[WIP] RC Chassis V6

[z3_2drive]

Hello! I haven't received my last bulk order from Canada so I'll go ahead and start the WIP topic as the model stands now. I have finished the rear axle and won't make any changes until I see fit. The difference between this version compared to the previous 5 is that I want to attempt more complex suspension systems while still retaining enough strength for the speeds seen with my V5. The drivetrain is different in order to accommodate the rear suspension. 4 Buggy motors driving a 40 tooth gear from the slower output, which drives a modified 4L differential that I've had for a while-it can handle more torque. Photos:

It can be locked but I used the driving ring as more of a spacer.

I used pneumatic cylinders with Lego springs inside similar to nicjasno's large scale builds. It might be too stiff but we shall see.

This version has the sturdiest construction with no chassis flex, and I'll try to keep it that way with a mostly studded frame.

I limited the travel so it won't scrape too easily, and the unequal length arms allow for gradual negative camber.

If you haven't noticed, the rear is an even stud length rather than the odd length I usually work with, so I had to use some odd pieces to get the desired features.

Like I said in another topic, I made sure the rear suspension used nicjasno's custom hubs, and this is the simplest and strongest idea I came up with.

Very unusual building techniques were used, but I'm very satisfied with the result. I might have to reinforce some elements later on.

Everything is snug, with no room to spare.

Hope you all like it so far, the next update should be when the frame starts to take shape.

Another note: only a few pieces were modified, which upsets the ancient purist inside me, but I promise I will avoid mangling parts as much as I can

[VKTechnic]

Looking good already!

[jorgeopesi]

Ouch... I am too much purist for this MOC...

[Boulderer]

Do I spy a crack in one of the components, in the final picture?

[z3_2drive]

Do I spy a crack in one of the components, in the final picture?

Yup, in this: For some reason I find that a majority of these are cracked, in that particular spot, without having any stress on them. None of the similar axle & pin connectors have this issue. Perhaps this is a common defect where simply putting axles through them cracks the thin plastic over time?

[piterx]

ehehe i'm expecting another epic fast thing :D

you know what? you should try to build a crawler with that power so it can climb and it can run as well...it could me sick!

[dropship]

Did you cut the differential?

[hrontos]

With 4 buggy motors it going to have a monster power. Looking forward to see it driving.

By the way what are those gray parts with 3+3 pin holes seen on this picture:

Edited August 9, 2014 by hrontos

[Black-Build]

By the way what are those gray parts with 3+3 pin holes seen on this picture:

They are from Bionicle Visorak's if I'm right, but i don't know the number.

[hrontos]

They are from Bionicle Visorak's if I'm right, but i don't know the number.

Thank you. You are right, it is part number 50904

[z3_2drive]

ehehe i'm expecting another epic fast thing :D

you know what? you should try to build a crawler with that power so it can climb and it can run as well...it could me sick!

I did try a prototype trial truck with this system at the same time Sariel was working on his own quad-motor truck...the extra power mine had proved to be too much for certain gear combinations, but the potential is crazy indeed. I think I'll give it another go after this project!

Did you cut the differential?

To purists' horror, I did. I've had this differential laying around for a year since I found the idea on Brickshelf - a small hole is drilled in the center on each side so a Lego bar/light-saber piece can be pushed through, allowing for 2 rather than 1 bevel 'spider' gears. I figured this model might need it to avoid breaking any 12t gears. The current weak links are the u-joints. They're best Lego can offer, but in the event of a crash or constant stop & go motion they will be in danger.

Thanks for helping each other identify the bionicle chest pieces The other rare pieces I used are the dark bluish gray Bionicle Torso sections.

[Rishab N]

Great work. This is going to be fast

[z3_2drive]

I'm back with a lot of progress and changes! I now have a rolling chassis and the next step is steering. I made a rugged chassis and a double wishbone front suspension based on nicjasno's design, but with many changes and improvements in strength. I passed a large hurdle, but the steering is killing me at the moment

Some differences from the idea I originally had in mind:

• Lose the Super Street Sensation wheels, replace with Chrome 42000 wheels.
  
• Slightly shorter chassis
  
• Almost fully studded frame, even in the front on the vehicle.
  
• Might allow more travel in the rear.
  
• Simple rollcage around electronics box (to come)
  
• Grease rear hubs
  

Here are the photos:

The proportions are closer to an RC car rather than a real vehicle, but hey, what am I building?

This is why I might increase clearance at the rear, but that would mean risking the U-joints...

This is a tough build when it comes to combining studded/studless dimensions.

^The beginnings of the rollcage which will strengthen the whole car.

^I had large plates, so I thought 'what the hell' and stuck em on. Also, looks may be deceiving, but the front and rear axle width is the same.

It makes for a lot of weight, but as a result there is minimum chassis flex.

^Nice chrome wheels from ChromeBricks. The suspension has kingpin inclination, unequal wishbones, positive caster, anti-dive, and Ackerman steering.

