Project: YOKOMO 870C - the 4th

Hello and welcome back to my blog! What happend to the world since my last arcticle? We still have Covid 19, Russia is still in a war against Ukraine, Elon Musk is ruining Twitter and we have record energy costs and we are still destroying our planet. So what can we do to not lost our mind these days? I personally try to spend much time as possible with my kids, doing my job (with not much motivation to be honest) and spending time with new vintage projects. I raced 2 amazing vintage races this year, made my first holidays since 4 years in the UK, wich was amazing and try to be as positive as possible.

I made 3 different Yokomos over the last years (see my other articles) and I had some ideas to build the ultimate Yokomo 870C vintage racing machine finally! I wanted to try different materials and some not-so-vintage parts to make this thing as strong and fast as possible!

The challenge was, to find parts, what fit technically, but also fits the neo vintage look. Some of you will definitely not like, what I did - but I like it so much! The car came out much stronger, faster und better looking, than I ever expected!

The 870C front. First of all you can see the "forged" carbon fibre front shock tower. This material is a high gloss full forged carbon material. Made from carbon chips. It looks so amazing! If you look close, you can see the 3D effect inside the material!

The original 870C body and wing - painted by the spanish paint master from Attack RC!

It´s all about the details!

All the decals are from MCI. Did I say that I love MCI?

Staring at my cars is my expensive hobby.

Made for vintage racing AND for the shelf!

Two well known rivals.

They look iconic and so awesome to me!

Now the hard facts about this car! The side view shows the inside of the right chassis side.

The left side. Blue is the theme here! As always I use a LRP Flow-X speedo and a Reedy 10.5T motor. For my opinion, the best power for a 4WD vintage car in a racing situation. More power means much more stress at the ball diffs, slipper and drivetrain, wich is definitely unhealthy.

The LRP 4000 shorty lipo fits perfectly to the blue colour-orgy of this car.

Team Associated 1.12 rear shocks at the rear and 0.89 at the front - with titanium nitride coated shock shafts. Front and rear arms are made from machined Delrin and they are strong!

Blue painted front and rear diff caps

Weels off! The beautiful machined front and rear bulkheads are from Custom RC Parts! Finally a strong alternative to the fragile magnesium parts.

Electronic department and the beautiful machined motor mount from a nice guy from Thailand. "Proudly made in Thailand" was written on the package. Good job!

The mid drive. The mid drive shaft assembly including slipper and locked front pulley is from a gentleman from Hong Kong. Great work here! The anit roll bar is made from 2.0mm piano wire.

The battery - removed from the car. You can see the 100g stainless steel plate to gain some weight to the car.

The plate is 3mm thick. Sometimes it really helps to calm down the car, depending the track and grip level.

The Highest RC steering servo with the transponder on top.

The steering assembly. Manobet bell machined aluminium crank arms from France. Because the old original Yokomo ball cups are often very brittle after 30 years and it is always a bit of lottery, if they survive racing, I descided to use Team Associated B6 ball ends and ball studs around.

You must be strong now! I used Xray T4 2021 aluminium front knuckles in combiantion with Re-release Kyosho Optima C-hubs. The brass king pin bushings are from Yeah Racing and reduce the eccesive play there.

I installed a Lapmonitor IR transponder on top of the upper deck to get live lap counting over my phone ear plugs while driving. This is the best way to get fast on a track in my opinion. You instantly get your laptime while driving, so you can adjust your driving style and racing line a little for the next lap and see/hear if that one was quicker, or slower. We all know, that a slow looking and unspectacular car is mostly the quickest on track.

The rear hubs are RDRP Kyosho RB6 rear knuckles from aluminium. They do fit and I designed the hubs back in time, when I worked for RDRP.

The undertray. At the front is the home made front bumper made from Kydex.

The movie!

3 buddies - the space goes tight on my photo table. The Works 91 did not get it to join them for this photo.

And how is this thing racing? I had the chance to give it´s first shake down on a touring car track near Hamburg/Germany. The 870C was super quick from the beginning. After the usual adjustmets of the slipper and diffs at the first run, the Yokomo drove like on rails. Easy to drive, forgiving and fast! The setup was good! To make a buggy fast and easy to drive is 95% the correct springs and shock oils! Sometimes you need to spend a whole day on a track to test different springs and oils to find the perfect combination for your car and track conditions. It is a lot of work, but it is worth! The other setup aspects, like camber rate, toe in/toe out, etc have only a little effect on your buggy and you can do this fine tuning after finding the perfect spring/oil combination. Now I have to fine tune things and make it even faster. I will definitely try to race it on some regular non-vintage races this winter. This car was made for racing - then and now!

Video from the first test session. I used a Reedy 13.5T BL motor this day.

I hope, you like this article! It is always a bit harder to find new ideas for projects. If I could motivate you to build your own vintage car AND to race it, then my mission is accomplish.

UPDATE July 2023

As I wrote in my GP3D Stealth Car 1989 article, I was able to drive the Yokomo at the beautiful dirt track at the EDC Kinzigtal in Germany!

The King Of Black Forrest vintage meeting at one of the most beautiful dirt tracks in Germany.

The Yokomo got some Proline Holeshot M3 rubbers and was ready to go dirty!

As expected the handling was absolutely amazing! This car is made for slippery dirt tracks - and you can feel it when driving. The Reedy 10.5 Motor delivered so much power, I had to find a way to reduce the punch. After the speedo setup to blinky mode I also reduced the high end point at the transmisster from 100% to 85%. That calmed down the car. The handling was so fantastic! No understeering, no oversteering. The Yokomo went nearly neutral through the corners and the suspension performed all the bumps and holes on the tracks pretty well! I made the 6th position in this race against some very quick locals here :)

The dirt looks good on this car. After this amazing weekend I only have one thing in my head: when can I race on dirt again?