Chassis Materials: Arrma's false advertising

[StephenSchandelmayer]

Internet speculation and crackerjack PHD's LOL sorry I couldn't resist. If you think Arrma, or Horizon for that matter would risk another lawsuit to cheat the consumer out of a few bucks your crazy. I don't even bother to listen to people explain how or what happened to their stuff any more lol " I only went off a 2 foot jump on 1s and it was on 50% power with LVC kicking in and the diff just exploded! My (insert 2wd plastic junk) would take that all day!" I don't understand it, these rigs are getting better and better with each version. Why are more people complaining now more than ever?

I totally agree with this lolol. Watching my dad beat the crap out of his poor K6 because of his unfortunatley poor skills in the way of air corrections and steering and really not breaking all that much makes me really question some people on here. Also he has driven it into a canal......3 times.

 

[FlipSide]

The real question is about the value, more than the material they are using (or not using, in this case). We'll never know what material Arrma is using.

At full MSRP, the EXB chassis is 55% more expensive than stock RTR and the M2C chassis is 83% more expensive than stock RTR.

I never tried an EXB, but from the numerous reports we can find here and elsewhere online, it seems you only get marginal gain (if any) for that 55% added cost with the EXB, but the added value you get with the M2C seems well worth the 83% added cost compared to the stock RTR.

Basically, I think it's probably better not to bother with the EXB chassis.

 

[N.Mango]

All food for thought. Everyone has some really good points made.

It's a well documented issue that has a well documented fix.
I think if you bend your chassis an upgrade is called for.
If you get the same chassis that you bent, then you're asking for it.

I personally think a new design would be the most cost effective way to fix this issue for Arrma.
I think a ribbed chassis design would do wonders to add strength to all of their chassis's.
But I'm sure they are happy with how things are. imho

 

[slick2500]

I'm no expert in metals or bending RC chassis, but I'm pretty sure a legit test would show that the material used is whats advertised.
If you truly think about the forces thats happening on the chassis while bashing it really shouldnt be surprising that it bends.
Any company has too much to lose by this degree of false advertising over something thats very easy to have tested.
This is just my opinion of course and would love this topic to be put to rest.
Arrma I'm sure know's the word about their chassis going around
that its weak and not made of what they say it is, and they should guarantee it so as to challenge us, the customer, to prove them wrong.
But until its tested this subject will be around for as long as bashers exist.

I agree this would be the only true way to test it. For the very least amount of $1000 or so one could pretty much ruin a company's reputation.
I personally don't think Arrma would take that risk. But if I'm wrong, the first to do so could get paid some pretty nice hush money.
STOP IT! BLACKMAILING IS ILLEGAL!!!

I'm no expert in metals either, but why does the 5mm thick 7075 chassis bend so much easier than the 4mm 7075 chassis?

 

[N.Mango]

I was wondering about that like everyone else.
I'm wondering if the aftermarket chassis's are CNC machined and not pressed? I know Arrma chassis are pressed. If so could it make a difference in the outcome of the metal?
IDK...

 

[hobo]

I'm no expert in metals either, but why does the 5mm thick 7075 chassis bend so much easier than the 4mm 7075 chassis?

its just like 6061 to me

 

[Adiabatic]

I was wondering about that like everyone else.
I'm wondering if the aftermarket chassis's are CNC machined and not pressed? I know Arrma chassis are pressed. If so could it make a difference in the outcome of the metal?
IDK...

I speculated in another thread about this:

It came to my attention that the EXB chassis is stamped rather than machined, which with 7075 alloy is usually done at high temperatures or after annealing and then requires the part to be precipitation hardened again to restore the T6 temper. It wouldn't surprise me if Arrma's contractor is using 7075-T6 stock as per the spec, weakening it as part of the stamping process and then failing to re-treat it before final processing (anodizing, laser etching etc.). Annealed 7075 has similar tensile and yield strength to 6061-T6, high temperature stamped 7075-T6 will usually end up with strength and hardness properties somewhere between the original material and annealed 7075, so this could neatly explain why Arrma claims to be specifying 7075-T6 but end users report that it bends about as easily as the RTR chassis (6061-T6) or is only slightly stronger.

