Thursday, October 5, 2017

Torque the ripper - TT02b gear destruction.

I got together with a buddy of mine this weekend, and the name of the game that day was "lets landscape his backyard".  Erm, we did laps, and laps, and laps of his back yard.  Many pounds of dirt were moved, grass or no grass. 

Suffice it to say, we had fun.  My car was doing some odd things.  We'll cover the electronics woes in a later article, but in this case, there was a clicking noise.  Sometimes.  Well my TT02b has eaten two, maybe three, diffs over the months I've owned it.  I figured I ate another diff.  I was already figuring I had not shimmed the diffs properly. 

Turns out, I was wrong.


There is something quite therapeutic about the after run cleaning.  The shocks are fine, the swingarms all drop smoothly.  Everything is fine.  ... Including the differentials.  Huh?  The diffs are fine?  ... what the?

Well... here's what was causing the clicking.


It seems my pinion moved on the motor shaft.  Then lodged itself in there.  Motor torque was enough to cause it to get pinned on the motor shaft, in spite of the loose setscrew.  What we're also seeing here, is just how tough the Tamiya fiber impregnated gears are.  There's nearly no wear on that spur gear, and that pinion is T O A S T. 

Well.. now i'm running a 25 tooth pinion.... and I swapped spurs because I had a few spares. 

If you look closely, on the right, you can see my friends "hey lets never have the shock towers get loose again" mod.  I've mentioned it before.  It turns out there's enough meat on the diff covers that you can through drill, and through bolt the shock towers.  I highly recommend doing this. 

Now... what will we break next?

The f104w transformed. A f104 pro?

The F104, and F104w are "related" cars.  And they can be converted.  the F104 front end is a lot more sophisticated than the sliding knuckles on the F104w.

I bought the wrong tires for my F104w, and the wrong body.  Between the two, I figured I was most of the way to converting the car over.

Well, here's the result:


Looks good doesn't it?  It's a f104 pro body and wing set.  I trimmed the "pro" refrences off, because i'm that sort of retentive.  


I am going to re-wire the guts of this thing.  The damping plate fouls a bit on the motor wires and battery wires.

For those who want to convert their F104w into a F104, here's what I needed:

F Parts: 42289 TRF102 / F104
Stainless Shaft: 58431 - 3x33.4mm F104
4mm Ball Connector: 44002 (Gold Color, 5pcs)
4mm Adjuster: 44002 - 6pcs
5mm Aluminum Ball Nut - Blue 10pcs
E-Clip 2.5 x 6 x 0.4 - 10pcs RM01 / F103 / FGX
Double Metal Shield Bearing 5 x 10 x 4 mm (2 pcs) - F104 Front Axle Bearing
M3x6 Flathead Screw (20pcs)
TurnBuckle 3x35mm(2pcs)
30mm m4 flathead screws.  (2pcs)

M4 nut (2pcs)


The conversion costs around $30.  To make the 3mm turnbuckles work with the 4mm adjusters, you need to drill them out quite a bit.

It looks a lot better.  It drives about the same.  I don't know if it was worth the effort.  But, it does mean that I can run in the local F1 r/c races.

Friday, September 22, 2017

The TT02b MS - Answering the question, again, of what happens when you turn a touring car into a buggy.


Mistakes.  They have been made.  In spades.  This time, it was some purchasing agents wanting to dispose of extra stock of some Tamiya buggys.  



Here we have, a TT02b MS.  
(Thanks RCMart)
Amusingly, TT02b based buggys are available for around $160.  They’re pretty complete, and include things like a nice ESC, and a motor.  However, this, is not that.  “MS” is Tamiya speak for “special edition.”  Something much better than stock, but much less than the “R” chassis.  R is for race, and come with a complete set of upgrade parts.

The TT02 is not a 4wd buggy, it’s a touring car.  Yet, here we are, staring at a 4wd buggy.  But it all starts back with that TT part of the name.  TT is Tamiyas new generation of touring car chassis.  The “b” part, is buggy.   This is not the first time this has happened.
Where the car came from
In 1992, Tamiya released the TA01 cars, and with it, started what was the parking lot racing boom.  Those cars had their roots in basher level 4wd buggies.  But very quickly they became their own unique chassis.  As soon as they got popular, everyone in the industry started making touring cars.

