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My losi lst e-conversion fine tuning

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Old 01-03-2016, 11:19 AM
  #1
grabbem88
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Default My losi lst e-conversion fine tuning

Hey guys I'm nit picking my build and since it's cold out I've decided to correct/ improve some things.

Losi lst first generation:

Castle mamba 2
Neewer 1700kv (it's ok)
Custom center diff/mount tower motor on top
48/14 gearing lowest in can go else motor hits servo
Hitec 7955 servo
Hpi gt2 wheels/tires
Axial battery tray and receiver box
Running on 4s 65c 5500Mah battery
Cooling fan on motor

Temps were 150-180 motor 90 on esc sometimes 110

12.8lbs fully dressed.

100k in front diff center diff 500k rear 10k

Complaints: like to lower temps a tad..but options are limited.

I need a 54t spur but don't think they make one?

Lower kv motor maybe? Will it offset temps?

Other get better wheels/tires that are lighter and not ballooning as much?

Rather convert hub/hexes to 17mm instead of 14mm

Instead of spending another $100 getting xxl arms carriers and 8 mm axle stubs and other needed gear I've been researching and it looks like traxxas Revo or xo1 17mm hex hubs Will work ??? I have extra 6mm stubs to make the thread ends right or left turn threads so not a big deal for those bushing inserts..

So this is what I got and like to get more input
Thanks art
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Old 01-09-2016, 11:33 AM
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Got any pics of the truck?

Motor will hit the servo? I'm guessing the motor is up front and the battery tray out back. Personally I'd reverse this so the battery will help keep the front end down. If the center diff is mounted to the center skid just rotate the whole skid 180 degrees. For the battery tray, use the stock throttle/brake and reverse servo mounts to get the battery tray up off the chassis. This will help clear the front chassis brace and servo wires just enough to get a tray in there. Yeah the battery will be higher but you'll notice the weight shift to the front more than the higher center of gravity.

What at center diff do you have? That'll tell us what spur gears are available without changing everything. I wouldn't get a lower Kv motor, you're on the low side for 4s already. Maybe a better quality motor, better yet a bigger better quality motor. Is your fan mounted on a heatsink? A fan just blowing on the motor is not going to be as effective as a heatsink/fan.

As as for converting to 17mm. The LST2 spec suspension used on the XXL2, XXL2e is the best way to go. The arms and knuckles are much stronger and pretty cheap from eBay chop shops. The cvd's are more pricey though. It's been awhile since I had the smaller stub axles but I did test fit Traxxas Revo/Maxx 17mm hubs on them. If I recall they fit the stub axle, the problem was the placement of the drive pin hole in the stub axle. On the LST/Aftershock the drive pin hole is further outboard than on the Traxxas. So with Traxxas 17mm adapters (or other aftermarket adapter for Traxxas Revo/Maxx) there is a space between the adapter and the knuckle that needs to be taken up with shims and washers. If you do this be careful to use a shims that are 8mm outer diameter by 6mm inner diameter. That size shim will only contact the inner race of the bearing (the right way to do it) so nothing will rub on the knuckle or the bearing shield.
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Old 01-09-2016, 12:30 PM
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Old 01-09-2016, 12:43 PM
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Old 01-09-2016, 01:04 PM
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I deleted a lot of pics and that is all I can find that could give an idea in what I created.

Servo doesn't hit anymore but 13t is my max

My mounts are non reversible since I made it over the diff

The front end stays down and control is very stable other than some touchy braking with mmb2 set at 2%''

I ordered xo1 hubs and I shimmed on the stub going into the first bearing

I'm thinking getting a new set of better tires than the hpi hot air balloons
Trenchers X or sweep racing off road belted

The neewer motor isn't bad and yes fan is on heat sink of motor not heat sink/fan combo mounted on the motor..

