harrier

My Feedback: (2)

I havea Rustler XL5 I think is the model that came with a Titan motor. I installed the CC Mamba 5700 and matching speed controller a couple of years ago. I had been running some 2500 3 cell Lipos in it no problem but the run time was terrible. I bought a MaxAmps 5000mah 3cell Lipo stick hoping I'd get longer runs. I do get about triple the time however I have to break up the runs because of themotor getting so hot. It goes into thermal shutdown after about 5 good minutes of fast running. I temped it once and it was around 242 degrees, and this was while it was still running. I'm sure it's hotter at shutdown or maybe the shutdown is 250?

Anyways, it runs longer with the body off, but that's no way to drive. I have a cooling fin on it but not sure it's helping enough. I run the motor at about 70% full throttle capability to help the heat situation and to keep from making it go vertical (wheelie bar helps out a lot).

What can Ido to help make this system run cooler besides not running the truck? Does the SC need a fan attachment ordo Ineed a diff SC all together? Is the battery with it's 100c continuous rating too much for this SC and motor?

Thanks

guver

My Feedback: (325)

Run the throttle back to 100% and gear it down to about 2 thirds of what it is now. OR use a 4600 or less motor.

harrier

My Feedback: (2)

So how do I gear it down? I don't even remember if I installed that "other" gear that came with the Rustler. All I remember doing was adding a metal gear (don't remember which one it was) b/c the Mamba obliterated the factory plastic or nylon one. Have not had any breakages since and it's been run many many times. I'd like to try the gearing just don't know what I'm looking at.

guver

My Feedback: (325)

Replace the pinion gear with a smaller one and/or replace the spur gear with  larger one.

Orion1024

You're gonna have to gear it way down running a 5700 on 3S...and even that might not solve your temp issues. I had high temps running a 4600 on 3S and gearing down didn't solve it. Honestly, you're probably going to have to run 2S packs with that 5700 to keep temps in line. I put a 40mm fan on my motor and it solved my problem, but a lot of people don't want to resort to using a fan. I have no problem with using one, though.

Lurp06x

SORRY TO BUTT IN. but whats the disadvantage of running a fan i got the same rc an same set up an looking at doing something to help with the esc an motor. do peolpe not runa fan because it draws power from the battery. if so who cares i would rather save my motor an have shorter run times an its not like it should change the run times dramatically? an if so can you just hook a seperate battery to the fan or fans if that becomes a problem? sorry again.

Paron34

My Feedback: (1)

Just never buy a battery under 5000 Mhz ,I keep hearing over and over the one thing you dont wanna skemp on is the batteries.

Druss

Depends, in some cases you physically can't fit a fan on. Some fans also require 12v to run.

I'm assuming you meant mAh not Mhz.... (skimp)

Paron34

My Feedback: (1)

lol sorry ,would you believe my last hobby before picking up RC's again was World of Warcraft for 4 years. Yes mah not Mhz lol hard to type with the kitten dancing on the keyboard aswell.

Orion1024

Some people are just down on the idea of using a fan and like to call it a 'band aid'...but I think some people just like to hop on the band wagon and use the latest buzz words that everyone else is using. As long as you are properly geared there's nothing wrong with using a fan for additional cooling...and it will make a huge difference. The only disadvantage is that it could get munged-up from dirt, mud or whatever. Nothing some motor cleaner spray wouldn't take care of. I've been using the same fan for a year now and it still works fine. It's been battered, slammed into curbs and the shroud is cracked...but it still works as good as day one. You want a 40mm x 10mm fan with the highest airflow possible...that would be about 7CFM. Here's a 5V fan with those specs:

[link=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300185363255&viewitem=&sspagename=STRK%3AMEWAX%3AIT&salenotsupported]40mm 5V Fan[/link]

It's been verified to fit and work well by another member of the forums. I'm using a 12V video card fan with the same dimensions and a battery pack. There's more than one way to mount it, but here's how I set up the fan on my Rustler:

harrier

My Feedback: (2)

OK, so back to the gearing I keep seeing. How do you know you have the proper gearing? Mine as I mentioned is stock but I may have replaced the pinion with the little extra one that came in a bag with the new Rustler, the one that said something like "if you want to really go fast use this". So I did. This was before even switching over to Lipo and Brushless power.

So, I'm really happy with the speeds I'm getting with this truck. We've gotten it around 75mph on radar. I don't want to downsize the motor b/c of cost of buying a new one. I'd just get another car/truck if I had to go that route. So aside from just only running it for 5 min at a time with the top off, how do you inspect the gears to know what you have? Do you count the teeth, measure the circumference/ diameter? Just trying to understand how different gearing will help overheating issues.

