Notorious Front bumpers are Notoriously easy to demolish

[SrC]

I'm not above engineering a better solution, too, if I can think of one. The way these turnbuckles attach is kind of spindly, and when one pops off, there goes the driveshaft, and that whole corner of the suspension. It's not very robust. Can I come up with better? I don't know yet. Maybe. I'm mulling that one over.

Need to drive better. Sorry....
Wrenching is only the half of it.

 

[arborvitian]

Need to drive better. Sorry....
Wrenching is only the half of it.

Driving skill or the lack thereof just doesn't explain why I ran 20+ packs without an issue, and then haven't gotten through one pack since I did preventative maintenance on my differentials. Something else is at play here.

 

[arborvitian]

Driving skill or the lack thereof just doesn't explain why I ran 20+ packs without an issue, and then haven't gotten through one pack since I did preventative maintenance on my differentials. Something else is at play here.

Looking back, I changed the oil everywhere, and kept blowing the front diff. First the out-drive pin, then the planet gear.

Hypothesis: The recommended center diff oil was too light. It was lighter than the center diff oil that had actually been installed from the factory.

After frustration with all that, I got some aftermarket "EXB" diffs across the board. I was impatient. I installed them without checking the oil. I blew the front diff, and then the rear.

Most of my parts finally came in, and I did a forensic analysis today. Rear diff, blown planet gear. Front diff, obliterated to Hades and gone. Center diff...

It had one black blob of goo the size of a BB, and was otherwise dry.

My replacement front diff was also bone dry. Bone dry.

Yeah, okay, I can see this. Center diff has no lube at all, so it's going 50,000 mph with no resistance. Transmits too much power to the front, which blows catastrophically. I don't realize what has happened. Why is it steering hard to the left? I keep driving until the rear blows catastrophically.

I think this makes sense.

So now I have 30 rear, 500 center, and 60 front, and all the diffs are actually full. I'm waiting on the shims to come in. The shims I ordered were wrong, and I had to back up and punt.

Maybe I can get this truck running again after all. It should go a lot better now that there is actually lubrication in the center diff. That could have been my problem. Although it doesn't explain why I started chewing up front diffs when I did the oil change. Unless they didn't have the same weight of lube as what the manual said they did. Maybe a mid-production change.

Who knows. This Notorious is either going to run long enough to burn through at least one 6S pack, or I am going to stick the entire thing in my forge and melt it to slag.

Uh. Also, I changed the front diff case, and switched to one of the Super Basher front bumpers. I think this bumper looks stupid, but it's the only sustainable option I have, long-term. Plus the 3DRC springs I ordered by accident fit this one, so yeah, may as well switch while I'm at it.

Stay tuned. Still waiting on shims.

 

[arborvitian]

So the shims came in, and I ordered the wrong size again. Seriously?

I decided to make my own shims. I have tons of shim stock. I really put in the effort, and made a good try, but sadly, I failed in the end. My shim punches didn't work. It took so much effort to make them that it's probably not worth trying a different version that might work next time. It's time to order new shims yet again. At least I finally measured, and I have an idea what size I need.

First, I made the punchy side kiss fit an out-drive.

Then I had to grind my very first HSS tool to make the groove on the cutty side. It worked pretty well. The two parts mate closely enough that you have to pry them apart afterwards, but they can be pried apart. It punched out a disc with a dome in the middle, but it didn't quite punch out a washer. Also, I didn't have any tool steel that big, so I used 1018, and I just beat the excrement out of it after a few tries, and it was done. Alas. Tantalizingly close, but no cigar.

Looking at the pics, it looks like my tool didn't quite do the job. The inner ridge doesn't have a sharp enough rim to cut. It was a small tool, and I already broke it, so that's all done now. I don't know how else I could have made this groove. This is not something you can do with standard carbide insert tooling at all. I made my tool like a tiny boring bar.

I'm going to go order the correct shims now, and wait. This truck has been down for like a month at this point. Painting the fancy Daphne shell was a jinx, apparently.

