***POWER***

CASTLE 1717 1650kv
CASTLE MAMBA XLX2
CASTLE BEC 2.0 WP (7.5v)
SAVOX 2210SG-BE (BEC)
FLYSKY GT5/BS6
ZEEE 4s 9000mah x2 (8s)
ZEEE 2s 8200mah x4 (8s)
19 TOOTH PINION
100K/500K/100K F/C/R LSD MAX DIFFS


***SUSPENSION***

SHOCK OIL 90w (1.2mm pistons)
SWAY BAR FRONT/REAR (2.9mm)

--SPRINGS--

35mm 38 lbs/in (FRONT ON ROAD)
40mm 38 lbs/in (REAR ON ROAD)
60mm 9.7 lbs/in
65mm 23.5 lbs/in (FRONT OFF ROAD)
70mm 7.7 lbs/in
70mm 8.6 lbs/in
85mm 6.9 lbs/in (REAR OFF ROAD)
95mm 5 lbs/in
110mm 3.6 lbs/in
110mm 3.2 lbs/in


***CHASSIS***

TAPE/GOO/SEAL BODY
BODY EDGE PROTECTION TRIM
BODY POST FOAM SUPPORT
BELLCRANK BEARING CONVERSION
BATTERY/ESC/RX RELOCATE
DUAL TRAY BATTERY HOLDER
DUAL FAN MOTOR COOLER MOUNT
DUAL 12v SERVER FANS
DUSTY MOTORS XXXL SHROUD
CUSTOM CUT SHROUD FAN FITTING
SCORCHED FENDERS
SCORCHED REAR AXLE GAURDS
M2C 2mm EXTENDED WHEEL HEX
TEKNO RC DROOP SCREWS
SHOCK BOOTS FRONT/REAR
ALUMINUM SERVO MOUNT FRAME
ALUMINUM STEERING ROD
ALUMINUM STEERING ARMS
ALUMINUM CAMBER ARMS
ALUMINUM CENTER DIFF MOUNT TOP/BOTTOM
ALUMINUM SWAY BAR LINKS

 

[MambaSenton]

Sounds like you achieved your goal!

Rig looks good

what speeds are you seeing with the 19t? Are you stock spur? I thought that might be under geared?

 

[UPPERDECKER]

@MambaSenton Thanks man. Yes, goal achieved. It's a great feeling having completed build, and have it be what you wanted and more. Though I am going to miss the build process, I enjoy it just as much as driving and can easily sink hours into it.
I ran my gear through a speed calculator and it came up with ~77mph full tilt. I never get to use it though, I find myself staying around 40% power output. Yup, stock 50t center. I thought it might be under geared too but I haven't needed more yet, still have plenty of power on the dial to go. The motor does get hot after longer hard runs too so I'm not sure I'd go bigger pinion.

 

[MambaSenton]

Right on man I hear you, the mexb was my first roller was a fun process getting closer n closer to the end goal was exciting. Than the first run oh the joyyy

That’s good to hear I’ve played with the gearing a little with 25/46(6S) it scoots but I think it’s a little to much, may drop to a 23 or even lower.

Where did you get your springs? Could definitely use Some myself

 

[UPPERDECKER]

@MambaSenton Oh dang that's some aggressive gearing. Compared to mine at least. Is the motor happy? How's your esc temps?
I always see people running close to 1:1 gearing on 8s but I guess I might be asking a little too much from the 1717, though my esc fan never even kicks on.
I got my springs from amain. I knew that the 1/7 road cars shared some springs so I went to the arrma parts cross reference page and looked for the stiffest springs they offer for them. 35mm ARA330631, 40mm ARA330599. I love them. They give the truck that super scale suspension when going over bumps at speed and keeps handling extra crispy.

 

[MambaSenton]

Motor is a tp4070 I’ve had the rig out 4x since built no over heating issues but it’s still early for weather/heat.

I’m sure if I ran all out in the next month or two like I do now I’ll have some heat issues with that gearing, have a decent fan set up time will tell

Thanks for those PN’s too! Will deff be looking into those

 

[Jerold]

Awesome. I like the details.