Digging deeper into the Rocker posts/rod ends/ shock shafts

[PPS-RC]

Bear with me. This is just what I do. I like finding problems and solutions.

So I am here with my Big Rock and am closely looking at the suspension. I've yet to break anything, but I think understand why I will.

There is a clearance issue with the rocker arms, and the lower spring retainer on my truck. it creates what I'm calling a "Stress Triangle". I over and under explain my theory in this poor quality video.

One temporary quick and easy free fix will be to make sure your lower spring retainer is oriented with the split in it between the "rocker arm plates" (I'm making this up as I go). this may allow the retainer to flex in a binding situation.

This may be enough, but it will wear on your spring rests. also, there is still no guarantee this will help you at all. it's just an idea.

Also, a not free or easy fix would be to redesign the rocker arm with clearance. this may require a metal arm, as you're cutting really close to that bearing.

Once you get rid of that bind, you're next limit is going to be the shock bottoming out, and that is typical for every other RC without mechanical limits.

To add limit straps to your truck isn't straightforward. there a bunch of ways to do this. the easiest way would be to remember this is a toy, and it's not that serious.

If you're like me and can't get past that, I have a couple ideas regarding limit straps that would be to tie them to the bulkhead screws, or making a custom bulkhead plate with strap mounts.

The only problem with either of these options is that it still puts stress on the rocker arm shaft.

My last idea is a rocker arm tie brace with built in adjustable limiters. This is not an easy or quick fix, but I might make this anyway as a fun project once I get my mill running again.

I'll keep thinking about this, but would love to see everyone's thoughts or ideas.

 

[WoodiE]

@Havoc, thanks for sharing this man. After seeing this video I'm really surprised we're not seeing a lot more busted shocks!

 

[PPS-RC]

@Havoc, thanks for sharing this man. After seeing this video I'm really surprised we're not seeing a lot more busted shocks!

It explains why a lot of the shock rod end failures look like they've been twisted/bent.

Overall, the plastic Arrma uses is pretty awesome. it's just rigid enough while being flexible. plus they built in some key "flex zones" to capitalize on it. This one detail had to have been overlooked, and that's honestly easy to do with a new and unconventional system.
If you were to move the shock mounting position on the chassis to the inner most hole (currently on the outermost) I bet it wouldn't bind. That was likely the position it was originally engineered to be in.

it just sucks that doing so will make your suspension more firm and less progressive. (It'll be like making a conventional shock more vertical).

I picked up some spare rocker arms, maybe I'll clearance mine for the lower spring retainer and see how it holds up. If all else fails... well I have spares.

 

[Maxxwrecker07]

Has anyone looked into Revo/Summit rockers? I imagine the gap between the "plates" is too small for the shock end and push rod, but they have that relief built in and might just work...

For what it's worth, I've moved my shocks to the innermost position for just the reason Havoc mentioned. It also aligns the shock better for hard impacts... while taking away the progressive nature... all things have trade-offs, unfortunately. I will say one thing though, nothing I've ever owned rc-wise will ever compare to the engineering marvel this thing is! Almost every aspect was thought out and executed. Other than a few stripped (12.9 grade!) screws due to GOBS of threadlocker I've had no issues whatsoever!

Another thought; has anyone that failed the rocker posts or push rod ends had failed rocker bearings as well? Mine collect dirt badly and I could see the seizing up pretty easily.

 

[Cheez]

Bear with me. This is just what I do. I like finding problems and solutions.

So I am here with my Big Rock and am closely looking at the suspension. I've yet to break anything, but I think understand why I will.

There is a clearance issue with the rocker arms, and the lower spring retainer on my truck. it creates what I'm calling a "Stress Triangle". I over and under explain my theory in this poor quality video.

One temporary quick and easy free fix will be to make sure your lower spring retainer is oriented with the split in it between the "rocker arm plates" (I'm making this up as I go). this may allow the retainer to flex in a binding situation.View attachment 3770

This may be enough, but it will wear on your spring rests. also, there is still no guarantee this will help you at all. it's just an idea.

Also, a not free or easy fix would be to redesign the rocker arm with clearance. this may require a metal arm, as you're cutting really close to that bearing.
View attachment 3771

Once you get rid of that bind, you're next limit is going to be the shock bottoming out, and that is typical for every other RC without mechanical limits.

To add limit straps to your truck isn't straightforward. there a bunch of ways to do this. the easiest way would be to remember this is a toy, and it's not that serious.

If you're like me and can't get past that, I have a couple ideas regarding limit straps that would be to tie them to the bulkhead screws, or making a custom bulkhead plate with strap mounts.
View attachment 3772

View attachment 3773

The only problem with either of these options is that it still puts stress on the rocker arm shaft.

My last idea is a rocker arm tie brace with built in adjustable limiters. This is not an easy or quick fix, but I might make this anyway as a fun project once I get my mill running again.

I'll keep thinking about this, but would love to see everyone's thoughts or ideas.