 

[Dan B.]

So the shims came in, and I ordered the wrong size again. Seriously?

I decided to make my own shims. I have tons of shim stock. I really put in the effort, and made a good try, but sadly, I failed in the end. My shim punches didn't work. It took so much effort to make them that it's probably not worth trying a different version that might work next time. It's time to order new shims yet again. At least I finally measured, and I have an idea what size I need.

First, I made the punchy side kiss fit an out-drive.

View attachment 304134

Then I had to grind my very first HSS tool to make the groove on the cutty side. It worked pretty well. The two parts mate closely enough that you have to pry them apart afterwards, but they can be pried apart. It punched out a disc with a dome in the middle, but it didn't quite punch out a washer. Also, I didn't have any tool steel that big, so I used 1018, and I just beat the excrement out of it after a few tries, and it was done. Alas. Tantalizingly close, but no cigar.

Looking at the pics, it looks like my tool didn't quite do the job. The inner ridge doesn't have a sharp enough rim to cut. It was a small tool, and I already broke it, so that's all done now. I don't know how else I could have made this groove. This is not something you can do with standard carbide insert tooling at all. I made my tool like a tiny boring bar.

View attachment 304135

I'm going to go order the correct shims now, and wait. This truck has been down for like a month at this point. Painting the fancy Daphne shell was a jinx, apparently.

I’m not following regarding the need for a ridge on the shims. For the center diffs, in my experience you only ever need one or two very thin shims just to insure that the bearings fit the mount with no fore and aft movement of the shaft. Some don’t even bother unless the movement is such that the center driveshafts can bottom out in the drive cups. I always shim them, but some don’t. If you run a spool it’s then common to need spacers/bushings to properly line up the spur with the pinion, but only then have I found that to be a necessity.

 

[arborvitian]

I’m not following regarding the need for a ridge on the shims. For the center diffs, in my experience you only ever need one or two very thin shims just to insure that the bearings fit the mount with no fore and aft movement of the shaft. Some don’t even bother unless the movement is such that the center driveshafts can bottom out in the drive cups. I always shim them, but some don’t. If you run a spool it’s then common to need spacers/bushings to properly line up the spur with the pinion, but only then have I found that to be a necessity.

The ridge was an error, not an objective. The shims I tried to make didn't work out. I don't want to reassemble without shims, because I'm trying to limit the possible things that could cause the diffs to explode. I'm so tired of working on this truck. Put it together, run it 10 minutes, back to the bench. I haven't made it through a single battery pack since it had the factory fill in all the diffs. I presume I did something wrong putting it back together, and I'm just trying to limit possible sources of trouble by doing everything textbook at this point.

Maybe this really isn't necessary. I needed new shims, because I boogered up the old ones, because the fit is extremely tight.

Oh well, waiting on shims now. I'll come back to this later.

 

[arborvitian]

Installed shims, reassembled truck.

First impressions: Wow, it's sluggish with the 30/500/60 oils, back to front.

Second impressions: It's making a bad noise in reverse, or even just when I hit the brakes.

Before I had killed one 4S pack, I broke something again. The front diff seems okay. Both axles are spinning. One of the wheels isn't getting power.

It looks like a pin broke.

If I fix it, then something else will just break next. If I want to drive and have fun with my dog, the 6S Notorious V5 is a terrible, terrible choice. I've dumped over $1,000 into this pile of garbage, and now I have to dump even more money if I want it running again.

For what? So it can break again, and I can dump yet more money into a lost cause?

I think it's bonfire time.

Edit to add: I slept on it, woke up, took a look at the truck. Broken pin on the knuckle side. No idea how to get any of that apart. It's probably different from every other pin I have, and there is still the grinding. Bad mesh somewhere, or something else about to give up. Probably bad mesh, considering.

This is beyond frustrating.

 

[SrC]

Driving skill or the lack thereof just doesn't explain why I ran 20+ packs without an issue, and then haven't gotten through one pack since I did preventative maintenance on my differentials. Something else is at play here.

