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I haven't been on the board in a while, so maybe this has already been figured out. Hopefully this is useful, though I think the time has run out on being able to do this due to parts availability. *EDIT* I see, now, some people already knew about LS258. So, sorry for re-posting*


TL:DR : For CV joints for the Rocky, you'll want to use LA258 universals, remove the wheel shafts that come with them (3 groove, UM510-02??), and replace them with the UM522-02 wheel shaft (2 groove). Add a 1mm spacer between the wheel shaft and hub.

Unfortunately, the LA258 CV's are hard to find because, as far as I can tell, they only came on the back of the Lazer ZX-5 SP, and nothing else.


The pork:

This is, basically, an update on this thread https://www.rc10talk.com/viewtopic.php?t=19856 which started, I think (before it was rage-edited), as a search for newer universals for the Optima, but turned towards questions about CV's/universals for the Rocky. A quick skim to refresh my memory, it looks like it was left at using the LA245 CV Joint, which is 62.5mm long, and trying to find a way to get around the wheel shafts they came with.

I have a few parts for my "Super Rocky" project and, recently, got a 3D printer of my own, so I was able to model and print the LA245 length axle and test fit them to a UM522-02 wheel shaft. I also printed a 1mm spacer. You can see, next to the gold universal, there's extra length:
https://drive.google.com/file/d/18Sis17pTcge4bn-Dc2Q6sVztbZMXhdGm/view?usp=sharing

Test fitting in the Rocky with an LAW30GM wheel hex, and you can see that there's interference. The rear will bolt together but bend the shaft when the suspension is compressed. The front won't even bolt together. *EDIT* BTW, on the rear I found a set of Tamiya outdrives that are VERY close to the Rocky/Raider outdrives. They're just a hair too long and will lock the rear. When I get further into this, I'll see if I can do some grinding to make sure they stay free.
https://drive.google.com/file/d/14lFsysaYU2o-E8mDlaNupuX43GTG2ohI/view?usp=sharing
https://drive.google.com/file/d/1i6cFF2Bfa02p2Yfa0ZcvnHBh67PPqI2-/view?usp=sharing
https://drive.google.com/file/d/12uD2D7-sKXceDQKWaTOJXtzCzSszqB54/view?usp=sharing

This picture doesn't really show it, but the center axle is printed in the 60.5mm LA258 length. It lets the front bolt together and move through the suspension stroke like the gold axle.
https://drive.google.com/file/d/1f7ho42kka3kzv1sisUO89LwcQi_floSe/view?usp=sharing
https://drive.google.com/file/d/13_HQmnxkQ-Y4dqO2CVjX5Yos1XGDyWYz/view?usp=sharing
https://drive.google.com/file/d/1DtfmZs0FmH-S50H02izEEKl68YV1Q1m3/view?usp=sharing

Here's the LA258 CV. I managed to get a couple from Japan on eBay, which wasn't the cheapest, unfortunately. But they've not been added to a kit in a while. I think I saw some for sale on Kyosho's Japan website, but that sells to Japan only, I believe. Next to the gold universal, you can see the difference in length is in the wheel shaft.
https://drive.google.com/file/d/1TxmTMVlZOkXmzSMqQsKf1Uv4snPWha7h/view?usp=sharing
https://drive.google.com/file/d/1Xv8XY9pbcIZwLiNcxCU6qFfoO7WMwjKy/view?usp=sharing

I assembled two of the axles with the UM522-02 wheel shaft and the 1mm spacer. Added to the front and rear they fit similarly and allow the suspension to fully compress
https://drive.google.com/file/d/1Fie-q5_j8NQh6dDAR2HPDDwotc8OfWoe/view?usp=sharing
https://drive.google.com/file/d/1iEFEbgzMEfGz3c0poPjrfNEctSqsp7oX/view?usp=sharing
https://drive.google.com/file/d/1EGoB713RUziA6u4wFsQoU1EwUQZhiwAh/view?usp=sharing