That eventually lead to the current state of affairs in on road racing, where the popular classes are mostly based on 4wd touring car chassis.  The bleeding edge of development, is mostly with on road cars, leading to the strange situation, where the 4wd tech from a road car, might just make for a better buggy.  

 

Touring cars, the have made the trip back to 4wd buggy have surfaced before. Most famously, In 2005, J Concepts released the BJ4, a conversion kit for the Team Associated TC4.  


And that’s how the TT02b came around.  Tamiya took their TT02 touring car chassis, and threw some long suspension arms on it.  I think I like what came of it.  

What is the TT02b


The TT02 chassis, is in it’s basic form, a very cheap tub chassis.  The sort of thing that comes with spring dampers, plastic drive shafts, and bushings everywhere.  I’m still mystified on how Tamiya manages the plastic drive shafts, and drive cups.  


It also comes with pre-molded steering and suspension links, meaning you can’t set it up wrong.  Typical of Tamiya, the motor mount has preset motor positions, so you can’t screw up the pinion mesh.

The car is a great measure of “enough”.  It’s stiff enough that the drivetrain doesn’t tie itself in knots.  It’s got enough suspension travel to be useful.  It’s complex enough to be an challenging build.  It’s simple enough to be cheap.  It’s price point is right where it’s an easy decision to buy.  

What about the TT02b MS


Well, “enough” isn’t exactly enough for what I want to do.  I want something cheap, but I also don’t want to pogo stick dampers, control linkages that can’t be adjusted, and I can buy my own motor and speed controller, thankyouverymuch.


But first, let’s take a good look at the platform in general.


The high points:

  • Sealed Gearboxes
  • Bellcrank Steering
  • 4 wheel independant suspension
  • A durable tub chassis
  • Integrated gearbox and chassis
  • Most TT02 parts fit
  • Radio protection box
  • Includes a Motor
  • Includes a Brushless Capable ESC
  • Wide range of gearing options

The low points:
  • The suspension arms are soft.
  • The tub chassis is flexible.
  • Lots of steering slop.
  • Questionable motor cooling.
  • Requires two sizes of bearing.
  • No caster.  
  • Plastic differentials.
  • Plastic differential drives.
  • Plastic driveshafts.
  • Plastic shock towers.

That’s where the TT02b MS comes in.  The MS comes with most of the basic bits you would want to turn the super basic chassis into something nice to drive.  Those are, a metal drive shaft, metal dogbones, metal outdrives, and metal rear hubs.  Along with that, you get composite shock towers, a full set of turnbuckles, Tamiya's oil filled shocks, and very little else.  


While the typical TT02 comes with an ESC, motor and tires, you don’t get any of that with the MS.  Which means my friend and I had to seek our own.  This is where mistakes start to rear their head again.  We bought 13.5 turn Brushless motor setups.  


The choice was driven by the local RC track specing 13.5 blinky as the motor setup of choice for their weeknight racing program.  

The whole drivetrain is supported by plastic.  In some ways that make me a little nervous.  As is typical, the main spur gear is plastic, and that doesn’t faze me at all.  However, the bevel pinion gears that drive the differentials, are also plastic, and I fear that under the full force of an angry 13.5 brushless they might give up the ghost.  


But that’s not all that has me uneasy, the differentials are completely plastic.  That includes the little metal spider that’s in the center of most tamiya diffs, and all of the gears.  I have a sneaking suspicion that the front and rear gearboxes are going to be the weak point on this car.  Time will tell on that one though.  



The Build



Building the TT02b is remarkably simple.  Everything builds up, or down, from the chassis pan.  The chassis pan is exactly the same as the one from the TT02 touring car.  This leads to the need to use some adapters.  


The swingarms use typical tamiya bent wire hinge pins.  The TT02 road car, uses large diameter plastic nubs on the swingarms to handle the hinge duties.  To take up the slack, there are plugs to take up the slack on the rear of the chassis, and some rather fiddly slip in adapters in the front.  

