My second electric rig, stampede 4x4 vxl

[olds97_lss]

After having a brushless revo for a month or so, I find I really like the quiet running and plug in and go bashing. Not to mention the amount of torque. So, figured I'd try out another rig.

I've wanted a nitro stampede for a long time, but the 2wd and single speed trans always kept me from pulling the trigger. After watching a ton of vids on youtube, and after getting the ERBE, I decided to get a stampede 4x4 vxl.

I almost went to a LHS a few weeks ago while out to lunch with my wife and bought one new, but I had bid the night before on one on ebay and it wasn't to end until the next day, which I then lost. Then instead of going and buying new, I bid on a couple more. Then I won one. Unfortunately, it wasn't nearly as good as the first one I lost. Photo's looked ok, but they must have used a fuzzy filter or something because when I got it, it was not worth what I paid.

All 4 corners were seriously sloppy, the front right had blow a bearing out completely. All 4 axles were/are worn to the point of nearly failure, the tires were so out of balance I couldn't even drive it anyway. The included lipo had all 3 of the balance wires broken so it wouldn't take a charge.

So, after inspecting it and ordering a list of parts I'm now waiting for, I threw on a set of 14mm t-maxx hubs (that don't really fit right) and slayer wheels/tires I had laying around and cutting/resoldering the balance wires just so I could run a pack through it. Man... is it slow. I figured the slayer wheels/tires were a bit smaller so it felt slow due to that. FYI, slayer wheels rub on the front c-hub when turning. The kid included a 17T pinion with it, so I installed that and it was faster, but still seriously slow off the line. Regardless, I had fun with it at the skate park and decided to just make the best of it. The 5200mah lipo that came with it only took 3200mah charge after running it until the LVC kicked in, so guessing it's just a junk lipo.

Then I read the manual more thoroughly about the speed control to make sure it was setup to have the LVC enabled and also noticed there were 3 profiles... sport, race, training. I turned on the LVC (it was already on, but was making sure), then set the profile to sport. Took it outside to find that the lipo it came with couldn't handle the amount of power it wanted... and it was fast. Like, seriously get into trouble fast. So, I aparrently had been driving it with the ESC in training mode. I put the 11T pinion back in and may take it out for a bit of a run after work. Then after I get all my parts this week, it should be good to go.


I have the following in the mail to me now:
2 x 7200mah 2S 90C SMC lipo's
RPM front carriers/c-hubs
RPM rear carriers
4 new stock slider axles
4 new chevron style tread stampede 3.8 4x4 (non-vxl) wheels/tires (I like the tread pattern on my other MT's)
14T pinion (probably unnecessary now)
4 12mm alloy wheel hex's
new fast eddy bearings for the diffs, all 4 hubs, steering and center shaft

From what I've read (and what I see on the truck), the stock sliders won't hold up very well. I'm hoping the new ones hold up a while.

Spent $300 shipped on the truck and $130 on parts. Buying new locally with tax would have been near $520, so I'm $90 short of that. I totally should have just bought new.

As it sits now.

Slayer tires rub here:

 

[hamz9561]

Brushless is addictive. Love the mERV. It's the 1/16 version of your ERBE. All of my electrics are brushless and i won't go back to brushed if I have choice.

 

[bifft it]

awesome

 

[HPIguy]

I have the 2WD version, and have had a ton of fun with it. Need to dig it out and fix it from the last high speed wheelie crash LOL. And I'm with hamz, the instant torque at almost any speed of brushless and lipo is so addictive.

 

[bifft it]

I also had a 2wd version.
Ratty kids fried the motor the first time they played with it.
Traxxas warrantied it and sent me 2 motors. then it sat in the shed for a long time untill i sold it a few week ago

 

[grgbulldog]

My friend had a brushed stampede back in the day. Fun little truck.

It still surprises me this is only your 2nd electric rig with all the years you've been around.

 

[hamz9561]

Olds loves the smell of nitro in the morning....

 

[olds97_lss]

It still surprises me this is only your 2nd electric rig with all the years you've been around.

No offense to anyone, I always felt like electric was too "kid/child" for me. The nitro and gas just seemed more grown up. Made feel a little less silly standing out there enjoying my hobby with people around. Really, running the stampede seems a little silly... however, doesn't diminish the fun I've had with it already. I'm having so much fun with this and my ERBE that I've been looking around to perhaps convert my savage X... maybe next winter.