If true this would mean Arrma isn't knowingly lying about the chassis materials but what we're getting isn't as advertised. Another possible explanation is that the Chinese contractor is substituting a different grade of aluminum and Arrma isn't bothering to test and verify the composition and strength post-production. This is a company that sends out obviously untested diff upgrade kits with incompatible screws for shipping to customers so that wouldn't surprise me.

 

[N.Mango]

I speculated in another thread about this:



If true this would mean Arrma isn't knowingly lying about the chassis materials but what we're getting isn't as advertised. Another possible explanation is that the Chinese contractor is substituting a different grade of aluminum and Arrma isn't bothering to test and verify the composition and strength post-production. This is a company that sends out obviously untested diff upgrade kits with incompatible screws for shipping to customers so that wouldn't surprise me.

Good point on their QC or lack of.
I hope they get their together.
But then again...its good business for the aftermarket guys.
And good business for the peeps selling take offs.

 

[Engineer]

I speculated in another thread about this:



If true this would mean Arrma isn't knowingly lying about the chassis materials but what we're getting isn't as advertised. Another possible explanation is that the Chinese contractor is substituting a different grade of aluminum and Arrma isn't bothering to test and verify the composition and strength post-production. This is a company that sends out obviously untested diff upgrade kits with incompatible screws for shipping to customers so that wouldn't surprise me.

Working in a regulated industry, material certs, first article inspections, lot sample audits are just the way of life. But alas, these are just toy cars we’re talking about after all….

 

[N.Mango]

Working in a regulated industry, material certs, first article inspections, lot sample audits are just the way of life. But alas, these are just toy cars we’re talking about after all….

I agree with all of it but a big money making TOY company that is risking a bad reputation if they are trying to sell B.S..

I agree with all of it but a big money making TOY company that is risking a bad reputation if they are trying to sell B.S..

I did notice how easily the Arrma chassis flexes while working on my build. I can see how one bad landing would tweak it bad.
Arrma should really step it up if they are seeing how many people are having issues. Toys to some hobby to others. No ones hard earned money should get "stolen" from them.

 

[21STalion]

I think a ribbed chassis design would do wonders to add strength to all of their chassis's.
But I'm sure they are happy with how things are. imho

Yes, I agree. These flat chassis plates are for economy. The molded plastic, while cheap per unit, cost a FORTUNE to make the tooling. The flat metal chassis is what allows Arrma to come out with so many cars - but as a cost savings measure.

I wish some company would make proper chassis, with thinner metal but actual load bearing structures.

Could be far superior

 

[Jerold]

I'm sure there is a materials or mechanical engineer that can explain this better (or maybe correct me please), but I think you would actually be better off with 7075 instead.

The strength of a material is defined by a lot of properties, smashing, stretching, bending, melting, shearing, etc... Where one material is "strong" others may fail miserable. For instance you don't want to make a plane from cement or fireplace from plastic. Each material is strong in different ways.

"A key difference between 6061 and 7075 aluminum is that 6061 contains less zinc as an alloying material. This makes 6061 easier to weld and work, but it also reduces the alloy’s strength and resistance to stress in comparison with 7075. ...

7075 was originally designed for applications, such as aircraft frames, where high strength and low weight are critical."
https://www.industrialmetalsupply.c...5 aluminum contains more zinc that 6061 alloy.

Back to there are a lot of "stress" parameters, but may mean easier to bend.

The real problem with the chassis is the design. It's a flat piece of metal with no vertical support all all. Compounded by the narrowing (least cross sectional area) of the where it mount so the front & rear diffs makes it a good locations to bend.

 

[21STalion]

But man is the chassis stiff with the m2c bottom, m2c chassis braces and any T2T brace. It's crazy stiff. Don't think you can ask for stiffer

 

[N.Mango]

But man is the chassis stiff with the m2c bottom, m2c chassis braces and any T2T brace. It's crazy stiff. Don't think you can ask for stiffer

I bet! I been considering a type of bash bar for my build but its a budget build and its not on the li$t.

I been kinda playing devils advocate since Arrma isnt part of this thread but the proof is around every corner that something needs to be done to their chassis.

