I had a buddy of mine install my gears about a month ago. He has done dozens of gear changes in the past.

Well, without thinking, we did not add friction modifier when changing the rear. The first 500 miles I have taken fairly easy. We did use Mobil 1 75-140 gear oil. Tolerances were within spec, but on the looser end of the spec. It was 31 degrees when we were installing these gears!

Once I realized I needed some friction modifier, I bought 4oz of it and put it in my rearend. When I removed my rearend fill plug, I noticed that it had quite a few small chunks of metal attached to it. The biggest being 2mm or so.

I have experienced no whine, no chatter, no clank, no slipping, nothing to suspect anything is "not right." The gears are 4.56.

So, does anyone think I did any damage? I am trying to refrain from removing the rear cover as new gear oil is going to run me another $80. Should I drain it anyway now that everything is "broken in?" - no pun intended.

Thanks

 

Hello & good afternoon!

Well, the friction modifier ( MC XL-3 for Ford gearsets) is primarily for the LS clutches , and to reduce chatter/ hypoid gear noise. I don't beleive it's absense during break-in, while not a very good situation in and of itself, would account for that kind of metal loss.

I would just go ahead and open it up, have a look, clean ALL the crap out of there and check for the root cause ... that does sound like excessive wear for only 500 miles, to me.

$80 - versus the cost of destroyed gears is not a serious consideration. Leaving that material would make me lose sleep at nite ...

Good luck!


MGD v4.1

 

If I were you, I would pull the cover. That way you can have the gears inspected, if they are ok them throw in some new gear lube (and friction modifier this time). But if you do see any sort of damage or bigger chunks of metal, then you would have to have to pull the cover to swap the gears anyway.

 

THanks guys. I will probably pull the cover next weekend.

 

x2, pull the cover for peace of mind. If it's bad, you'll know. If it's not, at least you'll be able to sleep at night!

 

I changed the gear oil today. The gear oil looked relatively clean. Of course, it was a little grey.....but not all grey. I checked all of the teeth on both the ring and pinion, didnt see anything missing. THe wear pattern looked near perfect. There was no more metal in the bottomof the pumpkin, in the oil, or in the cover.

The only pieces that I see that could be broken off was just some extra casting on the top of the pinion.

The bearings were discolored though.....to the point of being blued.

Royal purple is in there now.

 

You will get a little bit of metal shavings on a new gear install it is normally just to two gears meshing together. But you did do the correct thing in changing the fluid. I have seen the shavings after installing gears in some of the Jeeps I have helped on, I haven't done a gear swap myself but I have help and installed more lunch box lockers than I care to think about.

 

The blue bearings concern me. Iv seen that one other time on an axel that ran with no oil in it at all. It sounds like there is excess build up of heat on the bearings for some reason.

 

X2 There shouldn't be ANY discoloration on the bearings Do you know how much heat it takes to discolor bearing races. A LOT! That would concern me too.

 

I missed the blue bearing thing earlier. What bearings are you seeing that are blueing. Really there is no bearing you can see while changing the fluids. If you are talking about the bearing caps that hold the whole assembly in, you need to have someone check it out something is to tight.

 

Maybe I should not have said bearings. I attached a pic and circled where there is a round piece that is blued....there is one on either side...this may not be an exact picture. This piece was not disassembled when the gears were replaced. Everything is within tolerance. We were even able to reuse the stock shims.

I used 3.75 qts of mobil 1 75w-140 and there is 1000 +/-100 miles on the truck since the gear install. 80% of that driving is stop and go bumper to bumper traffic.

No noise from the rear whatsoever...not on acceleration, deceleration, nothing. No metal (other than some tiny tiny flakes) in the gear oil that was just changed.

 

did you put the bolt back in? also did you put the clips back on the axle? seems odd that they are colored blue?

 

I work at the axle plant where all our rear ends are made and I'm gonna look into it. I don't think the diff gears should be turning blue on you either. It still sounds like an over abundance of heat build up in the axle. The lack of friction modifier would only affect the clutch plates so something else may be going on there. Like I said I'll try to find an answer in the next few days.

 

Are our axles c-clipped? I don't have a clue. The part you are looking at is the face of the spider gears, but I don't have a clue why they would be blued. If you have an assembly similar to the one that is shown that means you don't have a limited slip rear end, it is an open rear. I would do as zabeard said and check that the bolt or drift pin (some carriers use drift pins) are in the center pin that runs through the center of the carrier. Still I dont see how there could be heat there as long as there is oil, most spiders are alittle on the loose side.

 

You don't add friction modifier to Mobil 1 LS 75-140, because Exxon Mobil already adds it to its gear lubricant.