Olds loves the smell of nitro in the morning....

That I do. Nothing like a good day burning through a few thousand cc's of fuel. Those days are few and far between for me now that I run alone. When there was a group of us, I could tear through half a gallon in a day. Now I'm lucky if I burn through 2 gallons a year. lol

Here it is now:

Rpm front carriers/spindles
Fast Eddy bearings everywhere but steering and rear. Steering bearings seemed ok and I'm still waiting for RPM rear carriers to put new bearings in.
New wheels/tires
12mm alloy wheel hex's
New stock slider axles
SMC 7200mah 90C 2S lipo(s)

I also pulled the diffs apart apart, cleaned, shimmed and loaded with 50K diff oil. I didn't have any 30K around. Used new bearings on both. Replaced X-ring o-rings in the diffs with some I found on McMaster-Carr. Hoping the hold up a while. The x-rings in it were all torn to shreds and there was almost no grease or oil in either diff.

Also, the drag link in the steering had a ridiculous amount of play. I ran it today with all the new stuff and it was like driving a drunk snake when on concrete. When on hard power, it would torque steer really badly. I'm not 100% sure, but the slipper may be slipping a bit much. Is hard to tell, the traxxas motor is really notchy and it's hard to hear much over the noise it makes with the drive train. Wheelied whenever I wanted, top speed could be a hair faster, but I don't want to over gear the motor/esc. May look around to see if I can find something with a few more RPM's, or at least wait until it warms up to get proper temp readings.

Anyway, replaced the drag link with a piece of 3mm threaded rod and a couple ball cups. Had to bend the rod and grind the the tops of the cups and where the ball ends mounted in the drag link holes for clearance on full lock and to avoid rubbing on the center axle. Not sure how long that will hold up.
It's hard to see, I should have taken a photo when I had it apart.

Trying to at least find some 3x5mm bronze bushings or something instead of the shoulder bolts so the bushing will wear instead of the drag link.

I didn't have much time to run it today, but I ran it pretty hard for 15 minutes straight. I wanted to see how it did so I could get whatever sorted for the weekend vs rushing through whatever this weekend then going out to bash. After 15 minutes, the motor was a bit warm to the touch and it was 40F outside. The esc barely felt warm.

I rebalanced the SMC 7200mah pack and it took 3000mah on the dot. So it seems, I should be able to get 35-45 minutes out of a pack. Since I have 2, I can easily run hard for an hour with this, then another 1.5 hours with my ERBE before my packs are all dead.

 

[bifft it]

try menards, lowes, or home depot for those bushings.
we have a hardware store called Macs. local thing
they sell all sorts of stuff that a true value would never sell. there is probably one like it in your area

 

[olds97_lss]

Got a short video of it today. Was on my own, so camera angles are what they are.

Think I'll drop the pinion down from the 14T I put in. The motor got up around 150F and the ESC to 110F. It was a warm 65F outside while I was running it. At the skate park, it ran 110 motor/95 esc. Would prefer to keep it closer to that when running in the grass if I could so I don't have to worry about it. I ordered a 12T and 13T to try out. Still got about 35-40 minutes on a pack though before the LVC kicked in.

It didn't occur to me to take a video until I was 10 minutes into my last pack after I left the skate park... was too warm for a jacket, but my jacket has a vertical pocket/zipper in it that I stuck most of my phone in while on it's side. So, once the video started, I couldn't see the screen to tell what angle I was at.

 

[olds97_lss]

Well, after regearing to a 13T pinion, I took it out to the parking lot after logging off from work the other day to try it out. It was drizzling rain a bit so the ground was wet and it was a bit cool, 40F or so. So, grip was minimal at best. After 5 minutes of buzzing WOT up and down my parking lot, I stopped in the middle and tried to get a wheelie... all 4 tires spun, then one side grabbed and it slammed WOT into a drain pipe. Blew apart a shock and snapped one of my new RPM rear carriers in half.

I don't have any support parts really for this other than what I've taken off and the spare bits/pieces the guy included. I have an integy motor fan somewhere, but can't find it. Have a feeling I tossed it... anyway, I lost the bladder out of the shock, so I couldn't rebuild it to run it this weekend. In my many drawers of parts, I remembered that I had bought a slayer at some point, so thought maybe I still had the springs for it and maybe I could cobble something up with a spare set of revo shocks. After finding they are a bit short for the rear and too fat for the front, I dug in my savage spare parts... back in the day, I had 8 OFNA 9.5 buggy shocks on my savage. I still had the shocks along with a full set of front/rear shocks from the OFNA ultra buggy I sold recently as I had put new ONFA 9.5 front/rear shocks on it. Unfortunately, the 9.5 rear shocks were way too long. I did fit them, but didn't take any photo's. I ran it for a bit, but it was very tippy since it stood so tall in the rear.

