Lunchbox - 3rd Shock vs. Ampro Transmission Brace

[Pukadon 0]

Has anyone tried comparing the Lunchbox 3rd Shock versus the Ampro Transmission Brace? I'm trying to decide which is the better option.

The Ampro Transmission Brace is 3D printed through Shapeways, and can be seen here: http://shpws.me/MVjN

I'm considering the Ampro brace because it's cheaper and requires less modification. The creators also say it works better. My concern is that 3D printed materials are typically weaker than other plastics. Related to that, there's actually a free version I could print on our Makerbot, available through Thingiverse, but I'm pretty certain that the Makerbot prints are weaker than Shapeways, which have a much higher melting temperature. 

By the way, this is my first Lunchbox. I built it just a few weeks ago and love it. So far I've only done basic mods / hop-ups, like the bearings and adjusting the front suspension to level out the wheels. I'm still using the standard friction shocks. 

 

[Hobbimaster 145]

I happen to have just installed an Ampro brace on my lunchie. I ended up using 3x8 tapping screws to secure it. It does seem to flex ever so slightly by hand, but cannot seem to break it as of right now. I have a Tamiya BZ motor in it, so I figure I would give it a good thrashing before adding one to my pumpkin. So far so good. I wish it came made from Delrin, I would have ordered one of those.

[TheMidnight Pumpkin 160]

I prefer the "pen spring" mod over the third shock, or the brace. (except I actually used copier springs) The idea being each end of the axle housing have a spring to cushion the impacts over unsprung twisting motion like with the third shock. But really its all personal preference....

But in reply to your question. I would go 3rd shock over the brace, so you get some cushioning effect.

[shenlonco 868]

 Fishing string mod for me I found it works best.

 

[matman 1466]

Ampro is a TC member pintopower  . 

So it comes down to budget ! . 

[nowinaminute 2055]

On 8/21/2017 at 4:56 AM, TheMidnight Pumpkin said:

I prefer the "pen spring" mod over the third shock, or the brace. (except I actually used copier springs) The idea being each end of the axle housing have a spring to cushion the impacts over unsprung twisting motion like with the third shock. But really its all personal preference....

But in reply to your question. I would go 3rd shock over the brace, so you get some cushioning effect.

You don't want any movement at all though ideally, with a third shock it only really dampens the slap, it doesn't remove it completely like the pivot. It's still possible for both sides to rise up simultaneously with a third shock which is the whole problem.

[TurnipJF 5364]

As I understand it, the Ampro brace makes the transmission pivot in the same way as it does on the DT-01. As a DT-01 owner, I'd say this is a very good thing. With the brace fitted, all damping duties are performed by the two main rear shocks, which is what they are for after all, and there is no slap whatsoever.

[whahooo 184]

I use a cheap Oilshock that was in my Box of spareparts .

 

I think the 3rd Shock Solution is a good One. The Oilshock cuts the "slap" complete and because of the Oilshock there is a bit of interia.

Also i leave the 2 Little Springs on each end of the axle housing that came with the Lunchbox Kit.

[Saito2 2921]

I kinda did both for mine. I used the 3rd shock but did several things differently. The length of the shock was adjusted to put the pivots are in the center of the slots like the Ampro brace. This allows full articulation from side to side. I also limited the 3rd shock's travel so at full compression, the motor doesn't hit the right rear shock. Other all this gives a little dampening to the slapping but still prevents total rotation. Of course all this is moot because under full throttle, the gearbox's rotational force is constantly trying to extent the rear shocks which limits there ability to compress over bumps.

[shenlonco 868]

I found the fishing string mod in my video above works best,  when you give it throttle it holds the pivot point down and dont let it slap and it also lets it swing side to side full throw, but the best thing about the fishing string mod is when you push the whole gear box up like what happens when you jump and get air the string mod lets the whole rear gearbox push up on the rear and front pivot slot parts so you get full suspension and the bump stop type dont allow this and 90% of guy's using the 3rd shock dont also because they use way to big of shocks in the application when you should be using a 1/18 - 1/16 scale small shock in this area so it fully can compress.

[Saito2 2921]

Honestly, I like the fishing string mod. Without redesigning the whole, flawed system, its simple and works surprisingly well. If a total redesign was in order, at best I see 2 choices. Do it the Tamiya way and make the rear like the DT-01 (Mad Bull, etc.) which works fairly well. The missing factor in the Lunch Box's case is the lay-down shocks which are taken out of the gearbox's natural rotational plane. Second, make some type of 4-link (not easy at all given space limitations) and mimic the suspension found on current mod Clods. Mod Clod guys are at the peak of motor-on-axle suspension development.

[nowinaminute 2055]

On 8/31/2017 at 2:00 AM, Saito2 said:

Honestly, I like the fishing string mod. Without redesigning the whole, flawed system, its simple and works surprisingly well. If a total redesign was in order, at best I see 2 choices. Do it the Tamiya way and make the rear like the DT-01 (Mad Bull, etc.) which works fairly well. The missing factor in the Lunch Box's case is the lay-down shocks which are taken out of the gearbox's natural rotational plane. Second, make some type of 4-link (not easy at all given space limitations) and mimic the suspension found on current mod Clods. Mod Clod guys are at the peak of motor-on-axle suspension development.

Agree completely. DT-01 sort of managed to make a silk purse out of a sows ear and works pretty well but multi link is the true path to making a solid axle work well, even on my cheap Chinese FY03 the suspension articulation is fantastic with no locking up under power. 

