Greyscale Racing MRCG, Summer '07

[color0]

Introduction
The MRCG project was intended from the very beginning to create the most effective chassis to ever compete in 1/28 RC car racing; to be a user-friendly, versatile machine that maximizes the driver’s potential on any given track. Based on Kyosho’s proven Mini-Z MR02 platform, we have created a new chassis from the ground up that combines smart engineering with specially-chosen materials to gain an edge in the budding market of 1/28 open-class competition.


At a glance
- Built on the race-proven Mini-Z MR02 platform; uses many MR02 parts
- Super-soft, highly adjustable flex plate suspension
- Tools-free quick-release battery system designed for endurance racing
- Ultra-low center of gravity and polar moment of inertia
- Durable 1.5mm/0.8mm FRP chassis
- Lightweight FRP/Delrin rear pod
- Unique 2-piece motor mount works with any 130-can motor
- Unique tierod steering system with optimized Ackerman
- Fully adjustable suspension: spring rate, preload, droop, ride height, camber, toe, roll center, damping
- 94 or 98mm wheelbase
- Compatible with Mini-Z MR02 bodies and polycarbonate bodies
- Hand-finished and pre-assembled chassis


Features

Ultra low center of gravity and polar moment of inertia
Like any good racing chassis, the batteries, motor, servo and electronics are positioned as low as possible to achieve an optimal center of gravity. But more gains are achieved in the actual chassis itself: the upper deck of the chassis and the top plate of the rear pod are reduced in size, thinner material is used for the servo strap, tierod, and battery strap, the upper tower for the front suspension is entirely removed, the motor mounts secure to the bottom of the rear pod, etc., all of which lower the CG even more. With the motor placed amidships and the narrowest battery configuration possible, the MRCG also achieves an extremely low polar moment of inertia. This combined with the ultra-low CG provides unparalleled steering response and corner speed.

Unique rear suspension
The MRCG's unique interpretation of the side flex plate suspension uses FRP flex plates instead of carbon fiber items. Being softer and more durable than carbon fiber, these flex plates give you more traction and less breakage in collisions. The chassis has been entirely cut out below the flex plates, allowing full freedom of suspension travel to maximize traction and improve consistency. A side-effect of this change, however, is a lowered roll center, which increases traction still. Optional side springs (not included) can be used in conjunction with the flex plates; preload is adjustable via threaded screws. Ride height is adjustable in 0.25mm increments using a combination of shims and the differential height adjusters; the shims can also be used to adjust roll center and droop.

Completing the rear suspension is a small disk damper. A Delrin post reduces unwanted friction for smoother action. The disk damper uses the same springs (not included) as other systems, and can be fine-tuned with combinations of springs, damper oils, shims and the top adjustment nut. Additional damping can be provided by an optional tube or oil damper (not included).

Lightweight, versatile rear pod
The rear pod is constructed completely of FRP and Delrin. The bottom plate is designed with more material for stiffness; the top plate is conversely thinner to save weight, and is open on the left side to improve motor access. And rather than using a large single bulkhead on each side of the pod, we split each one up into a bulkhead and motor mount to reduce weight.

The 2-piece motor mount clips onto the motor can and endbell, and then bolts to the bottom of the rear pod. Not only can it be used with any 130-can motor (since it doesn’t require drilled holes in the can), but it saves even more weight and sligihtly lowers the CG of the rear pod as well. This system makes removing/installing motors easier by giving you much more space to work with than other cars.

Some more rear suspension features are built into the rear pod: the differential height adjusters allow ride height adjustments in increments of 0.5mm, an optional tube or oil damper can be mounted to the hole in the rear pod’s upper plate, and the lower plate has a center mark to take the guesswork out of setting up the rear end.

Robust, lightweight front end
To create clearance for low-slung bodies without sacrificing durability, the MRCG uses two machined arms instead of a top brace to hold the kingpins. The minimalist design and Delrin construction of the arms keeps the total weight down. The FRP lower arms can be switched out to adjust caster; the kit comes with 0°, 2°, and 4° lower arms.

In addition, we utilized the servo strap as a tierod stay and created a linear steering rack like that of the Mini-Z MR02. Ackerman is optimized to provide smoother, more consistent steering. The kit comes with three tierods: 0°, 1° toe-in and 1° toe-out (abbreviated as -1°).

Quick-release battery system
The tools-free quick-release battery strap keeps chassis tweak consistent from pack to pack and allows for ridiculously fast battery changes. Twist both latches outwards and the entire battery strap comes off -- no need to fumble with clips, screws, or nuts. For those who would rather use tape to secure the batteries, we have cut two additional slots in the chassis to thread the tape through (not shown in prototype). Additionally, there is enough space in the car to fit a variety of lithium-polymer battery packs so you can choose how much power your want your car to put out.

Optimized for both 94mm and 98mm wheelbases
The MRCG's unique wheelbase system shifts the batteries backwards in the 98mm configuration and forwards in the 94mm configuration. This gives the car greater stability and traction on fast, flowing tracks and unparalleled agility on small, tight ones. All that is required to change between the wheelbases is to shift the front end forwards or backwards, and move the side body clips to the other slot.

