Savage Flux HP Gearing for 6S

olds97_lss

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I'm wanting to run my flux hp on 6S. Keep the 2x2S for my ERBE.

I have an rc4me.us center diff transmission (super 5SC), MMX/2200kv sensored system, proline trencher 3.8s.

On 4S, I was running 44/20 gearing and it did ok. I was going to attempt to drop to 44/17, but it won't mechanically fit. Can't slide the motor over far enough to make it mesh.

So, just ordered an RRP steel 47T spur for the savageX (RRP 7247). Guessing I'll have to find a bushing or bearing for the center, and likely a spare slipper pad.

I'm not sure what gearing to run. I'm just assuming I need to drop my gearing some to avoid overheating the motor/esc before I get through a set of packs. Before the center diff trans, I was running 21/44, but I had to be far less agressive with my trigger finger or it would just end up on it's roof constantly. Was also hard on diff pinions. I have a feeling 47/17 will be too low and I'm hoping it will at least mesh.

Just curious what others ran this thing on with 6S. Or did everyone just run 4S?
 

orzowei69

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I'm wanting to run my flux hp on 6S. Keep the 2x2S for my ERBE.

I have an rc4me.us center diff transmission (super 5SC), MMX/2200kv sensored system, proline trencher 3.8s.

On 4S, I was running 44/20 gearing and it did ok. I was going to attempt to drop to 44/17, but it won't mechanically fit. Can't slide the motor over far enough to make it mesh.

So, just ordered an RRP steel 47T spur for the savageX (RRP 7247). Guessing I'll have to find a bushing or bearing for the center, and likely a spare slipper pad.

I'm not sure what gearing to run. I'm just assuming I need to drop my gearing some to avoid overheating the motor/esc before I get through a set of packs. Before the center diff trans, I was running 21/44, but I had to be far less agressive with my trigger finger or it would just end up on it's roof constantly. Was also hard on diff pinions. I have a feeling 47/17 will be too low and I'm hoping it will at least mesh.

Just curious what others ran this thing on with 6S. Or did everyone just run 4S?
Hi. I run 6s on my three Savages. Theorically if you increase battery voltage by 1/3 then you will have 1/3 more rpm and should reduce pinion tooth count by 1/3 to compensate. One of my savys has 5SC center diff with 2200kV tork, 47T spur and 16T pinion. I am still tuning it and think that 17T pinion would be better. IMO 17/47 is a good start point.
 

olds97_lss

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Yeah, I thought the same thing. Go up in V, gear down. Was just odd that what I found was people were gearing up even more when running 6S for some reason. I couldn't find the source of any comment on the forums I saw that on, just a "this is common knowledge with the savage" comment and I wanted to know why, because it doesn't make sense.

For all I know it was due to the flux motor running too high of RPM and dyeing. While I don't run the flux system anymore, I'm still running a 2200kv motor (MMX esc). Then I thought perhaps I should source a 1800-2000kv motor instead if I want to go with 6S.

Thanks for the response just the same. I put everything back to what I had, 20T with whatever the spur is, then installed a motor fan, which was a pain. Wasn't even sure if the center bones could handle 6S torque either.
 

olds97_lss

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I have a feeling before the long weekend is here, that I'll have it swapped out with 17/47 using the savage-x spur I got. Will just need to find a center hub/bearing as it's the RRP spur that uses the bushing vs the later HPI steel spurs that do not. Will also have to find a slipper pad... think I have a few plastic spurs around.
 

orzowei69

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Thats good news, I am really interested in your opinion about differences in running 6S and 4S. I went straight to using 6S in my rigs (higher voltage -> less intensity -> less power losses in cables and esc).
 

olds97_lss

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I swapped it out last night, although, supposed to rain all weekend. Will try and get out between storms if I can though. I have a feeling I'll need to balance the 3.8" trenchers I have on it... 4S speeds weren't much of an issue, but 6S is a whole other level.

I ran 4S in it because I started running brushless with a v1 brushless revo, which can barely survive with 4S. So, all I had were 2S packs. Then I tried 3S in my converted ejato and stampede 4x4. The 3S packs I used were ones I made out of my old/tired 2S packs... then decided to try 6S in my outcast with some new 2x3S packs. Those packs also fit in the savage.

So now I have 4 HRB 5000mah 3S and 4 Hobbystar 6200mah 3S packs. Considering the suspension on the savage, I'll likely use the 5K packs in it and keep the 6.2K packs for the outcast as they weigh a bit more. Will see how things progress. For all I know, the MMX/2200kv system I have in the flux will choke and die on 6S trying to lug the savage around. I really hope not... as it was not cheap.

I'm at 47/17 in the flux now. Meshed up nicely. I'm running the RRP nitro savage 47T spur and RRP 17T pinion with trencher 3.8 tires (not the trencher x's).
 

