Kyosho Pro XRT build

[Lavigna]

Build thread for the unknown Kyosho Pro XRT 1/10th electric stadium truck . I have always thought it was a great looking truck. I would happen across a random picture of the truck when looking over vintage RCCA magazines from the mid 90's, and tell myself that someday I want to build one. About a year ago, after seeing a picture of the truck, I decided it was finally time to learn about it, and see what it would take to build one.

History: Kyosho released the Pro X buggy & Pro XRT truck in 1994. They followed the Triumph series. From the start, the over-engineered SST transmission (Super Sprint Transmission) and it's belt drive design, was the main weak point. Especially on the truck, with it's higher mass. It's rumored that Kyosho put a ton of money and resources into the design of the series. Sales were dismal, especially in the USA. As a result, Kyosho stepped out of the competition 2WD scene until 1999. While the Pro X buggy is relatively unknown in the US, the Pro XRT truck is even more rare.

This means finding XRTs for sale is very hard. Same with many of the parts, or sellers ask crazy prices. I started searching for a XRT for sale, but I have yet to find one. So I have been hunting parts. I have gathered a decent stash, but still need plenty more.

Here are a few pictures of the stock truck. These pictures are courtesy of BNGILES from TAMIYACLUB.COM.

[Lavigna]

Here is my current parts status. All NIP so far. I have been lucky to find some of the below pieces. The white parts have yellowed over time. I am not too worried about this because I plan on giving them the peroxide treatment once I have everything I need.

There are 2 versions of the XRT - Sport and Team. The Team truck features upgraded aluminum shock bodies, ball bearings instead of bushings, and upgraded tie rods. I plan to build this as a Team version.

My current list of needed parts are:

Body
Decal set
F & R tires
Transmission internals & outdrives
steering assembly
Front bumper
Body mounts
Shocks

[vintagerulez]

Very nice Project. I also love the XRT a lot.
it reminds me of a story that happend how i got my XRT a couple of months ago.
I was on the hunt for a PRO X buggy for quite a while when i found a guy from germany who offered even two of them on a local auction. I contacted him and after he sent me some proper pics of his cars, i bought the Pro X from him that was obviously in a better shape.
After i sent him the payment by paypal, he asked me if i would consider also an XRT to buy from him. I said yes, and so the other day he sent me a couple of pictures of a total of 4 ! XRT he owned, all complete and hardly used. I was totally overwhelmed and told him that i would need some time to choose the one i'd buy.

The next day i wrote him back to tell about my decision when he replied that he has just found another box in his loft, containing a 5th !! XRT Team Version he totally forgot about. This car was new built, but never finished, with box and everything. It all ended that i revised my decision and bought that 5th car from him, together with a PRO X buggy.

[Lavigna]

Very nice Project. I also love the XRT a lot.
it reminds me of a story that happend how i got my XRT a couple of months ago.
I was on the hunt for a PRO X buggy for quite a while when i found a guy from germany who offered even two of them on a local auction. I contacted him and after he sent me some proper pics of his cars, i bought the Pro X from him that was obviously in a better shape.
After i sent him the payment by paypal, he asked me if i would consider also an XRT to buy from him. I said yes, and so the other day he sent me a couple of pictures of a total of 4 ! XRT he owned, all complete and hardly used. I was totally overwhelmed and told him that i would need some time to choose the one i'd buy.

The next day i wrote him back to tell about my decision when he replied that he has just found another box in his loft, containing a 5th !! XRT Team Version he totally forgot about. This car was new built, but never finished, with box and everything. It all ended that i revised my decision and bought that 5th car from him, together with a PRO X buggy.

Consider me very jealous. I sent you a PM awhile back to see if you could put me in touch with the seller. I never heard back. Please let me know if you come across this message. Thanks. I would like to eventually find/build a matching Pro X buggy, when I am done with the XRT.

[Lavigna]

Build Update - I have found (I think) all but 3 parts needed to complete this all NIB XRT Team build. The remaining items I need are:

#XR34 - Body
#XR35 - Decals (I know of MCI)
#W5692 - Rear Tires

Please let me know if you have any of the above parts available for sale or trade. Thanks.

As I type this, there are still a few orders of parts yet to arrive, but I expect them all within a weeks time.

White Parts - (these pictures exaggerate the yellow/greenish color of the whites) I am currently giving all the white parts a peroxide bath to remove the yellowing. They are looking great, and nearly done. However, both sets of arms, and the rear drive hex's turned greenish in the peroxide (just like vintage RPM white parts). I sort of expected this. I took those pieces out, boiled them, and am soaking them in peroxide again. They should whiten up real well when finished.

