Super TZ and TZ-X Chasses

I first encountered Tamiya Mini 4WD race cars in 1997 when I bought my first two kits from an Asian bazaar in Seattle: a Thunder Boomerang W10 and a Black Stalker (both Super TZ chasses). Although these were marketed as 1/32 scale cars, I read that they were actually 1/30 scale. I built the Thunder Boomerang, installed a Hyper Dash motor in it, played with it a few times, noticed how fast it was, and then stored it in its box until 2021, almost 24 years later. The batteries were still in the car. Not surprisingly, it didn't turn on. I changed the batteries, the car moved a couple of feet, and then stopped. What was going on? I changed the motor and it did the same thing, moving a couple of feet and then stopping. Picking up the car, the wheels spun fast and made a high-pitched sound. It sounded normal to me, but I didn't have much to compare.

Little did I know, this little cog-like part at the end of the motor axle - the pinion - was at the very core of my woes. Notice the crack in the gear that shows up when I enlarge the photo? The actual size of the pinion is less than 5mm. The motor was spinning, but the pinion didn't turn much because it wasn't gripping the axle!

Replacing the pinion was easy and inexpensive. I bought a pack of carbon reinforced 8T pinion gears for $1.80. The car now runs fine, although a bit slow, even with a Hyper-Dash motor. There's nothing wrong with the motor because I installed it in an Aero Avante and there are no issues with speed. My Thunder Boomerang wasn't very sturdy as parts would fly off upon impact. I learned that I could replace the chassis with a new version of it, the Super TZ-X. Many Mini 4WD racers love this classic style design and seek out these long-lost cars. Unfortunately, it's not very easy to upgrade these classic chasses as the body or parts may need to be cut or modified to work with it. My practice run with it yielded unfortunate results. The car blew up on the track. Instead of retiring it a life on a bookshelf, I upgraded everything on it.

I added 17mm rollers with rubber rings and purple stabilizers up front and 19mm rollers with plastic rings and ball-race rollers in the rear. Adjustable mass damper weights were also added, two up front and four in the rear. I changed the gear from 4:1 to 3.7:1 and swapped the gear shaft for a fluorine coated gear shaft. The car is capable of handling a Light Dash motor. Anything more would be too powerful for its specs. I crafted a new piece of tech - The "Dragon Tail" - and installed it in the rear of the car. I shaved the rear carbon plate to keep the car within spec. The end result is Thunder Zero.

HobbyTown Tom's River Mini 4WD Tuned Class Race - September 11, 2021 - I entered Thunder Zero in the Tuned Class race and won a silver medal for my win at Hobbytown Tom’s River! Because I wanted this car to run in Tuned Class, I installed an Atomic Tuned motor in it. I found the purple stabilizers to be pretty useless for the Hobbytown tracks, so I replaced them with 16mm plastic rollers. I may have to rethink this as one of my plastic rollers and one of my tapered ball-race rollers got pretty wrecked on the track. I moved the rear mass damper weights towards the middle for better stabilization. Everyone raced beautiful cars. Mine was held together with a lot of tape as it endured many crashes in practice. I replaced and repaired parts after each run. I lovingly call it my Frankenstein car. After the race, I replaced the bad plastic roller with a good one and replaced the wheels with aluminum ones to get the center of gravity lower. These wheels are supposed to be specially designed for STZX chasses. I reduced the mass damper weights in the rear. I also replaced the crappy battery latch with a better one of my own design, a modified VZ chassis battery latch.

MA and MS Chasses

The Festa Jaune (MA chassis) is a hot-looking yellow sportscar. It's one of my box-stock cars. I did a motor break-in to try to coax a little more speed from the stock motor. As a result, my Festa Jaune is faster than my son's Festa Jaune Black Special and he actually has better tires!

The Exflowly (MS chassis) is another hot-looking car with a clear polycarbonate shell and a doube-shaft motor. You can see all of the innards of the car through its unpainted body.

AR Chassis

The Aero Avante (AR chassis) is a cool-looking car that looks faster than it actually is. Its body is literally covered with stickers. It was especially challenging to line up all the stickers as many of them are adjacent to one another. I upgraded my Avante with the AR Basic Tune-Up Parts Set (green parts above). I also built an AR Speed Spec version of the Aero Avante (blue parts above). I used the AR Speed Spec version in the Tuned Class races on June 12, 2021. It's not that fast, but it stayed on the track.

