Optima Mid Runner Budget Build to LWB conversion

[XLR8]

Awesome build! Looks beautiful for a parts car

So, the longer WB car uses a longer upper and lower chassis plate, belt, and belt covers? Oh, and a longer body I guess. Is that it or are there other differences?

The first longer chassis was the mid custom indeed exactly for the reasons mentioned above - that's also when 4wd's transitioned to saddle packs, although the MC could use lifted up sticks, still.

Other than these mods, and the usual availability of different shock/chassis material combinations, no mods iirc. Then they went to the Lazer (Legend in between but was it ever commercialized?). Then Kyosho fell off the face of the RC earth for like 10 years or so as the later lazer versions were desirable for sure but so exotic and expensive than even the most seasoned yokomo racers couldn't understand the product line Then the Lazer ZX-5 brought kyosho back to the top of the 4wd game.

Thanks a bunch for the wisdom and the history lesson Paul. This is why I'm here.

[XLR8]

So, the longer WB car uses a longer upper and lower chassis plate, belt, and belt covers? Oh, and a longer body I guess. Is that it or are there other differences?

Mid you decide you want to make it a longer wheelbase, I still have some chassis sets that are longer than stock and just under the kyosho version long wheelbase chassis. They are our original chassis from our trailing arm kit but cut down for stock suspension. The only thing we don’t have is the belt cover, which TBG sells.

Thanks Jeff. I think I want to go ahead and make the change now. So, I'm looking at the Factory Works webpage from your link, what are the part numbers I'll need to order?

[GoMachV]

your best to message me here, our website hasnt been updated in forever, and although most of the popular items are on ebay, it saves you the ebay fees going direct

[XLR8]

So the rere Optima Universals fit these without any mods as well? Both front and rear? Part OTW125?

I haven't actually tried the universals but I think they should since the rere dogbones and axles fit without mods. You probably already know this but the universals aren't as durable as the dogbones and axles they replace. I think this is why Kyosho didn't use them in rear which receives more abuse than the front.

[RCveteran]

I read that Lazer ZX CVDs will work as well with minor shim on inner hub. LA245. I have not tried myself to confirm.

[Coelacanth]

I read that Lazer ZX CVDs will work as well with minor shim on inner hub. LA245. I have not tried myself to confirm.

I believe those would work, too. They're 62.5mm, almost exactly the same length as the dogbones, crosspin-to-crosspin. I'm using GPM aluminum arms with 2 of my Optimas (a Turbo Optima and Turbo Optima Mid SE) and those arms are 5mm longer than stock arms. On those cars, I'm using CVDs that are 68mm, and they're a perfect fit. (62.5mm + 5mm = 67.5mm...close enough.)

The one thing to consider is original Optima axles were taper-fit to the hex hubs, while the Lazer CVDs and I believe the re-re CVDs are all straight axles with crosspins to lock the hex hubs onto the axles.

I don't agree that the CVDs would be weaker than the dogbones because I've seen a LOT of bent dogbones over the years, plus the dogbone crosspins were always wearing flat where they contacted the joint cups, and joint cups themselves had the slots wear notches out. With the parts all being separated and having a certain amount of freedom of motion, they were prone to wearing. At least with CVDs, this freedom of motion is greatly reduced.

[XLR8]

I could be wrong but I think the durability issue isn't wear at the pins but rather it's breakage on the axle and/or the shaft where they interface with the cross assembly ( the part that forms the letter "C"). I reckon that the material tends to be machined very thin in this area and if the parts are also worn, this area can become even thinner. I don't have any first hand experience with Kyosho universals but I continue to run AE universals on RC10's and I've managed to break more of them than dogbones. For me, the dogbones just seem to wear out over time - just as you've described. I'd read a post somewhere that the individual was experiencing a similar kind of failure with his Kyosho universals. BTW, I've never broken a CVD; they seem pretty bullet proof (so long as you secure the pin so that it doesn't fly out). Do you know if Kyosho ever offered CVD's that fit these vintage Optimas?

