TOPIC:

Hi
Tamiya av gears = ?
Tamiya brat gears = ?

Can any body enlightened me Please
Viking

AV pinion is 0.6 modular and Brat pinion use the 0.8 mod pinion, they will not match as the pitch is different.

Johnny Retro on here, wrote a great explaination on aother board I've found:

"It's never that simple, is it?

Gear pitch on RC cars made in the US (like Associated) and in the UK (Mardave) are expressed as DP (diametrical pitch) – an imperial measurement. The usual sizes are 32, 48 or 64DP, gears get finer teeth (and more of them) the larger the number gets.

To find out what pitch a gear is, you need to count the number of teeth, and measure the diameter – specifically from one “land” (the flat at the bottom of the gap between 2 teeth), across the centre to the land opposite, or if more convenient, from a land to the centre, and multiply by two.

Diametrical Pitch (DP) is the number of teeth, divided by the diameter (in inches) of the gear.

For example, I needed a new pinion for my RC10, but had no idea what pitch it was.

The radius of the spur gear was approx 20.75mm, meaning the diameter was twice that: 41.5mm, or (divided by 25.4), 1.634 inches.

The gear had 81 teeth on it, so 81T divided by 1.634” = 49.6DP … which just goes to show you I really ought to have used a set of verniers, rather than a ruler calibrated in single mm…. But it’s close enough to 48 that it was obvious I needed a 48DP pinion.

Afaik all Tamiya gears are metric though - metric gear pitch is expressed as ‘module’ (or modulus, or mod) – a decimal number such as 0.8, 0.6, 0.5, and so on.

It’s calculated as pitch diameter (in mm), divided by number of teeth = module.

“Pitch diameter” is measured from one “pitch point” across the centre to the opposite “pitch point” - if you look at a gear tooth, it's not a straight edge from the bottom of the tooth to the top - the point where the angle changes is the "pitch point".

Taking an 18 tooth Frog pinion (same as the Brat), I measured it and got a figure for the pitch diameter of 11mm.

11mm / 18 teeth = 0.61 recurring, or 0.6 if you round it, i.e. an 0.6 module pinion."

Not sure how relevant, or even correct that quote was, clearly my "Frog" pinion wasn't from a Frog or anything comparable at all, it must have been from a Scorcher or similar

Brat/Frog (+ORV in general) gears are 0.8 mod, AV are 0.6 mod. 32dp pinions are generally considered to be compatible with 0.8mod gears, this is handy if you want to switch from/replace a Tamiya Aluminium 0.8mod pinion to a steel 32dp pinion