Color of Differential Fluid?

dpricenator

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So I have a "click" somewhere in my drive train. I noticed the main spur gear was missing half a tooth and though that might be it. Ordered a new center diff assembly from E-bay, because I may as well get all the satellite gears and a new planetary gear too. Since I had already shimmed the center diff and had it in a Hot Racing Center Diff carrier, I figured I would just change the spur gear. When I opened up the differential, that I had been using, the fluid was not clear. It was grey. I could see the metallic shimmer of metal dust in the fluid. It was not chunky at all, still very smooth. I spun all the gears in there, and removed the satellite gears to check the planetary(?) gear on the bottom. Noting seemed out of place or damaged. I figured once I shimmed it, everything would be running a little tighter, so as it ran the edges would rub and smooth out, creating a fine metal dust, that mixed in with the fluid and nothing is wrong. At least that is what I am hoping.

Has anyone else noticed this change in color when going into a differential the 2nd time around?

I was hoping I had found my "click" with that spur gear, but it still seems to have the "click" and in fact it seems to have gotten worse. I guess I'll be diving back in, and double checking the drive train bumper to bumper. Ugh, It was tough enough finding the couple of hours I spent the other night working on it.
 

norcopunk

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Ya that's normal don;t worry. The diff gears wear into each other as they break in so some tiny bits of metal powder will work its way into the fluid. Not a problem at all.
 

Rich Duperbash

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So I have a "click" somewhere in my drive train. I noticed the main spur gear was missing half a tooth and though that might be it. Ordered a new center diff assembly from E-bay, because I may as well get all the satellite gears and a new planetary gear too. Since I had already shimmed the center diff and had it in a Hot Racing Center Diff carrier, I figured I would just change the spur gear. When I opened up the differential, that I had been using, the fluid was not clear. It was grey. I could see the metallic shimmer of metal dust in the fluid. It was not chunky at all, still very smooth. I spun all the gears in there, and removed the satellite gears to check the planetary(?) gear on the bottom. Noting seemed out of place or damaged. I figured once I shimmed it, everything would be running a little tighter, so as it ran the edges would rub and smooth out, creating a fine metal dust, that mixed in with the fluid and nothing is wrong. At least that is what I am hoping.

Has anyone else noticed this change in color when going into a differential the 2nd time around?

I was hoping I had found my "click" with that spur gear, but it still seems to have the "click" and in fact it seems to have gotten worse. I guess I'll be diving back in, and double checking the drive train bumper to bumper. Ugh, It was tough enough finding the couple of hours I spent the other night working on it.
Like Norcopunk said, totally normal. Fluid can go from grey/silver to very dark, almost blackish depending on how many bashes between fluid changes. The high heat created running at high speeds probably alters the silicone over time as well.
 

dpricenator

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OK, thank you guys. It made sense that it changed color, but comparing to your experience solidifies that. The bummer is now I still have no clue where this click is coming from. Probably one of the outdrive cups.
 

Rich Duperbash

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OK, thank you guys. It made sense that it changed color, but comparing to your experience solidifies that. The bummer is now I still have no clue where this click is coming from. Probably one of the outdrive cups.
No problem man. Could be a bent driveshaft, loud bearing, who knows...Lol. Sounds are tricky to pinpoint sometimes with all the other noise and chatter these rigs make.
 

norcopunk

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I would disconnect the center drive shafts and spin either end of the car and listen/feel carefully. That way you can at least determine if it's coming from the front or rear. Also, check the condition of the gears inside all 3 diffs. It is possible that they are not shimmed tight enough and are stripping against each other under load. Is the clicking only under acceleration or is it also there when just cruising slowly at a constant speed?
 

Camo

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So I have a "click" somewhere in my drive train. I noticed the main spur gear was missing half a tooth and though that might be it. Ordered a new center diff assembly from E-bay, because I may as well get all the satellite gears and a new planetary gear too. Since I had already shimmed the center diff and had it in a Hot Racing Center Diff carrier, I figured I would just change the spur gear. When I opened up the differential, that I had been using, the fluid was not clear. It was grey. I could see the metallic shimmer of metal dust in the fluid. It was not chunky at all, still very smooth. I spun all the gears in there, and removed the satellite gears to check the planetary(?) gear on the bottom. Noting seemed out of place or damaged. I figured once I shimmed it, everything would be running a little tighter, so as it ran the edges would rub and smooth out, creating a fine metal dust, that mixed in with the fluid and nothing is wrong. At least that is what I am hoping.

Has anyone else noticed this change in color when going into a differential the 2nd time around?

I was hoping I had found my "click" with that spur gear, but it still seems to have the "click" and in fact it seems to have gotten worse. I guess I'll be diving back in, and double checking the drive train bumper to bumper. Ugh, It was tough enough finding the couple of hours I spent the other night working on it.
My diff fluid is always dark grey silver when I change them in the stock diff housing and the HR one I think it's normal. As for the click I had the same thing it turned out to be the bearing at the back of the gearbox case it was totally mashed.
Good luck !!
 

Rich Duperbash

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OK, thank you guys. It made sense that it changed color, but comparing to your experience solidifies that. The bummer is now I still have no clue where this click is coming from. Probably one of the outdrive cups.
Just thought about something. anytime I've broken 1/2 or more of a crown gear tooth, usually rear, it makes a clicking noise off the input gear with each full rotation. Might pop off the gear cover and take a look.
 

dpricenator

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Thanks Rich. Trying to find the time. My kid made the All Star Team for Mission Viejo Girls Softball. They are practicing 5 days a week right now.
 

Rich Duperbash

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Thanks Rich. Trying to find the time. My kid made the All Star Team for Mission Viejo Girls Softball. They are practicing 5 days a week right now.
That's awesome!!! Sounds like a proud Papa. I've lost sleep with late night repairs when the kids are down, but try not to anymore. Family first always bro. You'll find the cause of that clicking. Make sure to let us know what it is when you do. Always curious about this sort of thing.
 

crankestein

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Yeah, I have opened a few diffs after many running clocked hours be it 1/5th or the Talion, the diff oil will look dark charcoal grey. My first impression is I am screwed up and the diffs are ruined, but underneath all that metal shaving the diff gears are fine.

On a side note, the same happens with full scale automobiles, mostly when new (not on all makes and models). Where when changing the oil some small metal shaving can be found. I had this Subaru Impreza, synthetic 5-30w, never knocked, quiet idle, and good power all across the powerband. It had for a while metal shavings when changing the oil. Dealership said that was normal breakin on certain new cars.
 
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