VS and VZ Chasses

The Lupine Racer (VS chassis) looks a lot like my Thunder Boomerang with the narrow wheels up front and wider wheels in the rear. I moved the 12mm double rollers from my NEO-VQS to the Lupine. I also upgraded the plastic keylet rings with bushings to round hole ball bearings and added skid brakes on the front and back. I did this without the use of front and back plates. I upgraded the car with side dampers. Although the VS chassis is an antiquated design, many racers feel this is an excellent chassis for competition as it has a narrow wheelbase for tight cornering.

The NEO-VQS (VZ chassis), in its Advanced Pack form, looks very pretty, but one of the things that bugged me was their choice of rollers, which are crappy 12mm plastic rollers. This "tuned" car was about as fast as my Festa Jaune. The VZ chassis is basically the next generation VS chassis with strong, removable front and rear bumpers.

I upgraded the rollers to 12-13mm rollers on front and dual 19mm rollers on back. It took me several hours of work to align them properly and get them to spin freely. I also added washers between the wheels and body to make the alignment more stable.

I upgraded the standard axles with hollow shafts to lower the weight. I also swapped the NEO-VQS wheels and tires with those in the Exflowly kit because I liked the chrome wheels. This new configuration now appears to be twice as fast as my Festa Jaune. When they start at the same spot, the NEO-VQS quickly catches up to the Festa Jaune in a few laps.

I upgraded the low friction POM keylets - the plastic rings that the axels spin inside - with hex-hole ball bearings and bearing roller spacers for a smoother wheel rotation. I changed the gear to 3.5:1.

I replaced the Light Dash (LD) motor with a Torque Tuned Motor (TT). TT is a monster motor after break-in.

On deck for the next upgrade is replacing the standard engine gear shaft with a fluorine coated gear shaft for improved motor performance, changing the rollers to 12-13mm with rubber rings.

The NEO-VQS Advanced Pack has hidden things to discover that become more apparent as you experiment with the car. Removing the yellow front bumper and sandwiching the black guard with both FRP plates reduces the weight by 5 grams and reduces the initial lap time significantly. I also chose the roundest of the wheels in the NEO-VQS and placed them in front and the roundest of the Exflowly and place them in the rear. Average lap times decrease from 1.4x-1.5x to 1.3x. Replacing the Energizer alkalines (46.73g each) for Energizer 1300mAh rechargeables (43.1g) results in a lighter car.

Even something so simple as a back latch (1.01g on an Aero Avante versus .53g on a NEO-VQS versus .42g on a Thunder Boomerang) makes a difference in weight and speed.

HobbyTown Tom's River Mini 4WD Tuned Class Race - June 12, 2021 - As weird as it sounds, I think Tuned Class is more difficult to win than Open Class. Maybe it's because there is greater competition and less ego involved. Everyone has to build their cars within spec without cutting or shaping parts and every car is limited to one of three low-powered motors: TT, RT, or AT. Most cars seem to use AT motors. I was surprised to see many cars with plastic rollers. Neo Victor kept flying off the track so I had to switch to heavier batteries and wait for a lower charge. I also switched its TT motor to an AT motor and changed the gear to 3.7:1. I raced the Blue Beetle and came in second in every race. Other cars were flying off the track and getting disqualified. In the races for the finals, I switched to Neo Victor so I could be competitive against the faster racers, but wasn't successful as my car was still flying off the track even with the lower battery voltage.

I purchased two copies of the NEO-VQS Japan Cup 2020, one for collecting and one for racing. I purchased an additional NEO-VQS Advanced Pack for spare parts and at least $100 worth of additional spare parts with the goal of creating a competitive racing car. In the following analysis, NEO-VQS Advanced Pack parts will be referred to as NVAP and NEO-VQS Japan Cup 2020 parts will be referred to as NVJC. Other parts not in either set will be identified by Tamiya part number.