The triangle is natures strongest design, that's why it's so common in engineering, from bridges and skyscrapers to toys. Hard to improve on. You seem to be on the right track, good luck with your ideas.

Bear with me. This is just what I do. I like finding problems and solutions.

So I am here with my Big Rock and am closely looking at the suspension. I've yet to break anything, but I think understand why I will.

There is a clearance issue with the rocker arms, and the lower spring retainer on my truck. it creates what I'm calling a "Stress Triangle". I over and under explain my theory in this poor quality video.

One temporary quick and easy free fix will be to make sure your lower spring retainer is oriented with the split in it between the "rocker arm plates" (I'm making this up as I go). this may allow the retainer to flex in a binding situation.View attachment 3770

This may be enough, but it will wear on your spring rests. also, there is still no guarantee this will help you at all. it's just an idea.

Also, a not free or easy fix would be to redesign the rocker arm with clearance. this may require a metal arm, as you're cutting really close to that bearing.
View attachment 3771

Once you get rid of that bind, you're next limit is going to be the shock bottoming out, and that is typical for every other RC without mechanical limits.

To add limit straps to your truck isn't straightforward. there a bunch of ways to do this. the easiest way would be to remember this is a toy, and it's not that serious.

If you're like me and can't get past that, I have a couple ideas regarding limit straps that would be to tie them to the bulkhead screws, or making a custom bulkhead plate with strap mounts.
View attachment 3772

View attachment 3773

The only problem with either of these options is that it still puts stress on the rocker arm shaft.

My last idea is a rocker arm tie brace with built in adjustable limiters. This is not an easy or quick fix, but I might make this anyway as a fun project once I get my mill running again.

I'll keep thinking about this, but would love to see everyone's thoughts or ideas.

Are you thinking of something like this?
http://www3.towerhobbies.com/cgi-bi...FY70cMlRaLDXSQMDI64ypdQkeIAxM6nhGjRoCkjzw_wcB

 

[Julian]

Guys - Manys rc garage on you tube addresses this specifically and the remedy is - from my cloudy memory a specific I think..... team associated shock end to replace the stock. The end is way more protected in a big way ........ just search big rock review on you tube - oh yeah dude has a crazy heavy accent - just bear with him......

 

[PPS-RC]

Has anyone looked into Revo/Summit rockers? I imagine the gap between the "plates" is too small for the shock end and push rod, but they have that relief built in and might just work...

I have not tried the Revo rocker personally. I know there has been mention of swapping the rocker posts for strength.
My only issue with swapping the rocker is that depending on it's ratio, you could drastically affect the way your suspension works. it may not be a bad change, but it may also have undesirable effects.

Are you thinking of something like this?
http://www3.towerhobbies.com/cgi-bi...FY70cMlRaLDXSQMDI64ypdQkeIAxM6nhGjRoCkjzw_wcB

Those look pretty awesome! they would need to be adjusted, but for $5 it's a deal just to not have to make the bracket ends. I really need to stop seeing things I want the day after placing my order.

Guys - Manys rc garage on you tube addresses this specifically and the remedy is... team associated shock end to replace the stock.

The Associated ends might be secretly fixing this problem. I say secretly because people have only been swapping them because they are "stronger" or "thicker". But if they are longer than stock, they would push that perch more away from the rocker, creating that clearance. If they are not longer, the pinch point will still exist, and your still putting that stress onto the shock shaft and rocker post.

I know my truck is basically brand new still, but I did notice something interesting and it may be strictly a coincidence. From the factory, 2 of my spring retainers were lined up like I mentioned, allowing flex. The other 2 were not. the 2 that were aligned in the manner where the retainer could flex, do not squeak. the 2 shocks with the pinch point do squeek. I know they all will end up making the noise, but I found it interesting those two started making it first.

A small side note about longer rod ends. Yes they will fix this problem; but may create another. I'm trying to figure out how to explain it.

In a fine tuning situation, for people jumping huge or running close to the ground, you're going to be compensating for that extra length. In essence you're shortening your shock body because your shock shaft will be higher in the shock at the same ride height. depending how much higher, may lead to popping shock caps.

The stress triangle pinch point may not be that serious. if you increase the strength of the parts in that area beyond the stress levels that could be generated you'll never break it. That solution may be as simple as Associated rod ends and E-revo or reinforced posts. I think at the end of the day, that's all that matters.

I just personally like finding potential root cause of things.

 

[PPS-RC]

This is interesting. I opened my spare rocker arms to check them out, and they are pre-clearenced stock, just not enough.

 

[WoodiE]

This is interesting. I opened my spare rocker arms to check them out, and they are pre-clearenced stock, just not enough.
View attachment 3809

I'm curious to see how the stock and GKA (@gregmbrandt) aluminum rockers compare.

