RC10Talk - The Net's Largest Vintage R/C Community

Back in 1988 or so I bought a Ultima Pro Kit#3117.
This is what it looks like a few weeks ago. I would love to find the sticker set shown on the manual. I have a new body on order.
( I found a set! Cool, appears be a good copy of the original: https://mciracing.ca/products/1-10th-kyosho-ultima-pro-decals )
Please allow me some of the back story.

I built the Ultima and raced it at several indoor tracks around Colorado. 3 I believe in the Denver area, one in Longmont, one in Ft. Collins. I lived in Greeley at the time so they were all quite a jaunt to go race. If there was a race going on, I went. Only one of those tracks remains open, MHOR. I believe it is the only indoor clay track in Colorado these days. Longmont has an outdoor track but I'm not sure what they race there these days.

My goal is to run this at MHOR again. I don't know if they do vintage racing there, I just want to get it on the track there once again. Back in the day there were 2 young fellers that kicked my butt at MHOR, (not that big of an accomplishment, I was never really a contender). Those were the owners sons, I'm sure he set up their cars, they were very good drivers. I met one of them again in 2020 when I tried a little racing again with my RC10B 6.1. He was running the place. Just over a year ago sold to a new owner, I spoke with the new owner on the phone but have not been there since that short session in 2020.

Anyway, back in 2019 a buddy bought me a RGT Bronco (RTR, low end 4WD). It caused me to think about that Ultima Pro I had still stored in a box in my shed.
I dug it out just to see what was still there. The dirt is from a flood we had in 2013 that, put a couple ft of water in the shed. I had fun with the Bronco, the Ultima remained unattended to. I started breaking things on the Bronco (axles) right quick. I had once again caught the RC bug. Bought an Axial RTR Cherokee, started upgrading it and going to the Comps at a local rock crawling shop (The Crawl Space). Much fun, built a TGH Sherpa and did a few comps with that. Bought and built up several Axial Bombers, a Losi Lasernut, and recently put together a Vanquish H10 Optic. The Bombers and such are ideal for running around the house, I have some good rocks, nice loose rocky hills, some deer trails behind the house to venture out on.

By now that Ultima had made its way to a shelf at my work bench. It started calling to me, I listened.

May 7th I started looking things over more closely and decided to take on this rebuild of my Ultima Pro. I was considering a new crawler but this just couldn't wait.
On the bench it goes: I started this rebuild a few weeks ago, tore it down completely, inspected, ordered and replaced a number of things. What a fun challenge this has been so far.

I am hoping to see how much of the original rig I can get to work. I hope to fire up the old electronics, including the AM rx and tx.

I started with an inventory of what I had in the box O crap.
Lots of cleaning to do.
2 nice kyosho motors and 2 stock can motors. The can motors were for running in the stock class, they had to be $20 motors and not rebuildable.
The AM radio controller. We had to put in crystals in the tx and rx. At the races there was a board and you picked your channel for the race. I only had 2 sets of channel crystals but didn't seem to be a problem.
Capacitors were needed to solder on to the motors to eliminate radio interference.

Most parts will clean up and should be usable. In theory you could look at re-release parts but a lot of them aren't compatible with the original cars. A repro body is available from Boki Racing https://www.bokiracing.com/product-page/boki-kyosho-ultima-body-wing and the stickers from MCI https://mciracing.ca/products/1-10th-kyosho-ultima-pro-decals.

Be aware a lot of old electronics just stop working from just being old, the materials break down and metals corrode, but if you plug them in and they run there's no problem using them. The crystals can be a pain, it is hard to find them these days and as they are delicate so easy to break.

terry.sc wrote: ↑Fri Jun 06, 2025 11:16 am The crystals can be a pain, it is hard to find them these days and as they are delicate so easy to break.

Fortunately, he has 75mhz Futaba. Futaba, JR, and Hitec crystals are all cross-compatable. New and aftermarket crystals are still common enough.

For reference, 27mhz AM is even easier. All brand crystals work together, and there are lots available (due to RTR's). Most hobby grade transmitters and receivers are compatible as well. If you can find the Xmods ch 7-12 crystals, you can double your amount of usable channels.

juicedcoupe wrote: ↑Fri Jun 06, 2025 1:56 pm

terry.sc wrote: ↑Fri Jun 06, 2025 11:16 am The crystals can be a pain, it is hard to find them these days and as they are delicate so easy to break.

Fortunately, he has 75mhz Futaba. Futaba, JR, and Hitec crystals are all cross-compatable. New and aftermarket crystals are still common enough.

For reference, 27mhz AM is even easier. All brand crystals work together, and there are lots available (due to RTR's). Most hobby grade transmitters and receivers are compatible as well. If you can find the Xmods ch 7-12 crystals, you can double your amount of usable channels.

I have two sets of crystals, one set still installed in the tx and rx and another set on standby.

The Pro-Tech Model #701 charger must not have been in the muck. The box is nice and clean the the charger is pretty pristine.
I opened it up to look inside.
If you notice the holes in the box, I drilled those to help cool the charger down better, I felt like it was getting pretty warm and heat is hard on electronics. I drilled holes in the side and on the bottom.

I get a kick out of that spring wound timer with the contacts in the top right of the pic. Pretty old school right there.

Step one for me, since it was already removed. Was to disassemble, clean , and inspect the transmission/ball diff.

