Brushless Savage Setup
 

Hello folks

I am new here. Dafni told me about this great forum yesterday. As I am converting my Savage 25 RTR to Brushless I read a lot of threads here and in other (german) forums. (BTW: excuse my poor english...)

I already placed an order for a Wanderer 20XL/9 and a Warrior 12020 at BK, but I can still switch the setup as I have to wait for some parts.
After speaking with different people in Switzerland and Germany I was surprised that the 7XL is the choise of many drivers in this forum. One thing that nobody discuss here is the problem of hopups that have to be made while using a motor with so much torque... In Germany everybody tells you first about the stronger dogbones, cup joint, diffs etc. you need. Are you driving the 7XL with stock parts?? The only thing I modified is a 4-spider diff. The drive train is still stock.

Before I ask the question that everybody asks, here is my (virtual-)setup:

- BK Wanderer 20XL/9 (kv: 1667)
- BK Warrior 12020
- 16 cells GP3300 (given as I already own this)
- fixed gear
- 16/49 or 18/49

I like to build a car that is not a material-killer(!) and I drive mainly in the gravel-pit (climbing & jumping), so speed is not the one and only. I used the savage speedtable to make some calculations and I learned a lot about the sweet spot and heat regulation from Dafni. Now I think that the setup above could be optimized for my needs.

With 16 cells (calculated with 1.15 volt) I get about 30'000 rpm which is clear below the sweet spot of 35-40'000 rpm. And the speed is also poor: 24mph with 16/49 or 27mph with 18/49 translation in first gear. What can and should be changed???

a) 20XL/8 (kv:1875 -> 34500 rpm) = 27mph (16/49) / 30mph (18/49)
b) 20XL/7 (kv:2145 -> 39500 rpm) = 30mph (16/49) / 34mph (18/49)
c) 20XL/7 and fixed second gear = 38mph (14/49) / 44mph (16/49)

Is it possible to drive the c-setup (second gear)? Or does it generate to much stress to motor and drive train?
To hit the brushless sweet spot under "normal" gravel-pit condition I think the 20XL/7 is the best choice.

What do you recommend? What's the golden setup?
Serum, Mike what do you think?

-- Dave


Remember: I don't want a beast that kills all the drive train parts (the Savage will be about 15 pounds).

Hi Atilla, glad you found your way to this place.
Don't worry about poor english, the folks here are very helpful and nice.

I exchanged some mails with Serum about your setup, but that was when I still thought you were going to use 18 cells.
I wonder what the gurus will say. I would still suggest the 7XL.

Not only the motor is a part killer, but the driver too!

Hi Attila! great to see you took this time to write in English.. (it takes me some time as well, to write in German, and it's not near as good as your english..) welcome to this forum!

The savage is a tough truck! that's for sure!! I am going to do a centerdiff rebuild on a savage soon, and i will include detailed pictures why i think the savage is nice for converting to BL..

You are from Germany, so if you ever waste a diff, get the Nitro-Mods spider mod!

16 cells you could use the 9920 with the 10L or the 7XL or 8XL, using the automatic transmission. (this RULES!!!!) (be sure to get the heavy duty 2nd gear mod)

About the weight;

My allmost complete aluminum savage weighted about 14,5 pounds, with 16 cells as well..

A friend of mine runs his savage with 14-16 cells with this 10L and a schulze 18.61 with the right gearing he can peak to 71 km/h!! Brushless is really strong.

Though the 7XL or the 8XL gets my vote. With the 8XL you will be able to run it on maxx 20 cells (with the right gearing) and the 7XL will let you run it with 18 if needed..

The runtime would be about 12-15 minutes. With the XL the motor will run nice and cool

The 8XL will give you a bit more runtime than the 7XL,

Remember, the kv ranges that Lehner has with their motors is under load. With the gearing you are using

If you plan on running 2nd gear, i would use the 8XL.. (with a 16/49 gearing it is really quick (40 mph))

:C: Weird statement from myself. I wanted to say it strongly depends on HOW you drive, too. Hope you get it.

Serum: Atilla is a swissie!

Atilla: I agree with Serum. A basher truck like the Savy should be fun with the auto tranny. Why not keep both gears open?
By the way, nice Avatar. Especially the truck :p

A truck? Ahh Now i see...

With the the automatic transmission I loose the reverse gear...

Which "heavy duty 2nd gear mod" do you mean?

2nd gear fixed could be an option. But with an 8XL on 16 cells I am always below the sweet spot (~33000 rpm). Something to care about??

The more I play with the speedtable the more I like the BK 20XL/7 or maybe the BK 20L/10. The L of course draws less amps, which means longer run time. But is an "L" strong enough for a Savage???

BTW: Why does a Feigao 7XL has a kv of 2382 and a BK 20XL/7 a kv of only 2145? I thought that they are more or less identical...?

OK, when you have to choose one of these setups, which one would you prefer? (always on 16 cells and with a BK 12020 controller)

a) BK 20XL/7 (kv: 2145, about 90-95 amps)
b) BK 20L/10 (kv: 2212, about 60 amps)

Speed is for both setups nearly the same:
1st gear: 16/49= 30 mph or 18/49 = 33 mph
2nd gear: 16/49 = 42 mph

Again: is an "L" strong enough for a Savage? And does it has more torque than a stock .25 nitro Savage?

