My Flux XL conversion with 1717 and center diff

Not your average Savage Hop ups. These are highly modified, with some home-made parts.

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s2022
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Re: My Flux XL conversion with 1717 and center diff

Post by s2022 » Fri Oct 19, 2012 11:16 am

Another not so good update... or should i consider it a statement of the power we play with...
Thanks god no expensive electrics involved, went for some fun today, and managed to melt down, literary melt the Center Differential!
I measured 100 deg C !
Here are some pics :  ......

100 deg C
the temp was measured couple of minutes after hearing the weird noises... thought the esc or motor then realized its the CD.

Image

the oil is every where

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The diff screws were dislocated, you can see the lower one as if bent, the screw is straight, but the melted plastic ....

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This is melted plastic

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Had to literary break it to get the internals out, getting them soaked and cleaned for further inspection.

Image
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RCS2022[/color]
[color=blue][i][url=http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=93732]Savage Flux XL; Mamba XL2; 1717; Custom CD; Mech Brakes[/url][/i][/color]

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Post by s2022 » Fri Oct 19, 2012 11:24 am

Here's a Video,

[youtube]
[/youtube]

After watching again I think I'd better re check the electrics....
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RCS2022[/color]
[color=blue][i][url=http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=93732]Savage Flux XL; Mamba XL2; 1717; Custom CD; Mech Brakes[/url][/i][/color]

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Post by FluxNZ » Fri Oct 19, 2012 5:57 pm

Strange how that happened. Was there binding in the CD setup for it to melt like that? LLkoolskillet had been running his for a long time with no issues.
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Post by s2022 » Sat Oct 20, 2012 2:39 am

I have no idea, I have been running it also with the same center Diff in its first incarnation in this thread since Jan this year. Moreover just rebuilt the Diffs Last week with the following weights:

100k  Center
60K    Front
30K    Rear

Even had a couple of runs with the rebuilt diffs before this happened.
Two things i can think of:

One, when rebuilding the diffs i had to scoop out some Diff fluid to get the level to the top of the cross pins (I had over filled it), could be it was still left with 1mm or 2mm over, can't confirm but no more than that.
Second, I was beating the s*** out of it with back to back WOT runs on asphalt on the second run. On the first set of batteries Off road (Old set, less punchy) I had the following temps:
Batteries     53 deg C
Motor         74 deg C
ESC            50 deg C
Center Diff  74 Deg C

On the second set, 2 months old Lipos with maybe 12 - 15 cycles on them, on asphalt, I had the following temps:
Batteries     40 deg C
Motor         83 deg C
ESC            55 deg C
Center Diff  100 Deg C

I recall reading it somewhere, the 1515 motor on the flux recommended max temp is 190 deg F = 88 deg C (I think its in the HPI flux manual), not gonna go there but i was still very high but within the max.

Anyway rebuilding the center diff with the Hpi Alum case, Lets see what happens next  :wink:
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RCS2022[/color]
[color=blue][i][url=http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=93732]Savage Flux XL; Mamba XL2; 1717; Custom CD; Mech Brakes[/url][/i][/color]

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Post by FluxNZ » Sat Oct 20, 2012 2:54 am

Somethings just can't be explained :D

You need to put some of those photos in the carnage hall of fame to freshen up that thread :wink:
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Post by s2022 » Sat Oct 20, 2012 3:09 am

Where is that?
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Post by s2022 » Sat Oct 20, 2012 3:13 am

Found it....  will upload the pics later, haven't seen it before, but mine is a bit lame compared to whats there!
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Post by LLkoolskillet » Sat Oct 20, 2012 8:21 am

Whoa dude thats crazy carnage. Ive ran my flux so hot that thermal kicks in. Yet I have not melted the diff. I agree somethings just happen without reason. As for over filling, even if you did the oil leaks out the screw holes when you place the ring gear on. I always have oil leak out when I rebuild.

I have touched the pinion after some long abuse and it burned the crap out of my finger

Ah wait check it out, I just realized why your diff melted. Look at how your setup is, its kind of a one piece design. Meaning that the motor is mounted directly to the mount for the diff. Alluminum transfers heat very rapidly sooooooo when your motor heats up and the spur and pinion heat up from friction, they transfer that heat to the surrounding metal. Where does it go, well forwards in your case thus causeing the diff housing to melt where it meets the spur. If you notice my setup the only part of the motor that touches the spur is the pinion. Everything else including the motor mount and plate dont touch the diff and diff mount. My heat it transfered to the right side TVP.