Both the front and rear suspensions hang off of the diff covers.  This means you’re just 4 screws away from having access to the diffs.  The build manual says to use a little bit of AW grease in the diffs.  It makes them a little stiffer, but nowhere near enough to make the car handle as well as it should.  If you can get your hands on it, I recommend some 200k weight grease packed into the front diff.  

Speaking of which, you can install the diffs upside down.  I’d say make sure you get that right, but it’s a good idea to assume that’s the problem instead of assuming you’ve hooked your motor up backwards. Not that I’d know about doing that sort of thing.  

The kit doesn’t come with tires, so you’ll need to provide your own.  We went with J-Concepts Bar Codes, and haven’t been disappointed.  Those tires come with “standard” foam liners, and while you can stuff the whole thing in the tire, I do not recommend that.  Trim the foam liners to match the width of the tire.  

Painting the body is a little, off putting, as tamiya builds go.  Tamiya recommends applying the stickers before painting, which means the overspray film is more or less useless.  You’re to apply the stickers, because there’s no other good way to determine where to do the paint lines.  I’m saying “be careful”  or put tape on the outside of the body once you’ve applied the big stickers.  

On a pleasant note, unlike many tamiya sticker sets, the MS sticker set, is friendly to different paint patterns.  My friend painted his car blue and grey, and mine is white and grey.  They look very good.

What needs fixing: AKA Living with the TT02b


The MS models are somewhat modified from the factory, and along those lines, I also bought a bunch of parts to install before I took the car out for the first time.  During the initial assembly, we installed the TT02 hard chassis, some TRF dampers, a 19 tooth pinion, metal motor mounts, and metal bearing supported bellcanks.  


These address a few things right off the bat.  First, the chassis is … soft.   The hard chassis has glass fiber injected in it, and is remarkably rigid.  With the airtime that a 13.5 powered buggy can get, plastic shock bodies just won’t have a good time, the TRF dampers have metal bodies, and can stop those from blowing out.  Running a car hard, can cause plastic to soften, so the aluminum motor mounts were called for.  The metal steering bits were to overcome the typical tamiya steering slop.  


I also cut small slices of fuel tubing to put on the steering and front suspension balls. This removed nearly all of the steering and camber slop.  Generally this isn't needed, but the car was wandering fairly badly. The arms still drop freely, but now there's a whole lot less wiggle room.
My goodness, there’s something magical about that first time you peg the throttle on a 4wd buggy.  They’re really quick.  Especially when you’ve got some reasonably sticky rubber on them.  Unlike a touring car, a buggy is sprung softly, and between the weight transfer, big contact patches from the 2.2” wheels, and that 13.5 turn motor, things would get going rather quickly.  

After a few months, a few things have popped up.  So far, I’ve stripped one differential drive gear, and one pinion.  I’m told that shimming the diffs to improve gear engagement fixes the issue.  For now, I have .3mm of shims on each differential.  And I have some GPM metal ring gears to replace the stockers if they strip again.

The fiberglass shock towers like to wiggle loose.  And the screws holding them to the diff covers aren’t exactly confidence inspiring.  Thankfully, where the shock towers mount, are in clear plastic, so you can drill through.  Once you’ve drilled through, you can then through bolt them.  Once through bolted, they do not come loose.  

The lack of front end kickup, makes hitting jumps, and landings a bit challenging.  This is a legacy of the touring car chassis, so I don’t know what can be done about that.  I just drive better.

I’m still deep on the tuning adventure with the car, right now I'm running 200k diff oil in my front gearbox, and the rear is essentially open.  My friend has 500k in his rear diff, but his car has never seen the track…   On the bright side, a complete replacement diff set is $7.  They’re cheap enough that you could buy a few, and with the quick access to the diffs, swapping them out for testing isn’t really a chore.  