Accepts both hard plastic and polycarbonate bodies
The chassis accepts both hard plastic bodies (Kyosho Auto Scale Collection, Atomic VDS and VDSII, PN Pan Car, etc.) and polycarbonate bodies (using body posts and an optional upper brace, not included). Because of its 94mm and 98mm wheelbase compatibility, the MRCG will fit any Mini-Z MR02 body and several other Mini-Z bodies as well. For polycarbonate bodies, an optional upper brace is available; the mounting points for the body posts are spaced far apart to provide extra stability to the shell.

Compatible with many Mini-Z MR02 parts
Being based off the Mini-Z MR02, the MRCG is compatible with all sorts of MR02 option parts: kingpins, front knuckles, springs, bearing sets, motors, differentials, oil dampers, wheels and tires, etc. (In the name of cost-effectiveness the base chassis kit does not include any of these.) You can convert your MR02 to an MRCG or build your MRCG kit from the ground up, the choice is all yours.

Option parts
As part of our policy of continuous development, we are developing a wide range of option parts to exploit the MRCG's immense flexibility. In the works are a super-lightweight ball differential, two RM rear pod conversions (one for "sane" and one for "insane" motors) and more machined Delrin parts; these will make the car even lighter, stronger, and faster, and we look forward to offering them in the future.

Partially-preassembled chassis
Every part in the kit is hand-finished before being put together and the entire kit checked for tolerances. Everything comes under scrutiny: the alignment of the front and rear ends, chassis tweak, proper action of the rear suspension, the ease of fitting screws and bearings into their holes, etc. With this process, we can guarantee the quality of the kit and you can have a perfectly-running car the first time around.


What You'll Need
- Superglue/CA glue
- Light threadlock
- Mini-Z MR015/02 knuckles, kingpins, springs, spring perches, c-clips, ball differential
- Aftermarket Mini-Z disk damper spring set (Atomic, PN, etc.)
- Mini-Z MR01/015/02 wheels, tires, bearings
- M2 locknuts (4)
- Micro servo (no wider than 23mm), servo saver
- Thin double-sided tape for servo
- Receiver and ESC (or combo)
- Receiver-compatible transmitter (and transmitter battery pack)
- Mounting tape for receiver and ESC
- 130-size motor, Mini-Z pinion
- Battery pack
- Charger appropriate for battery pack
- Hard plastic or Lexan/polycarbonate body, 94mm or 98mm wheelbase


Prototype Pictures

[RedSXmodder]

God Dang it all! Why do you have to keep torturing me with these images!!!!! I can't stand this waiting!!! Just get it out already!!!

...

Looks really good. I have to stop looking before I die of anticipation.

Later,
RedSXmodder

[mini-z drift]

is that for xmods?

[texan_idiot25]

Originally Posted by mini-z drift

is that for xmods?

Read the 1st thing he says....

This Mini-Z MR02-based chassis

I still think it would have been cool as an awd, 4 wheel steer chassis.

[RodsRUs]

thats pretty trick ****.
Do you just slap on some hobbie grade electronics and servo?

[color0]

Pretty much yeah. I reworked the side body clips just a bit, you can fit some LiPos in there too.

[color0]

After two months, I present the two iterations of the MRCG concept: these represent my blood, sweat, and tears poured into the task of designing the ultimate 1/28 chassis. Behold.





I'm undecided regarding which version will be sold (maybe both if the demand is high enough), but that's a decision for you guys to make. Please let me know!

[Sweed]

Oh, no, hide.. Color0 is here...
So the MM is becuase of the TGR Sinister's release?

Looks good.. Once again, I'm intrested in possibly buying the motor mount for a long put off project, but maybe the whole thing later in the year... ph2t's crazy MR-02 might stay put with this..

[RodsRUs]

If I was still into xmods I would still but one...
but can you maybe post one pic with a lighter back ground (white)to show more detail.
and are those rims your developing too!?

[Sweed]

Rod's, it's a Kyosho Mini-Z MR-02... Not an xmod..

[color0]

Rod- Can't reveal all the secrets just yet, hehe... and no, I'm not selling those rims. Display purposes only.

Sweed- People actually have been wanting MM since I first started designing. TGR was the last straw.

[RodsRUs]

I know what its for...
I ment mini cars period, not just mods. I should have stated that diffrently

[superinfinity]

I still want one......bad!

[color0]

Just letting everyone know that the rear-mount version of the MRCG chassis will most likely not make it to the shelves, at least not in the first release. The mid-mount design is more economical, so far more popular, and my machinist friend is worried that we don't have that much time to be making two versions.

If interest in the rear-mount version suddenly shoots up I will try to convince my friend otherwise, but tentatively, MRCG will be released only as a mid-mount chassis.

[texan_idiot25]

Color0's best friend is copy and paste it seems

Works for me, since I woulda gone for mid anyways (i think i said it on xmw, too early in the mornin)

[color0]

First batch of G10 prototype parts! The cut quality is no good, but it's mainly because I used a ruined endmill to cut with. The holes will be countersunk later, no worries.



I plan to get these parts made correctly before moving on to the fancy 4-axis work, so check back for updates.

[THE EDJ]

looking good! when do you think you are going to have a mock-up chasis built?

[color0]

No idea, right now I need to figure out how to properly machine the G10 so that the edges come out unfrayed. I do NOT want to sit on a bench and file fiberglass.

I should have everything I need to get started on the rest of the 4-axis parts, but it's going to be a lot harder.

[Azngtboi88]

dang, looks like an amazing design. Great job man i cant wait to see how it turns out!

[lol]

GO Cadnut!!! YEA ~~ XD nice job!! I'd be the first one to buy one =D