I might put a tekin 1900 on it cause I'm not going over 4s

Thanks for some input ...I got all winter lol
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Old 01-09-2016, 03:14 PM
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Oh and my center diff is a hotbodies 48t I did find a team durango 60t that would help a lot but not sure..
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Old 01-10-2016, 01:56 PM
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Ahh, I see what you did now. Custom center diff mount, not a standard buggy/truggy mount bolted to the center skidplate like I assumed. Well I'm not that familiar Hot Bodies but the HPI Trophy truggy (which is based on the old Hot Bodies Lightning) uses the same diffs as the D8 and the Trophy has a 50t spur gear. A 60t spur is going to slow you down too much, plus I highly doubt a Durango spur is going to fit HPI/HB diff cup. Most 1/8 diffs are pretty darn close in length though, Losi 8ight has a 50t, Associated has up to 54t and would probably fit your mount with the right bearings.

Just did a search on Neewer, looks like the Turnigy Trackstar. The Trackstar is an inexpensive motor that's not really known for ice cold temps. The Tekin should run a bunch cooler even though it's a higher Kv just because it's more efficient.
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Old 01-10-2016, 08:53 PM
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I can put any 1/8 center diff in it and I had the HB in my parts bin so I used it.

My driving style is probably 99% the problem and these hpi wheels balloon to like 9 inches and heavy

My motor rpm is 25k and I'm at 11.35 on gearing on the calculator
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Old 01-12-2016, 08:50 AM
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Some tires that don't balloon (like the sweeps) will help to slow you down which lowers the load. 1 inch of increased tire diameter equals 6mph in your case, more than a single tooth of pinion change makes. According to the gear calc your top speed should be around 48mph with 1 inch added diameter, kind of surprised the Neewer can't handle it.

Worth mentioning, a switch to a 50T HPI trophy truggy spur with 13t should bring top speed down enough with your current tires. Up to you which route you want to go. I'd probably switch to the 50t or larger spur though, gives more gearing options and allowing larger diameter tires too.

Last edited by Maj_Overdrive; 01-12-2016 at 09:07 AM.
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Old 01-12-2016, 09:23 AM
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Got my traxxas xo1 17mm hex I had the right shim (more like a washer lol) unfortunately those sleave cups are too small and kinda scares my why traxxas did that to the xo1 but I guess you don't jump it you'd be fine but I did notice that all of the hub is on the stub end so I'm happy with that.


Now would a 4s 65c 110 burst 6000mah battery cause motor heat towards the end of a 20min run vs a 5s or 6s battery running a 1700kv motor?

It takes like 6 back to back wot passes to get to 170 -180 but cools down quick...since my motor is up high in the body my air flow sucks..

I got my eye on a tekin t8 1700kv a caste 2000kv or 2200kv but scared I'll over heat those two?

I think I got a pic of diff but 50 would help
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Old 01-12-2016, 09:32 AM
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URL=http://s1003.photobucket.com/user/countrygurl78/media/Rc%20Cars/IMG_20150808_174242.jpg.html][/URL]
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Old 01-12-2016, 09:21 PM
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Here's the thing. Motors don't really care what Kv they are, they care about the load placed on them. How much load a motor can handle depends on how powerful and how efficient they are. Now the load is determined by vehicle weight, gearing, aerodynamics and the resistance offered by the surface being run on. Gearing is how we tailor the load to the motor, your motor could push a 20+ lb 1/5 but it would have to be geared for a really slow speed.

As for the Neewer motor, it's less expensive because the laminations that make the magnets are thicker and the amount of copper in the windings. When there's more laminations that are thinner the motor is more expensive but also more efficient. A higher quality Tekin or Castle of the same Kv is going to run cooler. But it could also be a higher Kv and as long as it's geared for the same theoretical top speed you have now the Castle or Tekon will run cooler.

Which brings us to some proven brushless theory. Yeah lower Kv motors tend to have a little more torque than higher Kv. But even though a 2000-2200kv Tekin/Castle has a higher Kv, when geared for the same top speed the Tekin/Castle will run cooler. I mention geared for the same top speed because if the top speed is the same the load will be the same assuming no other changes to weight, aero, and surface being run on. To keep the top speed the same you're going to need a larger spur gear though.