Then I decided to re-seal and oil the OFNA Ultra front shocks, since I had spare o-rings and whatnot. They fit on the rear pretty nice and the springs feel almost the same weight as the stampede springs:

With that done, I could run it tomorrow if it warms up a bit out. The shocks fit pretty good, but are too long for the front, so not sure what would fit there that would be 1/8th buggy tough. With OFNA shut down, replacing shafts and whatnot would be a pain, but I was just trying to get it together to perhaps run through a couple packs when it warms up Sunday.

I just ordered a full set of stampede shocks/springs to replace mine along with alloy shock caps as that seems to be the weak spot noted on many threads at the traxxas forum. I also got a center diff. Figured maybe I could eek a bit more life out of the stock axles before dropping $100 on MIP's. With the 3 or 4 outings I've had so far, the ears on the new axles I installed are getting a bit of slop already. Still, adding a center diff should help the front/rear diff life as well without fighting with the slipper that's annoying to adjust. Time will tell.

 

[olds97_lss]

Got another vid, put them both in the video section:
https://www.rcnitrotalk.com/forum/threads/stampede-4x4-vxl-bashing-videos.113805/

Unfortunately, for about 75% of the skate park footage on the second video, either the camera was off or pointing at the sky... oh well. Also, figured out that microsoft movie maker was converting the video to a lower resolution on import... which explains why the exported version looked considerably worse than the original off my phone.

The jump in the beginning into the ditch is a jump I cased with my ERBE, well didn't case it, but landed flat on the upslope, which busted one of my rockers.

 

[olds97_lss]

Got another upgrade, MIP X-Duty CVD's. Got them with $ my father in law gave me for my b-day. As a 40yo guy... it's weird getting cash for your b-day, but it's a nice gesture none-the-less. He knew it was going to somehow end up being for RC parts.

Unfortunately, the rear ones didn't come with the little grub screws with nubs to lock the hubs onto the diff outputs, so I found a couple HPI standard pins to use for the time being. Also had issues with the rear bearings binding when I tightened down the wheel nuts. These hubs are the slotted axles without hub pins, so the hub slides until it can't when you tighten the wheel nut. They come with a 2mm and 1mm shim, one for the back side (not sure what that's for) and one to go between the bearings. In my case, I needed 2.5mm between the bearings, especially with the RPM arm on one side. I added a couple .25mm shims between the bearings with the 2mm shim they include and was able to tighten the wheel nuts properly without any binding. The fronts seemed to not have an issue.

Of course, I took today off for my b-day and the temps outside are a high of 26F. Supposed to get to 32F Sunday, so perhaps I'll give them a go at the skate park then. See how much rotational mass these add.

I also used a wax based lube vs grease on the joints and slider part. That seemed to do well on my bones/cvd's on my savage-x, so guessing it will work well here at not collecting dirt while still lubricating.

I also had to grind out the hub area on the front c-hubs. Guessing the RPM hubs have a bit more material than stock. Without grinding, they fit, but fit tight and bound pretty bad. The larger sanding drum for a dremel was the perfect size to take out about 1mm and now they spin nice and smooth without binding.

Also installed the alloy spur bearing hub vs the stock plastic one. Can't see it, but it's in there. Guess the next logical upgrade would be to get the diff cups that use the x-bar and x-pin retainers... may worry about that if I decide I need to go with a larger motor and 3S to avoid overheating.

I have to say, this rig has been a total blast at the skate park. Electric is a ton of fun so far!

 

[olds97_lss]

Kind of fell behind on my own thread.

Since the last post, I've made some changes.

I ditched the wheelie bar thing. I didn't like how far it stuck out. I threw together and old revo bumper and spaced it away from the part the roll bar thing was mounted on so that the bumper makes contact before the body.

