Build Thread My Ultima Pro (re)Build Thread KIT NO.3117 from 1989 ish.

[JRFisher]

I have an Koyosho Ultima Pro that I built from a kit back in 1989 or so. It's been unused and in a box since about 1990 when I changed jobs. I wrote up my RC story in the intro section. I got back into the hobby in Mar. of 2019. I'll start my thread off with some pics of it's current condition (duplicating some of what I posted in my intro). My intention is to see how far I can get keeping as much of the original parts as possible.

This was how I found it in March of 2019 when I pulled the box out of my storage shed. A flood had come trough a few years back and soaked everything in dirty water so I have that to contend with. The electronics may just let all the smoke out when I try to fire them up, I shall see.

The box O stuff I pulled out of my shed. My fishing tackle box/pit kit is still useful. You can see the charger and AM radio.

The manual in excellent condition, already coming in very useful.

Those battery packs we would solder together, even an unopened "Matched Set". They would cycle the batteries and match similar charge/discharge batteries for the best performance. Also of note is the 3.5" computer disk box used for parts storage. (They held a whopping 720KB of data each after being formatted!) Also of note is the little dongles we would plug into the batteries after use to properly discharge them. I forget the name of those connectors I was using, at the time they were one of if not the best connectors. Some of these batteries still show voltage after sitting for 36 years.

These are the 4 motors I had with it. 2 of them are "can" motors that were required to run in the Stock Class. (limited to $20 closed can motors.)

Some parts still in their bags. Interesting the wrench most kits still include.

Just look at all them pristine tires!

The chassis without the rear diff, which at the time I recall I had removed to troubleshoot it.

And of course the body painted and decorated by yours truly I'm not impressed with my body painting skills, I have only slightly improved. I'll likely buy a new one and hopefully find some period correct stickers.

Anyway, that's my introduction to this project, lets get started....

 

[JRFisher]

Today I started looking into the rear diff. Full disassembly, clean, and inspect.

You can see the wear rings on the "Pressure Plates" where the diff balls ride. The shiny parts and darker sections are a problem. Those dark sections are not a lighting thing. The metal has come out there. I can feel a slight depression where the dark sections are. That must have been the cause of the grinding I had started to look in to back in the day. Clearly I didn't get this far then. I have searched for replacements but so far I have only been able to fine the complete ball diff unit for $100. An ideas on where I might get just these or other models that match?

I have ordered up a full set of bearings, oddly enough Fast Eddy Bearings does not sell a set for the ultima pro, and the others don't match exactly. The closest they have is for the Ultima Pro II which only has 4 of the 4x8x3 bearings and 2 - 4x8x3 Flanged. Weird, I'll work around it, you can order just the bearing you need from Fast Eddy, Fortunately the Ultima only uses a total of 14 bearing for the whole rig.

 

[CertifiedMike]

https://rwracing.co.uk/shop/ols/products/kyosho-diff-plates

These are cheap enough that I would order to try.
I just asked them if they knew if these would work on my Mids. They did not know.
I am also ordering a few to try.

The idler gears that I got from RW were nice. They cam quickly from across the pond too.

You might be able to resurface your diff rings or flip them over to get some more more mileage out of them.
Use steel balls or you'll go thru those plates every race.

 

[JRFisher]

Resurfacing might be an option, I could use a honing stone. Can't flip em, they are one way. Not sure if those you linked are exactly the same as mine???

Where would one get the steel balls? Balls of Steel that is. What are the stock ones made of?

 

[JRFisher]

 

[CertifiedMike]

Mids, lazers, and I assume Ultimas used 2 different types of diffs. 1 that uses the plates, one that does not.
Yours does not. You can try resurfacing. The washers might work sandwiched in there but I'm guessing they would make the assembly too thick.
Stock balls are steel.
Avidrc.com or kyoshoamerica.com should have those balls. 2 different sizes 3/32, not sure off hand on other size.

Same instructs for W0108 and W0109 ball diffs.

 

[CertifiedMike]

I have not ordered those RW racing rings btw. I don't know if they are supposed to replace the worn part that you have or the 'extra' rings.

 

[CertifiedMike]

I mispoke. They all use plates, some use an additional washer in there too.

