BMW M Roadster
Model Number: 58240




2WD Rear Wheel drive, gear diff


Four wheel independent double wishbone. Coilover friction shocks

Chassis Description

ABS Monocoque

Body Type

Clear Lexan polycarbonate







Wheel Base


Tread Front


Tread Rear



890g (chassis)




front:26mm radials
Rear:26mm Supergrip radials

The powerful BMW 'M' roadster is a car that everyone loves. A very distinctive bodyshell accurately modelled by Tamiya. Mated to the reliable and nippy M-04L chassis. (Description by acprc)

Unfortunately, Tamiya didn't give their model the deep dish wide rear wheels of the original M Roadster. [by Miramar]



3/7/2003 5:31:42 PM

Nice Jump up car Newbie racers, it has instead of a FWD or 4WD system, a RWD when mated with it's standard components it is set for oversteering (Pulling) by chassis (Not Good) however it is counted by the tyres low profile intermediates on the back and almost rally like intermediates on the front thus understeering (Pushing).

Im not pushing newbie R/C Drivers it's just i've been a newbie and wrecked my body shells hope they don't though

For newbies:
This is as you may know is "not a toy" this chassis is a god send for untidy or untrained drivers as the front bumper is made instead out plastic, (Solid bumpers are good but tend damage chassises easier) shock absorbing Urethane which works like the "crumple zone" in your car it makes some of the force dissapate into the Urethane and then hits a solid bumper at greatly lessaned speed (-10 MPH at least).

Newbie Driving technique:
keep between 1/3 and 2/3 throttle, full from start will mean it will spin or worse make your tyres (From rims) come loose (unless you have super glued them onto the rims). When entering a corner if going full to 2/3 throttle DON'T HIT REVERSE, this will send your car into spin (Like a handbrake), go down to 1/3 (If at full go down to 2/3 or 1/3 throttle) this increase load on the front suspension allowing you to turn (Full or 2/3 throttle tends it either to Understeer (goes straight for a while and massive turning arch) or oversteer (Instant turns into a spin, this if you wish can be used for sliding). The way you can tell if you are at 1/3, 2/3 or full throttle is the 3 - step speed controller that comes with the kit, you will begin to notice between the difference of 1/3 (Low Hum), 2/3 (High hum) and Full (Scream).

Newbie Performance and general hopups advice:
A new engine will pay divedands on performance, many are available but before we continue:

This is advice i did ask you to do anything, this means, advice taken from this review used on your RC car i have no controll over as every kit built is different.

The standard engine is a 27x1 this is called a "Stock Motor" these are industry standard and provide 15 - 20 MPH running on this Car w/standard kit

Modifieds are extremly powerful except they are either machine wound (No balencing), locked timing (Well balenced timing can mean a boost in power) and/are more heavy. Rule of thumb goes:

▲ More turns ("27"of 27x1) will mean longer battery life however loss in speed
▼ Less Turns will greater Power at the expensive of gearlife, running gearlife, and Battery life

▲More Turns ("1" or 27x1) means even greater power again at the loss reduced component life, this also means higher top wack
▼Less turns means more "Torque" which means more power delivered low down for acceleration however at the expensive of top end

They tend to be any where from 23 - 8 turns and 1 - 6 winds
12x3 will give this model (Standard) about 40 - 45 top wack (Est. amount)
17x2 will give about 30 MPH (Standard) (w/19T Pinion about 35 MPH)

Pros are very expensive but then tend to be higher quality, last longer and can rebuild with (If you find them) rotors when the company upgrades to the latest thing.

Tamiya has Alu dampers for £70 Appox $110 US for a SET! (2) however for this model Carson 50mm will work and are about 4x cheaper.

Ballracing is a good idea as it increases the life of gears and shafts within the gearbox and also allows the gearbox to take higher stresses (8/9 triples turns can possibly destroy the trans on this car) and will increase acceleration and top end because there is less friction between the Washers and shafts.
The gear pinions on this model are 17T, 19T and 21T and give a final drive of 6.82 (about 15-20MPH), 6.1 (20-25MPH) and 5.52 (25-30) however this means you lose alot of acceleration (Because your engine and Gearbox is under higher stress).

You can upgrade to the Type A or Type B tamiya slicks (These are either hot or cold tyres) if you want to be flash you can buy some "Coloured" Flange nut (They attach your wheels to the universal shafts).