Battery voltage. Once again assuming the same load/top speed, a lower Kv motor with higher voltage is more efficient than a higher Kv motor with lower voltage. This is because of the lowered amp draw. A motor is going to draw a certain wattage determined by the load. Since watts = volts multiplied by amps, more voltage = less amps. But the motors have to be similar (Neewer isnt similar to Castle/Tekin) and the load has to be the same between the different combinations for this to be true. I personally wouldn't run anything more than 5s through the Neewer motor and you'd definitely need a larger spur, probably 54t to keep the top speed down. In my experience and from others a Castle/Tekin is good for about 45mph in a truck like this. The Neewer on 5s is probably about the same, on 4s a little less because it has less power and will draw more amps.
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Old 01-13-2016, 06:40 AM
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Top speed was 41mph with 19/48 with this motor and tires were scary

I heard good reviews on urc and running 6s 63mph truggy set ups (
Thanks for the advice btw
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Old 01-13-2016, 06:41 AM
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Ok something weird happened and my post got chopped up lol
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Old 01-13-2016, 07:50 AM
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I'm having trouble posting too.

I dont know what to tell you about your motor. From pics I've seen it looks exactly like the Turnigy Trackstar and probably is the same as there's lots of clones. Anyway I've seen good and scathing reviews of the Trackstar. I can say truggies are generally at least 2-3lbs lighter. Also 19/48 has a theoretical top speed of 55mph (before factoring in tire ballooning), only getting 41mph makes me think it's down on power. A Castle /Tekin of 4274 (yours is 4268) would push it to 50mph easy on a 55mph theoretical if the batteries are up to snuff. And with 65c 6000mah they should be up to snuff. I've seen Hobbywing 4074 2000kv push a LST to 50mph no problem.

I dont know. If you need new batteries you could try going 5s or 6s and gearing down a little to keep the same top speed. It might reduce temps having more power with less amps being drawn. But the increased rpm could negate all that. Unless you really want lots more power I wouldn't go for new batteries and would replace the motor instead.

There are higher quality motors out there that'll perform much better. There's also larger motors that'll run much cooler. Monsters like the Castle 1717 or just longer 40/42mm diameter motors, like 4092's would be better in a heavy truck compared to the 4268 you have now. Btw most 1/8 motors are at least 74mm long, seeing only 68 makes me wonder if it's got a 380 sized rotor in it like the old Novak HV's did.
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Old 01-13-2016, 08:12 AM
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What I said in post that got deleted partially was

somebody took the neewer and castle apart and claimed they were the same on urc

Now my wife's 8ight T has a tekin rx8 2050 17/48 on 6s the temps were 160 170 all the way through the runs no fans or any heatsink

Hers weighs 11.3lbs my lst was 13.8 both fully loaded

So yeah something is lagging

I'm trying to snag a castle 1800kv cause my tekin was promised to my sons stampede when he blows his neewer 1700kv which is all good for me.

I might have to look in castle link and make sure timing is set right for bashing..think it's on 10 advance..
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Old 01-13-2016, 08:21 AM
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Quote:
Originally Posted by grabbem88 View Post
somebody took the neewer and castle apart and claimed they were the same on urc
Thats a load of crap. The thickness of the laminations the magnets are made of cannot be determined by the naked eye. Lamination thickness is one of the most dominant criteria for performance, efficiency and cost. And even if you could determine the thickness of the laminations by the naked eye, you'd have to destroy the rotor to do it as the magnets are covered by the wrap that holds them onto the rotor.

I was was going to say maybe post over on URC as there's some very knowledgable guys over there but that statement makes me wonder. Still I'm one of the more knowledgable here at the universe and I don't know everything and maybe I'm missing something. Doesn't hurt to see what URC and RCTech says.

When end you tried the 19/48 did temps go over 180f? If temps got too high the magnets become demagnetized and the motor will heat up more easily.
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Old 01-13-2016, 08:49 AM
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Well......I'm no longer a member their had my account deleted....lol oh well

On the other question no I caught it but it was hitting 190 so that might have damaged it....but every gear drop you'd think the temps would too?

Unless this is a buggy style motor ...the neewer motor I got has the heat sink rings on it.