I've changed out the motor/esc for a castle SCT V3/3800kv system. Which oddly at the same time, the receiver decided to die. I thought it was the due to the esc only putting out 5v. I'm sure that didn't help, but ended up being the receiver. It's a knock off spektrum DSM2 that uses a coaxial antenna vs the single wire all my old spektrum receivers use. My range went from 400+ yards to 100 feet. Basically just like the old spektrums. I installed a hobbywing BEC, but it wouldn't even supply enough current to turn the wheels in the air without causing the receiver to reset. Ended up getting another cheap one off ebay and it does way better. Keeps both fans spooling fast and the servo whipping with ease. Even with the tires held stationary you can barely hear the pitch change in the fans. The motor/esc seems to be doing ok. I haven't had it shut down on me yet. I've seen the esc/motor get to 124/154 respectively after running back to back 7200 2S packs with 14/54 gearing. With 13/54 gearing, it's as fast as the velineon 3500 with 14/54 gearing. It's a softer power off the line, but still has seemingly plenty of power for the rig. Wheelies pretty much whenever I'm under 1/2 throttle. I'd like it to go a bit faster, but I think without going with 1/8th scale electronics, this is how it will stay. The motor spins easier than the traxxas 3500. It doesn't feel nearly as notchy and the truck free rolls much more smoothly. I'm not seeing much different run times though. About 25 minutes per 7200mah 2S SMC 90C pack.

I also added a somewhat shoddy roll bar. I got a new body for it, but until I did something about a roll bar, I didn't want to waste the body. I've bashed it a few times and it's holding up ok. Looks awful, but keeps the center of the body from buckling which is what causes massive body damage during roof landings.

I've shelled out my 4th spur bearing since I got the truck. The last one took out the motor mount/brace:

I have a King Headz alloy motor mount/brace that using larger OD bearings coming in the mail. Hoping that helps with the frequent bearing replacement. It's a weird design on a bearing that gets a lot of abuse. It's what keeps the spur from trying to push away from the pinion and it also sends the power to the center shaft/rear diff, so the bearing is being pushed and twisted all the time. Only one side of the spur is supported well. The other side keys into a pinion gear for the rear diff that rides in a bearing. It's not the tightest fit between the center shaft and pinion, so the connection isn't the most solid. Considering the strain the diff pinion bearing is enduring already, having it support the spur load just seems short sighted to me. I'm lucky I didn't fry my diff.

Any more root cause analysis done on that thing @olds97_lss ?

Obliviously there was some decent heat being generated if it melted the plastic. Makes you wonder if the bearing got trash in it and seized or at least started to drag which caused the entire assembly to heat up.

@flm_savage
It could be something I'm not seeing. Dirt, sand or just the duration of time that I run it. I usually run it one pack after another for 2 packs worth @25 minutes each. I'm 99.9% sure it melted like this because when I ran it last weekend, it sounded awful right out of the gate. Instead of pulling the pack and not running it, I ran it. In my mind, it was a fried diff, so I just figured I'd run it until it stopped moving. It never did. Hindsight... hear weird noise... stop driving the thing! LOL

You can find my latest vids here:
https://www.rcnitrotalk.com/forum/threads/my-latest-bashing-vids.113919

 

[flm_savage]

So it appears to be the same central driveline as the slash 4x4. I haven't looked at any of the breakdown diagrams but visually it looks identical.
I'm going to take a look at mine and see if it is showing any signs of wear.

Were you using standard metal shielded ball bearings?
I have never looked into it but i wonder if you could buy a roller bearing or tapered roller bearing for this application. (EDIT: Can't find any in that size)
This is still a standard ball bearing but the load rating on it is higher than any others that i have found.
https://www.mcmaster.com/#5972k275/=17r04t2 Max speed is 37K RPM. Its early but my math says that even with a 3S lipo, geared at 14/54 your spur will be at less than 11K. 10935 is what i came up with.

I suppose an imbalance in the center driveshaft would cause vibration and additional radial load on that bearing. You could remove the center shaft, run a pack and check the temps and then install it, run another pack and see if there is any difference.

 

[Certified Mike]

Just thought I'd throw this in here... While I don't own one, this is excellent info for someone who does. Its easy to follow with good detailed information and pics. Great job with this (and the other models you've done)

 

[olds97_lss]

So it appears to be the same central driveline as the slash 4x4. I haven't looked at any of the breakdown diagrams but visually it looks identical.
I'm going to take a look at mine and see if it is showing any signs of wear.

