only running two diff gears

[team head]

what diff fluid to us when running only the two diff gear with new cross pin what does it help

 

[Billl DeLong]

This concept has been around since the beginning of RC... it was more common to see 2 bevel gear diffs in 2WD cars with less powerful motors. As more powerful brushless motors were introduced, it was necessary to upgrade to 4 bevel gears for durability, and then drivers quickly discovered they need to run thinner fluids with the extra gears than what they were used to.

I have never removed any bevel gears from my diffs but I have heard of some team drivers swearing they like it better for low grip conditions, and they caution the need to run thicker diffs but it just sounds gimmicky to me. In theory, durability has significantly improved with modern designs so you can get away with 2 bevel gears in the most brands, but I prefer to not temp fate and stick with the OEM design as intended. I mostly run at high bite tracks anyway so it's not worth the hassle for me.

 

[Matthew_Armeni]

If you want to try a 2-gear setup start with doubling the oil viscosity of your current 4-gear setup. For example, I was running 10/10/5 in my ET48 with 4-gear diffs. When I tried 2 gear, I went to 20/20/10.

 

[team head]

thanks for the info

 

[juliendogg]

If you want to try a 2-gear setup start with doubling the oil viscosity of your current 4-gear setup. For example, I was running 10/10/5 in my ET48 with 4-gear diffs. When I tried 2 gear, I went to 20/20/10.

How was the experience? Noticable difference?

 

[Matthew_Armeni]

How was the experience? Noticable difference?

It was a noticeable difference. To me, it sort of feels similar to running thinner diff oils without the negatives of thin oils. In my previous example of 10/10/5 4 gear versus 20/20/10 2 gear, I could put down faster laps with the 4 gear. However, during a race I have a harder time being as smooth on the throttle as I am during practice or qualy (especially when battling another driver), and I would sometimes have the rear of the truck step out on corner exit. When I ran the 2 gear, I could be a lot more aggressive with the throttle and the rear would stay more planted, similar to a 4 gear with lighter oils. The difference is that I feel like a 4 gear light oil car is more "active" and I have to be really on top of the car when I drive. The 2 gear with heavy oils has a lot smoother transitions when it diffs out and it requires less driver input.

 

[juliendogg]

It was a noticeable difference. To me, it sort of feels similar to running thinner diff oils without the negatives of thin oils. In my previous example of 10/10/5 4 gear versus 20/20/10 2 gear, I could put down faster laps with the 4 gear. However, during a race I have a harder time being as smooth on the throttle as I am during practice or qualy (especially when battling another driver), and I would sometimes have the rear of the truck step out on corner exit. When I ran the 2 gear, I could be a lot more aggressive with the throttle and the rear would stay more planted, similar to a 4 gear with lighter oils. The difference is that I feel like a 4 gear light oil car is more "active" and I have to be really on top of the car when I drive. The 2 gear with heavy oils has a lot smoother transitions when it diffs out and it requires less driver input.

That's great feedback, thanks!