Just a Rocky Project (Formerly "My Kyosho Developed Yokomo Envy")

[HS-YZ250]

Not much done. Actually, more done than first appears below, but haven't drawn in many new parts. Been too busy with the other hobby, but here's a shot for reference. I think this is what I'm going to try and do for the battery positions, though the Right side pack may be a tight fit, thanks to the mounts for the rear gearbox. The servo location is still up in the air until I can settle on steering mechanism, side stiffeners, and gearbox to side braces. The chassis plate, when trying to use the plastic rocky front kick-up, is tricky because the kick-up and rear gearbox are not in the same plane.

[orangemazda]

Looks like a cool project!

[HS-YZ250]

Trying to figure out the steering and front brace; This area is going to be a VERY tight fit! Other parts are mostly detailed, though I'm going to have to do a few iterations to match to the body, Some are roughed in.

[Mr. ED]

Was this abandoned?

[HS-YZ250]

No. It's not been abandoned; just on and off when I hit roadblocks or change my mind. Was doing a lot of dirt bike racing up until a couple of years ago, then had a brief stint in model rockets, then got into some work on my old truck, then Covid. The last burst of work was early this year so I could use it as an example for a 3D Printing demo at a science festival. I got the rear suspension up and a dummy link put in to hold the steering centered. Still a long way to go, though. The next big hurdle will be getting a steering system tucked in under the front chain sprocket while keeping the gains in the significantly improved bump steer.

Unfortunately, along with a lot of life shifts due to covid, my laptop with my CAD system went down, so I've got to get that going again.

To complicate matters further, I decided to make it a double-build and fix up the Rocky I had originally bought for the Gold Universals, years ago. Unfortunately, I missed the boat on the Gold Team Associated 0.71 stroke shocks they offered until just recently, so I've been trying to come up with an alternative. Wondering if I can use these on the back >https://www.associatedelectrics.com/teamassociated/parts/details/21534-ASC21534-shock_body_set/

Also got my fingers crossed that some CV joints actually make it here from Japan.

Here's how the cars currently look.

https://drive.google.com/file/d/1VVV2FqmrRwosYrPqTYS0pY6kP84FK__q/view?usp=sharing

Also compiled a database of Kyosho CV joints in the process, if anyone would find it useful.

https://docs.google.com/spreadsheets/d/1kF6AHPNXrmpZWUfXMB0b-yudygA8z7npwtXlfIJHQps/edit?usp=sharing

[HS-YZ250]

I don't think I'm ever going to find the time to get back into modelling a whole new chassis for this project so I'm abandoning that path and going back to where this started, which was piecing together an independent front suspension setup from Turbo Rocky parts. But complicated, of course.

BTW, if anyone wants to take a stab at following through with what I was doing, DM me and we'll talk about getting you the files and parts that I had made and collected for it.

So, here's the re-mock-up. I had a spare LA258 axle set in a box, fortunately, and was able to find one more online, so I put together a CVD set. I had to print out another couple of Watanabi inspired rocky wheels to get it on all fours. I'll probably look for a modern wheel/tire setup at some point, but this is fun to have for now.

I may have lost the special Rocky screws that hold the bumper on, annoyingly, but I have a Turbo Rocky bumper I'll put on later. When I figure out a mount for the RC10 style wing I'll be set with a very-80's looking car. I'm not a fan of the Turbo Rocky body so I'll cut up a TBG Rocky body similar to this. Debating trying to cut the nose similar to the Turbo Rocky or just cutting it to behind the front shock tower like in the image. I feel like the latter looks cleaner.

Ages ago I had collected some Turbo Rocky chassis parts and had originally wanted to use them before I had gotten annoyed at the front shock layout which lead to buying all the Associated shocks and re-engineering the chassis. So I swallowed my pride and put the front and rear towers on. I initially built the set of Optima Rerelease gold shocks I had gotten for my Lazer ZX. They look great but are an odd design, though I'm not going to worry about it. I gather they are the same geometry as the platinum shocks that came on the Turbo Rocky. Like the Turbo, this gave way too much suspension droop in the rear and no droop in the front. I want to try and balance this out and see how it works, so I dug into the plethora of Associated small bore shocks I have , eventually borrowing Associated's practice of mixing long shock bodies with short shafts to get something I think I can work with on the front and rear.

