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

I wonder if anyone have or know how to replace Robinson Racing Ultima/Optima spurr gears?

although i haven't used these i believe there is a metal insert(small gear) that meshes with the original gear mounted on the shaft.. the idea behind them was to give a more adjustable gear ratio and use a more common 48p spur..

I don't think I express my selves good enough

The bottom spur in the picture is compete with inner metal gear. The spur in the top of the picture is a replacement one. You have to be able to replace it otherwise they wouldn't sell replacement gears in different sizes!

So my question is how do I replace the spur, is the a special tool for this?

IF this is the same as on the other RRP's, They made two different systems.. One was a non replaceable gear and one that is replaceable.. The non replaceable ones had the gear molded to the smaller gear.. The other one had small screws to swap the spur gear.. It looks like the bottom one in your picture is the non replaceable type.. I don't have the RRP part like your bottom one, for the Ultima anymore (I had one many many moons ago ) when I had an Ultima for a month then sold it (got a Yokomo for it and the Ultima was a basket case) but I do have both systems for my Yokomo.. I'll pull them out and snaps some pictures to show you what I mean..

And then..........Oh I had these on my computer.. RRP non replaceable spur: I'll get you some better pictures in a bit..
Shawn

It's been a long time, but the inner and outer tubes are a press fit. They need to be pressed apart, sockets would likely be easiest. Iirc both pieces will look like flanged bushings with one fitting inside the other.

Ok here are the pictures of the two Yokomo parts I have.. These are the two systems I have seen for RRP spur gears:

Non Replaceable: Replaceable: Hope this helps you..
Shawn

gomachv wrote:It's been a long time, but the inner and outer tubes are a press fit. They need to be pressed apart, sockets would likely be easiest. Iirc both pieces will look like flanged bushings with one fitting inside the other.

Really? I tried that on one of my spurs and it wasn't happening for me.. They are two parts but I couldn't for the life of me get them apart.. Lucky it was a chewed up spur that let me sacrifice it.. Spur parts everywhere and the center was still intact.. Maybe mine was just frozen together..

Shawn

It's been a long time, thorp used the same process iirc, I'm still looking for the info tho

I would love to see the info.. I have 2 more of the press fit gears and would like to see a few things.. I'm subscribing to this thread.. gomachv GO!!

Shawn

I looked thru my thorp paperwork and although it lists the parts it doesn't show or describe how to.

From memory, a large socket was around the largest lip, as it gets pressed thru and into the socket. A small socket then fits against the smallest hole and pushes thru. As you press (use a vice) the small socket into the gear, it will push the large outer into the other socket. Make sure it's deep enough. Essentially the smallest diameter piece is part of the largest diameter piece. The other piece (gear) is the press fit around that inner piece

When it is time to reassemble, heating (the gear) and cooling (the hub) should help!

All my rrp sets are the press fit type. They all have noticeable machine marks from a lathe on the mating faces too. So, when they get pressed together, they virtually lock together with the rough machine marks. It may be difficult to get them apart.

rccars4sal wrote:All my rrp sets are the press fit type. They all have noticeable machine marks from a lathe on the mating faces too. So, when they get pressed together, they virtually lock together with the rough machine marks. It may be difficult to get them apart.

That doesn't sounds logic, why sell replacement spur gear if they are so hard to replace? There must be a simple whey to do it, maybe you need some tool to do it.

Being a press fit, they have to make sure that the parts stay press fitted. Im sure a vise, and careful tapping would get them apart. It dosent make any sense that they would be "easy" to take apart,, then they might always fall apart. Probably better to err on the difficult side when no screws are used.

I tapped mine apart with a 9 mm pin driver, better would be a 9.4mm pin driver (0.37").

Same topic: long ag. Might still be interesting to read.
http://www.rc10talk.com/viewtopic.php?f=30&t=3678&p=34335&hilit=ultima#p34335
I disadvise anyone from buying this crap from RRP