Schumacher Pro-CAT Project

Page 2: Pro Assembly

The box for the Pro-CAT is not very fancy, but it does have a nice display of information about the model on the back. Actually, it appears to be less about presenting information about the model and more about advertising optional parts.

The side of the box has a bit of information about the history of the original. Inside you just see a pile of plastic bags. Hard to see what's going on with the parts.

THere are a series of bags labeled A through G as well as a bag of tools, grease, oils, and thread lock. Inside each of the larger bags are smaller bags separated by step. You can see that Bag A contained the sub bags for Steps 1-9. This makes finding the parts for each step very easy. The XLS did something similar.

The rear gearbox appears identical to the XLS at this point, but there's a difference hiding within that lay shaft. On the XLS there was a ball differential between those small pulleys allowing them to spin at different rates. On the Pro-CAT they are both locked to the axle. The same goes for the lower pulley assembly shown on the right (called the Integrator on the XLS). All of these pulleys are now locked together and the ball differential for the rear wheels acts directly on the outdrives like a more traditional buggy. This makes it much easier to build, but also somewhat less wondrous. It took me a long time to figure out the transmission on the XLS.

Another change is the spur gear. On the XLS there was another ball diff built into the spur gear making it a bit wobbly, but here it is just locked to the shaft. The front ball differential is just like the XLS. Once both are complete, the main belt can be installed. The drivetrain is overall much simpler than the XLS with 2 fewer differentials. Still no slipper though. That's an optional extra. Those universal joints still need to be assembled by hand. No improvement there.

The front suspension looks identical to the XLS, but there is one important difference. Those two longitudinal screws you see are for tensioning the main belt. The rest of it is just like I remember, including the soldering required for the sway bar and the rubber band system to allow the front wheels to absorb impacts.

The lower rear arms have been updated to be more modern without a ball joint at the outer end, and the formerly fixed upper arms have been replaced with turnbuckles. These changes required a new outer hub, but it's still a strange round affair that sits inside the wheel.

The wonderful aluminum shocks are the same as before. They are still a trick to assemble, but I now have some Knipex snap ring pliers which made the whole thing much less stressful. You can also see a much more significant wing mount in the rear. This may seem like a good thing, but the design is atrocious. Installing the wing involves looping a rubber band through buttons on the wing and then through those holes on the wing mount. This results in an impact resistant design, but the pins holding the rubber bands could not be installed without modifying the parts. There was no clearance to install them. It was very frustrating. I would call it the worst design I've seen in an RC ever, but then I got to the servo saver.

This servo saver takes the award for the most frustrating, most poorly designed and documented detail I've ever seen in an RC. And that's saying a lot because I've built hundreds. In order to tension the torsional spring, the hook ends need to be folder over each other. The manual shows a nice little arrow as though this is easy. It isn't. I spent hours trying to do what was shown in the manual. It is simply not possible as shown. I eventually invented my own alternate method which worked with enough repetitions. It is a quality servo saver once built, but I never want to see one of these again.

Here's the box for the excellent LRP motor I used, and the original 28T pinion I tried before I realized how fast it was. I went down to 23T later. The picture on the right shows all the electronics installed and ready to drive.

The CAT wheels don't work like other wheels. There is no 12mm hex. Instead there is a cross shape on the end of the universal joint that mates with a similar cross on the wheel. This detail has to carry all the torque and all the weight on a tiny area. It's a pretty bad design, and it means that you can only use specific Schumacher wheels. The Pro-CAT uses white wheels as shown, but I wanted mine to look like an XLS so I swapped them out with the black versions that use the same mounting. There are other differences though. The black wheels have fewer internal reinforcements. The Pro-CAT also uses wider front tires than the XLS, but the old narrower tires are no longer available (in the USA).

This is not the same body as the XLS. It is a but lower and swoopier with a more curved window. There is a single window mask included, but nothing else. I masked of everything but the black and painted that first (masking shown at left). Then I painted the red stripe and backed it with white, followed by the yellow areas backed in white. I smoked the window of the body, then I put and additional layer of black on the wing so it would look all black from behind. The white backing really made the colors pop. I'm happy with it. The stickers are a little bland though. The Number 2 is from a surplus Tamiya sheet.

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