Gauging interest: Greyscale Racing MR-CG chassis

[color01]

Latest update 11/04/07

Introducing the MRCG: A pan chassis aimed at open-class racers who need a lower CG, more responsive handling, and more tuning options than a standard Mini-Z.

(RM prototype pictured, final car will have bespoke MM motor mount)





This Mini-Z MR02-based chassis has the following design features:
- MM configuration for agile handling
- Narrowest battery configuration possible to increase responsiveness
- Long flex-plate suspension similar to Mini-Z F1
- Compatability with many rear suspension configurations: side springs, tri-shock system, disk damper, oil damper, or any combination of those
- Battery pack placed far more rearward than in Mini-Z MR02
- Adjustable weight bias by shifting battery pack fore and aft
- Electronics plate cinches down on any AAA or lithium-polymer pack that fits
- Front end allows ride height to be adjusted fully independently of spring preload and front end maintenance without kingpin removal
- Thin fiberglass tierod and electronics plate, minimal hardware used in order to keep chassis weight low
- Compatability with many servos and electronics packages
- 98mm wheelbase

Parts included:
- G10 fiberglass chassis pieces: Main chassis, Front lower bulkhead, 0°, -1° and 1° tierods, Electronics plate, Rear body/damper mount, Body mount clips (2), Flex plates (2), Rear pod bottom plate, Rear pod top plate (for disk damper), Rear pod top plate (no disk damper)
- Delrin pieces: Differential height adjusters (for rear pod; 4 settings)
- Aluminum pieces: Rear pod left and right side plates
- Hardware: Stainless steel screws and nuts

Additional parts required:
- Mini-Z MR015/02 front knuckles, kingpins, springs, spring perches, c-clips, rear ball differential
- Mini-Z MR01/015/02 wheels, tires, bearings
- Micro servo (no wider than 23mm), servo saver
- Receiver and ESC (or combo), compatible transmitter
- Mounting tape for electronics
- 130-size motor, 48dp 2mm shaft pinion
- Battery pack
- Body

Optional parts:
- Extra MR02 front springs and spring perches (for rear end tuning)
- Atomic RM DPSII spare parts set (includes the 3 plastic shock assemblies and 4mm ball nuts)
- Atomic RM DPSII spare spring set
- Atomic AR-071 4.1mm ball nut (for the 3 plastic shocks)
- Disk damper post, friction disks, springs (Atomic, PN Racing, etc.)
- Small 2mm washer (for disk damper)
- Kyosho MR015/02 oil damper or equivalent

Rear end options:
- Side springs (adjustable preload via threaded nuts)
- Side plastic shocks
- Center plastic shock
- Disk damper
- Oil damper
- Any combination of the above


The MRCG was intended from the start to be a versatile, durable chassis, which explains the KISS design and the preference for using adjustable rather than fixed standoffs and mounts. The rear suspension was designed to give the user full tuning freedom; with no other chassis are mounting points for extra springs, shocks, and dampers so readily provided. The front suspension employs two stacked fiberglass pieces to hold the kingpin, but these pieces are stacked underneath the knuckle to allow easy maintenance without extra disassembly. Part functions are doubled by design -- the servo strap is the tierod mount, the battery strap is the electronics plate, etc. -- to keep construction simple. All this amounts to an lightweight, stiff, easy-to-maintain chassis that you'll appreciate every time you visit the track.

[pchan0]

I'm in for one!

Wow! that looks really cool. I like it even more thyan the pro-z chasis.

[color01]

Thanks guys; I also should mention that if there is a lot of interest I will do an MR015-width front end and caster option parts for both widths. I will, if I can find time, CAD up an approximation of the tri-shock system to give a better idea of how the final product will look.

(Off topic note to pchan: check your email please. Thanks!)

[byebye]

I'm interested. Put me down on the pre-order list.

-Byebye

[color01]

Noted, thanks byebye.



An approximated and highlighted damper system (obviously the real stuff is black). Shims will be provided, and can be used to alter the behavior of the springs.

[mini-z]

Very nice c - fancy selling them in the Shop here? Email me if so!

[color01]

Absolutely, but I need to put a few kits together first as a quality check. If the offer still stands in a few months, I'd love to have it sold here at the shop. Many thanks to you and arch2b.

[color01]

Here are the final pre-production renders: the servo, batteries, kingpins, knuckles and motor mount are for reference only and not included in the actual kit.

[byebye]

Looks great so far. I have a couple questions.

Will there ever be a tri shock for an MM pod?

And the front where the front clip attaches, it looks adjustable. Is it possible to include a top and bottom plate to sandwich the front clip? I've lowered a couple bodies in the past place shims between the chassis and the clip and found it was lower but could snap easily.

-Byebye

[color01]

I've been doing a lot of thinking about the same idea (when I am supposed to be doing my schoolwork...heck, it's 3AM over here). A compact, rigid disk damper + tri-shock system with a standard MM pod is just plain hard to do. There is one way I could envision it, but it involves the 3racing motor pod, and IMO that's not a great motor mount for serious racers. Any other way would involve a triangular mount held on by one screw, and that's not as reliable a solution as I would like. I might be able to make some parts that bolt on to the t-plate, but then there's the issue of that t-plate flexing in unwanted ways. So I'm pretty stumped with regards to an MM equivalent of what I've designed here.

If you have any ideas I'll definitely note them, but I think you also implied the question of whether or not I can create an MM car; the answer unfortunately is no, at least not in the near future. If I kept to my same design goals, it would be totally different from the RM car. Battery layout and the entire rear suspension would need to be changed, and right now I only have the resources to produce one product. Sorry.

As for the front clip: did you snap the clip or the chassis where it holds the clip? I'm probably missing the point here but I don't see how an additional CF bar is going to save the front clip in a high speed crash. I originally planned on the body clip being mounted on top of two nuts, a few shims, and then two more nuts which anchor everything together. If the front clip breaks that easily... I don't really have an answer, save for alloy or custom-made CF clips.

[byebye]

http://shop.tinyrc.com/product.php?p...cat=367&page=1

The pics aren't the best but it's the Atomic LCG motor mount. PN makes one as well but without the height adjustable bearing cups. This motor mount uses the same type of connection between dps and mount as your design but is an MM pod.

What I meant about the front clip is when you secure one to a stock chassis there is two screw holes, two pins and it is secured to the chassis with a solid connection. There is minimal movement up and down because it is attched under the chassis.

In your design the clip does not have a top or bottom plate to keep it from moving up and down. But of course until you have built it we won't know if it is an issue.

Either way I think you are doing a great job.

-Byebye

[color01]

I have that MM pod too. But it illustrates the point I tried to get across, that I would have to make a triangular adapter piece for three shocks, working against each other, that could at any time twist the adapter piece around and screw up the handling. I might be paranoid but I would like to stay away from it, even if many other open-class cars use it.

The front clip is secured tightly as far as my design goes, I don't think that will be an issue.

I read through the Pro-Z thread and all the troubles Scott had with getting his product out... I'm going to do my darn best to keep up communication with everyone, and hopefully, with less custom machined parts (all the metal hardware is standardized) and a reputable CF machinist (Dragonplate), everything will fall into place as I want it to. I've emailed all the companies I'm relying on for parts, and most have been quick to respond.

[arch2b]

would you like me to add an 'ask greyscale racing' forum? this owuld give you a public support forum if you want.

[color01]

That would be great! But I don't think it should be added till the product actually exists.

Mini-Z: I have emailed you from the profile link, so please check and tell me what you think. Thank you so much for the offer!