48dp to 64dp gearing
 

Looking to change my pinion and spur from 48dp to 64dp because the noise is annoying :lol:

Currently the FDR is 5.7 with pinion 25t and Spur 84t.

Looking to match the FDR (internal ratio of 1.7) with 64dp but worried about the fitting.

So far ive got my eye on the 108t Spur and 32t Pinion.

On my current setup i have barely any space to get a larger pinion or spur.

Car is Xray T2 008.

Anyone got any experience? I hear if you match the Ratio the actual diameters of the gears are the same, but not sure as there is obviously more teeth.

Other than the fact that "gear noise" is usually as a result of worn gears, pinion or spur (or both) - as long as you keep the same or similar diameter spur you shouldn't have any problems making the change over from 48p to 64p.

Final drive ratio (FDR) has nothing to do with it, it's basically the simple math you should concern yourself with Spur gear tooth count divided by Pinion gear tooth count. In 84p, 84/25= 3.36 ... so in 64p, 108/32= 3.38 (or 104/31=3.35).... or as close as you're going to get.

Hope that helps :)

I have found the answer, i hope it helps others as there is not much info about on gearing.

Gear Diameter = Metric Pitch * Teeth

Metric Pitch = 25.4 / diametral_pitch (48 or 64)

For 48dp
25t Pinion = 25.4/48 * 25 = 13.23mm
84t Spur = 25.4/48 * 84 = 44.45mm
Total = 57.68mm

For 64dp
32t Pinion = 25.4/64 * 25 = 12.7mm
108t Spur = 25.4/64 * 84 = 42.86mm
Total = 55.56mm

So now i know i have nearly exact same ratio and that its only 2mm smaller in total diameter so hopefully itll fit perfect. Ive ordered my parts and will reply with results.


Gear Name...Metric Pitch... Diametrical Pitch
Mod 1.5.......1.5012.........16.92
Mod 1.0.......1................25.4
32dp...........0.7938.........32
Mod 0.8.......0.8.............31.75
48dp...........0.5292.........48
Mod 0.4.......0.4.............63.5
64dp...........0.396...........64

Its a simple coversion.
your current pinion is 25t 48dp so
25/48 x 64=33.33 so you need a 33 t 64dp pinion

your current spur is 84t 48dp so
84/48 x 64=110.25 so you need a 110t 64dp spur