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I have a HW 10.5 for my Bosscat. The motor manual says to gear for ~8.00 final drive. I can, or could, achieve this with 28/92, except 21 is the largest pinion that will physically fit with a 92 tooth spur. (I don't have any smaller spurs.) 92/21 x 2.42 = 10.6 FDR.

The Bosscat manual was written for brushed/NiCad of course. 10.6 FDR is about what it recommends for a 13 turn brushed.

So, what do you folks think? Don't do it? Try it and check temps? 10.6 and 8.0 seem to be worlds apart, however a 10.5 brushless is probably reasonably close to a 13T brushed.

I am not racing. I will probably just put slicks on and run on pavement. Run time is of no concern.

It'll probably still be much faster than the vintage chassis and drivetrain can handle.

Definitely need to go 8.0 or even as low as 7.6 you should be able to find a 86 or 89 t spur easy enough. Do you have a slipper fitted or is it just the u 277 layshaft?

I’ve run as low as a 8.5 on original transmission just make sure your diffs belts and slipper are set right

It has the original slipper. It is the Bosscat "competition" (1992?).

Retro rc wrote: ↑Thu Nov 10, 2022 9:04 pm you should be able to find a 86 or 89 t spur easy enough

How right you are! I finally got the ship notice on my Cougar. It has an 86 tooth spur standard according to the manual and exploded view. I have the pro transmission (can't call them "tranny" anymore, that has a new meaning) for it, so will use the 86 on the Bosscat.

The 86 won’t fit on the bosscat, the slipper spur is different to the cougar I’ll try and post some pics later on for you.

I have the 86 tooth spur from the Cougar Classic now. It seems that all I need to do is cut away the center section (the thick center with provision for the drive pin). The 2 screw holes to attach the spur gear to the Bosscat splipper housing are there and in the proper location. I won't even have to cut with surgical precision, as the 2 screws will locate and align the spur. Good thing, "surgical precision" has never been an option for me.

My Top Cat and 1 of my 2 Cougars will run the pro transmission, so I don't mind cutting the one spur gear.

Random observation: the re-re Top Cat is essentially the same car except for the front suspension, but came with a 95 tooth spur gear vs the 86 on the Cougar. Good on Schumacher, as the 86 is probably useful in more scenarios than the 95.

For future reference- Drilling a 5/8 inch hole through the center of the Cougar/Top Cat spur gear worked perfectly. It bolted directly onto the Bosscat slipper.