about: Prepare Your Mini To Win
How to Race Prepare a Tamiya M03 Mini.
Prepare your Mini to win How to Race Prepare a Tamiya M03 Mini
Roughly based on a guide produced by Leighton Buzzard Model Car Club (Thank You!), it has been slightly re-written to reflect our rules. This will be added to as more information is available
This is not necessarily the definitive “How To” guide, but a collection of hints and tips on how to build and prepare an M03 for racing. Follow this guide and your car will work. Then it’s just practice, practice, and practice.
The number 1 resource on the net for mini’s :
RC-Mini.net – Australian Mini’s, Great RC-Mini Resource!
www.rc-mini.net
M03 Variants
There are a few different variants available of the M03 chassis, they obviously have different bodyshell’s (Apart from the M-03R that doesn’t come with one!) and most have different length wheelbase’s. Below are the current kits available, the wheelbase is specified in brackets:
#58211 – Tamiya Mini Cooper (Short)
#58368 – Tamiya Suzuki Swift Super 1600 (Medium)
#58400 – Tamiya Mini Cooper S 2006 (Long)
#58427 – Tamiya Fiat 500 (Medium)
#49417 – Tamiya M-03R Chassis Kit (Short/Medium/Long)
The Basics
An out of the box standard kit can be made to work, and although for the inexperienced this can prove difficult to achieve,
with a few optional extras and some simple modifications, a race winning chassis can be built. Where to start, and with
which kit? This guide will focus on the more popular (and cheaper!) Mini Cooper Short wheelbase car. So, what do you need?
Bearing Set
The standard M03 Mini part #58211 is supplied with “Plastic Bushes”. While they do the job, the friction they cause
dramatically slows the car down. The Number one purchase should be a bearing set. Tamiya can supply a set, part #53348,
but they are expensive. Many local hobby shops can supply bearings sold loosely, and at a better price. If
yours doesn’t, a search on ebay should find you a set for under £10.00. You will need 12 – 5×11x4mm bearings and 2 –
5×8x4mm bearings. These can then replace the plastic bushes as you go through your build process. The M03R comes supplied with a bearing set.
Dampers
The kit supplied friction dampers can be made to work, but for the inexperienced (and experienced for that matter) they
can be difficult to set up. Your second purchase should be some oil filled dampers. Tamiya CVA Plastic Dampers work very well(#50746), and reasonably priced too.
For those with more money than sense, the new M Chassis Dampers (# 54000) are an aluminium version of the CVA damper, these are reputed to be the best dampers on the market. There are also many other manufacturers that produce
alternative dampers for the M Chassis cars. Tech Racing, 3Racing, Topcad, Yeah Racing, GPM and Exspede to name
but a few. But be warned, some of the far eastern produced accessories are of a very poor quality.
Springs
The kit supplied springs are too long for carpet racing. You will need Tamiya part #53333 Short Spring Set, or #53340
Short Spring set. As well as being shorter, the optional spring set allows you to fine tune the suspension settings. The
#53333 set comprises of Blue 15.27lb, Orange/Red 13.24lb and Yellow at 12.90lb. There is also a further optional White
Spring, harder than the Blue at 17.24lb, which is included in the #53340 set. You don’t need the White Springs, but if
funds allow, they are a worthwhile purchase.
| Colour | Spring Rate |
|---|---|
| Yellow | 12.90lb |
| Orange/Red | 13.24lb |
| Blue | 15.27lb |
| White | 17.24lb |
That’s it. That’s all you really need to buy to make the Mini work. There are hundreds of optional “Hop Up” parts available,
from a myriad of manufacturers. Most of which are just bling and a complete waste of money. Some will offer a
performance enhancement, some will offer strength or durability, and they’ll get a mention as the build is completed.
Building Your Race Winning Mini
The tricks are now how you put it all together, and how you set it up. I’ll go through the build manual in page order. Just
build it as Tamiya states in the manual, with the following suggestions. If you’ve already built your car, take the
opportunity to strip it completely down, give it a good clean and check it for any worn or broken parts, and then rebuild it
this way. It will work.
Differential
Firstly, our regulations dictate the use of the kit supplied geared differential only. Build it as the manual states on step 1,
and to be honest, you’ll have a reliable and strong diff that should last you a long time. However, I’d strongly recommend
some minor modifications as you put together the gears. Before you place the Planet Gear, #MA22, on to the 3 pronged
gear holder, #MA20, place a small 0.1mm or 0.2mm shim, from Tamiya part #53585 Shim set. The manufacturing
tolerances are not that accurate, and the shims help seat the planet gear on the holder, taking out some “slop”. The build
manual suggests you use a thin coat of grease on the metal components. This will help with longevity, but, ultimately, it
will slow the car down ever so slightly. I use a dry PTFE Lubricant (from the Cycle department at Halfords) to avoid any
additional friction.