Its all a conspiracy I tell you.

 

[arborvitian]

Its all a conspiracy I tell you.

I'm more than willing to accept that it's my own incompetence. I'm not qualified to change the oil on a toy truck, evidently. Everything since then has just been one failure after another. The most recent failure definitely isn't driving style. I barely got the front wheels off the ground. I was trying to break in the new gears gently, and not doing stunts.

I didn't blow up any of the diffs, at least.

 

[SrC]

Yeah I always do tight figure 8's with my new diffs for the first few minutes. For a break break-in.
Sometimes I will use a Drill on the bench to break them in before installing back into the bulkhead. Mostly for the Center diff.
And Fr and Rr Main gear Shimming is so very important. Best to make them on snug side. Because after a break-in, the Main+ Input gears will loosen up for sure. After several packs, I might even re shim again. Depending how I like the slack. Then I am good for another 20-30 packs of bashing, before diff maintnenance is done. That is the Arrma recommended interval.
Out of all of my 19 models here, of various brands.... I find Arrma 6s diffs to be finicky, Being a slave to them. I must have rebuilt 6s diffs well over a hundred times easily. That's alot of Diff oil. I do it in my sleep now. I have 9 Arrma 6s rigs here.

My Tekno MT410 diffs for example still never touched since I first built them, and is older than all my Arrma's here. The Tekno diffs still run like new. You pay for that however.

 

[arborvitian]

Yeah I always do tight figure 8's with my new diffs for the first few minutes. For a break break-in.
my Arrma's here. The Tekno diffs still run like new. You pay for that however.

It's amazing how insidious this is. The source of my most immediate failure is a $13 part. While I'm in there, I should get blah blah, and now I have another $75 invested in a lost cause. It's just going to blow up again. It probably will blow up again, because of the crunchy grinding noise I never diagnosed.

I think this truck is trying to tell me that it hates the Barbie Pink dog shell, and wants a stock shell again. It drove so well with a stock shell. Ever since my first custom pink shell, it has been crapping and peeing broken parts. I haven't had any fun with this truck in like two months. I should stop throwing good money after bad, and just light this thing on fire.

Sigh.

 

[arborvitian]

So I finally got time to diagnose the horrific grinding noise. I pulled the front driveshaft. No noise. Reinstalled that and pulled the rear. Hideous noise. Definitely the front diff. Then I pulled apart the diff case I just installed, and, uh, well.... I'm pretty sure I found the problem!

I've barely run the truck around, and did that in pretty much 15 minutes of light test driving. It's not gear tooth engagement at all, the drive pinion is just eating the differential housing. Uhhhh? I'm not entirely sure how that even happened. I'm going to blow out the aluminum dust and try to figure it out.

 

[arborvitian]

Set screw, I'm thinking. I haven't made time to take it apart far enough to fix that yet. The brand new diff housing is a complete mess, with aluminum fragments deeply embedded into the plastic. Pretty much a disaster, this truck.

 

[Garcbomber]

Yeah the only way an input can float into the carrier housing is if the set screw isn’t preventing the shaft from axial play. That or you put an EXB input on, but it would’ve required a lot of stack up to go wrong and would’ve never coasted/noisy operation. Same effect if you overshimmed a blx spiral 10T input, but you’d know right away when assembled if there was an interference.

Lessons learned are never forgotten, you’ll get there soon and diff building/powertrain understanding will only continuously improve. Don’t give up, a few more tear downs and observations and you’ll build them in your sleep with only minor maintenance.

 

[arborvitian]

So I finally got around to tearing it apart. The set screws will neither tighten nor back out. The brand new diff housing is hopelessly contaminated with metal gunk. The bearings are gross and short-lived.

I started putting together a shopping list for all the parts I need to fix this right, and it came to over $100.

Good money after bad.

My Notorious is now up for grabs as a parts truck. Make me an offer!

 

[SrC]

So the shims came in, and I ordered the wrong size again. Seriously?