Scooter

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Hey olds how do you like the center diff over the trans ? I’ve been running all stock set ups on both 6s and 4s in both hp and xls and have had no issues yet, but I do have a few with Alza center diffs but just haven’t run them at all to compare
 

olds97_lss

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Well, mine isn't a direct drive alza, so I still have the slipper and other gears in the trans, so a lot more rotational mass. I'd have to guess that an alza setup would be best.

I really like it. Wish my ERBE had it, or that traxxas had a good one for it. It really calms the truck down and makes it a lot easier to drive hard. It also helps the diffs and center axles last longer since there's some give in the drive line. If you ran the slipper loose enough to have give, it would just cook, so it's kind of pointless. In extreme situations, it will slip, but I broke 3 or 4 diff pinions before the center diff and haven't broken one since the install. All it takes is one harsh landing trying to recover from a flip or bad take off and poof, blown pinion. I've had many landings since the center diff that would have definitely busted a pinion without it.

I run pretty heavy oil in it, a mix of 2/3 500K and and 1/3 1M. It will still unload to the front if I really lean on it for a decent amount of time off the line and if I just hammer it, it will still end up on it's roof, but it's a lot more forgiving. I started with just 500K, but it was too light. Would unload to the front pretty easily, so I tore it all apart, removed some and put in some 1M. Now it's about perfect.

Now... that was all on 4S. Will see how it does on 6S soon hopefully.
 

Scooter

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I see you run a lot of different trucks and seem to bash pretty good so I wondering what one is your favorite
 

olds97_lss

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For electric, the outcast. For nitro, my 21TM revo. If I had to get rid of all of them but one from each type, those are what I'd keep.
 

olds97_lss

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47/17 wasn't low enough. Well, not enough for tall grass and 80F temps. I probably could have left it, but I dropped it to 47/16, which barely fits. Really, I should go with a 49T spur and the 17T as with 16/47, I can barely get mesh that I would like. It's just a small blonde one loose for my taste. Will see how it does.

I ran it today at the skate park and the more I run it, the more I'm really liking it with 6S. Without the center diff though, pretty sure it would be nearly undriveable by me. I have roughly 750K in the center diff. 2/3 500K-1/3 1M and it unloads to the front a lot more now than it did with 4S. So much so that I usually have to try to pull a wheelie. I had the MMX set at 90% punch control (100 is the most limited) and the "starting mode" set to soft/mild (whatever the lowest is). I increased the punch to 80%, so will see how it reacts now.

Looking at the data log, it didn't overheat. It got warm (217F max), but the cut off is 239F. Granted... 217F is hot. So gearing down is pretty much a necessity. What's strange is when I hit it with my temp gun, I never saw it over 145F at the connectors or anywhere I could hit it. Hard to even see the heat sink under the housing, let alone get an IR read on it. The log showed the motor peaked at 144.1F, so that should be fine.

Will see how it does next time.
http://gmarquee98.x10host.com/myPics/98gmarquee/ESCSettings/2019-0608-SavageFluxMMX-6S Hobbystar6200-50C-CortlandOrDekalb-TVC.jpg
 

olds97_lss

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I was able to find a 48T steel RRP spur, so I have put that in, now I get good mesh. Haven't bashed the last post though as it's been raining every weekend. And supposed to rain all 4th of July weekend too. Starting to go through RC withdrawal!
 

olds97_lss

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Hoping the cap pack I just made helps the ripple a bit. Also pulled the stock castle fan off the esc and tentatively mounted a hobbystar 30mm aluminum frame fan on it. They blow a ton of air. It was too big to fit in the X fan cage, too tall and about 1mm too big to fit in the square. Probably should find some mesh or something to put over it. I also wired it directly to the receiver like the motor fan I have under the esc so it's always on. I wasn't sure where to mount the cap pack I made, so just put a bit of foam under it and ziptied it to the roll bar side.







Still haven't had a chance to run it with the 48T.
 

olds97_lss

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Cap pack helped my ripple voltage. Went from 3.4V to .98v. ESC still runs hot even with the 16/48 gearing, but the motor did ok. Per the log, the motor got up to 154F and floated around there, but the esc got to 180F half way through the 20 minute run and pretty much stayed there too. Didn't shut down on me. Via my temp gun though, the highest I read was 140F for the esc on the fins and 150F on the rear of the motor.

Can see the footage here:
https://www.hpisavageforum.com/thre...with-a-cap-pack-at-the-grass-bmx-track.19445/
 

Biddie_fiddler

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Hey @olds97_lss, what motor & esc are you running that gives you data logs etc?

I've got the popular hobbywing ezrun max8 combo - its amazing for entry level stuff but looking at something more serious as I want to look into converting my savage into more of a truggy style racer...
 

olds97_lss

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@Biddie_fiddler Castle MMX. My flux came with the first esc HPI offered I think, which was a MMv1 that wasn't waterproof. I was on the fence between the MMX and MMv2 when I got it, but figured I'd spend a few $ more for the MMX/2200kv sensored combo to try out a sensored system.

