ARB air locker....I need to ask you all that has one a very interesting question.

OK so I spent my tax returns this year on front and rear arb lockers. I am taking my time installing them tho. I installed the rear locker a couple of weeks ago, and just spent all weekend installing my front locker. I have not even plummed air to them yet. I test drove my truck last night after the install, no noises, in or out of 4x4, smooth as silk. So this am I was going to install the skid plate and figured I'd check the oil in the front diff first. THE OIL WAS GREY....with only 20miles on the diff. Very very fine metallic particles suspended in the oil. I flushed it out a few times with a few more quarts of oil and test drives and it has cleaned up. Just for giggles i checked my rear diff oil...THE OIL WAS GREY....WTF?? Same as the front, but ive got alot more miles on the rear diff. I know arb says to change the oil after the first 1500 miles, but they dont really say why. IS THIS NORMAL? I have no noises in either diff, shop tested the lockers and they are functioning. Anybody else have this problem?

 

Gear pattern test looked good?

 

Can you post a picture of the color? Slight grey would be ok, but if you have a solid GREY color, either your pattern is off....Probably on the gear side not pinion, or there is a bearing issue causing metal shavings to come off.

 

Ill try to get a picture tomorrow. I am a mechanic, thats what I do for a living. I have built countless axles. Ive never seen anything like this before. This is my first air locker install tho. Gear pattern looks good, backlash is good. All new bearings in the rear. If there was a bearing failing I'm pretty sure I would hear something. I'm very anal with noises on my vehicles. I plan on flushing the rear like I did the front and drive it a few hundred miles and recheck it.

 

OK, here's a pic of the oil out of the rear diff. It's on a clean piece of cardboard. It looks more black than grey today, guess its had time to settle. Anyway, I have since flushed the rear diff along with the front. I'm going to drive it a few days and check it again...keeping my fingers crossed. Note, this oil has only 2k miles on it...

 

Im curious on how you did the gear install as it sounds like the gears aren't set totally right.

1. Are they new gears? Or the old stock ones? If new, discoloration is normal. The coating gets worn off. In originals. A small amount is okay because chances are you didn't get it 100% back to where it was. A lot out of the stock gears means there could be an issue. But a little is normal because the gears have to re wear. That's why you change the oil at 1500. With new gears it's even sooner.

2. You use a new crush sleeve for the pinion or better yet, upgraded to a solid spacer? You should reuse the stock one ever.

3. The lockers aren't perfect matches to the stock carriers so all the backlash and pinion depths need checked and adjusted. I'm assuming you did this?

Not to sound condescending or anything. Just asking for more info.

 

I really don't want to sound negative to the comments given....I do thank you for your replies. Yes I know what I'm doing. The only parts that were replaced in the rear axle was the bearings and the carrier. No pinion depth required. Yes I used a new crush sleeve. Had to re shim the locker to get the correct backlash.....as for the front the only parts that were replaced was the carrier and one bearing that was sent with the locker kit. I spend half a day shimming the locker to get the backlash and preload correct because this is a clamshell front axle. Again no need to mess with pinion depth, old gears were reused. Anyway I don't want to sound like I'm ranting, because I'm not. Anyhow, all of that is beside the point I've been around long enough to know that if something's not right in a gearbox you will HEAR a noise. Maybe a whine, tip in whine, tip out whine, growl, hum, squeal...a leak could maybe even be found. I've not experienced any of that. Both gear boxes are silent across the range of operation.
Ok getting back to the question at hand....for the owners of an arb air locker...was your break in oil dis colored at the time of draining? That's really my whole question! Lmao. Like I said don't give me any heat for sounding like a butthole please as I do appreciate anyone's input no matter how helpful it may be... Thanks guys

 

My oil was not discolored when I installed... but it was a used locker on original gears. To me, your oil really doesn't look bad at all. (Maybe it's my computer screen) I would think that any freshly machined part will let some fine shavings loose. That being said, did you check your pinion depth just to be sure? (How do you know that it was correct to start with?) You can always just drive it for another 3-5K miles and dip my finger in there to check it periodically.

 

Yeah that oil was a real pretty gold color going in, now it's just black or really dark grey. Doesn't smell burnt, smells like regular gear oil. Ok, about the pinion depth...pinion depth is only required to be checked when installing new gears. It is the relationship between the pinion and the housing, it also effects where the wear pattern or pressure will be applied on the gears teeth as they mesh. I have never personally changed pinion depth when reusing the same gears in the same housing. This is because a wear pattern has already been established and I don't wanna screw with that. So, even if it was wrong from the factory...that's where it's worn in at so I prefer to keep it there. The backlash and preload on my front axle was a lil tricky but I finally got it where I felt comfortable putting it back in. But what you suggested is exactly what I plan to do...run them a few hundred miles and recheck to see if any material has returned. Thanks again

 

It's probably just the new bearings breaking in a bit then. I bet your fine. I agree the oil doesn't look bad in the photo.

 

I personally think it's coming from inside the locker...spider gears wearing in or something. Not for sure tho, that's why I asked you guys.

 

UPDATE::: so after flushing front and rear several times I got about 200 miles of a test drive in today and what I did yesterday. Anyway drained the oil for my final change until my next big service. Oil looked like I could've re bottled it and carried it back to the store! Looked very good so now it's time to wait and check it every week for awhile. Considering that the front fluid got into that shape in just 20 miles, and now after 200 miles its clean as a whistle...I'm feeling a lot better about my install!

 

What the arb gear oil recommended