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

In the mid to late 1980's, I believe Race Prep sold an electric offroad motor with a ceramic armature shaft. Does anyone know the name of this motor?

Dirtdiver

Mark Westerfield at RCHR in CT can tell you. Had a short conversation about it last weekend!

The motor was the standard orange Race Prep stock, with a ceramic shaft armature. I don't recall seeing it called something different, but everyone had to had one—until they started cracking the armature shafts.

I always wondered how the ceramic shaft worked out and now I know the answer.

I pulled the old RCCA magazines out of the parents basement this weekend and found the old Race Prep ad from 1990. I'll post it here soon. They also used the ceramic shaft in their Pro Modified motors from that era.

Dirtdiver wrote:I always wondered how the ceramic shaft worked out and now I know the answer.

There is a reason no one still uses them.

What was the perceived advantage back then? Less bushing wear? Lighter than steel?

Weight, mostly, but IIRC there was talk about heat, but it was all bunk in the end. At the center of a rotating mass like an electric armature, the weight isn't nearly as crucial as it is outwards. And durability was a major problem—from collisions to over tightening pinions. Not one other motor builder ever used ceramic arm shafts in any of their motors, if that tells you anything.

It will be interesting to see the armature made of newer ceramics, such as zirconium.

Ceramics 20+ years ago is definitely no comparison to modern one

The Race Prep ad reads, "Ceramic Armature Shaft. Dissipates heat from commutator and bearings - true to 0.0005" - improves magnetic field of armature core."

I'm not buying the dissipates heat from the commuter and bearing pitch as ceramics are well known insulators.

The ad also doesn't make any referrence to what type of ceramic was used for the shaft but I would guess probably aluminum oxide (Al2O3).

Race Prep Ad from 1990

I used to run them back then. They looked trick, but were a pain in the rear. You had to be very careful tightening your pinions and if you stripped a grub screw you were screwed as you couldn't use a puller as it would snap the shaft right off. Had to drill them out. I went though a fair amount of armatures...lol.

I was looking for an old ad and stumbled upon this thread. Here's my new 19D ceramic. Sadly it didn't come with the original header card.

I assume they only used this on mods. A ceramic rod on a brass bushing doesn't sound like a good combination.