I've since "waterproofed" the original esc and have it as a spare as well as a second traxxas MXL6S which is a MMv2. Neither of those log anything.

Considering my temp issues, I'm thinking I may have to step down to a longer 1800kv motor, but will see how it does. Honestly, I don't drive it much as I have too many trucks for one guy, but I get a bug to run one and I'll run it for a month, then put it on the shelf and run another.

I end up with a csv file that can be imported into a log viewer program from castle where you can toggle a bunch of stuff. This is what it looks like when everything is in view, a bit of a nightmare:


This is just the motor/esc temp, ripple and volts:



I'm not sure why the motor temp is 238.3F at the very very end. Guessing it was a glitch in the matrix or something.
 

Biddie_fiddler

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That ripple tho... :love:

a ripple ave of 300mV is fairly acceptable considering how unstable the load from ESCs and Motors are. You've done well sir!

What cap value(s) did you use??
 

olds97_lss

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1800uf. I crudely wired 6 of these in parallel:
https://www.digikey.com/product-detail/en/EEU-FM1V182/P12410-ND/613771

I used hot glue to hold them all in place, then walked around them with some 10 or 12AWG wire and cut nicks in the wire, dobbed flux, soldered, etc. Then I filled all the gaps pretty good with hot glue and wrapped it in tape since I didn't have any shrink wrap large enough.

The FM series are supposed to be low esr. Says it on the info page on digikey:
https://www.digikey.com/catalog/en/partgroup/fm-series/3610?mpart=EEU-FM1V182&vendor=10

Odd that they don't mention it in the mile long list of specs for the individual caps. Either way, seemed to really help the ripple.

I bought 18 of them with the thought that I'd make one for the outcast and perhaps the ERBE. With the lack of real estate on the outcast... and my lack of motivation, I likely spent $24 on a bunch of caps I won't use. lol! (was $23.56 shipped for 18 of them). But after seeing the impact on the ripple... I may get motivated enough to make a couple more for those 2 trucks.

Put a xt60 plug on it and crudely solder it onto my esc wires near the esc. Glad I added the plug as I was unable to download the data with the cap pack connected. Well, I didn't try downloading with power supplied to the esc, just from PC to field card to esc, which supplies power to the esc so you don't have to have packs plugged into it. Guessing if I had packs plugged in, it would have been ok.

You can see it here ziptied to the roll bar with some stiff foam supporting it underneath:


You can also see the splitter I put at the receiver end so I can unplug the esc without taking the receiver out. I made another splitter (that you can also kind of see there ziptied) out of the smaller JR 2 pin plugs for the two fans that goes into the other port of the 3 pin splitter. So the HS 30mm fan on the esc is always on as is the one under the esc pointing at the motor that you can see peaking out just a little.

The motor one is on a little L plate I made with a cut out so the fan isn't blocked:
 

Biddie_fiddler

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Bloody hell @olds97_lss I posted on this thread without even knowing ??

I have the robinson racing gen3 47t spur and a 20t pinion. Been running on 4s most of the time with no worries and no heating!!
I have the basic ezrun combo from hobbywing sporting a 2200kv motor with no fan on the motor.

A while ago I starting doing a write-up on setting up RC cars, including gearing. I should really finish that up at some point I reckon.
In the document I added a graph for gear ratios shown below.
7081

My understanding is that a higher gear ratio (shorter/smaller pinion) will give you more acceleration and torque meaning you lose on top speed. We're running MT's here so high speed is really not a big thing :p

The one key issue I see with this, and you've proved it in your posts above, is that as you go down in pinion size you're gonna start to see heat on the motor. Think of it like a car winch. They have super high gear ratios to give you insane torque but comes at a cost of heat. You can't run a winch for too long or you'll burn out the motor.

So basically the TLDR of this post is:

Get a cooler for your motor if you're running 6s
 

olds97_lss

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Well, first my issue was my esc ran hot, which it still does, but less so after gearing it down. Now it's not hitting the thermal shut down at the 15 minute mark and I'm able to run pretty hard until LVC. With it geared down, now the motor is seeing higher rpm's more frequently, so the heat moved.

I'm guessing in the end, I'll need to replace the motor with a lower kv, possibly longer can with more torque then I can gear it up to retain my top speed while it remains at a safer temp.
 

olds97_lss

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From what I've read, if you have to motors the same length/diameter, the one wired for lower kv will have more torque, be more efficient, run cooler. Then you gear them up to compensate and they continue to run cooler.

I'd likely look for a longer can as well as longer can motors typically have more torque as well.

So, lower kv and longer can in theory helps with overheating when geared for the same speed.

I doubt I'll do anything right away with the savage as I've converted my ERBEv1 to a v2. The motor really screams with the 2200kv/mxl-6s system in it. However, in it, your limited in space but I think you can still fit a bit longer motor than stock. Between it and my outcast, the savage is just something else to run when I feel "savage'y".
 

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