fragile spur gears???
 

Hi guys... i run a, E-maxx with a feigao 9L, and 14 cells, 70/16, andd BigJoe tires...
Since I try to have more acceleration in programming my TX, i destroy all my spur gears... With 75% of EPA that works correctly, and when i arrive at 80% I begin to ear a bad sound... and some teeth of the spur gear are completely flattened... Is it due to the heat of the motor that melt the plastic spur gear? (my motor, axle and pinion are pretty hot, and my motor plate also... more than 100°C)
I run a RRP slipper, 70/16 ratio ... All was right until I tried to have more punch in modifying TX parameters...
Someone told me that it is due to my slipper, that is tightened too much... is it right???
I tried to add a fan on motor but it did nothing better... Do I have to run a steel spur gear with my alloy pinion??? I think that's it's not the way to solve my problem...
Please could someone help me??? Does someone know the best ratios to run my setup???

70/16 is pretty tall gearing, and no i don't think the motor being hot will melt it, but if you have the slipper set to loose, especially the RR one, it will generate heat and cause the spur gear to fail.....you need to crank it down as tight as possible, and make sure your gear mesh is as close as possible, I use a thin peice of paper to set my mesh, and it works great...try this gearing....16/66 ...everything will run cooler and you will get better speeds if the motor and surrounding areas will not be hot....I think your overgeared and it is causing heat issues or you have something binding in the tranny or in your drivetrain...check it all out and drop your gearing soome and see what happens...

Sjcrss, 16/66 is a taller gearing then 16/70...Try something like 13/66. Your motor and ESC are getting WAY to hot. You want to try and keep them around 160* F or below.

ooops my bad.....didn't realize that...thanks squee....then I'de try the 13/66.....if you need a 13t pinion I have one....

Usually, you would run something like 14/66 or maybe even 15, but the Big Joes will require a lower gearing.

I think you need to gear up to more like the stock gearing if the motor is all that hot.What are the esc and battery temps like?
Edit:forgot about the big joes,the gearing squee suggested sounds about right in that case.

The heat is probably coming from the slipper slipping too much though,you need to tighten it down as much as possible,seems like your melting the spur gears.Probably the reason it doesn't do it at 70% epa is the slipper isn't slipping then.

Oh guys you're really helpfull, all thanks for that! i will try to modify my gearing like Squee said before, then tight the slipper a little bit less...
For ur information, my esc stays cold, no problem on that side... but my motor is at more than 100°C, because a little drip of sweat became steam when i put my face over the motor to see what was broken... not more than 120/130°C imo... what is impressive is the temperature of my motorplate and of my pinion!!! i never encountered this problem before (before i ran a HVmaxx, and this feigao9L with a 74/16 ratio....) 74/16 ratio was well and funny to run, until i tried to gear up with a 18T pinion... sorry i discover the limits of the Feigao 9L... :(

I will let you know what happens asap!

fab.

If you keep running your motor at 100C. It is not going to last. Just some helpful advice.

How many cells you running on the 9L to?

[QUOTE]E-maxx with a feigao 9L, and 14 cells but the question is what controller is he running?

I run an E-Maxx with a 9L and a 9920 and the motor gets about 140°F, usually a little less, on 16/66 doing mostly high speed street running with 14 GP3300's. The ESC is usually less than or equal to 120°F. I run stock tires though and have a fairly lightweight truck with barely any aluminum at all. I am running 16/72 because it's about 104°F outside right now:036::013::026:. I am fairly happy with the speed, but could someone let me know if I am seriously over or undergeared? This seems to be the motor/ESC's happy gearing, but I would like the motor to run a bit cooler. I haven't stripped any gears with my setup, though my tires are so old they can't get enough traction to lift the front tires up unless I floor-it on my cement driveway.
Just thought I'd let ya know as I run a similar setup.

Brijar!!!

You could have Mike make a 14 pinion for you. Otherwise, put a heatsink on the motor...

In my experience with the 9L 14 cells tends to make the motor very hot. You are spinning it almost 45,000 rpm at that rpm its gonna get hot. I have much better luck w/ the 9L when I keep it down to 12 cells or 4s lipo.

At 14 cells and the 9L you will constantly be fighting excess motor heat. 14 cells works, but its really pushing it.

I have no problem running a 9L, BK9920, 16/66 in an emaxx on 4s lipo or 12 cells. I can run it all day and never get the motor or esc over 120. But just to be sure I have a small fan on both the motor and esc.

If you continue to have heat issues, I'd cut down the cell count.

Edit: Or get a bigger motor...

Faggz main problem is the Big Joes in combination with the over gearing.