It is possible however, to tune the diff, altering its action by stiffening it. This can be done in one of two ways. The first, is
to place a second shim after the planet gear is fitted to the holder, again, 0.1mm or 0.2mm, and, then place a larger
shim, I use an AE product, part number #3911, underneath the main thrust washer, #MA9, before you put the main gears
into the diff holder. This effectively locks up the diff. You can also build the diff as above, but before you put the gear
cover on, completely fill the diff with a heavy grease. Again, this helps lock up the diff.
The locked diff will give you more traction pulling out of turns, but you will lose some steering action. You will also see a
significant increase in tyre wear. Having tried both methods, neither offers any increase in overall lap times.
You can also purchase an aftermarket Speed Tuned Geared diff casing and spur gear set made from Delrin, produced
by both Eagle RC and Nikis. Don’t bother. They will spin slightly smoother, but they are not as durable, and will need
replacing on a regular basis. The same can also be said of the aftermarket metal spur gears. A footnote on gears. While
we allow the use of aftermarket gear sets, you must retain the original gear ratios.
Front Chassis Section
After the diff’s are fitted to the casings by way of two solid steel shafts. A Hop Up option, of lighter
Carbon or Alloy shafts is available. I will admit, I use them, but there really is no need, so save your money.
Not forgetting to install the battery holders (there is no need for the optional quick release battery holder, just use the kit supplied parts) fit together the two front chassis halves. A quick note here on screws. You can buy Alloy, Titanium and Stainless Steel screw sets. You don’t need them, although with the addition of a good hex head driver, they remove the chance of stripping a standard cross-head screw.
Build the front arms as instructed in the manual, and attach them to the chassis. As our regulations give you complete freedom in respect of suspension arms, I’d better run through the options available.
– Alloy Wishbones. Very shiny, very pretty and possibly the biggest waste of money on a Mini. Apart from the extra
weight, the stronger Alloy Wishbones will put a tremendous strain on the wishbone screwpins, and worse, on the chassis
if you have a heavy impact, and if you’re new to Racing, you will have some heavy impacts. – After market plastic, or Delrin Wishbones are also now available from a few manufacturers. They offer no advantage,
other than when and if you need to replace the standard front arms through breakage or wear, they are a bit cheaper. I
use Delrin Arm’s from Yeah Racing with their optional Titanium pin’s using the more common “C” clip fixing
method. Their design does offer a slight increase in travel, allowing some Droop adjustment, although this is restricted by
the overall length of the damper shafts.
You have a number of choices of upper camber links available. The kit links are fixed in length giving about 1.5 degrees
of Camber. You can buy some aftermarket alloy links, another complete waste of money. It is possible to make some
adjustable turnbuckles, which will give you another tuning option. (This method can also be used on the rear links) You
will need some 10mm Turnbuckles, Tamiya part #53892, and some 5.00mm Ball Ends, Tamiya part# 50797 and a
5.00mm Spacer. The Ball Ends will need 4mm cutting from their length (please be careful when handling sharp knives)
then simply attach a Ball End joint to each end of the 10mm Turnbuckle. As the original camber links are offset, you will
need to place the spacer under the Ball stud on the front hub carrier to provide an equivalent offset. You can now adjust
the front Camber. I have found running the car with zero front camber gives you a bigger contact patch (tyre to surface)
and gives improved drive out of corners, and from a standing start.
A very worthwhile Hop Up is to fit Tamiya part #53218 Hard Outdrive Cups. No performance gains, but
as the name suggest, they’re made of a harder material, and will last much longer than the kit outdrives, #MA17 and
#MA18.
Building the front axles. This can be a weak point on the MO3 Chassis. The Hub Carriers, part #B1 and
especially the steering knuckle, part #B9 are prone to breakage. You do have some options however. You can replace
both assemblies with the equivalent assemblies from the M03M Swift models. These have been slightly redesigned
making them a bit stronger. You will need Tamiya part #51238, which is the F Parts spruce from the M03M Swift kit. Be
warned, the bearing sizes on the M03M are a different size. There are also Alloy Knuckles made by a number of companies.
As the weakest link in this instance, the Alloy knuckle is a worthwhile purchase. Once again, the quality of some
manufacturers components is questionable. I can only recommend Tamiya’s own, part #53523. So far, they have been
bullet proof! Replacing the kingpins, MA1 in the manual, is another option. Alloy, Titanium, Steel, Blue, Red etc etc, are
available. They’re not really needed, so save your money unless you have an abundance to spare.
Driveshafts and dogbones. I prefer at this point, to replace the kit Dogbones with a set of Universal Joints. As ever, a huge choice is
available. Save yourselves time and ultimately money, and buy Tamiya #53597 Rebuildable Assembly Type Universals.
