Anyone interested in the new Redcat KAIJU MT 1/8

[AngryEngineer]

Hi everyone, new guy here although I've been following along since I got my Kaiju last year. Quick question for the experts here.

So far my weak link has proved to be the CV drive shafts. I broke one several minutes into my first run that Red Cat warrantied and just exploded another today. Before I buy the stock Redcat part (RER12426), I'm wondering if there are any upgrades. Will the EXT ones fit and are they an upgrade?

 

[Hector_Fisher]

Hi everyone, new guy here although I've been following along since I got my Kaiju last year. Quick question for the experts here.

So far my weak link has proved to be the CV drive shafts. I broke one several minutes into my first run that Red Cat warrantied and just exploded another today. Before I buy the stock Redcat part (RER12426), I'm wondering if there are any upgrades. Will the EXT ones fit and are they an upgrade?

Looks like the EXT and Kaiju driveshafts have the same part numbers per the exploded view diagrams at the end of the manuals.
https://dealer.redcatracing.com/manuals/KAIJU_MANUAL.pdf
https://dealer.redcatracing.com/manuals/KAIJUEXT_MANUAL.pdf

Where has the CV been breaking? Pics are helpful for diagnosis.

While redcat does kind of have that notoriety for shoddy quality control/materials, i don't think you'd be so unlucky as to get two bad parts in a row. Something tells me there is another force at play that's causing the breakages. Knowing where the breakage is will help.

 

[AngryEngineer]

It's just material quality unfortunately. Both have been at the pin that interfaces with the drive cup. The original breakage was a rear and today's was a front.

I was just hoping there was an alternative. I hopefully don't keep breaking these at $12 a piece.

 

[Armarookie43]

Hi everyone, new guy here although I've been following along since I got my Kaiju last year. Quick question for the experts here.

So far my weak link has proved to be the CV drive shafts. I broke one several minutes into my first run that Red Cat warrantied and just exploded another today. Before I buy the stock Redcat part (RER12426), I'm wondering if there are any upgrades. Will the EXT ones fit and are they an upgrade?

That's strange. I've bent some driveshafts on the Kaiju, but have yet to snap one like that

 

[Hector_Fisher]

That's strange. I've bent some driveshafts on the Kaiju, but have yet to snap one like that

^^^ exactly, that kind of makes me more suspicious that there is something else going on. Pins would really only be snapping if they were binding on something. On your other wheels, when you actuate the suspension up and down, do the pins contact anything, or are they close to contacting anything? @AngryEngineer , are you running bearings over the drive cups or drive cup sleeves at all?

 

[AngryEngineer]

Don't think anything is binding, looked at the suspension pretty thoroughly. The first one to break was within two minutes of running it. The second after about 10-12 runs. First was bone stock. Although for the second, I am running bearings on the out drives, but they have been ground down so they can freely move.

Like I said, my fairly educated opinion is that it is a material issue since both have cracked right around where the pin is inserted and fixated through the shaft. That is the thinnest material area and it make sense it would be the highest stress area.

I'll have some new ones in hand in case they break again, but I am very surprised no one else has broken them based on how easily they've broken.

 

[Hector_Fisher]

Don't think anything is binding, looked at the suspension pretty thoroughly. The first one to break was within two minutes of running it. The second after about 10-12 runs. First was bone stock. Although for the second, I am running bearings on the out drives, but they have been ground down so they can freely move.

Like I said, my fairly educated opinion is that it is a material issue since both have cracked right around where the pin is inserted and fixated through the shaft. That is the thinnest material area and it make sense it would be the highest stress area.

I'll have some new ones in hand in case they break again, but I am very surprised no one else has broken them based on how easily they've broken.

My follow up thoughts:
-If we assume it was a bad batch of driveshafts, then if any of the new driveshafts break (very likely the new ones wouldn't be from the same "bad batch" since you bought it ~a year ago), i have to assume something else wrong is going on there that's causing the pins to bind somehow. Otherwise, a new set of driveshafts should fix the issue.
-I couldn't install bearings on my kaiju's drive cups because the driveshaft pins were too long. If it's not a material quality issue, then it's likely binding on the bearing and you may need to shave the pins down a bit.

The only other pin issues i've seen in this thread are pins coming out of the end of the driveshafts that @KnowAir has mentioned before.