General Radio Gear tips:
There is nothing wrong with using a 3-step speed controller but to get the best performance out of the car as well as lighter weight a "Electronic Speed Controller" (ESC) can be purchased (This replaces to the secondary servo and 3-step Speed Controller (About 250 Grams) they can also take high voltages and some are waterproof.

The main problem is that when the Resister (Big White block) becomes hot it loses efficency and therefore power and when the batt. gets to critical level the servo locks, a Failsafe will save you lots of money in damages if you're car goes in the beginning of a turn (Before the steering servo is activated), it works by looking at the batt. level and servo status and makes the decision to make the servo return to "normal" position.

Can give you an advantage on bigger more powerful motors and can make the steering more agressive and controllable.

your tamiya 1400SP is a Ni-Cd 1400mAh battery meaning it can be charged faster then a 1700mAh (Tamiya's Next stage up) it is lighter and relases more power however it has a lower run time than the 1700mAh.

3600mAh Metal Hydride "Matched" Batteries will (As some one said down the local model shop) "Rip the Gearbox out" a 2400mAh semi-matched killed a 12x3 motor. Matched Batts will release power twice as fast and twice as long, as a similar tamiya varient, however their recharge time is longer.
A 1500 will last 10mins on Stock motor
A 1600 will last 12mins on stock motor
A 1800 will last 18mins on stock motor

Speed controllers (ESCs) Claim they can take upto or greater than 10 Cells which is:
6Cells: 7.2v
7Cells: 8.4v
8Cells: 9.6v
9Cells: 10.8v
10Cells: 12v
However tamiya don't support anything higher than 6 cells, what i heard on some forums is "Piggy backing" or "saddleing" the battery where they buy 8 cells and place 4 and solder them together and do the same with other 4 and place them either side of the chassis. If you are a newbie I do not recommend making you're own batteries they are about £40 for a 6 Cell (might be $60 US) kit and if you do it wrong you have to buy another one.

Keep at least 3 different ones if you are going into competion, keep at least 4 for general usage (On race days they are all set to one or two different Frequencies) 27MHz and 40MHz are the norm in the UK (I think in america uses 35MHz).

Lighting General tips:

■ Tamiya titanium screws (about 10grams)
■ MO3/TL-01 Quick release Batt holder (About 10 grams)
■ Alu Servo stays (about 5 grams)
■ Buy a micro drill and use it on the chassis. WARNING: This is irreversable and can destroy the structure of the chassis, althought you can lighten lots. good place is on the battery's access end holder.
■ Replace rims with either Tamiya's one piece racing wheels (I don't think they do this any more) or after market "Dish" wheels (Althought this makes the car look less real it can increase aerodynamics).

General safety tips:

Running the car at high speeds can damage:
■ the engine
■ Gears
■ Tyres
■ ESC/Speed Controller and resistor

Crashing into wall/inanimate objects can damage:
■ Chassis (BAD!)
■ Body (can be replaced at about £20 ($30 US))
■ Losing body clips (Replace the small ones on the outside with large varient (Used on battery holder))

Parts from other models/Hopups

OP470 (53470)
Lightweight carbon wing make Four holes (Using the micro drill 4mm bit) and put the uprights and then the rear wring, this is good for people with oversteering problems. Ways to get around is to swap the front and rear suspension units over, this will give you understeer as the rear suspension will crash out sooner instead of waiting second which can cause it step out.

Thank you for reading this, maybe I'll produce a book one day "Radio control cars for dummies"


12/2/2002 6:29:45 AM

Throughout the late nineties, Tamiya expanded their prolific RC collection by issuing cars based on a unique series of "M-chassis". Whereas nearly all the rest of RC-dom churns out 1/10th scale cars defined by chassis with 250mm-260mm wheelbases, Tamiya's M-chassis cars pioneered wheelbases spanning a shorter 225mm-239mm so that they would TRULY be accurate 1/10th scale representations of the real thing.

The M04L chassis is one of the latest rear-wheel-drive incarnations of this evolutionary branch. Unlike the predecessor rear-wheel-drive M02L chassis that spawned the Tamiya Porsche Boxster, Porsche Carrera, and Mercedes SLK, the new M04L brought improvements like independent dampers at each wheel rather than shared horizontal monoshocks. Redesigned steering geometry was made more direct and improved on the Ackerman angle. A large urethane bumper also provided much-needed impact protection in the front.