And the smaller motor, if you want the big joes, you need an XL

Okay guys, it seems to have been fixed... Squee was right with his ratio proposal :)
I also untighted my slipper and now I can play with 100%epa... but top speed is considerably affected.
Motor temp gets down, and had to cut 2 wing of the heatsink (my model is a 540C 9L+9920) to catch the right gear mesh with the 66t spur......
>>> Do you think that I can try 18/66 without problem?
>>> Can someone give me a range of ratios to run with my BigJoes, I only have 40series 6.5"tires...(mulsher, masher, bigjoe)?

18/66 is a taller gearing than your were running........so no. Well unless you want a 50 MPH fire ball :005: . Basically you could play with the gearing a little. Somewhere from 12 to 14 tooth pinions. No higher or it will get hot like before.

thanks for these informations Squee ;) therefore i have to conclue that this feigao 540C 9L is not as fast as i thought... perhaps a 7XL should be the motor i need???

I've another question: what glue to use to bond the front endbell of my motor? CA glue or Araldite??? (i think the heat has fused the stock bond... )

what do you all think about a Feigao 8XL??? is it a good motor to run with the BK9920?

The 7XL will be a good motor as will the 8XL, but it depends on what you want, speed or runtime. Also, I would NEVER glue the end bell on. There only pressed on from the factory. If you have a RCM heatsink, you don't need to worry about it. If you don't have one, you might want to get one.

my 9L is a 540 C ... no need for a heatsink, but i thought to buy a 8XL plus the RCM heatsink... or another one... ok ok i'll bought the rcm one :) hem...
can i keep my actual gearing with the 8xl?

The XL will need a taller gearing than the 9L but will also need a 5mm pinion. Not sure about your 9L...Does it have a 1/8th inch shaft or 5mm?

i have 12T to 20T 5mm bore pinions... but i think there will not be enough difference between 9l and 8xl to satisfy me...

Put more juice in it then! LOL

yes that's what i thought!!! lol! :)
Prhaps a 4s or 5s lipo would be nice... but probably too much y motor...
I have more and more fun with the 9L since Squee gave me the good ratios to use... that's amazing how the motor behaviour is different with my new ratio (16/66)... old one was 16/72, the motor didn't "took its turns"...
I will have a look at Maxamps products... 4s lipo should be a solution...

>>>Please, can someone confirm that 5s lipo are too much for a Feigao C 9L + bk9920 ???

With the 9920, i would go 5s

i will try to find 2 5s packs... don't want to brek the balance of my car...

Mike has two 5s apache that i hear are good. spendy, but good

now i would like to complete this post with some pics of my cars, to thank you for your time helping me to find the way to go with my stuff.
God bless RCMonster.CoM !!! thanks holly guys :)


http://www.chakaboum.com/emaxx/P1030180.JPG

http://www.chakaboum.com/emaxx/P1030166.JPG

http://www.chakaboum.com/emaxx/P1030192.JPG

don't let some unused cooling fans in your case, there is always a way to use them!!! ;)
http://www.chakaboum.com/emaxx/P1030203.JPG

Why are you running Walbash's?? They are made for the Revo or a 3.3 Maxx with the new knuckles. Those rims actually make your truck as narrow as a old pre-2.5 maxx. By the way, you said your running 16/66!?!? Thats higher than 16/72. You went the oposite way. Whats your temps as of now? It might have been under geared instead of over geared.

??? i never had any problem with the wabash, my temp is under 90°C with the 16/66 ratio... and runtime is about 15 min. This is a legend... that's not because the manuf. doesn't advise the use on e-maxx, that you can't use them...
Why should it be a problem? you seem to be horrified... personnaly i like this drive style... i also run mashers and mulshers on 40 serie beadlock wheels...

i don't understand you about the gearing, it's just a question of rims wideness, not diameter???

No, your still overgeared alot. You need to try 13/66 like I said. NOT 16/66. Actually you don't need to compensate gearing for the width but for the diameter. The Big Joes are taller than most so you need to go to a smaller pinion. Try 13. Your temps should be around 160 degrees F or below.

Only thing about the Walbash's are they there intended for the Revo or a Maxx with Revo knuckles. Otherwise they make it pretty narrow which makes it unstable in the turns.

just a little bit more drifty! ;) you should try to see!

thanks for ur help, i will try 13 but it will affect my top speed considerably...
i'm curious...

with top speed your overheating, so you need to gear down.....something has to give......you can't have the top speed you wan't without something happening, so to cool it down and have a reliable system....you need to gear down like squee said...to a 13t....and yes your speed will suffer, but your system will run cooler and more effecient to...so their has to be a trade off somewhere...sadly...it's you speed...

Not really so bad when you consider over gearing could fry your motor AND ESC.