If I were in your case, i'd just get the new batch of driveshafts/CV's and run them to see if they break. If you're suspecting a bad batch, then you should be golden on the new ones. Keep track of which is which!

 

[AngryEngineer]

Appreciate the follow ups.

I'll keep track of these in the future to see what is up. I'm hoping it was just a bad batch but time will tell. It could be something crazy but I really don't think it is a bind issue. I was able to grind down the pins enough that they clear the bearing while maintaining a full range of motion. And the first breakage was before the bearings were even placed on the out drives.

Thanks for the help!

 

[KnowAir]

Appreciate the follow ups.

I'll keep track of these in the future to see what is up. I'm hoping it was just a bad batch but time will tell. It could be something crazy but I really don't think it is a bind issue. I was able to grind down the pins enough that they clear the bearing while maintaining a full range of motion. And the first breakage was before the bearings were even placed on the out drives.

Thanks for the help!

I haven't had any failures like that yet either, had mine since 2020. What do the drive cups look like? Are they cavitated? Like this?

 

[Devin]

I bought a new roller and built one with all the aluminum hop ups, a Mamba Monster 2 esc/ 1515 2200kv motor, 35kg DS servo and Proline belted badlands. I drove it a few times just to get it dialed in and then let it sit as I wasn’t really crazy about the way it handled. I recently sold it to a guy and he has pretty much broken something every time he’s driven it. It was snapping axles left and right on 4s, I couldn’t imagine what it would break on 6s. I guess the moral of the story is that they cannot handle Castle power. I was pretty disappointed because I was just going to use it as my beater, but it’s hard to beat on something that constantly breaks.

 

[Armarookie43]

I bought a new roller and built one with all the aluminum hop ups, a Mamba Monster 2 esc/ 1515 2200kv motor, 35kg DS servo and Proline belted badlands. I drove it a few times just to get it dialed in and then let it sit as I wasn’t really crazy about the way it handled. I recently sold it to a guy and he has pretty much broken something every time he’s driven it. It was snapping axles left and right on 4s, I couldn’t imagine what it would break on 6s. I guess the moral of the story is that they cannot handle Castle power. I was pretty disappointed because I was just going to use it as my beater, but it’s hard to beat on something that constantly breaks.

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Yeah. Maybe the extra weight and the Castle system are too much for the axles? I've never snapped an axle on mine even on 6s with the stock system and no aluminum upgrades.

 

[KnowAir]

I bought a new roller and built one with all the aluminum hop ups, a Mamba Monster 2 esc/ 1515 2200kv motor, 35kg DS servo and Proline belted badlands. I drove it a few times just to get it dialed in and then let it sit as I wasn’t really crazy about the way it handled. I recently sold it to a guy and he has pretty much broken something every time he’s driven it. It was snapping axles left and right on 4s, I couldn’t imagine what it would break on 6s. I guess the moral of the story is that they cannot handle Castle power. I was pretty disappointed because I was just going to use it as my beater, but it’s hard to beat on something that constantly breaks.

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Can't say I'm surprised..the drivetrain is barely adequate for the stock system on 6s. Adding more power and weight can't be helping matters.

 

[Hector_Fisher]

This is the exact reason I got the Kaiju over the MT8. Plastic chassis for the win! The only thing I broke today was one of the fans that come with the powerhobby heatsink.

 

[Bdb69]

Do you happen to have a link or no where I can get some of those?

 

[Hector_Fisher]

Anybody have issue swapping to aluminum hub carriers? Swapped over part for part but the spindle is binding somewhere. Can't get smooth steering action. I'm using all the bushing it came with.

I think the problem is that the lower bushing doesn't protrude from the C hub. Meaning the screw contacts the C hub rather than the bushing, so it can't spin freely.

Anyone else had this issue?

 

[KnowAir]

Anybody have issue swapping to aluminum hub carriers? Swapped over part for part but the spindle is binding somewhere. Can't get smooth steering action. I'm using all the bushing it came with.
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I think the problem is that the lower bushing doesn't protrude from the C hub. Meaning the screw contacts the C hub rather than the bushing, so it can't spin freely.
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Anyone else had this issue?

I have the same setup, plastic spindles with aluminum carriers. It's been a while since I put them together,but I don't recall having that issue. Are the bushings different from top to bottom? Maybe they're in the wrong positions?