The drawback to using this is the wheel shaft is too short for the original Rocky wheel, which has a thicker hub. I'm using an old set of HPI wheels that have a much thinner hub and will leave room for a locking nut. I tried using a TTFW113 wheel hub, which is .5mm narrower than the LAW30, but that didn't give enough thread to get a locking nut full on with the Rocky wheels.
https://drive.google.com/file/d/15hWSgO7TREwUxN8O_eRGaE-Okv9yWD5P/view?usp=sharing
https://drive.google.com/file/d/1IODDi3nVaQWBuk0KMmXdBMpvRgU2DhxI/view?usp=sharing


So, I created a spreadsheet of Kyosho CV joints to help me with my Super Rocky project, if anyone else would find this useful https://docs.google.com/spreadsheets/d/1kF6AHPNXrmpZWUfXMB0b-yudygA8z7npwtXlfIJHQps/edit?usp=sharing .



I used Kyosho manuals and exploded views to create it; managed to find an option part in a parts list, too. The exploded views on newer kits had the axles and wheel shafts noted with individual component numbers (-01, -02), so you often find Lazer and Ultima part numbers together. Also, you can buy those parts individually, which would be handy in this situation, because you wouldn't have a spare wheel shaft. But neither the manual nor the exploded view had LA258 broken down by component and nothing came up on eBay or Kyosho when I entered LA258-01. Wonder if it's a part for an Ultima or something else. Anyone know any other Kyosho off road cars that use CV joints?

Also, the Gold Universals came with a "half-spring" to hold the U-joint "Cup" in the differential. You can't use the original Rocky springs because they're too big. I need to find a substitute for that. I thought I saw some newer kits using a piece of foam, but newer kits retain the cups internally, so the foam is probably more to keep dirt out and will break down fast. While I may have found a replacement for the stock rocky spring on McMaster, the half-spring seems a little "specialty", and almost seem like cut down mechanical pencil springs.

Anyway, hope this helps. I've got a free Google drive with limited space and I don't know about bandwidth limits, so grab pictures if you want them. If I get to where I'm able to attach images, and there's enough desire to preserve this info, I'll upload them.

Found an easier solution for the rocky, ran the 3racing universals for the optima ( very reasonably priced) and swapped out the M10 x 5 x4 mm bearings for M10x5x3mm, gives 2mm of wiggle room and they fitted nice with some shimming.
Also the Tamiya hard outdrives splines fit right up to the factory diffs and easy to source

Tamiya OP-218 #53218 Hard touring.

If you're wanting to ditch your JIS plastic thread hardware for hex drive but don't want to thread M3 machine screws into all the plastic holes, which runs the risk of stressing the screw holes, Axial has a variety of fasteners in M3 and the elusive M2.6

Kyosho has a lot of M3 as well, but the button heads are too large to fit in the counterbores on the Rocky. Here are a few M3 options. I used M3x12 on my Parts-To-Runner Rocky that has the Factory Works chassis set. Though I measured one take-off screw at 12mm, and though they all seated, it looks like 12mm might be too long for some screw positions, so consider the 10mm and 8mm if you rework it. BTW, I'm likely going to abandon my Super Rocky and rebuild it as a standard Rocky, and I'll be using a lot more.

AXIC0120 HEX TAP BUTTON HEAD M3X8MM BLACK (10)
AXIC0121 HEX TAP BUTTON HEAD M3X10MM BLACK (10)
AXIC0123 HEX TAP BUTTON HEAD M3X12MM BLACK (10)

Additionally, the M2.6 screws can replace the shock adjustment collar screws (10mm) and Wing adjustment screws (12mm) on the Lazer ZX-R
AXIC0424 HEX SOCKET TAPPING BUTTON HEAD M2.6X10MM BLK(10)
AXIC0425 HEX SOCKET TAPPING BUTTON HEAD 2.6X12MM (10)

They offer a variety of flat head style as well.
Here's a search for "Self Tapping Screws"

Axial also has these 30mm steel turnbuckles. They seem to fit better in the original Rocky rod ends than the current LA43H "Hard" Ball Ends I'm using, but Kyosho has other ball end options I've not tried
AXIC1634 TURNBUCKLE M3X30MM (2)

As cas22 mentioned above and verified: the Tamiya outdrives, part number OP-218, can be substituted for the RK-21 outdrives.