  • The NVJC opaque yellow plastic molded parts are lighter than the NVAP translucent yellow plastic molded parts. I did not replace any chassis parts with NVAP parts.
  • The NVJC wheels are carbon reinforced wheels (Y-spoke). These should be stronger than standard wheels. They also add an understated beauty to the car.
  • Like my NVAP car, I removed the A4 front bumper for a savings of 2.12g and a faster burst of acceleration in the first lap.
  • I removed one of the FRP rear plates for a savings of 1.93g. I double-stacked one set of the brakes to make up for the lost plate.
  • I shaved off the sides of the chassis for negligible weight savings, but it looks cooler and more streamlined.
  • I replaced the 60mm hex shafts with 60mm hollow stainless steel shafts (part number 15440). According to Tamiya, "this shaft weighs 2/3 of the normal shaft and has the same strength." I cleaned the hollow shafts with rubbing alcohol to remove metal dust. This improves the overall efficiency of the shafts so the wheels can rotate faster.
  • I replaced the POM keylets with hex hole ball bearings (part number 15287) and bearing roller spacers (part number 94768) between the chassis and the wheel. I cleaned the ball bearings with lighter fluid for 4 hours, shaking the solution every hour, to remove oil residue. I cleaned the ball bearings with rubbing alcohol to remove lighter fluid residue. The POM keylets do a very good job as stock keylets, but the ball bearings reduce the lap times by .03 seconds. I discovered I did not need washers in between the spacers and wheels. The act of removing and inserting the wheels on the shafts multiple times decreased the gap between the wheels and the chassis.
  • I replaced the front rollers with 12-13mm double aluminum rollers (part number 95581).
  • I replaced the rear rollers with 19mm alumonum ball-race rollers (part number 95582).
  • I replaced stock propeller shaft (beige pinions) with NVAP hollow propeller shaft (green pinions). I cleaned the hollow shafts with rubbing alcohol to remove metal dust and saved .36g.
  • I kept the 3.5:1 gears from NVJC. These gears are faster than the 3.7:1 gears frin NVAP.
  • I replaced the switch terminal cover with the NVAP one for better durability. The NVJC switch terminal cover kept popping off on impact after course outs. This led to a weight gain of .04g.
  • I chose the 950mAh Fujitsu batteries that weigh 36g over the 1300mAh Energizer batteries that weigh 43g for a savings of 7g.
  • The overall weight of my NVJC is 105g, a savings of 10g over my NVAP.

HobbyTown Tom's River Mini 4WD Open Class Race - May 8, 2021 - I entered Neon Vicky in my very first Open Class race. It had trouble staying on the track on its second 90 degree angle turn. Neon Vicky was faster than every other car in the field, but it flew off the track on that right angle turn. The racemaster looked at my car and said I should pitch the wheels inward. He also said I could add more weight to the front of my car. Changing the batteries from NiMH to alkalines helped keep the car down somewhat, but it still flew off the track. I changed the front plate to carbon and replaced the 12-13mm aluminum rollers with 19mm aluminum rollers with plastic rings. I added two weights up front with a shorter shaft to keep the weight towards the ground. I reattached the rear underguard, realizing that it was needed to keep the screws from catching against the top edges of the track. A drop test revealed a good balance. I replaced Neon Vicky's switch terminal cover with an NVAP switch terminal cover for better strength, since the NVJC one kept lifting up after impact. Under the body shell, I changed the blue sponge pad on the passenger side to pink to match the driver side sponge pad. I shaved the two humps at the front of the carbon plate to keep the car within spec. I moved shortened the body damper in order to move the side weights closer to the front wheels like the NVAP. I also added lightweight weights to the front of the car for better balance. It should be able to handle jumps better with the body damper and additional weight. I added MadTang custom wheels with a combination low friction/super hard tires and 72mm hollow propeller shafts for better cornering. I attached two mushroom ball heads on the front roller shafts to deal with cornering. I attached a ball head under the main screw of the canopy so there won't be any accidental sticking after a jump. Surprisingly, the cars weighs the same as before.

HobbyTown Tom's River Mini 4WD Open Class Race - June 12, 2021 - I entered Neon Vicky in my second Open Class race. MadTang's custom wheels/tires helped my car stayed on the track better than with my regular wheels/tires. i didn’t win anything in the race, but i feel my car is a few tweaks away from succeeding. The amazing thing is the car is so fast even without a ball bearing and fluorine coated gear shaft in its gear! I wonder how my car would fair with a slower motor and 3.7:1 gear.

I reinforced the switch terminal cover with small pieces of sponge to prevent it from popping out upon impact.

HobbyTown Tom's River Mini 4WD Open Class Race - July 10, 2021 - I entered Neon Vicky in my third Open Class race and won a bronze medal for my win at Hobbytown Tom’s River! My prize was a new motor for my son’s car. For this race, I replaced the Sprint Dash motor with a Hyper Dash motor and added wheel stabilizers in place of the mushroom caps.

