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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

EDIT:AWD?

does it LOOK AWD?

You can totally see the nuematic AWD dual anti shock motors!

Really great design, if I ever get ahold of a mini-z I'll be sure to buy one! Which looks more possible with me moving to a bigger city and in a neighborhood. I love living in the country so much

i ment is it coming in AWD, like a option. i can clearly see that its not AWD now.

SHAUN wrote:You can totally see the nuematic AWD dual anti shock motors!

Really great design, if I ever get ahold of a mini-z I'll be sure to buy one! Which looks more possible with me moving to a bigger city and in a neighborhood. I love living in the country so much

If I were you shaun and was really interested in this chassis, I'd buy it and build the mini-z up from there. This setup seems pretty loaded color, I especially like the multiple suspension options.

I'm getting ready to buy a 4-axis CNC mill, so why not take advantage of its capabilities? Front end thoroughly redesigned and miscellaneous things updated.





To do list:
-Delrin servo mounts/reversed servo (servo horn relocated farther inside): allows for lower shells, a slight problem with some existing designs (TGR, Iwaver, Pro-Z).
- MRCG-specific aluminum motor mount: 1-piece main body, with Delrin ride height adjusters (0-1.5mm ride height reduction) and slide-in motor installation (see HPI Pro4 Hara Edition).
- Use M2 locknuts as threaded spring perches for the rear end (save money relative to Atomic Delrin spring perches). M2 locknuts should work with MR02 springs, but definitely work with MA010 springs.
- Delrin 3x6x2.5mm bushings to replace the sloppy stock Kyosho bushings in the rear left wheel.

wow. looks alot less cluttered.

Well, my to do list is now done. For this motor mount, I moved the motor a little to the left in an attempt to better balance the MR02 rear pod (which is originally imbalanced towards the differential side). The ride height adjusters will be cut from Delrin to reduce wear, which has been the only complaint against them.

After another week's worth of work, I present the MM iteration of the MRCG concept. Has the same rear end setup possibilities as the RM version, same overall adjustability, just in mid-motor format.



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!

So can you post up a list of which mini-z parts are compatible? Or maybe a list of what one would need to buy in addition to the chassis in order to have a working car? Can you stick a mini-z PCB on there with a steering servo and go?

Sure thing.

Required parts:

Front kingpins
Front knuckles
Front MR02 springs
Front spring perches
MR02/015 c-clips
MA010 springs (probably the shorter type) for rear end adjustment
MR02 differential
Bearings
Wheels
Tires
Motor, Pinion
Reciever, ESC
Servo (Hitec HS50, Futaba S3111, or similar)
Body (98mm only for MM version, 94-98mm for RM version; 70mm minimum width)

Optional:

Friction damper post
Friction damper disks
Oil damper
Atomic RM DPSII spare shocks

So I've left existing tuning parts out of the picture because Atomic, PN and Kyosho have done a good job on them already. The MRCG chassis kit, whether RM or MM, will include 3 tierods (-1/0/1), 3 sets of caster blocks (0/2/4), and a motor mount with 4 ride height settings.

Cheers

That sounds propper!
Can probably build from buying the listed parts and end up with a spanking mini-z for around stock? I know it should be more but you get what i mean

You're going to have to bear with me with some novice questions, as I got my start in r/c cars with bits.

For a chassis like this, is there any alternatives to a mini-z pcb for the receiver/esc portion? A reciever is basically where you put the crystal, receive signals, and control the steering; and the electronic speed control may or may not be incorporated/onboard, correct? Is it sometmes two different units connected to eachother? What will you be putting in your best buildup of one?

Is a servo for steering in this the equivalent of the motor and pot on a mini-z? Is the centering function that the pot provides just incorporated internally in the servos yo mention?

I'm just not familiar with the various combinations and terminology of electronics that are used in larger-scale r/c. I know I could go searching all over, but I'm mainly interested as it applies at this scale for this chassis.

SuperFly wrote:For a chassis like this, is there any alternatives to a mini-z pcb for the receiver/esc portion? A reciever is basically where you put the crystal, receive signals, and control the steering; and the electronic speed control may or may not be incorporated/onboard, correct? Is it sometmes two different units connected to eachother?

Yes, yes, and yes. The cheap alternative would be the Losi Micro-T PCB, then more expensive, modular ESC and Rx separates like Novak Spy, Spektrum Micro, etc.

What will you be putting in your best buildup of one?

I'm opting for the Micro-T electronics, cost-effective and quite compact. Performance-wise it should be on par with Mini-Z electronics, perhaps not as smooth on the throttle steps. Then a Hitec HS-50 servo (sans guts) and either a standard 4AAA pack or a LiPo.

Is a servo for steering in this the equivalent of the motor and pot on a mini-z? Is the centering function that the pot provides just incorporated internally in the servos yo mention?

Yes and yes. The only trouble is that standard servos incorporate the servo control circuit, which will need to be removed if (and only if) you use a standard servo with Micro-T, Mini-Z, Iwaver, or any other electronics package that already has the servo controller incorporated into it.

I'm just not familiar with the various combinations and terminology of electronics that are used in larger-scale r/c. I know I could go searching all over, but I'm mainly interested as it applies at this scale for this chassis.

You *could* go all out on this chassis like some people have done with their Mini-Z's (for example: pchan0's 2.4GHz, Xray ESC, digital servo MA010), but on the other hand you could buy a Micro-T PCB and servo, plug together, hook up the motor and batteries and be set. Hope that helps.