 

[Cr3pitus]

So here is a comparison of the stock rod ends to the team associated 89077 I replaced them with. As you can see it's significantly thicker and has bulk reinforcement at stress areas. I think it's important especially for the top rod ends because they take more multi directional stress than the bottoms, which are basically an attachment point for a two dimensional lever. The top ones are torqued more than one way. I'll keep reporting in as I do little tweaks. Great delve into the design of the cantilevers themselves.

 

[PPS-RC]

I'm curious to see how the stock and GKA (@gregmbrandt) aluminum rockers compare.

From the pictures of the GKA rockers that I've seen, this has not been compensated for, however he did implement mounting options that may negate the need. overall I like his design.

So here is a comparison of the stock rod ends to the team associated 89077 I replaced them with. As you can see it's significantly thicker and has bulk reenforcement at stress areas. I think it's important especially for the top rod ends because they take more multi directional stress than the bottoms, which are basically an attachment point for a two dimensional lever. The top ones are torqued more than one way. I'll keep reporting in as I do little tweaks. Great delve into the design of the cantilevers themselves.

Fantastic shot! makes it super easy to see just how huge they are in comparison.

I do have a pack of those rod ends on order (Tower only had one in stock)

Also, I think I've been thinking of things wrong. People have been breaking the shock rod ends and the pushrod ends. are they only using the associated parts on the pushrod?

Honestly, for myself, what got me back in the game was tooling around with my fathers Summit. I was super impressed with it's cantilever suspension, and it's lockable diffs (sound familiar?) then the Nero popped up. I pretty much bought this for its suspension. All of my desired suspension features are here and I'm super excited to tweak it. Firstly, I want to make it stay together.

 

[Cr3pitus]

Here is the bottom of the rod end. It's a tight fit. Didn't have to shave it down to make it fit but you gotta push to get it in and use the small pivot ball that's supplied with the 89077 pack. The ball still fits over the a arm screw so it's money! I heard of some people replacing the end of the shock but it looks fine to me so I'll probably just do the rod ends between the cantilevers and the a arms

 

[Trigeminal]

So here is a comparison of the stock rod ends to the team associated 89077 I replaced them with. As you can see it's significantly thicker and has bulk reinforcement at stress areas. I think it's important especially for the top rod ends because they take more multi directional stress than the bottoms, which are basically an attachment point for a two dimensional lever. The top ones are torqued more than one way. I'll keep reporting in as I do little tweaks. Great delve into the design of the cantilevers themselves.

Hey buddy, looks good! I ordered the parts and will do the same...

 

[Cr3pitus]

Hey buddy, looks good! I ordered the parts and will do the same...

Nice!
It'll be awesome to see how it helps with durability.
I also did this as a prototype this afternoon.
https://m.imgur.com/a/SimGf
Diy suspension limiters I've been thinking of but decided to try because of this thread. These are just my prototypes to see how the work and see if I like the location. If I do I'll sew a strap with a loop in it. I added screws to each a arm in the hole already there for the mud guards and then tied that screw to the front bumper screws for the front suspension and made a friction lock in the aluminum body's slot in the rear.

 

[Cheez]

Designed from the ground-up by experts who understand the importance of strength, speed and incredible value, ARRMA vehicles are ‘Designed to be Fast, Designed to be Tough’.

 

[Cr3pitus]

Lol. I mean I still think this is a pretty tough car. I broke mine on a pretty big and poorly landed crash from a jump. I can't blame the engineers for that. I've broken my mini e Revo on much smaller crashes and it doesn't weigh anything

 

[Cheez]

Been there,done that.
It's all about the finger on the trigger!
Getting our fat fingers into tiny parts is as much fun as watching the demolition.
Our triumphs and failures keep us and those engineers busy.

 

[Josh nortz]

https://arrmaforum.com/threads/nero-rocker-arms

 

[blumully]

Hello everybody,
I´m new here because I have the same problem:
One of the rear Shock Shaft of the Nero broke at the end of the thread for the second time. But only at one of our two cars.
The only difference between our Neros: the green one has improved Shock holder (AR330338). That could be the reason why the Shock Shaft is broken because there is not enough flexibility.
Fact is: the only reason why the Shock Shaft is broken -> sideways forces which are not allowed.

@Havoc, thank you for your picture of the rocker arms, and the lower spring retainer.

I have also the possibility to create my own rocker arms (Aluminium) to be sure that there is enough space between spring retainer and rocker arms. Are there any other requirements which must be considered?

Sorry about my unprofessional english, I´m german.

 

[Cr3pitus]

I noticed these shocks are 16mm wide, as are many aftermarket shocks, and as the team associated rod ends fit on the truck, I'm wondering if they have an aluminum shock cap that will thread on our shocks. It would be epic if they did because then the remaining weak point would be on the shock rod end, which to me is a much more preferable point of failure since you would just have to replace the shock rod end which is super quick, and doesn't result in a disgusting bajillion gallon shock oil mess. A plastic point of failure is definitely necessary, especially on a truck this heavy. I would just it to be at that point in the suspension instead of on a messy end.