 

[milehighspeed]

Could just be the design of the kraton and its bracing concept and dimensions etc…puts too much stress on the chassis. Material can only take you so far if the design doesn’t marry up with it. Which is why I’m quietly rooting for Team Corally. New direct competition in the brasher market creates:

1. more innovation and different ideas (Corally is bracing things very differently)
2. options if you truly feel arrma isn’t up to snuff
3. Forces Arrma to react.

Time will only tell if Corally’s concept on bracing and support marry better with their 7075 chassis, but anybody see the brutal chassis shot Razrc gave the new Kronos right out of the gate? Man, that probably should have ended his day right there and I’d think even if you had M2C you would have been afraid to look at the end result of that hit. So seems like early results are looking good.

Don’t get me wrong, i still appreciate my Arrma cars and don’t want them getting chopped but a little more competition to exert some pressure here and there might be nice.

 

[N.Mango]

Silly example but best I can think of.
Punch the flat part of a car door and you make a dent. Punch the body line of same door and you break your hand.
If truck beds were flat it would bow with each step and pop back out like a soda can. But the ridges make it strong enough to walk on and carry a load without bending.
So yea...a better design is definitely ready to be made but maybe cost of redesign isnt on the table for the company. IDK

 

[SuperFanBoy]

Couple things I think are worth noting. A few years ago Arrma was in a bad way, they were close to closing their doors. A bunch of companies fates were on the chopping block. Hobbyco going under almost took half the hobby with it. So, now with big baller Horizon to help fund all their wants and wishes they are coming out with guns blazing! Most think these things take what, like 4-5 months to design, right? Whats the big deal its just a program and some molds ect lol These take a long time to go from idea to market! Years! obviously if your just making rigs from existing parts thats a diff story but still. At the rate they are growing I'd say they are doing ok QC wise. Not saying no room for improvement but as someone thats ordered from the factories its a never ending problem.

Other thing to note is FLEX isn't a four letter word. Ok maybe it is lol point is, flex is fine, a good thing if your set up correctly. Flexing and bening able to return to original form is a plus. When you make one part with zero flex it transfers the energy somewhere else. Hate to do it but use the XMAXX as an example. some flex is good. thats about all the XMAXX got right lol I think the key is to both absorb some of the impact energy AND transfer it throughout the rest of the RC I've got a chassis that's 1/2" thick 7075 and there is ZERO flex. It's also heavy as balls and not on anything I'm building ATM or even planning on building. Long winded, I know. Bored lol

Silly example but best I can think of.
Punch the flat part of a car door and you make a dent. Punch the body line of same door and you break your hand.
If truck beds were flat it would bow with each step and pop back out like a soda can. But the ridges make it strong enough to walk on and carry a load without bending.
So yea...a better design is definitely ready to be made but maybe cost of redesign isnt on the table for the company. IDK

Yea that it. thats why they put the ridges on the back of the V5 chassis's. Part of this is the long game, keep in mind. the EXB is just in time for a V2 My bet has been we see a new updated design this summer. I think they are going to update the 3s and 4s lineup when the 4s gets flowing again here in June or whatever.

 

[Surchaufeur]

I bended and shrewd the exb hackman plates. My chassis also bended a few times but because of the junk tower to tower brace. Since i got rid of that it never bended again. We can argue its soft and all. But stronger than the RTR ones. Most people don't want to spend 200$ on a chassis also(my currency). Can people heat threat their chassis at home? Is it possible?

 

[slick2500]

I bended and shrewd the exb hackman plates. My chassis also bended a few times but because of the junk tower to tower brace. Since i got rid of that it never bended again. We can argue its soft and all. But stronger than the RTR ones. Most people don't want to spend 200$ on a chassis also(my currency). Can people heat threat their chassis at home? Is it possible?

I found this on a quick Google search

HEAT TREATING
7075 may be solution annealed at 900°F for 2 hours at temperature, followed by a water quench. The alloy may then be given a precipation hardening (aging) heat treatment. Precipitation strengthening (aging) is done at 250°F for 24 hours and air cooled for T6 .

 

[Surchaufeur]

Oof