 

[KnowAir]

Anybody have issue swapping to aluminum hub carriers? Swapped over part for part but the spindle is binding somewhere. Can't get smooth steering action. I'm using all the bushing it came with.
View attachment 247059
I think the problem is that the lower bushing doesn't protrude from the C hub. Meaning the screw contacts the C hub rather than the bushing, so it can't spin freely.
View attachment 247062
Anyone else had this issue?

@Hector_Fisher How'd you make out with this?

 

[Hector_Fisher]

Oof, sorry this thread slipped under the radar LOL

I'm pretty sure I was assembling it wrong. I should have taken a cue from what I have been seeing elsewhere on the kaiju. For example, the outer hinge pins have a long screw and locknut on the other end. You're not supposed to tighten the locknut down all the way. The idea is that the locknut insert keep the nut in place and you set it to your desire location so the hinge pin can freely spin. I think some of the upper link connections are the same too. This was just a big "D'OH" for me, since all i had to do was back off the spindle top and bottom nut like 1/4 or 1/2 a turn and the spindle turns freely. Pretty sure it's designed to be like that, since even though it isn't torque down, there is still alot of resistance on those thread. i don't think they'll back out.

I was thinking it was more designed like my HPI bullet, where you have to crank those screws down tight or they come loose! Can't even begin to tell you how many of those I've lost over the years....

 

[KnowAir]

Oof, sorry this thread slipped under the radar LOL

I'm pretty sure I was assembling it wrong. I should have taken a cue from what I have been seeing elsewhere on the kaiju. For example, the outer hinge pins have a long screw and locknut on the other end. You're not supposed to tighten the locknut down all the way. The idea is that the locknut insert keep the nut in place and you set it to your desire location so the hinge pin can freely spin. I think some of the upper link connections are the same too. This was just a big "D'OH" for me, since all i had to do was back off the spindle top and bottom nut like 1/4 or 1/2 a turn and the spindle turns freely. Pretty sure it's designed to be like that, since even though it isn't torque down, there is still alot of resistance on those thread. i don't think they'll back out.

I was thinking it was more designed like my HPI bullet, where you have to crank those screws down tight or they come loose! Can't even begin to tell you how many of those I've lost over the years....

HaHa, yeah my TRX rigs are like that too, keep backing out. Glad you got it together.
IMO, the kaiju is one of the most underrated rc's out there right now. A couple key upgrades and they're a blast. Rebuilt mine last winter with new front and rear diffs, some mojave arms and 4mm hinge pins and it's stout. Beat the crap outta that thing.

 

[Hector_Fisher]

HaHa, yeah my TRX rigs are like that too, keep backing out. Glad you got it together.
IMO, the kaiju is one of the most underrated rc's out there right now. A couple key upgrades and they're a blast. Rebuilt mine last winter with new front and rear diffs, some mojave arms and 4mm hinge pins and it's stout. Beat the crap outta that thing.

Absolutely agree!

Picked mine up earlier this year for $330, which was a total steal. If feel a little bad because mine has definitely been treated as a beater... I treat my KEXB better than my Kaiju, but that's because I am scared the kraton will break LOL. I don't want to break the $50 chassis or bend a $40 (jennys) shock tower, and other parts can get expensive real quick on the kraton IMO. I still send the kraton big sometimes, but only when the conditions are right and I'm confident I can land the jump. With the kaiju, I just kind of "go for it" Honestly, the kaiju can handle some real punishment. There will be many times we'll be out bashing, and i'm kind of going hard on the kaiju, botching big jump landings, attempting wonky front flips, crashing on pavement and such. And my buddy is looking at me dumbfounded like "how much did you pay for this thing??? $330???"

With all the replacement parts i've bought and even upgrades (and the only reason I bought the alu rear hubs and front carriers vice replacements is because i got the truck for so cheap), i'm still total about the price of a regular KAIJU. So i'm very happy with the purchase. I broke a turnbuckle this weekend, but that was after me going hard with it for two 6s packs and about an hour of smiles! So far, in overall "smiles per dollar" for bashing, the Kaiju is the breadwinner

Haven't had any issues with driveshafts or drive cups yet (the tips of the cup started to splay out in some area), but if I do, i'll probably consider the mojave arm mod!