I just ordered those plates from RWracing. I'll let you know if they are the same as mine.

 

[RudyF6]

In to watch this - I have the same car, charger, AM radio and tackle tool box!

 

[CertifiedMike]

Also, I think I might have missed what you were saying about your adjustable shocks... are your shocks the Kyosho platinum shocks?

I have rebuild a bunch of golds... just starting on a set of platinums.

What a weird set up!!! I hope I can restore them!

 

[JRFisher]

My shocks are the normal gold. An aftermarket kit had "variable rate" valving. Essentially a tapered rod that matched a hole in the piston. As the piston travels up, the oil path gets more restricted. The shock gets stiffer as it travels upward. Not sure if it was that effective or not.

 

[CertifiedMike]

My shocks are the normal gold. An aftermarket kit had "variable rate" valving. Essentially a tapered rod that matched a hole in the piston. As the piston travels up, the oil path gets more restricted. The shock gets stiffer as it travels upward. Not sure if it was that effective or not.

I never saw a set like that. Cool!!!

 

[Guest D]

Welcome to RCT.

 

[JRFisher]

Not much today, had to attend the grandson's graduation in Denver, very proud of the young man, glad we were able to be there. However, his class was over 800 people! We were a group of 7 for 1 graduate, imagine the audience size. I hate crowds...

Anyway, took a little time tonight to clean and inspected the rear A arms and associated parts. Dog bones are in fine shape. Missing one e clip, but digging through my parts bins I found a few I didn't know I had. Not sure how many I will need and which sizes I will need. One was the right size too! Very sweet. All the bearings are shot but I am replacing them all anyway.

Little steps forward.

 

[JRFisher]

Looks like I'm missing a piece (I'm sure it won't be the last) they call the "Motor Guard Collar". Pretty specialized. Might be able to replace it with a stack of washers.

 

[WutUp Clegg]

If you are interested in selling those motors, let me know.

 

[JRFisher]

They have followed me around for 36 years, I believe I'll hang on to them. Do they have any collector value?

I recall having to solder those capacitors/diodes/ whatever they are on to them. I guess for radio interference reasons.

I'm certainly no expert, back in the day we messed around with differing spring rates and stepped brushes. There was no internet in those days, most of what I learned was from the magazines and local hobby shops.

I'm still a fan of brushed motors and hopefully they will spin the tires on this rebuild.

Jeff

 

[JRFisher]

In to watch this - I have the same car, charger, AM radio and tackle tool box!

I like your Bronco, and the Bronco sitting on it. I've owned 3 of em ( full size) over the years. Great rigs.

 

[JRFisher]

Time to tackle the chassis.

Look at the length of that antenna wire! And I had a bunch of it coiled up.

The Manual gives specific direction on how to shorten the antenna wire by coiling it in a specific fashion. They do similar things when coiling a CB antenna, in which case they have you wind it in a figure 8 pattern. I guess just a straight coil induces some kind of interference in the antenna.

A whole batch of Futaba.

That's enough for today, tomorrow I'll disassemble and clean that front end. Then it will be time to begin putting her back together. (Waiting on a few things to come in the mail.) Still have the shocks to rebuild on the way back together. I'm pretty sure those white A arms are aftermarket from back in the day.

If anyone has any experience and knowledge about how to properly take the case off the rx and speed controller hit me up. I see the little tabs that snap together when assembled and I might be able to just push on those and pry apart but I'd sure like to hear from anyone who has been there and done that. I just want to look inside for any crud build up before I put the juice to it. I plan to power things up before installation just so I don't have to redo my efforts.

So far this has be quite a fun project. I first assembled this thing 36 years ago while living in Greeley CO, been a lot of changes since then.

Jeff

 

[JRFisher]

If you are interested in selling those motors, let me know.

They have followed me around for 36 years, I believe I'll hang on to them. Do they have any collector value?

I recall having to solder those capacitors/diodes/ whatever they are on to them. I guess for radio interference reasons.

I'm certainly no expert, back in the day we messed around with differing spring rates and stepped brushes. There was no internet in those days, most of what I learned was from the magazines and local hobby shops.

I'm still a fan of brushed motors and hopefully they will spin the tires on this rebuild.

Jeff