The alloy cup will help but I think if the setup gets that hot again. your going to melt the pinion or the spur, ie strip teeth
[img]http://i1105.photobucket.com/albums/h358/LLkoolskillet2/skillet1.jpg[/img]

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Post by johny723 » Sat Oct 20, 2012 10:57 am

there must have been some friction. either from gear mesh or some angles between dogbones and outdrives or more likely, the spur was rubbing against some metal. these things heat up rapidly  when there is some friction
if it was from the motor, transferred via the motorplate to the diff as Llkoolskillet says, your motor would be toasted just liek the diff.
a bad sound during the whole video and rapid heating suggest some rubbing
check the spur and outdrives and dogbones, they must have some signs of rubbing and friction

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Post by s2022 » Sat Oct 20, 2012 11:37 am

LLkoolskillet, I see it the other way (I could be wrong though), the heat transfers from hot to cold or less hot, and in line with what johny723 also chimed in. the motor being less than 80 deg could be helping the plate not go higher in temps. Moreover the plates have lots of holes / cutouts to aid cooling instead of being one big bulk. In fact as the Center Diff is getting hotter than the motor i think it could be the reason for the high motor temps not the other way around.

I agree johny723, will do a thorough check and update here, good i haven't put it all back together yet, just rebuilt the CD.
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Post by LLkoolskillet » Sat Oct 20, 2012 12:22 pm

Your gear mesh is way to tight, mine will make the same sound when not properly set.

As for the heat transfer, his mount is like a heat sink soaking the heat up. I made my previous statment without watching the video. That being said you are still transfering heat to the diff from the motor that is a fact regardless of how many holes the metal has. Friction would be the main culprit here, so I would reset the mesh and try again.
[img]http://i1105.photobucket.com/albums/h358/LLkoolskillet2/skillet1.jpg[/img]

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Post by johny723 » Sat Oct 20, 2012 1:01 pm

look for circular signs of rubbing and wear on the chassis, diff mount and the diff itself. a pinion/spur gear mesh is not likely to cause such friction.
I suspect that a part of driveline was in contact with the chassis or the mount.

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Post by s2022 » Sat Oct 20, 2012 1:35 pm

[quote="LLkoolskillet";p="851879"]Your gear mesh is way to tight, mine will make the same sound when not properly set.

As for the heat transfer, his mount is like a heat sink soaking the heat up. I made my previous statment without watching the video. That being said you are still transfering heat to the diff from the motor that is a fact regardless of how many holes the metal has. Friction would be the main culprit here, so I would reset the mesh and try again.[/quote]

The sound is not from the gear mesh, got this video after the weird sounds started sounding. Was smoother than that when everything was normal. The sound is from the center diff internals, upon dismantling the truck, when i would turn one diff out cup i could hear and feel the internal gears crunching.
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Post by LLkoolskillet » Sat Oct 20, 2012 1:53 pm

Have you cleaned the gears yet? Im quite puzzled now  :?
[img]http://i1105.photobucket.com/albums/h358/LLkoolskillet2/skillet1.jpg[/img]

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Post by s2022 » Sat Oct 20, 2012 2:56 pm

uploading...
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Post by s2022 » Sat Oct 20, 2012 3:05 pm

Below are the pics, to me there was no rubbing;

The TVP side where the diff just touches, as can be seen, had to previously mill a small poxket for the 50t spur to fit clearly. Obviously no rubbing.
Image

These re the layout of the pieces
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Ring gear side, also very minor rubbing, I would say not the cause.

Image

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Some rubbing can be seen here; but not the cause I suspect, its just a blemish, These were due to the plastic cup rubbung after it melted

Image

Two of the bevel gears (worst 2), the others installed in the diff already.

Image

Moreover forgot to photograph the bearings, but also they are in great condition.
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RCS2022[/color]
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Post by johny723 » Sat Oct 20, 2012 4:23 pm

I would call it an ICD - Idiopathic Center diff Disease :D

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Post by s2022 » Sun Oct 28, 2012 3:10 pm

LOL! Like the nickname!
Getting it  back together, but too busy these days.
Hope to get a run soon.
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RCS2022[/color]
[color=blue][i][url=http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=93732]Savage Flux XL; Mamba XL2; 1717; Custom CD; Mech Brakes[/url][/i][/color]

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Post by s2022 » Fri Nov 30, 2012 4:03 am

Was Bored, digging out some old files, trying Race Render, and the result  ==>

[youtube]
[/youtube]

The videos and eagletree elogger v4 logs I found were for my first setup of this build, before the CNC second incarnation. My HD wing cam is trashed now, planning a Gopro hero 3 soon!

In the mean time hope you enjoy!
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RCS2022[/color]
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Post by s2022 » Sat Dec 01, 2012 11:28 am

Even more carnage....

Gave the transmitter to my 6 year old, in a cramped space, all i Hear is a LOUD thud! and this
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