BMW unveiled it's Z3 roadster to the world in 1995 (US sales in 1996) and the 321hp take-no-prisoners M roadster variant late in 1997. The characteristic handling prowess along with BMW's return to the roadster market after their 507 in the fifties and limited production Z1 in the late eighties was the recipe for an instant hit.

The real-life short wheelbase of this roadster meant it was the perfect contestant for immortalization as a Tamiya RC model. In 1999, Tamiya released kit #58240 -- the BMW M roadster. The bodyshell is a perfect, accurate replica of the real thing. Details right down to the tow-hook hatch indent on the rear bumper was modeled faithfully. Wheels resemble the real M-stars issued by the factory. Oval side mirrors finish the aesthetic touch.

In building the kit, everything comes together without problems, however those who've built larger/fancier Tamiya cars will miss some expected features in the M04L. In order to introduce M-chassis kits at a low price, things like oil-filled shocks, ball bearings, ball differential, and swaybars have been relegated as hop-up options. Without these, the standard kit should still serve most beginners and intermediates nicely.

Advanced drivers seeking to maximize the potential of the M04L chassis should find the process rewarding. The recipe for a race-worthy M04L chassis include:

BALL BEARINGS: This M roadster kit requires twelve 5mmx11mm and two 5mmx8mm bearings. Be sure the gearbox assembly has received it's complete prescription before re-joining the halves. The remaining ball bearings are applied to the wheel carriers/uprights.

BALL DIFFERENTIAL #53267: Replace the standard planetary gear diff with the compatible TA03 ball diff. This allows limiting the amount of slip which is often crucial to any tail-happy (oversteer-prone) rear-wheel-drive chassis.

OIL-FILLED SHOCKS #53280: The standard shocks are merely lubricated spring dampers. They degrade after a while; drying out and loosing it's smoothness. Replacing it all with oil-filled shocks will enable experimenting with different damping viscosities. The tendancy to traction roll under high-speed cornering can be dialed down by lowering the overall chassis through shock travel adjustments and softer overall settings in the rear.

SWAYBARS #53382: A set for the front and rear helps to keep the chassis level during high-speed cornering. This hop-up is specific for the M04L chassis.

SHIMS: This kit like many entry-level Tamiyas exhibits some play in it's suspension joints. Fortunately a good deal of this "slop" can be fixed by strategic use of shims like those offered by Kyosho (#96643)

HEAVY DUTY SERVO SAVER #50473: Another source of the kit's slop comes from the stock plastic Servo Saver. By replacing this with the nylon & metal Servo Saver found on the TRF414 cars, an amazing amount of slop can be eliminated.

TOE-IN REAR UPRIGHT #53345: This upgrade changes the 1° toe-in in the rear wheels to 2°. This is designed to provide more straight-line tracking stability at high speeds. However, by implementing only one or the other, it's possible to use this upgrade to fix any toe-in indiscrepancies in the original assembly. On two newly built M roadster kits, assymetrical rear toe angles were observed first-hand. This problem resulted in the chassis consistently skewing to the left under hard acceleration. Installing only one of the uprights fixed the thrust angle and thus kept the car pointing straight.

CENTER-OF-GRAVITY REBALANCE: The original instructions call for mounting the ESC and Receiver on TOP of the M04L chassis, but many racers have been spotted relocating their components to flank the left and right sides of the steering servo. Having the components at the top means a center-of-gravity higher than necessary. The kit actually features an unused part (tree "A", piece #2) that creates a platform on the left side of the chassis. This should hold a receiver nicely. Relocating the ESC to the right side without obstructing access to the chassis screws may take a bit of ingenuity, but is completely attainable. This not only helps "CoG", it shifts the weight slightly forward resulting in an improved front-to-rear weight ratio.

Once the M04L chassis is appropriately upgraded and shod with tires matched to it's running surface, it should feel exceptionally agile in handling the corners and feature steering that's surprisingly crisp... worthy of the BMW badge.

How will the future treat the collectibility of the Tamiya #58240 BMW M roadster? Some of the indirect signs are promising. The two previous BMWs released by Tamiya, #58113 BMW E30 M3 Schnitzer and #58171 BMW 318i STW are highly sought-after not just by young Tamiya hobbyists, but from older, fanatical owners of full-sized BMWs. The worldwide appeal and instant recognizability of the Z3 & M roadster may spell an equal level of demand from multiple crossover groups long after Tamiya has put their #58240 kit into retirement.