Were you using standard metal shielded ball bearings?
I have never looked into it but i wonder if you could buy a roller bearing or tapered roller bearing for this application. (EDIT: Can't find any in that size)
This is still a standard ball bearing but the load rating on it is higher than any others that i have found.
https://www.mcmaster.com/#5972k275/=17r04t2 Max speed is 37K RPM. Its early but my math says that even with a 3S lipo, geared at 14/54 your spur will be at less than 11K. 10935 is what i came up with.

I suppose an imbalance in the center driveshaft would cause vibration and additional radial load on that bearing. You could remove the center shaft, run a pack and check the temps and then install it, run another pack and see if there is any difference.

I only run 2S, which makes it even more odd that they fail so much. I have always been using rubber shielded bearings. The standard slash 4x4 and stampede 4x4 use the same parts for the motor mount. The LCG version is different, odds are though, same bearing, just moved to change the CG.

Will see how the larger bearing does when I get it. I really have a feeling it's the lack of downtime when I run it that is causing it to fail. When I run it, I running almost constant for an hour at a time. I don't think I have the mesh too tight and everything appears to spin true and freely with the motor out. More so now with the motor in with the castle motor as it rolls a lot more smooth than the velineon when off power.

Just thought I'd throw this in here... While I don't own one, this is excellent info for someone who does. Its easy to follow with good detailed information and pics. Great job with this (and the other models you've done)

I try to catalog my stuff like this so I can keep track of what works and what doesn't. Pretty sure I have a thread that I started for nearly every truck or engine I've had. Well, quite a few anyway. LOL! I forget stuff, so taking the time to post photo's and write out what it does and how it reacts reminds me why I did it. When you bash alone and have 5+ vehicles, you tend to let some sit on the shelf for months or years without running them. So when you do, you forget why you have that weird washer on that one part... then remove it and suffer again.

 

[Certified Mike]

I agree. I have a large tray containing a lot of very small trans parts spread across it. I took my revo trans apart... Again... And then got caught up in doing a TON of 1:1 repairs. After farting around with the car so much, I have found little time and less interest in messing with the revo stuff. Esp since the revo stuff is a nuisance. Just a bunch of annoying things I need to do. I get annoyed when I feel like I'm repairing things that I didn't do or cause like opening the races ever so slightly so they slide into a shaft that seems was machined poorly causing a bad fit. I totally understand wanting to know where you left off... I am going to need to start at square 1... AGAIN! Lol! The only good thing about this is THIS TIME I found the OTHER pair of gears that I apparently roasted when I blew it up. I am annoyed with myself that it took me so long to find them as I've torn it down and rebuilt it a few times now. I thought I was shimming it wrong! Lol! I just want to get it fired up. There is a GREAT construction site RIGHT behind my house that is just BEGGING to be run!!! Lol! The Jato just isn't the truck for these conditions tho.

 

[WoodiE]

Man that chassis would look great dyed black.

 

[olds97_lss]

Got the new king heads motor mount in. Was hoping to run a lot tomorrow, but got some stuff going on at work and need to stay in the house and wait for developers to do their thing so I can check their work for an emergency release on memorial day. Strange to me sometimes what an "emergency" is...

Anyway, I just took it back apart so I could post a photo of it... while doing that, the bearing fell out and I noticed that the new king heads mount with the larger opening for the larger OD bearing leaves a hole right at the bearing face under the motor for dirt and whatnot to get right into the bearing:

I filled the gap with hot glue and pressed both sides with an aluminum rod while it was still hot to kind of create a plug for the hole.

After reading online, quite a few people have issues keeping bearings alive in their slash and stampede, they block the tunnel with velcro so sand and whatnot is less likely to get to the bearing. To do that best, they mount the velcro with the soft side touching the shaft and put silicone sealant or some such to fill the gap around it, so the tube touches the velcro all around and the gap is filled with silicone sealant keeping it in place. That seemed like a lot of work, so I just put some double side tape on the shaft and stuck some velcro to it. It barely touches the inside of the tunnel, so will see how that does to keep sand and whatnot out of there:

For those interested, this is the bearing size comparison between the stock bearing and the king headz bearing:

While putting the shaft back in and the spur/slipper, I noticed that the shaft can move forward/back quite a bit. Guessing this is normal.

All the way forward:

and back:

It was a bit more, but I moved the star end on the spur shaft a few mm forward and reapplied locktite to the set screw before putting it back in. It was loose, could have swore I put locktite on it before.