Space is the main obstacle as you say, especially if you intend to keep the axle spacing the same. It has been done though. The actual procedure isn't all that difficult, some rods and ball links is all you need really, just a case of getting the dimensions right and finding sturdy areas to mount them. When I inevitably get a Lunchbox I will definitely try it. I also want to try it on one of my Nikko "HAWG" type trucks, they also have solid axles although they work a little better thanks to the box being mounted on long arms like a Marui Big Bear and also the front axle is also powered as it's twin motor and it tends to push the rear down under acceleration and helps to cancel out the effect of the rear end wanting to lift up. It still definitely stiffens up at the rear under power though.

[novicelad 784]

Here is my incredibly crude fix, don't care what it looks like it fix's the issue.

[Tamiya80sBuggyFan 14]

I have a Hornet that iv brought all the AmPro 3rd printed front and rear suspension upgrads for. And iv also tried the the 3rd shock mod using a Sand Scorcher re-releae dampers fitted upside down with a cut down Hornet front spring added and using Tamiya Yellow dampering oil. And when compared to AmPro transmission brace also with Super Hornet rear inspired shock mount.  I would say the results in a straight line on grass at full speed are about the same. There is still a lot of little up and down movement in the back. A lot better than stock but it's still can not absorb ruts in the ground at high speed like my Tamiya Wild One does. Iv had no problems with strength of AMPro 3d printed parts. I would even say they are near unbreakable on grass and mud. Maybe if you run in to something hard at full speed it would brake. But iv flipped and rolled the Hornet countless times on grass and mud and it's always been fine. But one good thing I will say about the  3rd shock mod over the AmPro transmission brace. If you sent the spring hight tension and oil thickness just right. So that spring is just about pressing the rear transmission down to the end of its travel when the spring is at its resting position. But the spring still lets the rear axel move side to side buy compressing the spring. I found my Hornet could corner faster without rolling over as often. As the 3rd shock mod can me set to work like an anti roll bar if you get the spring tension and oil thickness just right.

[Kingfisher 1162]

20 hours ago, Tamiya80sBuggyFan said:

Maybe if you run in to something hard at full speed it would brake. 

 

Feels bad man. 

[khyzersoze 264]

I wonder for parts like the arms... if it'd be better to take the 3D printed part and try to wrap it in some kind of fiber like carbon fiber or fiberglass.... then epoxy it in hopes of increasing its strength.

[Kingfisher 1162]

4 hours ago, khyzersoze said:

I wonder for parts like the arms... if it'd be better to take the 3D printed part and try to wrap it in some kind of fiber like carbon fiber or fiberglass.... then epoxy it in hopes of increasing its strength.

If you look in my pic on the other arm, that's how I repaired it. Epoxy and fiberglass cloth. After I did it, I said to myself "This will never break in the same spot again".

...Then, my girlfriend destroys the other arm. 

[Country Mike 117]

Theres this guy on youtube, cr_lintow with a stretched lunchy tub and hes got a 4 bar setup on the rear transmission. I wonder if anyone has looked into it? Be ace to have versatility.

[Kingfisher 1162]

2 hours ago, Country Mike said:

Theres this guy on youtube, cr_lintow with a stretched lunchy tub and hes got a 4 bar setup on the rear transmission. I wonder if anyone has looked into it? Be ace to have versatility.

I acquired some M3 threaded rod, and an extra gear box to chop up with intentions of trying to make a 4-link setup for the Lunchbox/Pumpkin. Then I found the Ampro trans brace and that idea got put on hold. If I break one of the trans braces, I plan to revisit this idea.

[Saito2 2921]

I typed 4 link Tamiya Lunch Box into Youtube and saw a nifty idea for eliminating the lack of available space for a 4 link. This enterprising fellow simply turned the gearbox around (and cut off the original mount pivot). With the motor hanging out the back, there's plenty of room to make a 4 link. Furthermore, it puts the shocks in front of the rear axle line which is how all top mod-Clod guys do it now.

[Kingfisher 1162]

17 hours ago, Saito2 said:

I typed 4 link Tamiya Lunch Box into Youtube and saw a nifty idea for eliminating the lack of available space for a 4 link. This enterprising fellow simply turned the gearbox around (and cut off the original mount pivot). With the motor hanging out the back, there's plenty of room to make a 4 link. Furthermore, it puts the shocks in front of the rear axle line which is how all top mod-Clod guys do it now.

Found it. Thanks. Looks like it works quite well.

 

https://www.youtube.com/watch?v=ymPvXAfGxic

[GregM 1099]

I had the 3rd shock, before I moved on to the Ampro brace. I like the latter more than the former. It's simple and efficient.

[shenlonco 868]

Fishing string is your friend and works best 

[smirk-racing 120]

On 9/15/2017 at 11:11 AM, Kingfisher said:

Found it. Thanks. Looks like it works quite well.

 

https://www.youtube.com/watch?v=ymPvXAfGxic

Awesome find - not an easy video to locate... but what an interesting mod.

 

I have a 4-link setup on mine too, although without flipping the gearbox. What do you think the change in weight distribution does to the handling? I run a brushless motor so I have to work hard to tame the wheelies as it is. With the motor further out in the back I think the problem would be worse, although the rotation of the motor would change as well, so maybe it would be a wash.

[Kingfisher 1162]

My guess is that wheelies would be even easier, and handling would remain about the same, or not make that much of a noticeable difference, though it may get tail happy on non-grippy surfaces like gravel at higher speeds. But, that's just a guess. Only one way to find out though. 

Got any pics of your 4-link setup? I'm curious to see.