95PGTTech 1/10 2WD ECX Ruckus build

[95PGTTech]

bent ANOTHER hot racing bellcrank arm, same spot. zero help from HR again. straightened it out, removed the anodizing chemically/mechanically, and sent it off to have my friend TIG weld it.

Went to traxxas arms PN 3741x, the ends are now not all metal and the rods are much beefier. I got a set of RPM rod ends for them too. Much less play as people advised. Ordered 2 kits covered all 6 arms and left me some extra. Finally shortened some wires and soldered on new connectors. went to the large (thick) aluminum hubs front and rear

 

[95PGTTech]

Ended up replacing all the wheel bearings with those sealed metal ones. At least one FastEddy bearing in each hub was bad already grinding as it went around. We will see how these hold up. Finally found a 16mm washer to get as big as the wheels would allow. Still had to drill out the center to 4mm to make it work, but now there is so little play in the wheels with all the upgrades compared to stock.

Put RPM bellcrank in it for now while waiting on my arm to get mailed back. We did a new best 47mph considering the grass is that high we are pretty happy with it. It's certainly faster than the dogs now.

Chasing down an issue. The new 2S 100C batteries (both) have a really short run time. Like two minutes. Some of it I'm sure is running the lights and the drag brake, but I took a look at the alarm and it's showing like a .5V difference between the two cells. I have one of those balance chargers that charges it through the balance port, they don't sit for a long time, I charged them right out of the box before using. So I got a "real" charger and we have been trying to discharge and recharge at a very slow rate to get them to balance like the youtube videos. I think we are .3V apart now. I think part of the runtime issue is the ESC sees the lower cell which is probably only starting at 3.75 or so to start and hitting the LVC. We also got a 21tooth pinion to try.

 

[95PGTTech]

It is a MONSTER on 3s. I can’t imagine this thing once it’s dialed in on the big motor and geared. Probably lost 5kph easily due to grass/terrain and wet

Overall it’s actually slower than 2S. 40kph give or take on average runs because it power wheelies even rolling into the throttle and softened through ESC and controller settings. If you let out and let the front end come back down and roll back into it, it goes right back up. If you aren’t completely straight on the hit, it wheelies and tumbles sometimes pretty violently.

 

[95PGTTech]

Well, the inevitable happened. 3 year old with a 50mph capable missile eventually outran his talent. Speed brakes weren’t speedy enough and took it into a metal guard rail at GPS says 40kph.

Chassis is fine. I actually have that lower block from another package I ordered for wheel hexes but I need to order bumper LCAs and pins. The GPS was mounted to the front bumper and hit the 3d printed case directly. I messaged the seller on eBay and ordered another, the GPS doesn’t have a scratch on it.

 

[WithinU]

Ouch!

 

[95PGTTech]

Hot Racing lower suspension mount arrived. Got it and the RPM arms installed. Waiting on hinge pins and front bumper to arrive from Horizon Hobby. It’s all back together otherwise, and put the crappy stock tires back on. I’d rather be spinning them than wheelie/tumble machine. Got spares?

Here’s our 4WD thread
https://www.ecxforum.com/threads/1-10-4wd-build.3326/

As disappointed as I am in how I underestimated the lack of aftermarket/replacement parts for it so bad (and my complete hatred for Hot Racing), we did learn that for sure we should be in a 4wd monster truck chassis for what we do with RCs

 

[95PGTTech]

Pin set and new front bumper installed. Back to running just fine. Figured out the best combo is the 2s battery with the stock tires on the front and the badlands on the back. With all 4 stock tires it’s just a donut machine and not fun to drive. With all 4 prolines it grip rolls every turn. Even now it power wheelies but it’s liveable. On 3s it can’t apply any of the power, ever.

If we hadnt moved to the 4wd, we could probably do some more with this - shocks, aluminum shock towers, wheelie bar, front weights, play with alignment. We will probably just keep it as a backup toy for the days we are servicing the other truck. Eventually I’ll move the esc and motor out of this one and put the 10BL120 and goolrc 4300kv into it and sell it. It really isn’t even useful as a parts truck, the 2wd and 4wd are nearly completely different in all parts.

 

[95PGTTech]

Punch 1 (minimum setting)
Wheelies from a dig and floats the front end/sometimes power wheelies but very controllable.

 

[95PGTTech]

Honestly, I’m surprised it took this long to break a stock axle. We are still on stock internal trans gears too

 

[95PGTTech]

Did some disassembling, measuring, and test fitting to mount the Traxxas wheelie bar. Detailed How To thread here:

https://www.ecxforum.com/threads/how-to-2wd-wheelie-bar.3333/

Installed the Tazer ESC and 3300kV motor (stock stuff from the brushless 4x4) as we begin to get this one final sorted out and prepared to sell. Got all the wires soldered and organized, going to keep this on 2S 50C batteries I have sitting around. Zero point in giving this thing a bunch of power it can't put to the ground. Doing a wheelie and donuts is fun for all of about 5 minutes but really takes the fun out of driving when it does NOTHING BUT wheelies and donuts. Especially when your driver is 3. Current gearing is 48P 21/87. Motor stays ~ 170F measured infared. I'm sure it would be even cooler if our terrain wasn't predominantly tall grass. Replaced the right rear wheel bearings again. Can't really figure out what happened, possibly a casualty of the axle going south.

