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My Ultima ST GP "Type-R/EVO" 20th anniversary project with 3D printed "CF" parts. >

My Ultima ST GP "Type-R/EVO" 20th anniversary project with 3D printed "CF" parts.

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My Ultima ST GP "Type-R/EVO" 20th anniversary project with 3D printed "CF" parts.

Old 03-11-2020, 02:14 AM
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And the CF/PETG version came out perfect:

Gearbox covers were sliced for 0.20 layer height (speed, not quality).

Edit: Installed the bearings, ball diff, titanium idler shaft, idler and input shaft bearings and test fitted it on chassis. Its spot on. Couldnt be more happier with it. It took 3 printed prototypes before printing the final gearbox covers:

- First prototype was purely to check out the gear tolerances
- Second prototype was for screw locations, and to check that the gearbox fits in the rear bulkhead slot
- Third prototype was for the brake system

I did some slight changes to the design between the third prototype and final CF printed part.

Pics (only two gearbox screws are installed in these pics, so the covers are not tightly squeezed together):

Titanium on left, stock brass piston on right:

Brake system partially assembled:

Next step is to design some small parts, machine the input axle and find correct length universal joints. The diff outputs are narrower than stock, so i need longer than stock axles.

Gearbox covers and support released:


Last edited by HiTec90; 03-11-2020 at 05:52 AM.
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D3MON (03-13-2020)
Old 03-22-2020, 12:59 AM
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All right. After many different slipper clutch designs i think i finally found one that would work with 3D printing. At least partially. I dont have a lathe. If i had, it would have been really easy to make slipper parts from aluminum. The original Type-R/EVO Kyosho parts are discontinued, so no help from there. And newer models dont have the "quick release" type of spur gear like Type-R and EVO had. And i really wanted the slipper that has that feature.

So. The idea:

Old worn up diff output cup + 30mm OD/ 6mm ID / 1mm thick washer.

I designed a 5mm to 6mm adapter collar, so i could center the washer to 5mm bolt, that goes through the diff output cup and washer. After the washer was centered, i tightened the nut for the bolt and welded the washer to the diff cup from 4 points. (Sorry, no pics).

Then i removed the collar and tested that the washer didnt warp during the welding -> everything was okay. I then grinded 2mm off from the cup from the gearbox side, because it was too long.

Then design a outer skin for the cup/washer combo, that has the correct shapes for the brake disc. I also though about aesthetics, so i designed a part that would hide the welds.

Part on the right:

From another angle:

Printed from PETG/CF and installed over the cup/washer combo:

Okay, so here we go. Spur gear hub and 30mm OD fiber gasket as a slipper pad:

Assembling the outer parts. Spur gear hub + outer washer + slipper pad centering collar.

Loosely over the input axle:

With spur gear:

I cant confirm that this works yet, but i dont see why it wont. The fiber gasket might need to be replaced with more grippy material, but otherwise this should work. It was very hard to design these parts with the materials i have, as there isnt lots of space and the spur gear needs to be exactly in the right depth, so the right rear lower suspension arm groove is in the right location for the spur gear. 1mm off and the suspension arm hits the spur when in full shock absorber compression. Im very happy that i could do this -R style slipper hub, so the spur gear can be easily removed with 2 screws without touching the slipper setting.

I drilled the hole for the input gear locking pin previously (no pics sorry). I still need to make a M5 thread to the titanium input axle for the slipper spring adjuster nut and a small groove for the slipper hub locking screw:

I also re-designed the rear bumper and battery holder. This design replicates the original Type-R/EVO design as much as possible and also stiffens the rear section of the car greatly:

I also found cheap FZW15 diff gears so i bought 2 sets of these (each set has 2 gears). These go to the RS-build as this EVO has ball diff. Steel gears on the left, stock on the right:

Last edited by HiTec90; 03-22-2020 at 06:38 AM.
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D3MON (03-22-2020)
Old 06-03-2020, 03:06 AM
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Small update. I havent had time to finish this up, but i did buy rare-ish newer assembled EP Type-R version of this truck.

Click image for larger version

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This should help with modeling some of those Type-R specific parts, even though some EP parts are ofc different. I havent received this truck yet, hopefully it arrives this week.

Plan is to model the chassis plate etc... I dont know if i will even assemble the truck. I will definitely do a mould from the Type-R body, because its impossible to get nowadays. EP Type-R manual also needs to be scanned, because that is not available in online. Even Kyoshos website doesnt list that manual.
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D3MON (06-04-2020)
Old 06-08-2020, 04:25 AM
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Picked up the package this morning. 4 hours of measuring and drawing and the chassis is almost complete. Just needs small details here and there and also rounding up the sharp corners:

And here is the first test version that my i3MK3S just started to print. The first PLA proto will take about 6h 45 mins to print and it will take about 100gr of filament with all the support structures. However, PLA is cheap, so if Prusaslicer calculated correctly, the filament costs for this print will be under 3 euros (forget that front lower plate, i didnt remember to remove it before taking that screenshot).:

Last edited by HiTec90; 06-08-2020 at 05:32 AM.
Old 06-12-2020, 09:11 AM
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build/fabrication as always looking great man!
wont be long till you can just print yourself a full one of these lol.
pretty awesome you were able to find a NIB kit of the Type R, really makes me wish that i had gotten into rc much prior to when i did, but at the same time, i probably would have been to young to care for them properly, one of my favorite platforms of rcs is the 1/10 scale nitro STs, but sadly they seem to becoming rarer and rarer, with the only current one in production that i know of being the TRX rustler.
great seeing your progress!
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HiTec90 (06-21-2020)
Old 06-21-2020, 01:28 PM
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Thanks for the reply! Yea, im currently building an electric version of this truck as im saving some extra money for the nitro engine for this car.

Yea, the new, in package Type-R was a real find! I drooled that from Kyosho magazines when i was a kid, but my budget only allowed to buy an Racing Sports version. Weird to think that it took me 20 years to buy one. I just wish that was a Nitro version, but yea, that doesnt matter a lot, im trying to recreate that myself with this project.

Im also sad to see that these Stadium Trucks are dying class. I hope this small project of mine will save even couple of these Ultima ST:s when people that have possibility to print/get printed my parts.

I started young with RC models. My first "proper" car was Marui Hunter somewhere in 90:s when i was under 10. I still have it. Then came Kyosho PureTen Alpha 1 EP (4WD with belt driven), Ultima ST GP, PureTen Alpha 3 GP. Then i sold everything except the Marui and Ultima ST and bought some EP planes after flying my dads old nitro trainer plane. Then came the Nitro boat (AirStreak 500) and some EP helicopters.

Then with Ultima the spur gear stripped the final time and replacement couldnt be found anywhere. It left standing on a shelf. This was a excellent hobby as a kid and its an excellent hobby as an adult. There are two guys that are already told they revived their ST:s with my parts one is an adult and one repaired it for his kid. Those stories are great to hear and i would love to hear those more.

The Type-R EP story and a kind of modified "replica" im drawing can be found from this thread: My Ultima ST EP Type-R BNIB 20th anniversary project with 3D printed "CF" parts.

As for the TRX Rustler, i thought to buy it, but once i see how "plasticy" and cheap looking the build and parts quality was, i left it out from my plans. Only modern ST i would love to own is Kyosho RT6, but its seems to be impossible to found here in Finland.

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