TOPIC:

The separate pinion number 3505018 for the Madcap must be a Tamiya peculiar...
It is the exact same setup as the Astute, only that mentions 3515016 as the parts number for the basic pinion.
Spare parts numbers, range of the pinions and even the two spurs match with these cars.

....I was gonna say isn't the Madcap the same setup as Astute?
Monster beetle & pumpbox are different gearboxes - MB is similar to frog, PB is like grasshopper, & I think I'm right in saying the large wheel versions have a motor adaptor plate to be able to use the daft-small pinions. This is also the reason the pinions are relatively long

Okay, that would need a rectification in the first post then.
Next car, Saint Dragon has the same setup as the Astute and Madcap - and also mentions the peculiar parts number.

58082 Madcap - 23T 0.6mod (3505018) with 70T spur, range is 16-23T pinion, kit comes with 70T and 77T spur
58083 Saint Dragon - 23T 0.6mod (3505018) with 70T spur, range is 16-23T pinion, kit comes with 70T and 77T spur
58084 Ferrari F189 - 17T 0.6mod (3515010), range is 13-20T
58085 Avante 2001 - 20T 0.6mod (3515013), range is 12-23T
58086 Toyota Hi-lux Monster Racer - 18T 0.6mod (3515011), range is 14-19T
58088 Mercedes-Benz C11 16T 0.6mod (3515009), range is 12-16T

This post will be edited to complete the list...

Nissan Kingcab (Same chassis as Hilux monster racer) also uses Astute gearbox, but uses the 77t spur (77t is listed as 'not used' for the Astute, but it's part of the same gear parts tree)

Ah, just twigged - the Astute pinion doesn't look aluminium, I wonder if it's titanium & that's why it's got a different number?

I would be a very interesting detail...
Losing the original pinion doesn't sound like a good thing to do in that case.

I wouldn't take it as gospel - my Astute's second hand & it could well be that someone put that pinion on as a 'hop up'. Would work out to be a nice explaination for the part numbers if it was original equipment though!

Probably only someone that's building his NIB Astute or Madcap (maybe other models?) could tell us...
There's nothing on line about it. Ah! A bit of mystery!

More on 0.6 mod (aka AV) vs 48dp gears - as I've said before, they mesh fine, but 48dp pinions are smaller than 0.6 mod ones for the same number of teeth, for example:



This is not a problem if your car has slots for the motor screws, but as most Tamiya cars are fixed positions, 48dp gears can't really be used



TBH I'm finding it hard to differentiate between 0.8 mod & 32dp just by looking at them, but 0.8 mod teeth look a little "pointier" as the pitch point (the point at which the angle on the tooth changes) is fractionally lower down the tooth, and the angle is slightly less, and steel pinions (i.e. they react to a magnet, but be sure the magnet isn't reacting to the grub screw) are almost certainly 32dp, not metric

That's great info.
I've been convinced by now 0.8mod and 32dp can be safely switched.
Even sounds like the diametrical one would give less wear, it being not so pointy.
Might be advisable to maybe not mesh it too tight though...

Reminds me to do some more research for the list.