So I've broken mine. My friend has broken his. On a bad landing, I caught a rear swingarm, and stopped the buggy dead. That landing ripped the pivot pin out of the rear of the car, swung the swingarm back, and tore the hard plastic chassis. I suspect a normal ABS chassis would have been fine after that crash, excepting the whole rip the swingarm out thing. But.. we'll never know on that one. In another crash, I broke the ears off a steering servo. The servo mounts are a bit soft, so I think that figured into that bit of damage. Oddly, it seems that the front shock tower is a bit of a weak point. If you're industrious, it might be worth copying it in carbon, as replacement FRP ones aren't exactly cheap. Finally, the car has a habit of dropping front dogbones. When that happens the steering locks to the side. I think some CVD's would fix the issue. But it doesn't happen often enough that i'm really worried about it. And CVD's aren't exactly cheap.

How can I buy a TT02b, whats the best to buy?

The TT02b is available in three flavors.  The Neo Scorcher, the Plasma Edge II, and the Dual Ridge.  The TT02b MS is built off the Dual Ridge.  
  • Neo Scorcher - 58568
  • Neo Scorcher Bright Pink Metallic - 84387
  • Dual Ridge - 58596
  • Plasma Edge II - 58630
  • Neo Scorcher Blue Metallic - 47346
  • Dual Ridge Black Metallic - 47355
  • TT-02b MS - 84418

The TT02b MS is definitely the one to get right now.  (as of September 2017) For $160 you get the car, and a bunch of upgrade parts that really do make the car better to own.  So that's where I'd go.  What you don't get, is a motor or ESC.  A stock tamiya motor is about $10, but who'd do that in this day and age of crazy brushless setups.

Thanks for reading.  I'm sure there will be updates in the future!

-Nero













Wednesday, September 13, 2017

Tamiya M05 - Last weeks news, but still an interesting platform.




Being a gearhead, and a RC person brings up some conflicts from time to time.  The Tamiya M-chassis cars exemplify this.  With a boot.  On your toe.  


I enjoy driving in a spirited manner.  I enjoy feeling a car sliding around as the limits of traction are found, exceeded, and reeled back in.  Logic indicates, if you’re accelerating, you want the power going to the rear wheels.  In a world where your derriere is attached to that chassis, it works out pretty well.  

R/C cars are tiny, have lots of traction, and very low polar moments of inertia  Put those in a tumbler and shake, what comes out the other end is a recipe for difficult driving.  By managing front end traction, you can get a car that’s very consistent to drive.  That’s where FWD chassis and the modern touring car chassis come into play.  And, you get really good braking as a nice side effect.  

Where did the Mini Chassis Come from?

Another goal in our hobby is to have something that’s scale.  Usually, the more so, the better.  Big 4wd trucks have 4wd.  Sports cars have Rwd.  Well, Tamiya thought if they were going to bring an Austin Mini to market, it should have Fwd.  And…. In 1994 that’s where the M01 was born.  

Tamiya went all out on the M01.  The car they released, was a classic Tamiya Tub, with four wheel independent suspension, and a clever setup to get the weight spread nicely between the ends of the car.  


They pulled tricks out of their back catalog.  The hairpin coil springs, and monoshocks at both ends.  It’s hard to get a lower CG than with that.  The steering servo is at the back, and it’s all housed in a classic Tamiya tub style chassis.  The M01 was good.  It was enough to spawn racing classes.  And a huge aftermarket.  

A huge aftermarket is a sign of two things.  First, popularity, and second, there’s things that need fixing.  

If there’s a lesson to be learned, is that big open tubs aren’t magic when you go racing.  And the monoshock has always gotten replaced with upright shocks whenever tamiya updates a chassis to perform better.  I wonder why they don’t work harder to eliminate bumpsteer.  

Somewhere around then, Tamiya also released the RWD version of the M class chassis.  They never really caught on with racers.  On a single lap basis, a RWD M chassis could turn a faster lap time.  But for the duration of a race, the FWD chassis would turn in more consistent lap times, and almost always beat out it’s RWD cousin.  Thankfully Tamiya hasn’t given up on the RWD mini chassis, but they’re still not exactly popular.  

