In need of advice regarding gearing

[mothman]

Im working on a BL Savage project. Planning to run this truck with 7XL and 5s Lipo. I havent decided on the controller yet. But I've short listed 2 controllers so far, MGM160 and warrior 9920. Im working on the motor mount right now. So i need to order 7xl in order to make sure that the measurement of the motor mount are accurate. Since im going to order the 7xl from Mike, i'm going to order all of the stuffs (pinion, spur, motor, controller etc) that i need for this project from him at once.

So i need some advice on the gearing option( pinion and spur) for my savage. Im not looking for speed, 35-40mph is more than enough for me. Im looking for run time and i dont want to fry the controllers if i gear it too high or too low. FYI im going to use savage GT Tires, 6"x3.15" (since the gearing depends on the diameter of the tires).

My second question is, which controller I should get? the MGM 160 or the warrior 9920. Since i cant use the mechanical brake if i convert the savage to BL, Im going to rely on the controller for the brake. So I need a controller that can take a bit more punishment.

So i really hope you guys can shed some light. I'm going to order all of the stuffs from Mike in 2-3 days time (except for the 9920 if i decided on that one)

All help, advice and comments are greatly appreciated.

Thanks

[Serum]

I would take the MGM controller, it has got some nice features over the 9920 and the last called is rather hard to get at this moment..

You can keep using your 2 speed transmission. that would be no problem.. The size on the 7XL; 25 mm heart/heart for the two M3 bolts to mount it on. the length of the can is 74mm, keep in mind that the wires come from the backside, the diameter of the can is 36mm

About the speed you wanted to reach; your better of with a 4S lipo then!, using the 2speed makes the 15/49 the best gearing for your wish of 40 mph.

Feel free to use this XLS sheet to calculate the gearing/speed you need...

[mothman]

Serum, the reverse cannot be disabled on the MGM controllers. Since Im using the 2 speed tranny, wont this be a problem?

And if i use 4s Lipo, is that strong enough to run the heavy Savage?

[coolhandcountry]

ON the mgm it will only go to reverse if you go to reverse on controler to activate brake then to neutral back to reverse. If you just hit the brake once you have no problem. If you get what I am saying.

[mothman]

I got wat you say. That means I have to hit the controller just once to activate the break. but then wat if I dont want to activate the sudden brake (hard brake)? I just want to tap the controller few times to slowly brake.

and serum, how long does it take to shift to 2nd gear? I heard its really fast. Is that means the speed for the 2nd gear is more important?

[coolhandcountry]

If you tap it. You will go to reverse. Have to learn a more consistant pressure. If you tap it the motor will spin in reverse. Possible over wind.

[mothman]

Originally posted by coolhandcountry
If you tap it. You will go to reverse. Have to learn a more consistant pressure. If you tap it the motor will spin in reverse. Possible over wind.

Woo!! thats not cool. There no other way to stop the truck slowly other than hit the brake at once?

[coolhandcountry]

Unless you figure a way to disable reverse in the esc. It was a thing in the other thread. Mike had a problem at the track at monster madness. he would tap the brake then hit it again and it would do an endo. Don't mean to be the one to tell you this but someone has to. Bat fish has the issue on a jato to. If you hit the brake you have to bump the foward and then brake. Is another way.

[crazyjr]

Hey Mothman. If you have a computer based radio (JR Futaba Airtronics ect) see if you can use the third channel with the throttle so you can set the throttle at zero brake and full throttle then set the third channel at full brake and zero throttle on the brake servo so you never have to worry about accidently hitting reverse. you may have to use reverse when programing but you can dial it out when done.

[Serum]

I know someone who uses his third channel for braking. You can easely adjust the shifting point of the 2 speed. And yes, you must look at the speed with the 2nd gear.