The rack is just temporary, because getting it perfect is a complete pain in the megablocks

^This is what I'm most proud of-at first I had no clue how I would implement the large cylinders between the wishbones, and then I thought 'Why do I have to?'. Luckily the width of the vehicle turned out to be perfect, accompanying the two cylinders in a very aesthetically pleasing manner. And to someone who loves suspension like I do, watching the compression is absolutely wonderful...I should make a gif

If you have a spare 32L axle, stick it on your MOC to make it look like an old-fashioned RC car!

My next update should be here once I figure out the damn steering. At the moment the perfect rack length adds up to 19.5 studs Wish me luck!

Edited August 13, 2014 by z3_2drive

[Black-Build]

Holy ****, that chassis looks strong man! I dont hope its getting to heavy...

About the steering, I'll wish you luck.

[MajklSpajkl]

Hi, I feel a bit cuckoo about the cylinder suspension. I've seen it a couple of times and automatically concluded, that it has to be based on hydraulics - like the exit hole is shut forming a closed chamber of air. Now i see that it is actually a spring inserted inside . Do you know where can I find more about this mod?

Thanks

[Bzroom]

Hi, wow that's a beast. I dont see any anti-dive though. It actually appears to have "increased-dive" geometry in the front, and no dive or jack resistance in the back. Also it looks like your steering arms are too equal length and parallel for ackerman. You also appear to have a significant bump steer. Sorry for the strong critique. I love suspension too.

Fortunately your ackerman and bump will be affected by your final rack design.

Those cylinder mods make me cringe :(

To achieve the anti-dive in the front, you'll actually want the top wishbone tilted forward in the front (yours is tilted backward). You'll still want to retain the aft positioning (for caster), but just reverse the tilt of the top. (or bottom).

You want braking force, when draw from the contact patch to the CG to have a parallel line with the wishbones for ant-dive. Your force from contact patch to CG is closer to perpendicular which will have a significant dive affect.

Edited August 14, 2014 by Bzroom

[z3_2drive]

Hi, wow that's a beast. I dont see any anti-dive though. It actually appears to have "increased-dive" geometry in the front, and no dive or jack resistance in the back. Also it looks like your steering arms are too equal length and parallel for ackerman. You also appear to have a significant bump steer. Sorry for the strong critique. I love suspension too.

Fortunately your ackerman and bump will be affected by your final rack design.

Those cylinder mods make me cringe :(

To achieve the anti-dive in the front, you'll actually want the top wishbone tilted forward in the front (yours is tilted backward). You'll still want to retain the aft positioning (for caster), but just reverse the tilt of the top. (or bottom).

You want braking force, when draw from the contact patch to the CG to have a parallel line with the wishbones for ant-dive. Your force from contact patch to CG is closer to perpendicular which will have a significant dive affect.

Ah, I have that wrong? Well it's good to check. I'll make adjustments. Steering is far from final and it's what I have planned, yes. Bump steer is there because of the improvised rack I have just sitting there for now. The cylinder mods...it hurts to remove the inlets, but the dampening+spring action really helps when it runs! I'm still strengthening everything in the front as well as removing as much weight as possible because it struggles in acceleration. I predict the final weight to be 1.6 kilograms. The rear has no complex geometries for the sake of strength, but I could whip something up if it helps. I like critiques, keep 'em coming because this is in alpha stage

EDIT: About the cylinders, You carefully pry open the black caps with thin pliers, pull out the cap/rod assembly, remove the top (there are 3) rubber washer and place the remaining two back in. Take the spring from a 9.5L extra-hard shock absorber and place it in the cylinder, followed by the rod assembly. Snip the inlets for room in your suspension/air flow. I got the idea from others who have done this modification, but I don't think anyone has explained how it's done. And about anti-dive, I'm still learning about the many angles involved, but I do recall this this.

Edited August 14, 2014 by z3_2drive

[Bzroom]

You're right, there's quite a bit of conflicting information. It helps to really understand the forces at play and make your own decision:

http://www.autocrossitalia.it/autosprinttecnica5.JPG

http://forums.pelicanparts.com/uploads5/Anti+Dive1111185104.jpg

http://www.team.net/TR8/tr8cca/wedgemath/04_anti_dive/anti_dive_html_70debd78.jpg

http://motorsportrants.files.wordpress.com/2012/01/diveanti1.jpg

The idea of anti-dive is to not have braking force cause suspension compression. The easiest way to do that is to ensure that your braking force (from contact patch to CG) is as close to perpendicular to the suspension as possible. You can imagine if it were parallel to the suspension, then all of the braking force would go into the suspension and there would CRAZY dive.

[z3_2drive]

Interesting, thanks for the info. I'll see if I can make my own diagram. Considering the stiff and high clearance setup in the front, maybe such forces wouldn't be a problem? I definitely want to keep the caster as is, though. The most important issue at the moment would be the rack.

[Bzroom]

All these advanced suspension techniques are definitely overkill for lego. EXCEPT: bumpsteer. You will notice bump steer when RC-ing around.