Sad part is my losi comp crawler with dig pulled has a 13.5 neewer sensored motor and never gets over 120

Talk about hit and miss
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Old 01-14-2016, 05:25 PM
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Ok I had to go look up the motor I bought it's a 4076 42mm by 72mm rpm 50k

I talked to castle and he (joe)said to drop timing to 0 from 10
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Old 02-20-2016, 10:07 AM
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Update:

5s lipo
0 timing helped
Trencher x wheels/tires

Silly goofing around back and forth driving 141/150

Hitting short grass ramping wot burst runs

170/180

So either driving style or motor can't hang?

I see a 1717 castle big block in my near future
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Old 02-20-2016, 09:13 PM
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Quote:
Originally Posted by grabbem88 View Post
Update:

5s lipo
0 timing helped
Trencher x wheels/tires

Silly goofing around back and forth driving 141/150

Hitting short grass ramping wot burst runs

170/180

So either driving style or motor can't hang?

I see a 1717 castle big block in my near future
I'm having a hard time following what gearing and tires you're currently running so refresh my memory please.
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Old 02-20-2016, 09:45 PM
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Tires are trencher x taped

And gearing is 14/48

My truggy which is lighter obviously
Runs a 17/48
Tires are src terrain crushers and never gets to 130
With a tekin 2050 4030 motor

So the motor has to be my problem not being efficient

This thing does weight 15lbs though.
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Old 02-21-2016, 01:54 PM
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The motor has to be able to handle YOUR bash session, however hard or easy it might be. If it can't handle some grass and a few consecutive wot throttle passes then you gotta gear it down or replace it. I think 14/48 on Trenchers is too much for a cheap Chinese 4074, 12/50 on those tires would probably be a safe bet.

If you're going to replace the motor stay with 1700kv or preferably less to help with gearing options. The 1717's 1600kv will help a little but the motor's 50mm diameter won't. I can tell you from experience that the 1717 will be really close to the diff output with 12/50 gearing and you also have the steering servo to worry about hitting. If you don't want to rework the mount or chassis layout then maybe you should consider something like a Leopard 4092 instead.
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Old 02-21-2016, 03:21 PM
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I can get a 13t pinion but 12 will cause motor to be cocked.

I can add a spacer under diff mount I mean tooth mesh doesn't take much to get right or mess up.

An axial yeti xl uses a 2200kv motor and it's huge with a 13lb weight with 5th scale wheels

I know the transmission is different with a 80 spur and 12t pinion could be wrong but 50mph gearing can't be far from me with my diffs being different

After 25 minutes 3.71 on the cells and 171 isn't bad
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Old 02-21-2016, 09:54 PM
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The Yeti XL 2200kv is a Castle motor anodized gold instead of green. Yeah some of what you pay extra for is Castle's advertising and warrantee (Neewer and the clones have neither) but your also paying for a better motor. Magnet lamination thickness and the copper used are the big determining factors in cost and performance. Thinner laminations cost more but have more performance and greater efficiency, then there's the Nue/Castle design.

But I've already mentioned all that and I'm not going to argue it further. That's why I said whatever motor you choose to run has to hold up to YOUR bash session. If it's not working for you it's not working for you. It's my personal experience and others, that a higher quality 4074 motor (like a Castle 2200kv) should be geared for about 45mph in a vehicle like the LST. Some can away with gearing for about 50mph depending on exact weight and surfaces being run on but generally 50mph and above it's time to look into adding a fan. This is a generalization and is meant for a fairly safe setup where you don't have to be afraid of overheating if you use the throttle. It also assumes a variety of surfaces including grass and summer time ambient temps not cold winter ambient temps. You're nearing temp limits with a fan, in colder ambient temps on grass, draw your own conclusions. And the reason your motor cools down fairly quickly is the because of the fan and cold ambient temps.

Also don't forget you can increase the spur gear size as well. The 50t HPI Trophy truggy spur should fit your HB diff and it'll both give you some clearance and gear you down a little at the same time. A larger spur and/or shimming the diff up would likely be required if you went with a 1717. Awesome motor by the way, have one on my LST XXL feared for about 55mph on 6s, no fan, no temp issues ever. Good luck

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