HobbyTown Tom's River Mini 4WD Drag Racing - May 8, 2021 - Pengo - Drag Racing is a new class in Hobbytown Tom's River. I initially just wanted to be a spectator, but I ended up competing in it and won. We were allowed to use tuned class racers. My entry was a fully optimized box stock Penguin Racer. My Fujitsu batteries were charged at close to 100%. I recharged my batteries after every heat.

Tuned class motors (RT, AT, TT) are not the most powerful motors. You could go with RT, a speed demon with low torque, or TT, a torque monster with low speed, or AT, a balanced lower-powered combination of both that is just one step above BX, a basic box stock motor. My racer had huge wheels, which are traditionally used for speed cars. I felt that TT was the best choice for my car. In fact, I think the TT is probably the most powerful motor of the three. It really packs a punch so long as you keep your car's weight real low. Just before my first drag race, I made some quick decisions on reducing my car's weight:

  • Swapped the battery clip (2.1g with penguin) with a standard VZ chassis battery clip (.58g with no penguin) to reduce the load by 1.52g.
  • Swapped the VZ back latch (.53g on a NEO-VQS versus .42g on a Thunder Boomerang) to reduce the load by .11g. The Thunder Boomerang back latch is one of the lightest I've come across. It is .01g lighter than the animal VS chassis racers.
  • Changed the gear from 5:1 to 3.7:1.
  • The overall weight of my Penguin racer was 80g without and 115g with batteries.

With a TT motor, 5:1 gears yield 19 Km/h whereas 3.7:1 gears yield 29 Km/h.

Several people wanted to buy the Penguin racer after they saw me win. In the final race, I won by a roller length, so there's room for improvement. I improved my Penguin Racer DRE (Drag Race Edition) with the following upgrades:

  • Changed the gear from 3.7:1 to to 3.5:1.
  • Changed the gear to include ball bearing and fluorine coated gear shaft.
  • Remove the spoiler to reduce the load by 1.7g.
  • Swap the Thunder Boomerang back latch with a rubber body catch (part 95393) to reduce the load by .35g (.42g versus .08g)
  • Pengo now weighs 78g.

With a TT motor, 3.5:1 gear, and pink Fujitsus charged to 1.51V, the car can go 31 Km/h. Adding a bearing spacer to my gear actually reduces speed, so I omitted it.

HobbyTown Tom's River Mini 4WD Drag Racing - June 12, 2021 - Pengo v2 - I entered the drag race at Hobbytown again and won easily. My car has become something of a curiosity for other racers who are used to racing circuits. One racer asked to see my motor because he couldn't believe my car could be so fast with a tuned motor. I think he expected to see a more powerful motor in my car so he could prove I cheated, but he was surprised to see a TT motor in my car. Most people who probably pick an RT motor because RT emphasizes top speed, but, from my tests, a TT motor is faster than an RT motor. Plus, it seems that a car with a TT motor appears to go faster and faster the longer it's on a straightaway. "Don't change a thing on that car," the racemaster said, "because, right now, that's the car to beat." Of course, I tuned it again, because that's what I do.

I updated Pengo with an Avante polycarbonate body and a rubber body catch. Pengo now weighs 108g with batteries and 72g without. It should have been a little faster now with the lighter body, but the Tamiya speed checker says that both versions have the same top speed. The speed checker never tells the whole story, though. I lost in the July drag race finals. The other racer had a car with an Atomic Tuned motor. That was an eye-opening experience to see his Atomic Tuned car beat my Torque Tuned car on a straightaway.

July 14, 2021 - I removed one set of rear rollers and replaced the steel wheel shafts with hollow shafts.

Penguin racer, 3.5:1 gears (blue/yellow), fluorine coated gear shaft with 520 ball bearing (no spacer), carbon reinforced crown gears, standard propeller shaft (mustard), blue POM 620s, 60mm hollow stainless steel wheel shafts, TT motor, Avante poly shell, rubber body catch, one set of rollers front and rear.

B.A.R.T. - The Golden Rules of Tamiya Mini 4WD Enthusiasts

  • Build with care and respect.
  • Augment when needed.
  • Race to beat your own scores, not anyone else's.
  • Thank your fellow racers after every race.

The beauty of Mini 4WD racing is anyone can race and anyone can win: young or old, male or female, novice or pro.

