Front and Rear Differentials - Cleaning and Fuilds

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cordell12

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I was putting my Kraton back together after installing my new pinion and setting the mesh. I noticed the little coupler that attaches to the input shaft on the front differential/gearbox had come off from my last crash. I saw no other way to get it back on besides taking the whole front steering assembly off the chassis. Once off I was surprised to e able to look inside the gearbox. I assumed it was a seal box, as I have read about people changing diff fluids. So inside my gearbox was grease (dirty diff fluid), the gears were basically metal on metal, no fluid/grease on them. I then decided I need to order diff fluids for the front and rear. I have a shim kit already from shiming my the new center diff. My concerns with adding the new diff fluid is leaking. How does the fluid remain in the gearbox and not leak out? The gearbox did not appear to have any sort of gaskets where it touches the chassis.

Also, any recommendations on fluids? I have 100k in my center diff currently.
 
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cordell12

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edit...found a YouTube video.


So the grease I was talking about was the input gear and the spur gear. Can I add fluid to this area, directly inside the gearbox shell? I know I need to open the diff, like I did with the center diff, but what about outside for the input and spur gears?
 
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RCROD

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edit...found a YouTube video.


So the grease I was talking about was the input gear and the spur gear. Can I add fluid to this area, directly inside the gearbox shell? I know I need to open the diff, like I did with the center diff, but what about outside for the input and spur gears?
The silicone diff oil "only" goes inside the diff case (AR310433), that has all the small planet and sun gears, the same as you did with your center diff when you shimmed it. No oil goes in the gearbox (AR3108540), or yes it would leak out. The front/rear gearbox do not have a gasket, but the removable gearbox cover is a tight fit to usually not allow dirt in. You just want to use some good thick grease where the large 43T Spiral Diff Crown Gear (AR310497) meshes with the 10T Main Input Gear (AR310498).
 

RCROD

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The silicone diff oil "only" goes inside the diff case (AR310433), that has all the small planet and sun gears, the same as you did with your center diff when you shimmed it. No oil goes in the gearbox (AR3108540), or yes it would leak out. The front/rear gearbox do not have a gasket, but the removable gearbox cover is a tight fit to usually not allow dirt in. You just want to use some good thick grease where the large 43T Spiral Diff Crown Gear (AR310497) meshes with the 10T Main Input Gear (AR310498).
Also check to see if you can add another outdrive shim (13x16mm) to the crown gear side, but make sure diff still turns smoothly, before closing gearbox cover.
 
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cordell12

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appreciate the response. I had seen that same looking grease inside the center diff that had grenaded, so I figured it also needed to be replaced with a thick diff fluid inside the actual gearbox as well.
 

RCROD

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appreciate the response. I had seen that same looking grease inside the center diff that had grenaded, so I figured it also needed to be replaced with a thick diff fluid inside the actual gearbox as well.
I'm not sure if the V1's came with silicone diff fluid or grease installed? Also, the previous owner could have possibly changed to a thick grease instead, not knowing to use silicone. However, I suspect, since your center diff exploded, this would cause metal shavings to darken the oil and also thicken it when it exploded? This would then look like some bad dark grease, instead of oil possibly?
 
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cordell12

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I'm not sure if the V1's came with silicone diff fluid or grease installed? Also, the previous owner could have possibly changed to a thick grease instead, not knowing to use silicone. However, I suspect, since your center diff exploded, this would cause metal shavings to darken the oil and also thicken it when it exploded? This would then look like some bad dark grease, instead of oil possibly?
This is probably exactly what happened. I know he had said the diffs were shimmed, but never mentioned if fluids or grease were used. Just took the front diff apart and there is fluid in it though I need to change it. It's grey in color, probably from the gears but it is fluid. Being the front has fluid the center more than likely did as well. The heat, metal shavings, and the fluid being old, it turn into a paste like substance. All I know is I spend more time tinkering than I do driving lmao. Got some 50k, 100k, and 10k fluid on the way. Love me some Amazon Prime!
 

RCROD

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This is probably exactly what happened. I know he had said the diffs were shimmed, but never mentioned if fluids or grease were used. Just took the front diff apart and there is fluid in it though I need to change it. It's grey in color, probably from the gears but it is fluid. Being the front has fluid the center more than likely did as well. The heat, metal shavings, and the fluid being old, it turn into a paste like substance. All I know is I spend more time tinkering than I do driving lmao. Got some 50k, 100k, and 10k fluid on the way. Love me some Amazon Prime!
Yes, that makes sense. It like what fluid weights you're going with. On my V3 Kraton, I went with 50K/100K/7K (I like tons of power going to the rear).
 

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