Hey Jeff, I've located the item you've referenced on ebay and went ahead and purchased it there. I thought this would be simpler for me since I already have a paypal account with ebay. I was running the car again today and I think the extra WB is exactly what this car needs. Thanks for chiming-in and letting me know the kit was available.

[Wahrsuul]

At the time, you could just buy the longer chassis, top plate and covers (I think) and stretch a standard optima mid. I bought all the parts, then soon after just bought a Mid Special (I think). I also have the Turbo Optima Mid Special (I get lost with all the versions) it's the one that came with the CF chassis. I ran the stretch for a while as my racer, the picked up a Lazer ZX. It was about then that I PCSd back to the states, and where I was they didn't do any outdoor or off-road racing. So I kinda fell out of the hobby.

[Lonestar]

(I get lost with all the versions)

See? I'm not the only one

[Coelacanth]

Do you know if Kyosho ever offered CVD's that fit these vintage Optimas?

I don't believe they did. I think I misunderstood your previous post about universals to mean CVD's. Kyosho did make universals to fit the Optima series, complete with tapered axles for the original tapered-hole hex hubs, but the CVD's didn't come until the Lazer came along, I think. Those all had straight axles with holes drilled for 2mm crosspins, which solved the problem of the friction-fit hubs slipping on the tapered axles.

eBay is full of listings for cheap aluminum 12mm hex hubs in different thicknesses that capture the crosspins and lock onto axles with grub screws. The aforementioned Kyosho LA245 CVDs have the correct bone length (62.5mm) but the axles are just a smidge short. Kyosho LA258 CVDs have bones that are too short (60.5mm) but the axles are 1mm longer; notice the 3 lines scribed into the axles. I made hybrid CVDs with the 62.5mm bones and longer 3-line axles, those are almost perfect, as long as you use the 12mm hexes with crosspins.

[XLR8]

Thank you Coelacanth. You've just spared me a ton of time and $'s. Now, when I'm ready to upgrade to CVD's, I'll know exactly what to get.

It's been really dry here lately so, before running laps, I've been watering my little backyard track to settle the dust and to aid traction. Yesterday, as a test, I ran the Mid on an un-watered dry, slick and dusty track surface and I found it to be much easier to drive fast. The car was less tight and there was much less tendency to oversteer at corner entry. Overall, the car responded a bit more slowly and predictably and I seemed to be able to control it more effectively using the throttle. I also tried Hole Shots on the front (because I have them so why not) but they just added front grip and increased oversteer.

I was also running my B3 at the time and found it to be very hard to drive on that loose surface. Normally, the B3 is extremely predictable and easy to control but now I can see that it definitely does not like a dry track. The handling characteristics for the two cars on that surface could not have been more different.

I still need to finish my XLS runner (rebuild and upgrade) and gain some track time with it before making any comparisons between the two 4wd's. However, at the moment, I think this Mid in its current configuration is the quickest off-road RC I have ever driven. I'm having a lot fun with this car.

[Wahrsuul]

I was just looking at the build pics of my Lazer ZX. It looks like it has the taper axles on it, not pins.

[RCveteran]

I am going to build a rare Optima Mid Short Wheelbase Custom Special CVD Type RBZ5.4 edition.

[Coelacanth]

It's too bad 3Racing no longer sells CVDs for the Lazer; I bought a few sets that worked perfectly (for my modded width cars) at the 68mm length. They were under $20 for a pair. I believe the fronts were ZX5-19/HD and 68mm, the rears were ZX5-20/HD and 65mm.

https://www.3racing-parts.com/kyosho-lazer-zx5-front-universal-shaft-heavy-duty-3racing-zx519hd-p-10001431.html

They also sold a 4-piece shock set that was a great fit for the Optima series, needing only minor modifications to fit. I bought a set, I wish I bought more, though.

http://os.3racing.hk/products.php?products_key=2607

[XLR8]

It's a shame indeed; those are some really nice parts. So what's the story with 3 Racing (I've not heard of them before)? Do you reckon they've stopped supporting Kyosho products entirely or is it just vintage stuff? RC seems a particularly difficult market to predict (and be profitable). I don't envy those businesses who struggle in RC these days.