When I first put mine together before making the CV post, I noticed a slight binding as it felt like a spline would catch something, but it's not an issue now. I've done some running and they seem like they MIGHT be more durable than the RK-21's. What's also nice is the center shaft is pressed into one side so you won't lose it if a dogbone pops out, and they're substantially cheaper than what people were last asking for the RK-21. The downside is they're for a discontinued kit so I'm not sure what the supply is like out there.

Thanks, cas, for taking the risk and verifying that.

Something I tried to explore was a yokomo axle that is 60.5mm. Unfortunately, none of the wheels shafts would fit the Rocky hubs right. Yokomo offered a wheel shaft in aluminum, which would be neat. But unless the yokomo CV joint is compatible with something else, this is a dead end.

Hey HZ,
Ive been getting a few parts off these guys
https://www.plazajapan.com/4955439029060/
you need to be patient as the search engine is nothing like we are used to, but if you find the parts they are very cheap.
They only stock OEM parts on this site, or BANZAI japan no aftermarket stuff, but they are HUGE.
My go to was always A Main, or RC Mart but with the cost of shipping from USA is just so ridiculous, 4 plastic rod ends and a carbon front tower was $10UD with the only shipping option being $43USD.
They are also silly fast, delivered to New Zealand in 3 days for about $8USD.
I got around the CVD clearance by sourcing 3mm wide bearings instead of 4mm, then i could play around with clearances, shims etc, Much easier.
Also Aliexpress for Metric and imperial hardware, you can buy as few as you want, stainless cap screws m3, 4-40 etc all the washers and shims too.
Cheers

Sorry P.S,
I have found that on some of those Japanese sites it can be easier to type say "OPTIMA MID" into google translate, they cut and paste the Japanese characters into the search engine on their site.
Can dramatically increase hits, but usually downloading a manual and finding the actual kyosho part number works great too. It is a very different search engine, but if you are patient its surprising what stock they hold.

Forgot about springs! For out drive spring replacements on the Rocky, I've used a couple.

* For direct OEM replacement, which you'd need for the stock dog bones, I got these (i think) from McMaster-Carr

It's been a while since I've run dog bones so I don't recall if the springs in the wheel axles are the same as those in the out drives.



* For the CVD conversion I needed a spring that was shorter and could compress flat, and used this

When i first did this conversion I trimmed off the last, smallest coil to allow the spring to fully compress. But the last time I put them together I recall not thinking I needed to. Definitely test fit when you do your assembly and use eye protection if you trim because that last coil will shoot off.

Has anyone noticed that "universal" swing shaft OTW125C for the rere Optima kits practically drop right into the Raider? Sorry for the cross post, but I thought it might be relevant here.
You have to leave the red shim out, as it is slightly too thick. A small about of shimming is needed/available to dial-in the engagement. This is what I get with it shimmed on the outside of the bearings:
With the Optima hex adapters, there is just enough shaft to accommodate the stock Raider Pro rims:

Is this the same application that the 3Racing part Cas22 found also fill?

I think the 3Racing part isn't available anymore, so that universal is probably the only readily available option.

Any chance you're able to measure the length of the axle section from pin to pin?

I added the Optima Mid World Spec and the OTW125C to my spreadsheet.

You can add the spreadsheet right to your first post if you like by simply copy/pasting the link.

Lowgear wrote: ↑Sun Apr 06, 2025 5:08 am You can add the spreadsheet right to your first post if you like by simply copy/pasting the link.

It's the last link near the end of the post.

I was thinking I should eventually go back and upload the images of my test fits rather than leaving them linked to my google account.

I should have been more specific by saying if you add the actual URL of the spreadsheet to your post, it will embed it. The current one in your post is the share link which is slightly different.

Here's the link to add to your post if you'd like the spreadsheet to display:

Looks like they are 61.5mm: