Project: Yokomo 870C Worlds Car Masami Hirosaka 1989

Aktualisiert: 17. Dez 2018


Welcome to my Blog! This is the first entry of my constantly growing RC Car Blog. I will try to document every single RC Car project from my collection. And this so exactly as possible. I start first with the Yokomo 870C Masami Hirosaka Worlds Car from 1989. Masami won the IFMAR Worlds 1989 in Sidney/Australia with this prototype car. My idea of neo vintage is, to convert this amazing piece of artwork into a "modern" Vintage Racer. Some people will not like, what I did, but I loved the idea to mix some stuff and knowledge from today to make something very special to race this beast from the east!


Masami Hirosakas original Yokomo from the IFMAR Worlds 1989


No replica. But something special with a modern touch! This project was one of the most complicated vintage cars I ever made. The result is a refined and very nice looking machine for vintage racing!

The Yokomo 870C body is one of the most beautiful buggy bodies ever made. It stands out of the crowd. I tried to match the painting as close as possible. The rear wing is mounted different to Masamis original car. And I put some large end plates on the wing, what we we all loved in the late 80´s. I put some oldschool and some modern Logo decals on the body and wing to demonstrate the modern touch of this buggy.


If you look hard, you spot some differences to Masamis original car. I put longer front shocks and new designed shock towers on the car. The result is a little more up and down travel, what helps on rough and bumpy tracks. Masamis prototype car has a very special suspension. The Yokomo team used the original rear suspension arms for the front in combination with the early Yokomo front knuckles to have a wider front width. The knuckles are super rare and I was more than happy, that my friend Cedric Devillers was able to provide me with a pair. The original Yokomo Worlds Car has some machined super long rear arms in combination with modified Team Associated RC10 rear hubs. I chose to print those arms at Shapeways. They are pretty strong and flexible and hold many runs without breaking. Instead of preparing the RC10 rear hubs, I made a new CAD design to fit metric ball bearings to fit the Yokomo universal drive shafts.I made them with 1.5 and 3.0 degrees toe-in. They are also 3D printed and are surprisingly strong.

Looks fast!

I really love the overall look. The form of the body, the Masami paint and the pink Yokomo wheels. For me it´s pure work of art.

If you think, long suspension arms needs long shocks - wrong! There are the shortest Team Associated RC10 rear shocks installed. I also used the clamp style spring adjusters, instead of the c-clips. For racing on carpet tracks, I put some Schumacher Dart tires on the rims. And they work very well.

It was no easy task to find drive shafts with the correct length. Yokomo made so many different lengths of universals, that it took a while to find the correct ones. You can spot the connector between the inner hinge pins. They help to reduce excessive play at the holes of the magnesium gear box. I also had the make a special rear anti roll bar for this suspension geometry. I used 1.2mm piano wire.


The magic of colours



The newly designed chassis is based on some drawings from my friend Cedric Devillers. But made to install a low profile shorty Lipo battery. I am sure, Cedric, as a hardcore original freak, was not happy, what I did with this new chassis. But the result is a super clean layout with nicely installed electronics. Some years ago a friend gave me his KoPropo PS87 servo. Of course it finally found it´s place in this Yokomo! You can see the FET Booster in front of the Novak FM NER-3FM reciever and the Novak 410-M1c Speedo. Of course I use a Reedy Motor for this car. It is a Reedy Titanium Motor with a 13x3 rotor. This is a lot of power for this car. believe me! I also used a RC10 antenna mount with a grub srew to secure against lost antennas. Of course I painted the gear covers with Tamiya metallic green to match the body paint. I really love those colour mix on this car and the colours of the 90´s in general. It looks much more interesting than todays boring black/silver edges design of everything.


The 3D CAD drawing assembly. Thanks to Cedric for his great help with datas!


What a nice fortune, that I am a RC Car designer. So designing a new chassis is daily work for me.


The chassis without wheels. I used the option lightweight wheel hub. And I used Lunsford titanium turnbuckless all around. I use Lunsford since many years and the quality is superb! But if you compare the 15+ years old with the latest ones (same design), you will spot a slightly difference in quality and material. If you ask me, the older turnbuckles looks better in quality. Who knows. The transmission set up is for front and rear ball differential and the middle one-way. Why not the slipper? Because the Yokomo slipper plate and belt pulley are made from one-piece aluminium. It is nearly impossible to find this part, where the pulley is not completely worn out. So the one-way solution may be not perfect for todays racing, but at least the pulley is made from steel and will hold forever - hopefully. For the nerds (Hi Cedric!), Masamis original Worlds winning car has some fine pitch pulleys and belts. I use the normal pitch standard belt. There was only one problem: The chassis is longer, than the kit chassis. So no original Yokomo front belt wanted fit. My solution was to make a custom belt from a manufacturer with the correct lenght. Now I use a 3SM 513 Bando belt and it fits perfectly.

Is this vintage? Is this a modern buggy? I like, what I see. The basic design is nearly 30 years old.

The carbon fibre chassis is really narrow. Only the wide undertray and body make it looks wide.

The 3D printed rear suspension arm and it´s rear hub to fit metric ball bearings.

Close up of the lengendary Novak Electronics speedo and reciever. The dominant FET Booster of the KoPropo PS-87 servo.

Front suspension. Look at the front knuckles! Crazy rare stuff! As a side note: Kyosho Optima aluminium knuckles fit as well, without modifications.

How does it drive?

I drove this Yokomo several times on carpet/Astro turf. And it was amazing! The Yokomo drivetrain and it´s suspension works without any problems and you can drive it fast and precisely. The handling is great and the jump capacity is really good. Maybe the Reedy 13x3 motor is a little too much for this car (it is a last generation brushed rotor - not the old style thing). Plus, the car weight is extremely low with 1350g. race ready. Next time, I will install something with less power. The great thing on vintage racing is - it brings immediately your feelings back from the old days. The handling and the technology of those 30 years old buggies makes you instantly younger when you drive it! You forget your daily troubles and insanity in the news, your 20Kg overweight and your lost hairs. Just for 5 minutes, when you stand on the drivers stand and keeps pushing your dream vintage buggy around the corners, just like in the good old days, when we were young.

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