Orion1024

[link=http://www.castlecreations.com/support/documents/speed_and_gearing_chart.pdf]This[/link] should give you an idea where you need to be geared.

harrier

My Feedback: (2)

Wow, so I think I've definitely gone over the 200 degrees several times. Hopefully I haven't damaged the motor. I'll check with some hobbyshops to see what gears they have. Thanks for the input!

harrier

My Feedback: (2)

OK I've found out that I have a 86T spur and counted the teeth on the pinion and it's 23.  So I've done some research on Traxxas website and their largest spur is 90T and looks like I can get pinions all the way down to 12T on the other hobby sites.  According to the chart on CC site the recommended range of pinions for my motor is 12-17T for offroad, and 13-18T for onroad.  I do both about equally.  So I'll probably wind up getting a few pinions and a 90T to try out.

While I'm waiting for the order to arrive, can you school me on ratios?  How does the ratios affect the temp and or performance?  For example how would adding a 90T spur and a 16T pinion be different in terms of noticable performance to my existing 86T / 23T setup?  Just trying how this all works.  Thanks.

Orion1024

Normally the best advise is to start with the smallest pinion, check your temps and go from there. However, with pinions that small they might not reach the spur gear...that is without lengthening the bottom motor screw cutout. I can't say for sure because the smallest pinion / largest spur gear I've used is 15 / 87. Your gearing is going to depend on your tire diameter...for larger tires you would need a smaller pinion. The majority of you final gear ratio is going to be determined by the pinion size, because you're using a large spur gear. Use this [link=http://scriptasylum.com/rc_speed/_top_speed.html]Gearing Calculator[/link] to determine how the gearing will affect your top end. As for the result on temps, you'll just need to try various gearings out and see where you stand. I would start with one of the smaller pinions...maybe a 15T.

Orion1024

Just plugged in some numbers...

With 15/86, 3S LiPo, 5700KV, 4.4" tires, and a conservative .125" radius ballooning I got 56mph. 16/86 is 60mph and 17/86 is 63mph.

guver

My Feedback: (325)

Have you spent much time on a 15 or 18 speed bike? It is exactly the same concept with you as the motor.

You have a limited amount of power (torque) and a limited amount of rpm (motor rpm)

Run in high gear for level,smooth,down hill roads and you can pull it.
Run in rough terrain, up-hill or pull some extra weight and you will require the lower gears to achieve.

Hope this explains what your rc is going thru.

Count number of teeth and divide spur gear by pinion to get the gear ratio (this means that the pinion spins 86 turns to every 23 turns of the spur gear) and is a 3.74 ratio, When you went from 2S or 6-7 cells to a 3S you spun the motor 50% fater and need to gear down to achieve the same rpm. You need about 5 to1 ratio now. You will lose 30% top speed and is a trade off. You can have one or the other, not both.

IloveMYxt2

Try a 14t pinion and 90 spur and go from there. If your temps are good, then put a 16t pinion and try that. Try to run the biggest spur, that makes a big difference in temps.

I also put a heat sink and cooling fan on my Slash with the 5700 and running 3s lipo. Temps are around 150 with the fan on. Check it out:

http://www.rcuniverse.com/forum/m_87...tm.htm#8807142

harrier

My Feedback: (2)

I ordered a 90T spur, and 12, 16, 18 and 19T pinions.  They didn't have a 14T pinion.  I look forward to seeing what diffs it makes.  Thanks everyone that has contributed their knowledge.  I will post back to let you all know how it is progressing with the new gears.

monsterbombs

just a quick comment on fans. they shouldnt be used
to solve a over heating problem but as someone mentioned
if the gearing is good can be used for added cooling.
my experience with fans/heatsinks, especially with brushed
motors is not only does it keep the motor cooler it performs
harder for longer. and really the fans draw little power.
a little bit of airflow goes along way. i actually cut a
square in the roof of a body, put flyscreen behind it, and
a fan. just to suck air through the body.
my 2c.

harrier

My Feedback: (2)

OK, so I got my gears in the mail today. Put the 90T spur on no problem. 23T pinion set screw is stripped. I've tried gripping it with pliers and using an extractor. How the heck do I get this stupid thing out?

overrev

Drill it out.

FairTax4me

Be careful not to bend the motor shaft when you're grabbing at the pinion with pliers. Try super gluing a hex wrench (use just a very small drop of glue) into the grub screw. Sometimes that works.

It also helps to make sure you have the correct size wrench.

Redvanmafia

if you got that many heatsinks, and you still overheat your doing sumthing really really wrong, i wish i had that heatsink set up so my motor could be Cold like -1 or 2 degrees lmao

grbxtony

ive had similar problems, as ive hit 200 degrees a few times running 8.4 4500mah nimh and have managed to do fine without the body and reprogramming the esc via computer but im thinking ill need to down size to a 12 tooth pinion if i have the largest spur availible which is a 52T?