The M03 is the next FWD chassis.  Predictably, Tamiya shoved the laydown shared shocks in the bin, and went to some super short vertical shocks.  In an effort to improve weight on the front end, the steering servo was moved on top of the gearbox.  The chassis was changed to a tubular girder of sorts.  And now most of the driving gear was directly attached to the gearbox.  

Happily, this arrangement eliminated a whole bunch of steering linkages.  And the separate shocks now allow for easy corner weight adjustment, and stops the sides of the suspension from affecting each other.   But it also brought the CG up.  In a chassis that didn’t need a higher CG.  How bad was that? Well we’ll get to the rolling tendencies in a bit.

The high mounted steering servo took out a whole lot of slop in the steering department, but the high mount also left the servo linkages in an awkward shape, so again, the chassis is haunted by bumpsteer.




The whole “machinery section” of the car, was screwed to the “drags behind” section with 4 screws, loaded in shear.  I think this was a mistake, putting the whole load of the car on 4 screws like that.  It seems that so did Tamiya.  Because they definitely did something about it in the next revision.  

What about the M05?

In 2009 Tamiya released the M05. As a Mini Cooper.  The M05 chassis is quite a demonstration of cheap plastic engineering.  Without needing a pile of other parts, it provides 3 wheelbase options.  It’s very stiff.  The battery mount allows for easy, quick, pack changes.  The electronics all mount as low as practical in the chassis.  This includes the motor, ESC, receiver, and steering servo.

The M05 went back towards a more balanced chassis, like the M01.  Instead of packing everything on the gearbox, the M05 has trays to mount the receiver and ESC back near the rear axle.  And the Steering servo is in a pocket down low in the rear of the chassis.


The high points:
  • A Sealed Gearbox
  • Bellcrank Steering
  • 4 wheel independant suspension.
  • A stiff chassis to let that suspension do it’s job.
  • Integrated gearbox and chassis.
  • Dizzying array of upgrade and option parts
  • Easily changed wheelbase options
  • Radio trays and integrated transponder mount.
  • Still uses the same body mount post positions as the rest of the M series.  
  • Includes a Motor
  • Includes a Brushless Capable ESC
The low points:
  • The suspension arms are soft.
  • Most models come with friction dampers.
  • Limited gearing options.
  • Lots of steering slop.
  • A bad case of bump steer.  (at least it’s symmetrical..)
  • Designed for Stick Packs (Excepting the M05r)
  • Questionable motor cooling.
  • Requires two sizes of bearing.  

Criticism of the M05

The M05 still has the typical Tamiya problems.  Namely, gearing choice, bump steer, steering slop, and battery compatability.  That said, steering is a big deal, figure in at least the cost of an aftermarket bellcrank setup when buying your car, you’ll have a much better time if you do.
The M05r takes care of every criticism, straight from the factory.  The price reflects that.  I paid $99 for the MX-5 model I bought.  The M05r is currently $190, but it was closer to $300 when I built my car.  

And if you buy a normal M05, parts to address the bits that bug you the most, are pretty cheap.  For example, the version 2 chassis set is $9, and allows the use of modern square LiPo packs.  Stiff suspension arms are $8.50 for the set.  And a set of shocks is $40.  

I ended up going the “buy the base M05, and the parts I want” path.  Four months down the line, i’m not sure I made the right choice, but I’m still very happy with what I have built.  

Building the M05

Building the M05 is a little tricky.  Typical of Tamiya, the process is straightforward, and very well detailed in the manual.  The gearbox is buried in the middle of the front chassis halves, the shock tower, and steering gear all attach to that gearbox.  That’s to say, if you lunch a gear in the transmission, or you want to do diff work, you’re going to be turning a lot of screws, for a while.  

That layering, is where the strength of the chassis comes from.  The rear tub, attaches to the gearbox through wedges, ensuring the screws that pin in in place, aren’t taking the load, and the chassis always assembles exactly the same.  

Sadly, most revisions of the M05 come with the recent, and darned near hateful friction dampers.  While the old friction dampers had a rubber tube, some grease, and a metal piston to get some damping, these new ones are just a clip together shaft that guides the springs.  


I bought the MX-5 model, because it was the best looking, and happily, the cheapest,  When I placed the order, I also ordered some Mini CVA shocks, a 17.5 brushless motor, the Version 2 chassis parts, bearings, and Yeah Racing’s aluminum steering gear.  

That’s a long list of parts to order off the bat, and a significant chunk of money.  The shocks being about $20, the bearings another $15, chassis parts $10 and the steering kit $15.  In the end, it was a 160 car instead of the $100 I picked up the “kit” for.  

Building the car takes some time.  There’s bits you wouldn’t expect to need to build.  For instance, the rear loopy chassis braces aren’t part of the rear tub.  And the rear suspension arms are actually two piece assemblies.  


It’s a pleasing job, for the most part.  Just be sure not to get ahead of the manual.  It does things in a specific order, to deal with that layering thing.   

This isn’t the first M05 I’ve owned.  But it is the first I built from scratch.  The one I owned before, had the aluminum steering rod, and some aluminum bits in the steering.  In the interest of seeing what the stock setup was, I did build my car with the stock plastic steering assembly.  At least for bench testing.  


I was not happy, at all, with how things went with the plastic rig.  The bearings around the steering rack, and the bushings they ride on, really do need to be metal.  Any slack in there ends up being exaggerated by the rest of the steering assembly.  All of the aftermarket bits end up coming with a set of bearings for the bellcrank to run on.

There’s a lot to be said about the steering.  It’s still got that obnoxious Tamiya bump steer.  Between a properly set ride height, and some shims on the tie rods, you can dial most of it out.  While we’re on the subject of ride height, that ends up being something of a problem.

In the US, there’s several sizes of CVA shock available.  None of them are “super mini”.  When you look for recommendations on what to put on your M chassis, they all indicate the mini shocks.  Installing the mini shocks with their biggest internal spacers, sets the fully compressed ride height at something like 7mm.   


Racing setup guides, tell you to set the normal ride height to 5 or 6mm.  Not, fully compressed…  So that sent me to find shocks that were proper.  The M05r comes with the proper shocks.  And, if you do some digging, pairs of super mini shocks are on the market. (Tamiya part: 507046)  Those are what you’ll need.  Unless you’re in the market for the metal bodied shocks, which retail for nearly $90.  (Tamiya part: 54000)

Since that was a “straight from Tokyo” order, to get the super mini CVA shocks I got to drive the M05 on the tall setup for a while.  
My M05

My M05, was built up with a smattering of upgrade parts.  That is, the aluminum steering kit, aluminum outdrives and constant velocity joints, aluminum rear axles, super mini CVA shocks, a short steering servo, and the version 2 rear chassis parts.  

I also went about 90% of the way on doing the body right.  Tamiya is a serious model making company, and their bodies reflect that.  Take your time, and understand what should, and should not be trimmed on your bodies.  With Tamiya’s mold making skill, sometimes the edges that “look” like body trim lines, are not body trim lines.  
The MX-5 body, is two color.  So you need to do a fair amount of masking.  With clear bodies, you start with the dark colors, and work your way to the light colors.  The MX-5 needed all of the red areas masked off, before the black was sprayed.  When you do the masking, it’s best to do lots of small bits of tape.  Also, to Tamiya’s credit, if you don’t get the masking lines perfect, they provide decals for the outside of the body that cover most masking sins.  

I made the mistake of using rustoleum paint to paint my body.  It absolutely does not bond to lexan.  It looked really good on the initial application.  Then I made several more mistakes.  First, I sprayed the red to soon after the black, and ended up with a little crazing of the black paint.  Then I went to do a backing coat of white paint behind the red, to make the body look more solid.  I layed that on to thick, and several places the paint peeled up from the lexan.  

Don’t do what I did.  Buy lexan/polycarbonate specific paint.  Use really thin coats.  Give 3-10 minutes between coats.  And keep using thin coats.  

What this lead to, was paint flaking off the car every time it hit something.  I came home from one trip to the track with a clear bumper and quarter panel Later, to repair the paint, I used polycarbonate paint.  So now the body has what I find to be a pleasing mottled effect where the paint was repaired.  

Driving the M05

On most surfaces, the M05 is a perfectly well behaved machine.  That is until you get on a high traction surface.  In my case, that means carpet.  But lets talk about FWD driving first.  

Rear wheel drive is “the thing” for going fast.  This is because in a corner, you’re constantly needing to add energy to redirect your cars momentum.  This means you need to apply forward force at the drive wheels, as well as deal with side force on those tires.  

To turn the car, you need to apply ~more~ side force, to the tires steering the car.  For a reasonably well balanced car, (either through tire area, or carefully choosing the placement of mass on the chassis) rear wheel drive will let you stress the tires at the front, and back the same.  Potentially leading to the fastest cornering speeds.  However, this sort of force balance is fleeting, and has two breakdown paths.  First, you apply to much force to the driving tires, and you run out of traction in the back, and the car starts to step sideways.  Second, you apply to much steering input, and your front tires can’t keep up, and the car pushes out of the corner.  

Pushing is usually stable, and easily handled.  The back end stepping out, is a much more complex task to manage.  

The big advantage of FWD, is that over driving the car, all ends up with the same outcome.  The car pushes.  This is a stable, predictable, and easy to handle outcome.  

And now we come to MY front wheel drive car.  I bought the car, and installed the big pinion, and a 17.5 brushless motor.  The car was quite quick.  Much quicker than my VTA setup TC4.  Without a lot of care, the front tires would spin all the time.  The narrow chassis and sticky tires lead to a lot of weight transfer.  Mid corner it would spin up the inside tire, if it didn’t just roll over.  

On pavement, the M05 is entertaining, just like a high powered FWD car.  Stab the throttle, and it goes mostly straight, until the tires stop spinning.  Throw it into a corner, it’ll push, to varying degrees, and you can drive mostly on the throttle.  That was great, until I got to carpet.  

The local track has CRC black carpet.  This is some very sticky stuff.  Even without tire sauce, the car just wants to play turtle.  Thankfully, the MX-5 body really tends to roll to the tires.  

Rolling over is still a problem I haven’t entirely solved.  Mostly due to being stubborn I suppose, as if I have traction, I want to preserve it.  The prevailing wisdom, is that you should limit the steering input, to reduce the amount of early turn tire loading, and use tricks to reduce traction as the car loads the outside tires.  Namely, supergluing the sidewalls of at least the front tires, if not both the front and rear tires.  


In spite of not taking time to really deal with the handling (rolling) issue, I find the car very fun to drive, even on the carpet.  Provided I get the corner entry right, weight transfer and the differential limit the applied power, mid corner, preventing rollover once the turn is initiated.  …  On carpet.  

Running around on pavement, the story is quite different.  The car just behaves.  In fact, it’s almost boring with how well it behaves.  For a race car, that’s a great thing.  It’s the car i’m most comfortable handing over to people to try out.  

What needs fixing
Even in it’s factory stock form, the M05 is pretty competent.  And very low maintenance.  

For a car I’m going to drive, I want at least functional oil filled shocks.  The next thing, is to get the steering slop reduced.  

Stiffening the differential would be beneficial as well.  As long as the car isn’t tipping over mid corner, being able to apply more power in a turn is useful.

As usual, you can go a long ways with Tamiya by shimming much of the slop out.  I was able to put shims around both the front and rear axles, the steering knuckles, and the suspension pivots.  $2 in shims made the car much more stable in a straight line, and took the wiggle out of the car when it transitioned from left to right.  

Now, there are serious racers that use this platform.  And to that end, everything could be fixed.  Well almost everything.  Amusingly, there seem to be no chassis stiffening components.  There are high end shocks, glass reinforced suspension arms, adjustable camber links, aluminum knuckles and hub carriers, balance weights, heatsinks, cooling fans, CVD drives, ball diffs, spring kits, and sway bars.  

They are all worth something, but as usual, it’s the world of diminishing returns with upgrade parts.  If you really want to go racing, with the recent price reduction of the M05r, that would be the way to go.  

How can I buy a M05, whats the best to buy?