Thanks!
-- Dave

Well now. Let start with the feigo and bk motor kv. feigao does theres not under load. bk does theres under a load. Sure on paper they seem like you would get more run time out the 10L. The 7xl has more torque so it takes less power to do the same thing. You should have about the same run time. I run a 14 l right now. I had a 7xl. The 7xl had alot more power. The run time may be shorter with the 7xl. I get about 30+ min on a set of batts right now. I am not easy on a truck though. I have space and I let the truck go. I have need for speed. I would like to try a 8 and 9 xl. Just to see what they do. One guy said 25-30 min on a 9xl. He has more torque than me to. Close to same kv rating as well. but the 9xl has more draw than mine. 9 xl has about 74 will mine is only about 40. In my opinion. Go with the xl motor.

Oh yeah, I forgot. You already told me. The Oneway bearings...

OK, after reading this thread I know more about the "sweet spot" thing. Summary: every setup has it's own sweet spot.

-- Dave

Of course. But according to Mike, BL motors are most efficient around 35'000rpm.
Sweet spot and Most efficint spot are not necessarily the same. In fact they are two different things. YOu can "tune" the sweet spot by gearing, but max rpm is given by voltage. Just make sure the sweet spot is in the efficient range :)
The best is to start somewhere and observe the temps.

Let's put this sweet/efficint thing another way: The sweetspot concerns the gearing. It's an equation on gearing, weight etc.
The efficiency is a constant at a given voltage, if I understand it right.

I still don't know which motor I should take. Maybe I'll go for this one!!! :devil

Check it out!

-- Dave

Yeah, someone already posted this beast here. But I thought you don't like the nitro noise....:L:

The 10L like i said, is strong enough for a savage. A friend of mine reaches 71 km/h with the 10L on 16 cells. on 14 cells it allready is faster and stronger than a .25 (fixed in 1st gear that is)

this is the heavy duty 2nd speed i am talking about..

You don't really need a backwards, and you could use a backwards conversion for your savage.

i saw a bl savage with a 9L and a warrior for 300 bux.

If you want to stick to 16 cells, the 10L gets another vote from me.

fiego is the best value
Ps. Any1 got a used brushless sytem for tradeE!! i got 3 revos and i cant get any of them tuned!! save me from this nitro hell!! PLZZZZZZZZZZ:cry :devil :cry :devil :cry

Thanks for Input. One last question (I hope...):

Let's stay with this two setups:
a) BK 20XL/7 (kv: 2145, about 95 amps)
b) BK 20L/10 (kv: 2212, about 60 amps)

KV and so top speed is nearly equal. What about the run time?

Does the 10L really has a noticeable longer run time because of the less amps? Or does the more torque of the 7XL is balancing this?
Does the 10L is more kindly to the drive train while accelerating?

Thanks again
-- Dave

I never had a 10L, but I give it a guess:
Runtime should be more or less equal, I think.
If you have a twitchy throttle finger, the 10L should be more forgiving on the driveline.

In the end, it's up to you. Both are great motors, no doubt.

Get the 7XL the best motor money can buy.. It runs silcky smooth if you want it.. And it has got enough torque to put your savage on its roof in a blink of the eye.. On 16 and 18 cells..

I would recommend the 8XL if you are planning on running 18 cells and up..

7XL rules. It has got a nice kv range, and on 16 cells it is a true blast. More power than the 10L. the runtime depends on your finger. The 7XL can drive as long as the 10L, it will run faster if you give it a WOT, so don't expect more runtime if you are running 5mph faster..

i love the 7XL being smooth and predictable...

I love my 7XL too. As you may have heard:D If you want an XL Can, get the 7. If you want an L Can, go for the 10.

As mentioned before, Serum's the Savage guru. I would blindly follow his advice. For he actually knows BL Savages, and has experience with different motors.

Holy hell, that thing truly is a beast! :eek:

OK, I go for the 7XL . The order is already changed. Thanks for all your suggestions. I will send some feedback.

-- Dave

Hello,

I'm new here on the forum and I'm also planning to build a BL savage. The esc will be the warrior 9920 and the motor 7XL (almost certain)

Does de 7XL also perform well on 14 - 16 cells? Because I don't want to put 16 - 18 cells for the first runs.

Thank you,

Jasper

Welcome my fellow Dutchmen... (land of the clogs, mills and good advises (referring to this thread here, no arrogance intended... ;)

you can use the savage with the 9920 and the 7XL on 14, 16 and even on 18 cells.. Trust me.. 18 is a BLAST!!!


If you need to know something or need any hints and tips, feel free to ask..

What savage are you going to rebuild? (.21, SS.25 SSK4,6?)

Thank you for the quick reply, my fellow Dutchmen.

I'm going to rebuild an savage .25. I thought at my self what I have to change.