They are the most expensive from the outset, but will outlast all alternative at least threefold.
I’d recommend you replace the kit pinion with Tamiya’s optional Hard Coated variant, #53509. The kit pinion’s can “hook” through use. This is where the leading edge of the teeth gets slightly
worn through contact, eventually resembling a italic hook shape. A hooked pinion will cut through a spur gear like the
proverbial hot knife in butter.
Rear Chassis Section
You have some optional parts worth considering. To give the car a bit more stability, replace the rear hubs, part #B4, with
the optional 2 degree rear toe in hubs, Tamiya part #53345. Also, recently made available following the launch of the
M03R Chassis, are some 1.5 degree rear toe in hubs, produced Alloy only, they are very expensive.
When assembling the rear section try and fit your electronics inside the rear chassis. Receiver first. This is not always possible, as some receivers are simply too big. It’s not too important, as receivers are generally very light anyway. If it does fit, push it as far to the rear of the chassis as you can.
The kit supplied Electronic Speed Control, is a great bit of kit, and more than good enough to win you races. Please, don’t
waste money buying a high end ESC, you will not notice any difference. The ESC is next, and it will fit, just. You will only
squeeze 75% of it in, but don’t worry, when the two chassis parts are joined, there is just enough space in the front
chassis section for the remaining 25%. By squeezing all the electronics into the chassis, and not mounting them where
the build manual suggests, you are lowering the centre of gravity by quite a considerable amount. This will noticeably
improve the chassis handling characteristics. Fit the two sections together, oh, and don’t forget to re-tighten the screw in
the rear section.
Dampers
Build the dampers as recommended by the manufacturer in their supplied instructions. I smear some Associated Green
Slime on all the O-rings and on the damper shaft during assembly. Take your time, checking that the shafts are the same
length when you screw on the lower Ball Ends. I slightly overfill the dampers with oil, and then compress the piston a few
times, turning the shaft at the same time, to ensure you remove most of the air trapped in the damper body. I then leave
the damper for at least 10 minutes to let any smaller air bubbles get to the surface. Screw the top on a few turns, and
very slowly, fully compress the piston. Any residual oil will escape from the top as the pressure builds, and you should
end up with an air free damper, that has a small amount of rebound, where the damper will slowly extend on it’s own. I
use either 50 weight Silicon Oil in the front with the Blue Springs, or 60 weight with White Springs, and 40 weight at the
rear with Orange Springs. When attached to the car, the shorter springs should mean that the lower suspension arms are
at least level with the floor.
Servo
Fitting the servo. A couple of tips here. You will note
that the manual shows the servo posts, #C12 in step 20, as having one hole to mount the post to the chassis and one
hole to mount the servo to the post. Using a small drill, I recommend you place a second hole in the post, allowing you to
use both the upper and the lower mounting lugs on the servo. This will greatly reduce the risk of the servo coming lose
during a race. While we’re on the servo, please don’t waste money on a super quick, high specification servo, it really isn’t
needed. The servo in my car is pushing two years old, gets used every week, and cost under £5.00. Another worthwhile
purchase is a combined transponder mount and servo (see photograph above) plate that fits across the top of the
chassis. It helps clamp the uppermost part of the chassis together, at the points where the servo is attached, and greatly
reduces flex caused by the servo. Please note we don’t advise running the transponder in this positon, as it as high risk of beding damaged!
Tyres
Probably one of the most important little tricks that’s used to dial out grip roll, is to Superglue the tyre walls. You only glue the front tyres, and I promise you, this will do more to take out grip roll than almost any other changes you make.
The kit tyres work well enough on our carpet. They can suffer from glazing on the rear tyres. This is caused by the
undriven rear wheels, not working hard enough, and picking up residual tyre additive left on the carpet. This will form a
hard surface, and the rear end loses all its grip. Simple to cure. Scrub each rear tyre before you start the race meeting
with a medium or course Emery or Wet and Dry paper to remove the glaze. While we’re on the subject of additive, try and
use it. LRP produce an additive especially for carpet racing in an easy to use applicator. Coat the entire surface of the rear tyres before you race, remembering the wipe it off before you go on the track, as the grip levels increase significantly through the evening the additive will be less required.
So, paint your shell (try and use a bright colour that’s easy to pick out against our Grey carpet) and get booked in. You
are ready to race.
Some useful web site links
Leighton Buzzard Model Car Club
www.lbmcc.org
RC-Mini.net – Australian Mini’s, Great RC-Mini Resource!
www.rc-mini.net
Tamiya USA
www.tamiyausa.com
Tamiya
www.tamiya.com
RC Racechat Forums.
www.rcracechat.com/vb