My FLM Savage Build

[tonkabilly]

Well I think all the best laid plans just went to hell. I put the motor in and it touches the battery using 52/17 gears. I think I am going to have to start over. I think 4s will be the way to go. Now just have to figure out if I keep the Medusa (1600kv) and the ESC. From what I read the motor might be a little lacking? Should I go up to a 2000 or 2200KV motor?

[lincpimp]

Originally Posted by tonkabilly

Well I think all the best laid plans just went to hell. I put the motor in and it touches the battery using 52/17 gears. I think I am going to have to start over. I think 4s will be the way to go. Now just have to figure out if I keep the Medusa (1600kv) and the ESC. From what I read the motor might be a little lacking? Should I go up to a 2000 or 2200KV motor?

For a heavy truck 6s is better... Did you try the battery both ways, as it is narrower on its side? Also you can put spacers under the motor mount, which raises it up so that the motor shaft is closer to the center line of the spur, where the spur is widest. I have seen people do this to gain clearance between the motor and batteries.

If you go with the flux center shaft for the tranny it effectively locks it in 1st, which will require a larger pinion to get the correct top speed...

I will plug some numbers in to the calc.

you have 6s lipo, a 1600kv motor and something like 6" tall tires, correct?

[tonkabilly]

Yup. Set-up is Medusa 1600, 6s Lipo, and I have Proline Holeshot MTR tires. I would like to stay with 6s but there is just no space for the two. Obviosly I have some tinkering to do but just can't see this working without reducing the Lipo size to at least a 5s?? Yes I did flip the batteries.

[lincpimp]

Ok, if you run the flux center shaft/gear in the x tranny, pn hpi100905, it is just like locking the X tranny in 1st gear.

With that tranny ratio and your 6s/1600kv combo you could run a 52/25 spur/pinion combo. That would get the motor well away from the tranny. If the motor mount does not have enough adjustment, you could go with a 47/23 spur/pinion setup and that would yeild the same ratio (about) I figured that you are using 40 series bowties (by the pics) which are around 5.75" tall.

Set the motor and mount up with out a pinion, and place the battery in the chassis, adjust the motor as close to the battery as you feel comfortable (leave 1-2mm between) and measure from the center of the spur gear to the center of the motor shaft.

The 52/25 combo would place the center of the motor shaft about 40mm from the center of the spur, the 47/23 would give around 37mm. Your 52/17 combo is about 36mm, so the 52/25 would most likely get the job done.

Plus you only need to buy the flux center shaft/gear and the 25t pinion from mike, (25-30 bucks for the 2) which is much cheaper than another lipo or motor...

Calc info for the 52/25 gearing with flux tranny ratio:

Differential Ratio: 3.3076923076923075
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 52
Pinion Tooth Count: 25
Total Voltage: 22.2
Motor KV: 1600
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 2.08 : 1
Total Ratio: 15.24111 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 35520 RPM
Vehicle Speed: 39.87 mph (64.04 km/h)
Effective KV Value: 1600

If you have room you can run the smaller 49-47t spurs to up the speed a bit...

I went thru all of this with my flm chassis savage... Hope the info helps! And keep in mind with the flux internals on the tranny you can use motor brakes and motor reverse, instead of mech brakes.

[tonkabilly]

linc, you rule
I will give this a try and order some extra parts and see what I come up with. Thanks for the help. Didn't think about the extra size on the pinions
Just mean another 2 weeks before this thing is running.

[lincpimp]

Originally Posted by tonkabilly

linc, you rule
I will give this a try and order some extra parts and see what I come up with. Thanks for the help. Didn't think about the extra size on the pinions
Just mean another 2 weeks before this thing is running.

No prob, I must have fooled with gearing for about 10 setups with the flm chassis. Seemed like you had to lock it in 1st and use large pinions if your motor speeds were around 45mph, that way the battery and motor would fit. I did not like the idea of raising the mount up, so I got around it with gearing. I had the chassis built for over 6 months and never ran it...

[tonkabilly]

Ya I am just too stubborn for that. After all the time and cash into this thing there is no way it is going to sit there.
Besides, its driving the wife nuts that it is not done yet. She will probably driving it anyway. She is scared of my Baja.

[tonkabilly]

Well got everything mounted up. Made some risers for the ESC plate to lift the controller up a bit higher. Have the Lipo, motor and ESC all installed and everything fits very good now. Just waiting on the tranny gear and the larger pinions as well as a new rx and I am ready to go.