- spider diff in front and rear
- motor mount (e-maxx motormount or something else? Who can make that? I can't cut alu at myself)
- braces on the left and rear of the chassis for holding the cells
- changing the springs

Is this a good list? Or have I forgotten something?

Thank you,

Jasper

I will answer it a bit deeper later this evening,

the thing is;

You can buy a complete kit from Nitromods in Germany, which includes the batterieholders, motorplate, pinion and the special driveshaft, that kit is 89 euros.. (not too expensive imo)

As I know Nitromods sells the kit without the batteryholders. Monsters Paradise sells the same kit (from Nitromods) with the batteryholders for 95 Euros.

-- Dave

that's a nice price? i didn't knew nitromods sells it without those batterieholders..

That aluminum you need a just some U-profile for the batterieholders and a 6mm thick plate for the motor. If you have got a dril, a few rasps and patience, you are able to make them yourself...

The deal with the .25 savage went off, so I have to find another rolling chassis.

On ebay I found this: http://www.sickhobbies.com/frameset.htm

This is the New Savage SS 4.6 Roller, comes with 4 Hardened Dog Bones / Hardened Diff cups & Tran Cups/ DDisk Brakes / Adjustable upper Arms / 4 Bevel Gears / The Cam Type Steering Servo Saver and The 2 speed up grade

Build your own Racing TRUCK

What is MISSING is : Motor / Tires / Shocks / Motor mount / Body Cover

This is a UNUSED UNOPENED SS 4.6 Kit

$225.00 + SH

I only have to buy the stock SS shocks: 17,95, body: 20 and tires and rimes. What are the best tires? The HPI dirt bonz or the Proline bowtie tires?

And is it really necessary to get the alu HPI shocks and GPM diff housings?

Is the drive train off the 4.6 SS strong enough to reduce the BL power?

Thank you,

Greetz Jasper

Hi Jasper.. I am thinking about buying the K4,6 as well, and those dirtbonz are really good, with RPM stablemaxx rimms, you can't go wrong.

Imo the drivetrain is strong enough, i would get a set of aluminum differential housings (the ones that go around the entire diff) and a set of HB lighting diffcups (number 8019, if i recall correctly..)

My guess is that those bones will snap, sooner or later.. (that's one of the reasons i am going to use a centerdiff in this one)

I would get a K4,6 here in holland, for 460-470 euro, and you can sell the motor/exhaust etc. (about 200 euro imo) and you have got all the other goodies needed...

Hello all, im new here & following this thread with interest, im considering building a BL monster truck to go with my nitros & was going to build an emaxx, but the drivetrain issues put me off a little, now that HPI have sorted the Savage with the 4.6SS it seems to make more sense to start with a Sav instead....

Can anyone give me a little more info on the conversion please ? i looked at the places selling it & though i can find prices i can't find any actual info, my main concern is the tranny, i will hopefully use a centre diff with custom dogbones as i have access via a friend to a machine shop, but if i were to stick with the stock tranny what mods do i have to make to it ? can i still get reverse etc ?

Thanks for your help in advance :)

Hi Motomaxx, welcome to this board.!

All things your asking are allready answered in severall threads..

I will combine 1 and 2..

if you'r planning on doing a diff conversion, you are on your own.. you need to make a motormount yourself, with a centerdiff holder.)(i am currently thinking/tinkering/building one too) (centerdiff converted E-savage) based on a K4,6.. Reason; bulletproof drivetrain with the proper hopups.. (aluminum diffhousings and HB diffcups)

the transmission of the savage is top notch, you only need to order the heavy duty 2nd speed.. if your planning on using the two speed, the kit monsters-paredise.de is selling (95 euro, about 110 dollars) comes with a motorplate, batterieholders and a special shaft, that replaces the two speed gears inside the housing (making it a one speed only) i prefer the two speed, quicker of the hook and higher topspeeds..) if you use the K4,6, you have got a dual disk brake..

A mechanical brake is easy on your controller..

The best setup you can get for 14/16/18 cells for the savage is the 7XL, in combination with the 9920 You can go bigger if you want, but i don't know what you expect from it.."

If you need to know more, feel free to ask, or just hit the search button

Sorry about not using search !! it's something i hassle noob's for too on forums im more established on :o

I'm pretty sure i could hook up the centre diff but having thought about it im unsure as to how id manage the steel spur/pinion combo, are pinions available to work with steel spurs ? i'm pretty sure all the centre diffs i could lay my hands on dont come with a plastic spur available....

So the kit available removes 2 speed, so i'd run a stock Sav spur & have single speed & brakes via the ESC ? though tougher on ESC that sounds promising.....

Just to throw a spanner in the works though i'v just seen BL MGT thread.... i have a well hopped up MGT with a .28 engine sat here i was considering selling :rolleyes: ... if i could work out the steel spur/pinion combo, i think that would be my favoured option, since my rolling chassis is already decked out with RPM arms/hubs, HCR Ti skids, HCR towers, AE FT shocks, steering, etc...

Decisions decisions.... :D

I know that the savage can handle it for sure! every truck needs to be converted.. (credo of the week...)

I really don't blame you for not searching.. I like people who jump onto stuff enthusiastic.. ;)