The front setup is a 0.89 body (I think) with a .56 shaft.
The rear was a little tricky. It's a 1.02 body (I think), but Associated didn't make a .89 shaft, and the 1.02 shaft made it the same as the optima rear. So I pulled out the 0.9in shaft out of the front of my old Pro SE shock, and it turned out pretty good, though you can tell Associated and Losi had a slightly different tolerancing as the Associated piston was a tight fit on the Losi shaft.

I still want to put a travel limiter in the front to reduce the droop a little because it gets close to the axle contacting the edge of the outdrive like on the rear with the Optima length shocks, and the shock seems to want to bind a bit at the end. But the max bump is on the nose, just using up all the stroke when the chassis is on the floor. I might gain a hair by using the proper Kyosho shock end vs the longer rod end.

Here you can see how the rere gold front shock doesn't use it's full stroke when the Rocky suspension bottoms.

The problem with this setup is I used the other .89 stroke shock on my Parts-To-Runner Rocky, so I'll have to buy more Associated shock parts. I'll have to think about what I want to do here. Currently I'm piecing together a new-ish build of a gold pan RC10 with Worlds Car geometry. For that I wanted that to have no modern looking coatings which would mean all gold body shocks, but I think the Worlds car took .89 front shock bodies which only came in teflon coated. I'll have to decide how I feel about grey bodies with gold caps (I know masami did that once) but if I go that route, I could get a V2 pair of .89 bodies and use them with the V2 1.02 bodies I mistakenly bought for the YZ10 on the back of the Rocky so I have threaded all around. Though I did want to try Fan RC Blue shock caps on this Rocky build and those don't fit the V2 bodies.

[HS-YZ250]

Rats. I was waiting for these to come back in stock because I wanted a blue 480T for this build, but they're now showing discontinued - https://kyoshoamerica.com/37033.html#catalog-product-description-additional

[HS-YZ250]

I thought I had hit the jackpot when I found this NOS .89 shock body at a hobby store with the original list price. But then I took it out of the package. Think associated will warrant it? Lol!

[HS-YZ250]

Had to break down and buy some shock bodies after the NOS .89 body was a defect. Found a top load threaded body set for not too much for a RC10B4.1 and had a few more bleeder caps that would fit.

Front combination: 0.89 stroke bodies, 0.56 stroke shafts, ReRe Optima Gold Springs, associated shock hardware, 20 wt oil.

Tuning the front is going to be a bit of a headache. The lower mount on the upright directs a lot of the spring force into the suspension components so it's difficult to find a spring with a high enough rate to hold the front end up. You end up with a heavy spring and very light oil combination. Here I had to use the Optime ReRe shock springs and I still think it needs to be heavier, but it'll do for now. Also realized the bleeder caps don't allow for M3 nuts, let alone ones with flanges, so I'll probably have to add a spacer or relieve the caps to keep them from binding.

Rear combination: 1.18 stroke bodies, 1.02 stroke shaft, associated black spring, associated shock hardware, 20 wt oil, rebound travel limiters

The rear is where I found the nut to cap interference, so they're currently backed out. Still feels like they're binding, but I'll get to working on them when I get everything else set up.

I have a servo in it now, and a battery rubber banded into place to get a feel for the suspension. I found a sketchy website in Singapore that claimed to have Kyosho 480T's in stock, so we'll see if I get something or if I get a fraud alert on my card.

I'm going to use a le mans esc and was hoping I could put in down inside the tub, but there's not enough room with the servo and servo saver, so it'll have to go on top where the cab for the body is.

I'm also debating wheels. I like how my watanabe wheels came out, but the tires are so small and hardened up. Hoping I can either find a set of newer tires that'll fit, or a wheel/tire combo with the right low offset.

[HS-YZ250]

Current state of things.

Back together with electronics. I have a Surpass motor in there while I hold out hope the 480T shows up. For now the ESC will have to live right under the cab.

Going to work on a mount for the rear body post/cable to drop it as close to the chassis as possible, which gives it an Optima feel. Also a block to attach to the rear shock tower to hold the RC10 wing tubes and wing. Also need to figure out a better way to hold the battery in place than the single reusable cable tie.

I found some blue springs for the front of the YZ10 that I might try on here because the Kyosho Golds still feel a little light.

I'll be happy to finally get rid of the original cut up body after all these years.

[HS-YZ250]

Small update. Working out how I want to mount a wing, and the nerve to cut up a new body like I have the original. In the meantime I dug out some Scorpion rerelease wheels I had gotten for my other rocky but never got around to putting on because they don't look as good ass the Silver HPI's. Put on some Pro Line Hot Laps for that radial tire look .The duratrax banditos I have on the old rocky are much better looking but, sadly, were discontinued in buggy sizes a while ago.

Also need to work out a way to keep the battery secure

[HS-YZ250]

I've had a lot of other things taking my time, lately, but RC projects occasionally pop in my mind. With this project I was stuck on what to do for a wing. I would have liked to to a YZ10 style mount on the shock tower to nod to the original intent but there wasn't really an option of doing that without fabricating a new shock tower. So I had settled on having to 3d print something to possibly mount, but once when scrolling through ebay results for "Wing mount" I got lucky and found that the Tamiya Top Force had wing mounts that turned the wire vertical rather than axially like the Yokomo. Better yet, when I got them mounted I realized the spacing of the holes for the sway bar kit was close enough to work with the RC10 wing wire.

Here's how the looks are shaping up compared to the stock rocky body arrangement. It looks wider than the Parts-to-Runner Rocky because the Javelin rere wheels have a shallower offset, which makes it about as wide as a Lazer ZXR. You can see in the hole that there's a gray piece towards the back. This is a 3D printed part for retaining the battery wires and mounting the rear of the body. Since the chain adjustment is done by changing the wheelbase, I would really like to mount the body entirely to the chassis tub, but there isn't a good spot without getting creative with printed body mounts, which I may try before committing to cutting out a new body.

Other note is the front shock mounts were a little challenging trying to get the front bleeder cap shocks to move freely through the stroke. The issue is, with the amount of front kick-up combined with the lower shock location, the shocks end up changing their angle relative to the tower a fair amount, so combined with the bleeder caps' size, I needed to find a way to relieve the spacearound the cap. I ended up using FanRC reproduction shock bushings because they're sized for 3mm screws, and used them with an old RC10 black travel limiter. Now there there is only a slight amount of binding in droop in the right front I can't yet identify. Also, the front and rear have about the same amount of travel, rear having down travel limits.

[HS-YZ250]

Finally replaced the original melted body! Not sure how I feel about my "vision" for the pain scheme, but here it is. I hate doing bodies. They never come out quite right. This I wish I had moved it forward about a mm and trimmed around the front suspension better.

Still have to sticker it up, figure out how to better secure the battery that likes to slide out the side, play with springs and oil a little, grease up the drive train, and make a motor plate. Also hoping to find some blue Le Mans 480S brushless parts to swap onto a gold 21.5, so I can keep with the yellow/blue scheme.

Can't believe I've been screwing around with this thread for over 10 years.

[cas22]

Looking great mate, liking those wheels and front shock stance, well done

[HS-YZ250]

Thanks! It's just a Turbo Rocky setup. Years ago I got lucky and scored the Turbo Rocky front gearbox cover, so I could use the front shock tower with the raider/turbo rocky front uprights with the added shock mount. This build originally started as trying to get a decent front shock location and angle on there. But time and priorities cut me back to just putting on a decent, tunable shock.

Also managed to get the turbo rocky front bumper.