What pinion to use when using the SSD portals

[Panther6834]

Ok...full disclosure...I am putting this in the SCX10.2 section, but I am NOT building an SCX10.2. Truth be told, I am building a Capra...but, it's more like an SCX10.2 than a Capra - the only actual Capra part is the cage. Here's a breakdown of what this vehicle is made up from, beyond the Capra cage (or will be, as it's just being started).

I'll stick with just the mechanicals, as the rest is irrelevant to what I'm asking. Steering with the source, power will be provided by 3S batteries. The transmission will be a SuperShafty-built 3-gear w/ 56T spur, housed inside the Vanquish machined aluminum housing. As this will be a 4WS rock buggy, I'll be using 2 Vanquish AR44 Currie F9 front axles, with 30T/8T ring & pinion front & rear. I know...right now, those reading this are thinking, "then there's no overdrive". Here comes the 'twist'.....

Instead of the standard steering knuckles, I'll be using the SSD portal knuckles, with the front portal gears swapped. In the standard 14T/16T (going in the rear), the portal ratio is 1.14:1...however, by reversing the gears (16T/14T), this creates a 0.875:1 ratio. With the portal gears set this way, this gives the front slightly more than a 30% OD.

So...the "big question" is, what pinion should I go with. Unfortunately, I don't know the formula to calculate final drive ratios. Even if I did know the formula, the fact that I'll be using portals complicates things. Added to that, I have no clue what the transmission output ratio is. Finally, added to all of that, I don't know what the 'optional' FDR range might be. I can't exactly ask this in the Capra section, as this vehicle will really be closer to an SCX10.2, just housed inside a Capra cage, thus I'm turning to those familiar with the SCX10.2...so, suggestions?

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]

 

[Panther6834]

A quick 'update' to my own post. Thanks to Durok & Joshs4x4toyz (in another thread), the biggest part of my questions have been answered. Durok provided info on the ratios, and Josh provided the FDR formula. So, a big "thank you" to both.

It appears that the transmission ratio is 2.6:1 (I'm fairly certain this is correct), and the axle's ring & pinion is 3.75:1 (I'm going this is correct). Combining that info with a 0.875:1 front OD portal gear ratio (the rear is 1.143:1), 2200kV motor, and 5.75" Hyrax 2.2 tires, it appears to produce the following FDRs, and "theoretical" top speeds:

10T - 8.98mph, 47.775:1
11T - 9.88mph, 43.43:1
12T - 10.78mph, 39.813:1
13T - 11.67mph, 36.75:1
14T - 12.57mph, 34.125:1
15T - 13.47mph, 31.85:1

As I posted elsewhere, I can't know if these top-speed calculations are correct, but I'd assume the FDRs are correct (again, if the axle's 30T ring & 8T pinion ratio is correct). To those reading this, based on these speeds & ratios, and assuming you were building a SORRCA Class 3 rig, what ratio and/or "theoretical top speed" would you be targeting? I don't mind purchasing 2, or even 3, pinions...but, I certainly don't want to purchase all 6, only to return most of them. Looking for input (hopefully, in all the right places).

~ More peace, love, laughter & kindness would make the world a MUCH better place [emoji1690]