I had removed it years ago because it was making an unusual noise and needed some love ($), best to my recollection. The front end also had issues, I'll get to that. It was about this time I made a major job shift requiring a move from CO to Idaho Falls ID. In a box it went and remained in that box until now. That was 1990.
The wear pattern on the pressure plates wasn't just a wear pattern, there was actual tiny pieces of metal that had scrubbed off. The black spots along the wear ring are where the metal is missing. I believe this was causing the noise. My best guess was the diff got hot and the embrittled metal began to sluff off in spots. After a bit of honing you can see the low spots, now black looking. I gave up on this honing attempt and ordered a new ball diff.

Time to disassemble and clean the chassis.
Futaba Electronics, I will revisit these later. Good grief, look at the length of that dang antenna! It's long even with the shortening procedure but that helps. Same concept as I learned when coiling up a long CB antenna cable. You don't want just a coil, it induces noise unto itself. For a CB antenna, they tell you to coil it in a figure 8 pattern.
That cardboard the antenna is wrapped around was cut from my charger box.

Front end fun.
The stock front shock tower was cracked on one side, I knew that back then and had bought a replacement which I didn't get around to replacing, I will do that now. Apparently "a round tuit" takes 35 years or so to accomplish.

In all, the front shock tower needed replaced, right side A arm inner suspension shaft was bent, and the bulk head was broken at the two rear plate connection holes. (Bought and replaced)

Clearly, someone was very hard on this thing.
I didn't notice back then but the shock tower is different than stock. Not sure if that was a mistake or supposed to be an improvement. I'll try to use it as is but the link connection holes are a bit different, this will cause some different dynamics, the mounting holes to the bulkhead are correct. Not like I'll be going to any nationals anytime soon.
Does that look close enough to straight? Nope, new one on order.
I had apparently "upgraded" the steering center rod to a turnbuckle type arrangement. Seems like the original was better. I'll go with that for now.
All fresh and assembled. (aside from linkages and shocks.) I did a little shimming to take up some slop.

Patiently waiting for parts to arrive. Turnbuckles, screws, misc.

I did a dry run on assembly to check for any show stoppers I don't have on order. The sway bar contacts the steering linkage. Dang it. I wanted to use that. The original A arms had an indent in them that allowed a proper fit. This Andy's A arm does not. It doesn't have a spot for the ball link either but I could have resolved that easily enough. I considered attaching it on the inside of the A arm but I was still getting interference issues when I cycled the A arm and steering.
I assume it was common to remove the sway bars back in the day, however, some are still used today. I thought it would be good to use them. I wonder if it makes sense to run it with just the rear sway bar?

Opened up and cleaned the transmitter. 8 Batteries and it seems to be functioning, even induced some static into my computer. If you zoom in to that old analog meter you can see the batter state is at 100%. Speed controller opened and cleaned. Receiver opened and cleaned. Charger fired up and charging the 38 year old battery. I made sure it was fully discharged, recharged, discharged, full charge again, ready for smoke test. Opened and cleaned the servo, it was perfectly clean inside, stock grease was redistributed. Those are the weirdest screws I have ever seen. 1/2 turn to full out. I started to unscrew and they came popping out like crazy. Very weird. Time for the Smoke Test!

Color me tickled! After being packed in a box in 1990, sticking with me after 4 house moves, enduring our flood in 2013 (that was most of the crud I have been cleaning off the rig and from inside the electronics) IT'S ALIVE! (well the electronic portion)

https://youtu.be/3K88ROaJsoM

Swath wrote: ↑Mon Jun 09, 2025 1:21 am Opened and cleaned the servo, it was perfectly clean inside, stock grease was redistributed. Those are the weirdest screws I have ever seen. 1/2 turn to full out. I started to unscrew and they came popping out like crazy. Very weird.
Servo.jpg

Have the same steering servo in my project. Probably 30+ years old and still works great.

Scottzone wrote: ↑Mon Jun 09, 2025 9:50 am

Swath wrote: ↑Mon Jun 09, 2025 1:21 am Opened and cleaned the servo, it was perfectly clean inside, stock grease was redistributed. Those are the weirdest screws I have ever seen. 1/2 turn to full out. I started to unscrew and they came popping out like crazy. Very weird.
Servo.jpg

Have the same steering servo in my project. Probably 30+ years old and still works great.

I find it all quite fun. And no software to update!

Swath wrote: ↑Sun Jun 08, 2025 6:09 pm The sway bar contacts the steering linkage. Dang it. I wanted to use that. The original A arms had an indent in them that allowed a proper fit. This Andy's A arm does not. It doesn't have a spot for the ball link either but I could have resolved that easily enough.
I considered attaching it on the inside of the A arm but I was still getting interference issues when I cycled the A arm and steering.

I assume it was common to remove the sway bars back in the day, however, some are still used today. I thought it would be good to use them. I wonder if it makes sense to run it with just the rear sway bar?

I used to run my old Ultima with just the rear bar, because the wider arms took away some steering and never needed one up front. My modern version runs with a front bar as well though as it's used for racing and uses modern tyres.


Mount the ball on the bar backwards to move the link to the gap in the arm and give clearance for the steering links.
You might have to dremel away each side to give clearance for the ball link to move freely. I had to take a little off each side until the ball pivoted freely. I also had to rake the corners off the shock mount so it didn't hit at full compression, but I'm not using Kyosho shock mounts on mine.