Shocks - I found (and paid good money) for a complete set of Team version shocks. I also found these vintage Option House W5105P anodized purple shock caps and collars. The collars are meant for the next version of Kyosho shock, with the threaded bodies, but they happen to slide perfectly over these shock bodies. I built up the shocks using these pieces, and I think I like the look. I may change my mind when they go on the truck, but the purple is certainly more eye catching than the stock black. Let me know what you think. As this will be a shelfer, the shocks are built dry, and easily changed.

Chassis - I love the looks of this chassis. Everything about this truck (besides some aspects of the transmission) show that it should be a very capable and fast ST. It is a shame it never got a chance to reach it's potential.

CVD Drivelines- I decided to polish these, as the old factory finish was not great, and I think the shine will fit well on this truck, and match well with the Team tie rods.

I am just waiting on a few packages of parts to arrive, and then I can begin the actual build. Building a whole vehicle from NIP parts has been slow, frustrating, and expensive. However, I think the work will result in a prime example of a XRT, and a decent build thread. Good times ahead I hope.

[stickboy007]

Damn, son...

Those purple shock caps are nice.

[jkelm24]

Awesome! Looking forward to seeing the finished build. The Pro X and Pro XRT represent (arguably) the last of the vintage Kyosho line... unless you're a true Kyosho die-hard and only recognize the Kogawa cars as the true vintage.

The Pro X and Pro XRT have always been interesting to me. The Triumph and Lazer ZXR were the last true Kyosho's in my mind. But the Pro X/RT have always been interesting in retrospect. They're conceptually a re-hash of Losi's Pro SE and LXT, but were released two years after the Losi examples.

Kyosho's SST transmission is a rehash of Losi's LRM design, which was first released in 1988 in the JRX2, and the Pro X/RT chassis is a conceptual copy of the Pro SE/XLT. These design concepts were already becoming outdated when Kyosho released them as 'new' in the Pro X.

There's some interesting history on this model (Pro X, not XRT) found on the vintage dirt-burner site. Sounds like Kyosho outsourced the design of the of Pro X to a group of former RPS/Losi designers...

[Mr. ED]

I was told not long ago that Gill himself participated in their design.
Now, if you look at the ultima and jrx2 front ends: it's pretty clear the kyosho design served as inspiration for the losi team back then.

[Lavigna]

The build has officially begun. Starting with the SST transmission, I quickly realized why this was the weak point, and probable main reason for the downfall of this series. Parts of it's design are total crap!

SST - I thought the differential was very smooth. Probably the smoothest diff I have ever built. However, I can see why it has been described as a weak point. It is composed of plastic gears and housings, which determine the alignment and structure of it, and therefore the entire transmission drive train. Once the cases are put together, and even before they are tightened, the gears are very, very notchy, tight, and misaligned. If fact, if this were not going to be a shelfer, I would not try running this transmission without some major refinement. The friction in this transmission would likely produce a ton of heat, and likely fry itself and the motor. The poor quality of components, and the poor specs of the transmission, are IMHO the reason the SST transmission builds into a big turd. Shame, as there is a lot of potential in the rest of the design.

For the outdrives, I upgraded to some vintage Thorp units.

[stickboy007]

Use the trick I posted in the other thread. It makes an enormous difference. Most of the bind comes from the mesh between the center diff gear and the input gear. Using a different combination of bearings on the input shaft to allow it to float while also keeping wobble at a minimum will free up the gearbox a ton.

[Lavigna]

^ Thanks. I have read your thread and appreciate all the time you spent to find and resolve the problem. I ended up working my transmission some, and it is now better, but still miles from a Stealth.

My build has been held up by a set of rear arms. I couldn't get the yellowed arms to whiten much. I ended up buying new front arms, and another 2 pairs of rear arms, trying to find real white pairs. The last pair of rear arms (3rd pair I have bought for this build) came from overseas, and took nearly a month. It ended up being worth the wait, because they are perfectly white. In fact, they are so white, they make the new front arms look a little yellow by comparison.

Updated pictures to come.

[Raul Garcia]

Awesome build.

[Lavigna]

She currently sits in Slider status. These pictures do NO justice. This truck looks super crisp and the colors really pop, in person.

I think I like the purple shock pieces. The truck doesn't have much color otherwise, except for the motor plate. I am a fan of blue and purple aluminum on vintage RC. Suggestion and opinions are always welcome though.

I still need to open the wheels, and mount and install the tires. Rear tires are the second to last part I need, but I am just going to mount some vintage Losi rears until I can find some real ones.

OG decals, and MIP cvds should be coming for this. That means a body (and a clear motor cover) are the last piece I need. Please let me know if you have one. I believe the Rampage body is identical.

[HorseNZ]

Sweet build. I had never heard of this truck until seeing your post, I agree the color combo of the parts is very nice. Bring back white nylon I say!

[Lavigna]

Wheels and tires mounted. The rear tires are Proline 92 Fuzzies. They will do until I can find the real ones.