 

[95PGTTech]

Wheelie bar disassembling, measuring, figuring out, etc. I posted some videos of it at work in the wheelie bar thread.

 

[95PGTTech]

Axle came in. Kinda impressed, actually. It allows use of the stock inner pin. I had to drill my Hot Racing wheel hexes out (5mm) to eliminate the outside shoulder. I guess I didn't get a pic, but it also required me to run A LOT more spacers between the outer wheel bearing and the axle/hex pin to eliminate the inner/outer freeplay of the axle (due to this axles pin hole being drilled much more outboard, same reason I had to drill out the hex). I didn't count specifically, but I went from two 0.1mm thick shims to probably 20+. Nothing terribly concerning, everything still ended up fitting nice and tight with the hex on there, just something I will probably want to go back, measure, and replace with fewer, thicker shims to make servicing easier in the future. If these axles were made specifically for this model, I wouldn't be very happy with all the customization needing to be done but I'm glad there is something available other than "better plastic." I left the stock left rear axle in it for now, but after running the truck a few times I have zero qualms about this axle ever breaking.

 

[95PGTTech]

Had the wheels off, this is what I meant about the shims. Stock axle on left with two 5mm x 0.1mm shims between the outer wheel bearing and the pin. New axle on right with 15-20 to get the same. Have about 0.1-0.2 end play (inward and outward movement of the axle). I'm afraid any tighter would tend to side load the wheel bearings. If they were tapered roller bearings like on a car, I'd definetely shoot for zero

 

[95PGTTech]

Fancy schmancy new wheels for the wheelie bar...I was looking for a little bigger diameter to effectively get more antiwheelie plus a rubber tire to (hopefully) do a small amount of dampening so it doesn't hit the bars so hard and upset the suspension. Traxxas 5186. Also upgrades it to ball bearings. The 0.5mm washers/spacers arrived so I don't have to run 22 or whatever the absurd number of shims was, haven't got them in yet.

Weather was bad, so bored I tossed the other axle in and the RPM rear A-arms. That was far more involved a job than I thought it would be motor/trans/rear shock tower all needed to come out. Next day take it to the park - his soccer practice got cancelled due to heat so I know of a park in a lot of shade where we can do swings and maybe run it on a different surface. Fire it up and click-click-click. Steering but no forward movement, ESC wires getting hot. Messed with it a little and with no obvious failure, just put it away before hurting something. Good thing I did, get home and try to rotate it over with the 7mm on the slipper clutch and motor/trans is completely locked. Removed the motor, it's fine. Trans is locked solid. WTF.

Take it apart, don't really find a smoking gun. All bearings look/feel decent. One of the 10x15x4 diff ones was iffy. With the case split, rotate the assembly is pretty okay but binds in one spot every time around (if watching the main big diff gear). No wear on the teeth. No chunks missing anywhere. Its definetely something with the big one, with just the two littles it rotates fine. There is a very faint mark on the inside of the case. My only guess is I ran a screw too far into the bottom of the trans and it bound up the big diff gear when I reinstalled during the rear LCA job. Ordered up everything new, case, fasteddy bearings, metal gears. I've had this thing apart and back together ten times and can't find a "smoking gun." In the meantime I'm going to see if I can clean up the tiny mark in this case with an xacto and see if I can get this going again as a backup. The ring gear on the diff has a little bit of runout, but who knows what the original tolerances were of gears like this made out of plastic. I don't know everything there is to know, but it's not often I get stumped mechanically.

Oh...and one of the axle allen bolts rounded off, in the new metal axle. That was a fun few hours drilling that tiny thing out. Those will be one time use from now on.

 

[95PGTTech]

Had some time to do some more digging around and cleaning. Trimmed out those very small protrusions into the trans case with an exacto - couldn’t even get pics, we are talking less than 1/16”.

Once getting everything really clean I could spot the impending failure of the input shaft gear - the pin is fine but you can see where the plastic gear is beginning to deform. For diagnostic purposes I cleaned it all up, packed the diff and the inside of the trans with waterproof wheel bearing grease, and put new bearings throughout. Reinstalled, much better. I must have just installed screws that were too long and they punctured the case and locked the diff gear.



I still need to wait on the axle pins and slipper clutch to road test it, and a metal gear set is on the way was well as a new case. I basically ordered enough stuff to build an all metal trans and have a stock parts stuff one as a backup. HR no longer makes their locker which leaves me with a few thoughts to solve the open differential problems - 30000 diff fluid, chemically weld the diff (JB weld, etc), directly weld the spider gears, or put an entirely different diff in it so I can use an aftermarket locker. I ordered the fluid as it’s the non permanent option. I also ordered a SMT10 all metal aftermarket transmission, Amazon had it on Prime. I’m going to see how it looks and feels in person versus the metal gearset of the stock trans.

