I like RW spur gears, they only take 8 balls but seem to last alot longer then kimbrough spur's. I generally go 6-8 runs in between rebuilds and only replace the hardware when it needs to be.

At the moment I'm using A normal size servo (digital, Hi-tec HS5925). It's A really strong servo and it's also fast (0.08 sec)
But it looks like everyone's using A mini type servo, is it really necessary (if so, why) and is it worth to invest in?

Mini is for weight and also most cars wont even accept a full size servo with the servo posts and mountin positions on the chassis.

Futaba 9650 is where its at. Hitek's dont center for shit, Futaba's center great all the time :) Also you dont need that much steering strength to steer a 3 lb car.

Whats the transmission ratio on a 12th scale?

i would think that depends on your spur, pinion and tire size, its infinite really, unless im an idiot

Then how do you find all those rollouts on gearchart.com You need the transmission ratoi, spur,pinion, wheel size.

Jon... It's 1:1.....

BTW... I have a whole chart printed out for a 96 tooth gear, I'll copy it if you want....

i dont know what the exact forumla is but its pretty simple, all you need is your spur size pinion size and tire size

Oh that explains it, thanks Allan. Um ya sure make me a copy that be great. I dont have a printer working in my house, so i decided to get it done in school, lol. I am supposed to be writting an essay right now, but i think rctech is better, lol

Roll out formula in excel:

Roll out chart

Thanks,
I'll see if I can find that servo somewhere so I can test it.
And I don't have any problem with Hi-tech servo's.
But I'll have to admit that I've never used A Futaba servo,
so maybe if I do I'll say something different!:p

Tried a 9650 at The US INDOOR Champs this year, and found it to be the biggest pile of junk I've ever strapped into my car. The KO 949 and the JR 3550 seem to be the most reliable, and precise, servos for 12th scale use. I have one of each, and have never experienced any problems with them. I'm sure it's possible that I just got a "bad" 9650, but that was enough for me.

servo
 

i agree. I used a 9650 for a whole season in one of my cars and while it centered well enough the gears got really sloppy after a short time. The KO 949 is far superior.

Hmmm.... this makes me confusing!:weird:
Are there other opinions about the mini servos?
And are there other servo's I can choose from?

Since I'm very satisfied with my current Hi-tec servo, I was thinking maybe this servo could be A good pick:

HS-5245

Did someone tried this one?
I've seen lots of (team) drivers using the Futaba, so I guess it couldn't be that bad....

I'm currently using a Hitec because it was all I could get locally but I'll be going Futaba digital in the near future....