Racer Chassis Class Weight (gms) Box (Km/h) Tuned (Km/h) Open (Km/h) Notes
Neon Victor
(NEO-VQS Advanced Pack)
POM keylets, 12-13mm front rollers,19mm rear rollers
VZ tuned          
^^^ POM keylets >>> ball bearings VZ tuned       21LD  
^^^ Duracell >>> Energizer 1300mAh VZ tuned 115
21AT 21LD  
^^^ v3
front bumper, 13mm alum roller, 13mm plastic roller, 19mm rear rollers, ball bearings, hollow shafts, steel propeller shaft
VZ tuned 105
Neon Vicky
(NEO-VQS Japan Cup 2020)
3.5:1 gear, ball bearings,12-13mm rollers front, 19mm rollers rear, hollow propeller shaft, Energizer 1300mAh
VZ open 105     35SD  
^^^ Energizer >>> Fujitsu 1.2V 950mAh VZ open 105     36SD  
^^^ v3
wheel stabilizers, front weights, fluorine coated gear shaft
VZ open 111     36SD
1.51V Fujitsu, Open Class Bronze, verified 33 HDw 9/5/21
(Festa Jaune (yellow))
MA box 98 22BX     Rayovac
^^^ v2
Festa Jaune poly, 3.5:1 gear, 12-13mm front, 19mm rear, body damper
MA open 113     32HD Rayovac
The Midnight
(Festa Jaune Black Special)
Avante mk2 body
MA open 132 19BX

(Owl Racer GT)
MA box 97 20BX
The Wasp
(Rise Emperor)
MA box 105 25BX     Rayovac, Box Stock Gold
(Shooting Proud Star)
MA box 105 26BX     NeoChamp, oiled motor
Thunder Zero
(Thunder Boomerang W10 v2)
redesigned rear, 3.7:1 gear
STZ-X tuned 106   27AT(**)
  Rayovac, Tuned Class Silver
Exflowly MS box 82 18BX     always CO

(Koala Racer Pastel Special)
5:1 gear

VS     16BX      
4:1 gear
VS     19BX
22TT 21LD
good with LD and 4:1
^^^ v2
3.5:1 gear with ball bearing mand fluorine coated shaft, roller spacer, hollow propeller shaft, 60mm hollow shafts, brass keylets, carbon wheels, super hard tires, 12-13mm front rollers with rubber rings, 19mm rear alum rollers and tapered rollers, Deluxe Dragon Tail 1mm blue brake
VS tuned 106   27AT(***)
27 AT Rayovac, 25 AT Fujitsu
(Lupine Racer)
VS open 86     25HD  
(Penguin Racer)
VZ drag 80   26TT   retired 5/8/21
^^^ v2 VZ drag 77   31TT   retired 6/12/21, Drag Race Gold
^^^ v3
Avante poly shell
VZ drag 72   31TT   Drag Race Silver
^^^ v4
hollow shafts, minus one set rear rollers
VZ drag 70   31TT   verified 31 TT 9/5/21
Panda Racer 2
4:1 gear
SII     19BX
(Ray Spear)
VZ box 71 23BX
  29HDb 69g without cowl and spoiler
Blue Beetle
(Aero Avante)
3.5:1 gear, Avante poly body, rear mass damper
AR tuned 97 17BX
40 UD Rayovac
(Phantom Blade Black Special)
3.5:1 gear, FM-A hollow propeller shaft
SXX open 80 21BX

24TT 31PD
mostly Rayovac tests, NeoChamp SD, 39UD
^^^ v2
rollers, mass dampers
SXX open 104       mostly Rayovac tests, NeoChamp SD
(Geo Glider Black Special)
FM-A box 90 24BX     Rayovac
(Copper Fang Black Special)
FM-A box 90 22BX     Rayovac
Dinah Shore
(Dyna Storm)
S2 box 77 20BX     NeoChamp

Note: the number in parentheses () is the weight of the car without batteries

BX = white box motor, TT = Torque Tuned, RT = Rev Tuned, AT = Atomic Tuned, LD = Light Dash, HDb/w = Hyper Dash black/white,MD = Mach Dash, SD = Sprint Dash, PD = Power Dash, UD = Ultra Dash
CO = car jumped off-course

Tune Dates

AT(**) - 7/20/21

Battery weights in pairs, heaviest to lightest:
Rayovac High Energy: 48g
Energizer Max: 47g
Energizer Recharge: 43g
Neo Champ: 36g

Fujitsu Pink: 36g

Mini 4WD Kit Rating Index


All images and work herein © 2007-2021 Clare Din. No reproduction without permission. All rights reserved.