 

[95PGTTech]

Put RCAWD front shock tower and lower control arms on to try and get some weight on this front end (and stop supporting H-R). The inner control arm pin mount is so sloppy for two machined parts. I can’t believe the RC world accepts tolerances like this, on a bike or my racecar Id lose my damn mind. I may just end up putting the RPM arms back on it. Looking into some brass wheel hexes. Anyone have any other front end weight tricks (preferably low) before I just build a damn weight bar?



James thought shaking my Monster would be funny. This is the thanks I get.



Playing around with the stock shocks (with 40wt and now aluminum parts) and the stock 4wd shocks.

Did a lot of cleaning up of our workspace you know how it gets with multiple projects. Mounted a fan to the ESC and while googling to find the right connector to plug into the diag port on Google found out dynamite makes a plug in fan unit. LOL.

 

[95PGTTech]

Shock rebuilding. Have some stock ones off the 4wd mind as well while I’m at it. Took a screenshot of the Tazer ESC parameters just in case I think about bumping up the motor again. I did end up ordering that fan. Old transmission out, new Axial one in. Fairly bolt in affair. Refined my wheelie bar mount just a little again.

Not my original idea, here’s the link for credit:

It’s a locker trans. For what we do, that’s a plus not a minus. I’m building a spare stock trans with heavy diff gear fluid to try and get as close to a LSD as possible as a backup. I need to fabricate a wheelie bar to trans mount and a trans to shock tower mount (I will not be doing what he did in the video).

The unit is awesome (on the bench anyway) for the price. Here’s a video:

 

[95PGTTech]

Rebuilding shocks. Put 40wt in the 4wd ones, added RCAWD components to the stock 2WD ones (caps perches bottom heim etc). They don’t make anything for the 4WD ones but I was able to press Traxxas metal balls into them and I’m searching for a generic spring perch and a M3 rod end.

Shaved some of the stock upper trans mount to get it to fit and replaced the stock screws with longer ones. I think I may just remake this mount entirely. Drilled a hole in the fancy red trans cover so I can adjust the slipper externally. I’m looking for a rubber plug.

Looking at the new trans case, those screw holes do not go all the way through. So the original cause of the locked up powertrain was me installing too long hardware back in when I did the RPM rear arms.

I was originally going to leave the rear shock tower stock, went aluminum on the front trying to get weight up there, but having to make my own motor/trans to shock tower mount I wanted the tower as rigid as possible to start. I didn’t really like all the red up front and found this silver option from RCAWD.

 

[95PGTTech]

Silver front tower installed (had to get the matching pair, duh!). RPM arms back on. So much less slop at the pin. Not perfect, some of it seems to be the H-R lower suspension block as bench testing RPM arms to a new OEM lower block is tighter. But that block just offers me too much weight gain so low in the chassis. I am not a huge fan of aluminum arms anyway, I want something able to bend/break. I have brass wheel hex on the way for the front and worst case I’ll fabricate a weight bar for it.

4wd shocks ready to go they are 105mm like the stock 2wd rear but the shock is quite a bit stiffer with the same preload spacer and slightly larger diameter. At full extension, it binds the steering and bends the bell crank slightly (now that I have the RPM plastic unit in there not the H-R aluminum). But the 90mm stock 2wd front leaves some suspension travel on the table.

 

[95PGTTech]

Front suspension is in except for the shocks. I’ve decided on the 4wd stuff for now, but I want to take between 5 and 10mm of travel out of them to get them to the 95-100mm range. I want as much suspension travel as possible without binding the steering. I have lower perches and metal rod ends coming so I want to wait to get those on first, it may make them a little longer. I’m trying to take advantage of this sets greater spring rate and rebound/compression in conjunction with the less in the rear to try and promote proper weight transfer on takeoff. Added stainless hardware. Rear suspension is done except for shock tower to trans mount. Both need to be aligned.

Had some spare time so put together the spare trans in case I don’t like the Axial locker. New case, all new Fast Eddy bearings, metal gear set, 30k in the diff and waterproof wheel bearing grease in the main trans, stainless hardware, new slipper, HR steel 48p 87t spur. Basically a brand new trans other than the input shaft, the pin, and the shaft for the center idler gear. It’s probably going to remain an expensive ornament inside our parts bin, LOL. Some sick part of me wants to put some big power and big traction to this and see what the limiting factor of it is, like a 3674 on 4S or see if you could cram a 42 series in there many can go 6S. What’s gonna give first? My money would be the metal gears and pins exert too hard on the plastic case and split/slot it. Maybe the 2 mount holes for the motor aren’t enough and the pinion to spur mesh grows under power and eats a gear.