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For someone looking to race nitro stadium trucks, the choice was once a relatively simple task. There were only two real choices: Team Associated, or Team Losi. In 2000, Kyosho stirred things up a bit when they released a truck of their own, the Ultima ST GP. When Mugen Seiki, a big name in the 1/8th-scale racing scene, released their truck, they made the decision for truck racers looking for a new ride just that much more difficult.
Features
Many of the MST-1's features are standard for nitro racing trucks, which may lead people to say that the MST-1 looks like a Losi XXX-NT. I'll spare you most of the boring details, and get to the good stuff. The truck is built on a strong, thick 3mm aluminum chassis plate, with a plastic upper deck, which holds the truck's radio equipment and fuel tank. The truck's suspension is nothing special, just the standard lower A-Arm/upper turnbuckle setup. Like the Losi truck, the MST-1's front camber links are mounted to the front bulkhead, in front of the shocks, allowing the shock to be mounted lower for an overall lower CG. Damping is provided by Mugen's excellent bladder-equipped, large bore shocks.
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The truck's steering is taken care of by dual bellcranks, with a built-in servo saver to protect the servo against hard hits. The drivetrain is also pretty standard. A two shoe clutch with spring transmits engine power to the clutchbell, which is mated to a spur gear and single disk slipper clutch. The tranny is a standard 3-gear design, with the brake disk on the lefthand side, similar to the XXX-NT. The truck also features a ball differential, steel universals, and an unconventional hex setup, instead of the standard pin mating straight to the rim. New trucks will include the aluminum hexes and uprights. The truck includes a Pro-Line Crowd Pleazer body, Mugen rims, and Pro-Line Bow-Tie and Edge tires, both in the M2 compound.
Modifications and Additional Info
The kit I bought was a display model for my home track, Delta R/C, in Antioch, CA. The truck is one of the original kits, and did not come with some parts the truck now comes with (aluminum hexes and aluminum rear uprights). The kit I bought included Mugen's extremely powerful MT12 Big Head engine and slide carb, along with a quiet Rex pipe and compact exhaust manifold. To tame the engine a bit, and make tuning easier, I installed an OS 10ER rotary carb and Lunsford adaptor. My truck did not include the proper brake arm for rotary carbs, so I had to do some creative bending of the brake linkage to get everything to work right. I'd also like to note that the body was not painted by me, but by a local painter/racer who goes by "wallshot" on the forums.
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The truck's suspension out of the box is set up a bit too stiff for most tracks. To fix this, most MST-1 owners drill larger holes in the pistons. I have heard of most people drilling a set of pistons with 1.4mm, 1.5mm, and 1.6mm holes. I looked through my bit collection and could not find anything smaller than 5/64"(roughly 2mm), so I decided to take the cheap route and use my 1.5mm hex driver to enlarge the holes. I simply pushed the tip of the driver into the hole, twisted until it felt free, flipped the piston over, did the other side, trimmed the flashing off both sides of the piston, and did the other hole in the piston. Here you can see the size increase after enlarging the piston holes (stock hole on left, drilled hole on right):
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I set up the truck with Losi Certified 30wt oil up front and 25wt oil in the rear. I also added Lunsford 2 1/2 inch turnbuckles to the truck for added durability over the stock steel turnbuckles.
Performance
After proper break-in of the Mugen MT12 engine, I took the truck to my home track, Delta R/C, in Antioch, CA. I hadn't run 1/10 scale in over a year, so to re-adjust to the different driving style 2wd requires, I entered the Sportsman 1/10 scale class. My two qualifying rounds were decent, but I was slowed down by a nagging push in turns, and overall numb feeling in the truck. It turned out that the servo saver nut had loosened up all the way, allowing the servo saver to easily compress and affect the truck's steering. Remember to threadlock your servo saver nut! I threadlocked the servo saver nut, and waited for the mains to be posted. Despite the issues with the servo saver, I qualified 4th, and readied my truck for the Sportsman 1/10 A-Main.
In the main, I got off to a bad start. I was caught in the first-turn pileup and caught again soon after being flipped back over. Once I settled into a groove and found the right lines(with help from my excellent pit guy, bigj), and started to notice the truck's handling characteristics, now that the servo saver nut was staying put. The truck is very easy to drive. It pushes slightly when on power, but has plenty of off power steering. If needed, the rear end can easily be kicked around with a tap of the brakes. The truck wasn't too difficult to put the power down, but I did notice that as the track dried out, it became easier to spin the truck around if I accelerated too hard out of a turn. The truck jumps very well, but occasionally got squirrelly if I landed wrong. A major plus was how consistent and predictable the truck was. This made it very easy to adjust to any changes in the track's condition as the race went on.
The Mugen engine was very reliable and easy to tune, thanks to the OS rotary carb. The engine ran cool all day(210-220*F), started on the first bump every time, idled well, got great fuel mileage, and was very fast. I highly recommend the kit with engine, which will save you money, and is very competitive.
The truck appears to be very durable. Nothing was broken during the race, but I did notice quite a bit of wear in the rear uprights(which should not be a problem any more, since newer kits include the aluminum uprights), and the front suspension block. I will be ordering the aluminum uprights and aluminum front block, and will update after I try the parts out on the track. The diff also wore quickly, and after one race day, feels quite gritty. Chad Bradley, a Team Mugen driver, recommends using Associated GT diff rings to fix this problem. The GT diff rings are not a direct fit, however. The inner diameter of the GT diff rings must be enlarged to fit the Mugen differential.
Final Thoughts
I bought this truck not knowing what to expect. If you are looking to get into 1/10 scale nitro truck racing, give the Mugen MST-1 a serious look. There are a few things that need to be worked out, but after those few problems are worked out, the truck is very worthy on the racetrack. Check back for updates as I log more track time with the truck, and test fixes for the truck's few small issues.
Likes:
-Handles well; very predictable
-Extremely durable
-Removable top deck makes cleaning simple
-Truck with engine package saves money
-Hex adapters make stripping rims more difficult, but...
Dislikes:
-...makes finding rims more difficult
-Some parts wear quickly
-Parts may be hard to find
For more information, be sure to visit the official Mugen Seiki site at http://www.mugenseiki.com/. Enjoy these extra photos.
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