I decided to make my own shims. I have tons of shim stock. I really put in the effort, and made a good try, but sadly, I failed in the end. My shim punches didn't work. It took so much effort to make them that it's probably not worth trying a different version that might work next time. It's time to order new shims yet again. At least I finally measured, and I have an idea what size I need.

First, I made the punchy side kiss fit an out-drive.

View attachment 304134

Then I had to grind my very first HSS tool to make the groove on the cutty side. It worked pretty well. The two parts mate closely enough that you have to pry them apart afterwards, but they can be pried apart. It punched out a disc with a dome in the middle, but it didn't quite punch out a washer. Also, I didn't have any tool steel that big, so I used 1018, and I just beat the excrement out of it after a few tries, and it was done. Alas. Tantalizingly close, but no cigar.

Looking at the pics, it looks like my tool didn't quite do the job. The inner ridge doesn't have a sharp enough rim to cut. It was a small tool, and I already broke it, so that's all done now. I don't know how else I could have made this groove. This is not something you can do with standard carbide insert tooling at all. I made my tool like a tiny boring bar.

View attachment 304135

I'm going to go order the correct shims now, and wait. This truck has been down for like a month at this point. Painting the fancy Daphne shell was a jinx, apparently.

Tekno 1/8 diff shims are a fit. # TKR1222
What most us use for the standard RTR Open diffs. If you run these diffs.
I make my own Sun gear cross pins out of HS Drill blanks, FWIW. Stronger.
When it comes to Arrma diffs, user error/building them, is to blame most of the time. After a 100+ rebuilds of them, you should get the hang of it.

 

[arborvitian]

So while I can afford another $100 in parts, I decided not to buy another $100 in parts. I need a new diff housing, new bearings, and a bunch of other random things. If I buy that stuff and put the truck back together, it will just need another $100 in parts and another $100 and another $100 and another $100.

My Notorious is going in a box now. I guess I'm going to try to sell it, and cut my losses. It was not a good investment after all. Meanwhile, my little 4S Outcast has survived all of this and more. It even survived my Great Dane stepping on it, repeatedly.

 

[Garcbomber]

The nice thing about the 3/4S plastic toys is they don't have a center diff to worry about, one less failure mode if you keep them box stock.

FYI, you can buy an entire Gp4(43/10) bulkhead assembly for less than $50-60 depending on location. I got both my typhon GP5 diffs from JRC for $68 shipped. That way you can plug and play for at least 10-20 packs before chasing your tail and overanalyzing rebuild information that's been vlogged dozens of times.

Good luck!

 

[arborvitian]

The nice thing about the 3/4S plastic toys is they don't have a center diff to worry about, one less failure mode if you keep them box stock.

FYI, you can buy an entire Gp4(43/10) bulkhead assembly for less than $50-60 depending on location. I got both my typhon GP5 diffs from JRC for $68 shipped. That way you can plug and play for at least 10-20 packs before chasing your tail and overanalyzing rebuild information that's been vlogged dozens of times.

Good luck!

If I'm chasing my tail, it's because none of this crap is obvious or accessible to an adult man who works 70 hours a week, and just wants his damned toys to work when he wants and has time to play with them. I didn't sign up to get a degree in RC engineering. I just wanted to have fun. I WAS having fun, a lot of fun, until stupid me actually read the service manual. I tried to comply, and I haven't had a truck that ran for more than five minutes since.

Who is really at fault here? The fat guy, or the company that makes excessively fragile junk that becomes a never-ending money pit the first time the factory oil is changed?

I will never buy ARRMA again.

 

[Denvermatt]

I used to blow diffs all the time. Then I was out driving rc's with another guy a few years ago and he noticed that I was landing off jumps with my throttle pinned down. The force on the landing on full throttle was killing my diffs. I haven't ruined any diff parts since I learned throttle control and to let off the throttle when my truck lands. I also second SrC with the tekno mt410 diffs. I've never replaced the diff parts on the tekno, or really that many parts in general since it's built like a tank.