Overdrive Percentages

[Maxxamillion]

Much of the overdrives these days are figured in percentages. The Enduro truck for example... 6% or 12 % overdrive (transmission OD).
Transmissions... 2.low & mullet trans have 30% overdrive....
What I am curious about is the overdrive percentage on the Vanquish F9 portal axles. 18/30 is the standard gear set. 20/28 is the overdrive gear set.
What is the percentage of overdrive that gear set provides? My math is not good enough.

The reason I ask is these trick belly dragger transmissions have 30% overdrive, which to me is excessive on a more basic, non comp trail truck (of course much crawling use also).
My though is if the transmission overdrives 30% to the front, could I overdrive my rear currie portal (guessing 15-20% overdrive?) and net a 10-15% final overdrive.

Or cheaper yet just use an Enduro trans and F9 portals and no overdrive gear set needed? My F9 portals are already in use on my slightly modified scx10 II (gspeed v3 chassis at the ready).

I am looking to build an all around trail truck/crawler in a gspeed fashion, but with a taller ride height (I need the ground clearance in my crawling country) and maybe 12-20% overdrive.
I see many beautiful gspeed trucks getting built, very cool all of them. Looking to put my own twist on it. TIA for enlightening me.

[mikemcE]

This might help



Hang up and Drive

[Maxxamillion]

Hmmm, I am not seeing my particular portal gear set for reference, 20/28. Is Capra F9 axles and their gearsets the same as scx10 II axles & gear sets?

[Fricker08]

According to super shafty’s page, these are the tgh gears for Capra and scx10.3 portals. Mild is 24% wild is 36%



Sent from my iPhone using Tapatalk

[twade984]

I would recommend watching this video from Harley designs if you’re not familiar with gear ratios, percentages or how to calculate them. He also linked a very helpful online calculator you can use if you know the front and rear final drive ratios, which I will link also.

https://youtu.be/RZS3i59okq4

https://www.omnicalculator.com/math/...age-difference

[Maxxamillion]

Thank you twade. Got it! You made it easy.
The Vanquish portal overdrive is 17.59% over stock.