Kyosho Optima for NVC

[Hcp22]

We have started a vintage race call “Nordic Vintage Challenge” inspired by me and Joel's visit to VONats 2013. The first race was held in the beginning of January this year in Eskilstuna Sweden, and it was an in-door race on carpet-track. The next race will be an out-door race on Astroturf and carpet track held in Oslo Norway in the beginning of August this year.

We have almost the same roles as VONats, but one of the differences is that, we have a 4WD Classic class race. Another thing that differs is the age for the Classic class; 2WD and 4WD has to be from -85 or older. The Kyosho Optima was first realest late in -85, just in time for Christmas sales. So this is what I gone build for the NVC 4WD-Classic race in Oslo. You can read all about it her http://www.ymr.no/nvc.htm

I have no experience racing the Optima, my first 4WD Kyosho was the Optima MID. So I will gladly take all the help and tips I can get from you guys how to tweak this car to be a potential winner.

Fist I needed an Optima for start, I had a vague feeling that had one, some ware among my other cars. But I couldn’t find it any ware… So I advertised for one in the “Wanted Forum” and got two answers... Then by change when I was looking for some parts among my things for this project I found it… or rather found them! I had two Optima chassis, one with a belt conversion that I totally had forgotten about.
The other one was a regular Optima chassis. But the nice thing with this last chassis is that it seems to be new built and never driven. That will suit my project perfect, I like new parts when I try to build a racer.

Someone might wonder how you can forget about two cars... Those chassis was part of deal a friend did. The seller (Canadian if my memory serves' me right) wane get rid of all "junk" he said. So my friend ask if was interested in Optima chassis for $50 + a part of the shipping cost. I look at some pictures and decided to hop on board. When the box arrived to my friend, he discover that there were two Optima chassis. He just called me and told me "you will get 2 chassis my friend", when they arrived I just peak's at them before I put them away. This was 3½ years ago...

And I found some part that I gather for an Ultima project and some parts that is from my race days in the 80’ and 90'.

[Coelacanth]

I'm digging the multiple hard final pinion gears and belt conversion kit. You won't need those for your build because you want to stay with chain--so send them to me.

[scootmike]

Looking forward to your build Lars!

[Hcp22]

I'm digging the multiple hard final pinion gears and belt conversion kit. You won't need those for your build because you want to stay with chain--so send them to me.

Would it be potential winner without those parts? ...

[terry.sc]

I have no experience racing the Optima, my first 4WD Kyosho was the Optima MID. So I will gladly take all the help and tips I can get from you guys how to tweak this car to be a potential winner.

Good choice of buggy, there was nothing to beat the Optima back then.

If you can sneak the belt drive in, go for it. The belt drive conversion wasn't available until 1987 though, just before the Optima Mid was released. A couple of modifications which help reliability are firstly use the Turbo or Mid wishbones, both are much stronger than the original Optima arms as they have a lot more material in them. If you look at the Mid arms there is a cut out in the arm at the chassis end, this lets you use 3mm model aircraft wheel collets to hold the inner pivot pins in place as the standard grub screws don't hold the pins in place securely enough.

While the Option House shocks won't be period correct, only introduced with the Turbo Optima, many of us were using RC10 shocks on our Optimas with Parma or CRP shock mounts, until Kyosho brought out the extended mounts on the Turbo Optima.

[Hcp22]

Thanks for the tip's Terry
The organizers are aren't hard on the rules, they just look at the year the model/chassis was realest. So they don't care if its Turbo Optima I'm driving or just the Optima.
In my opinion, this takes bit of the fun out of it. I was thinking of using Land-Jump shocks at rear and the shorter versions at the front, the same setup as I have on my Tomahawk R. Instead I will use the Kyosho Gold-shocks, I will use belt drive, I will use CF for some parts. And if I had a late, I would tried to make me a slipper that are a bit better than the OT-74.

So I'm pretty free doing what I want as long as I keep the railings... But that doesn't mean I will load it with modern parts, it have to vintage parts from the 80'.


BTW Terry

All are welcome to the Nordic Vintage Challenge, there are lots of cheep flights to Oslo Norway. From most of Europe it will cost less than $100 for both ways!

[Coelacanth]

What I've read is that OT-74 isn't even really a slipper, it just helps protect the gears when landing from jumps. Also, that clutch bell pinion you often see people selling on eBay apparently doesn't work too well, either.

[Hcp22]

I remember guys complaining about those " clutch bell pinion" when driving indoor carpet race back in the days. But still, a mini slipper would be a nice asset

[Hcp22]

I had tear down the NIP OT-74 to see how it works. And yes it's a tiny slipper with two slipper pads on each side of the gear. But everything is so ruff, so I don't think it will work as good as intended. This must be one of the first slippers that was made, or did Kyosho steal it from someone else?

[Coelacanth]

Ahh...the lovely OT-74 torque limiter. Here's more detailed discussion on this particular gear, which came in 2 different configurations (not including the original Optima's solid-shaft gear); my cars all have the one with the thick spring, which I've heard is the better one...but I can't comment myself as I don't have the kind with the little spring washers to compare with.

http://www.rc10talk.com/viewtopic.php?f=30&t=17162

[GoMachV]

I am pretty sure they were marketed as just a "protector" (actually I think your right, "Torque Limiter" is the term) and not really adjustable, a stepping stone to the optima mid style "protector" which was a stepping stone to a real "slipper". I would expect to see it melt that gear pretty quickly when used as a true slipper

The Racing Clutch was also designed to slip for better battery life and protecting the drivetrain, more for beginners than racers. The melting of the shoes was not uncommon when the beginners put real power to the ground

[Coelacanth]

It's true that they aren't adjustable, even though the brass nut is an oddball reverse-threaded lock-nut. You pretty much have to crank it on and threadlock it, or it comes loose anytime you go between forward & reverse with a lot of torque. Then, the nut loosens and your Optima hardly drives anymore.

[Hcp22]

Thanks for the link Marc, it was useful reading

[terry.sc]

The OT-74 was never intended to be a slipper, it was just there so that shock loads, such as when landing a jump, wouldn't put an excess load through the gears or motor. If you don't have it tight you will melt the gear. You could try using slipper pad material instead of the paper washers but you won't get anything like a modern slipper.

[Bormac]

Great idea Lars.
The Optima was my first racer back in the day and it got me hooked on r/c. Over the years I've built up a few more and have either driven or raced them on tracks here in Australia. Being able to relive all the memories of my ordinal car has been a lot of fun for me. It's a very worthy machine and with a few mods it can be quite reliable too.

A watch this thread and your build with anticipation.
Cheers- Jason