What Gene said. The first chain-drive Weavers had an 8-tooth upper sprocket. When some go-fast Lionel types complained they were too slow, Weaver began using a 12-tooth sprocket on their 3-rail models. They also added a flywheel and an improved motor, which was a good thing!
I changed most of mine to the 8-tooth upper sprocket. In one case I obtained more gear reduction by changing the bottom sprocket (from 12 to 16 tooth, I believe.) My real creepers got two-stage gear reduction towers with ball-bearing shafts. These were made by High Sierra (and sadly, no longer available.) They were set up 8:12 x 8:12 with 10:1 in the axle gearbox. The chain tension worked out just right. Nine motor revolutions to the inch!! They topped out around 45 mph, plenty fast for a small layout. Excellent for switching and would run at 3-4 mph all day. Good coasting too. And all this before speed control!
What I still like about them is with all that hysteresis I think it feels like you’re running a train. Sometimes speed control makes me feel like I’m controlling a robot 🤖
Several online vendors sell chain and sprockets for this system (which I believe is manufactured by Serv-o-Link.) At least one batch of sprockets I purchased was low quality. The chain didn’t lay right, they were noisy with poorly-formed teeth. So inspect your purchases carefully before installing! Also be sure to install the chain with the rough molding burrs on the outside 😜. Good topic!