If you’re going racing, buy a M05r.  It’s a great deal, and comes with the right shocks, tons of aluminum parts, the stiff suspension arms, and is ready for hard case lipo packs from the factory.  It’s hard to beat.  

The next best choice, is one of the special edition chassis kits, that comes with some basic parts.  

The M05 chassis is sold mostly as kits, with a few ready to run sets on the market as well.  It’s still sold mostly as a basic kit, so you won’t be finding many M05’s with oil filled shocks and other parts from the factory.  That really means buy the one with the body you like.  Tamiya body sets are not cheap, so getting the right one with your kit, is a big selling point.  

The following all do not include bodies, but do include at least oil filled shocks, and various other upgrade parts.  Generally speaking they are more desireable, but you’ll need to check them out on an individual basis.  Depending on release date, their prices vary wildly.  

58593 M-05 Ver.II PRO Chassis Kit
84424 M-05 Ver.II R chassis Kit

These have oil filled shocks, and a few other upgrade parts.
58443 M05 PRO Chassis Kit
84131 M-05 PRO chassis kit (Blue-plated version)
84204 M-05 S-spec chassis kit
92228 M05 S chassis kit

And this is just a bare special chassis.
84359 M-05 chassis kit Gold Edition

The rest are all basic cars with bodies.  They come with Motors, ESCs, and friction dampers.

58438 Mini Cooper Racing - M05
58444 Abarth 500 Assetto Corse
92213 Datsun 280ZX Sports Version
58454 Honda S800 Racing
58453 Alfa Romeo MiTo
58465 Fiat Abarth 1000 TCR Berlina Corse
58483 Mini Cooper '94 Monte Carlo
84183 Mini Cooper Racing (Finished body)
58503 Honda Ballade Sports Mugen
58520 MINI JCW Coupe
84316 Volkswagen Golf Mk.1 Racing Gr.2
58581 GoPro Monster Sport Super Swift
58624 Mazda Roadster
47308 Volkswagen Golf Mk.1 Racing Gr.2
58640 Mazda Demio / Mazda 2

Ready to Run:
84134 Alfa Romeo MiTo, yellow
84135 Alfa Romeo MiTo, black
84136 Alfa Romeo MiTo, silver


The M05 starts at $100, and they typically sell for $160.  The RTR models are closer to $300.  If your plan is to build a beautifully scale car, and drive in your driveway, or up and down your street, maybe your basement.  Just a plain M05 is a great place to go.  

If you want to go racing, I’d seek out a M05r.  And carefully compare the prices with the parts you think you’d really need to enjoy racing.  

Edit: At the time this was written, the M07 hadn’t been released.  If you’re giong racing, buy a M07.   My Car Today My M05 has seen a lot of hard track time. I've gone through a few sets of front knuckles, and rear hub carriers. I've even shattered some bearings.

That was a funny thing to discover.  I had the car on the work stand, and one wheel would just wobble.  Sadly, that was the end of the car for the day, I hadn't started stocking spare bearings yet.

I really recommend following Tamiya's directions to the letter when doing your body.  Don't cheap out on paint.  Don't mess around when you do the masking.  You'll end up with this:



Instead of this:



The new paint is metallic, and looks like the real car.  I backed mine with silver to make it opaque.  The top has Testors Flattening enamel.  It takes more time to dry than you might think, so give it a few hours before you start doing decals.



Don't be shy with that masking tape.  I do most of mine with cheap blue painters tape.


And you will be rewarded with nice sharp paint lines.

When I had decided that my old body was to messed up to save, I bought a second M05 kit.  A friend of mine was itching to build ~anything~, so she got to build the second (third) M05.



Her first build, took about four hours to do.



She was very proud of the car at the end.  ... and wanted to keep it.



That..... wasn't to be.  The car was ment to be resold.  Assembled, the M05 brought in $65.  Which means after the cost of buying a body kit, we got to build the car for free.

And to hint at what's coming soon, here's a picture of my trunk:


I really like this car.  There will be a tuning article coming up eventually here.  But this car will be taking a back seat to the M07 I just built.  





As usual, here's a few pictures that didn't make it into the article.