Ok so it's been just a little over 2 weeks since I rebuild the internals of my differential. Replaced the carrier (8.8 trac lok), ring and pinion, pinion bearing, and all the other various bearings. Everything has seemed to be functioning properly with no issues until Saturday afternoon. I went to Wichita which is about an hour from where i live to stay the weekend with the girlfriend and after a running a few errands we returned home and I noticed a smell that seemed awfully familier. I thought to myself "Hmmm, I know I took all those parts out of my trunk so where does it smell like I have a trunk full of greasy differential internal parts?" WELL, my heart sank as I realize it must be coming from underneath so I slowly sank to my knees and proceeded to bend down to peek under the car and that's when I saw it. A crack dead center in middle of my differential cover and fluid running out at a surprising rate. I couldn't believe it. I have no idea how this could have even happened. I have snapped a ring gear and crumbled a pinion gear inside of a casing once before on a Ford Torino and nothing happened to the casing. I don't get it, I am thoroughly confused. So anyways I drove the girlfriends car the hour to work this morning and will this afternoon be figuring out how to haul my car the hour back home so I can begin to figure out the hows and whys. Anyone else ever had this problem or seen it happen? Anyone got a extra diff cover lying around? Lol

Only thing I can think of is over-torqued cover bolts...? I'm sure you torqued them to spec since you've done all the work, but... ~shrug~

It is leading right to the bottom middle bolt.. Thats what it looks like atleast..

it looks bent in the center - no?

not sure that's a crack, maybe just a trail of oil from a hole up in the center.

Well, I got my torque specs from a friend. I guess they could have been off and I could have over tightened them. Could that really have caused a crack like that? The crack itself is circled in the pic and running down towards the bottom center bolt at an angle and up at an angle toward the bolt left of center at the top.

is it bent there? looks like it is kinked in - like you back into something.

No that's the natural contour of the cover.

Maybe it's the picture angle, but the contours on our 3 diff covers aren't as "bent" as yours. The cover should "bend" out, away from the fill hole and be a smooth, round shape. Yours looks like it has a crease in it; like maybe it was dropped on something.

I get what you're saying but I'm thinking it's the angle I will look again and get another shot of it. I am the only to ever have it off and I didn't drop it on anything. I don't have clue how it happened. It was driving fine and there were no noises of anything out of the ordinary. It was raining that day but it's rained before since I've had it back together.

where did you jack up the car at? somewhere other than from the diff right?

from the location and the fact that the crack doesn't go all the way to the edge I would assume that something hit the cover very had in that spot. I don't know how anything else could have caused it. At my house I would have to chalk this up to my kids messing with stuff. My 4 year old fried my last laptop by messing with the power adapter. Lukily I caught him doing it to the new one before I lost my second laptop in two months.

uh oh ....

Lol that's almost insulting but no i did not put a jack under the diif to jack it up. I have a shop with a nice four corner lift for getting it up in the air. I too had considered the fact that something might have hit it but what? I never heard anything hit it while my exhaust is loud I'm pretty sure I would have heard something hit it hard enough to crack it. I had just driven across town with it and back home. I don't know it's one of those mechanical mysteries I guess. Fortunately I ordered a new cover and it only cost me $30 but I hate the thought of have to take all that stuf apart again to put a fricking cover on. Blah.....

Lol that's almost insulting but no i did not put a jack under the diif to jack it up. I have a shop with a nice four corner lift for getting it up in the air. I too had considered the fact that something might have hit it but what? I never heard anything hit it while my exhaust is loud I'm pretty sure I would have heard something hit it hard enough to crack it. I had just driven across town with it and back home. I don't know it's one of those mechanical mysteries I guess. Fortunately I ordered a new cover and it only cost me $30 but I hate the thought of have to take all that stuf apart again to put a fricking cover on. Blah.....

hahaha, i thought you would find humor in that one, haha sorry, you know if you love your LS youll get it fixed and this will someday be the past, dont worry about it

did you just do a swap - or did the old diff break? maybe something hit the cover form the inside when the old one let go - which is pretty common.

I was thinking the same thing. But I didn't want to mention it. That would suck.

I just did an internal swap. The old was in pretty bad shape, you could grab the drive shaft and moving it in and out of the housing about and inch and a half. It's possible something did hit it from inside. It's possible something went wrong after the swap and hit the inside too. I just don't see that possible because it still functions fine. I Jb welded the crack refilled the fluid and drove it 50 miles back home at 65mph. No noise or anything.

Glad you got a temp fix for it. Just find a new cover and replace the cracked one ASAP. I would, anyways.

You should have used duct tape.

duct tape, or bondo works better, with the fiberglass:dancefool

I too had considered the fact that something might have hit it but what? I never heard anything hit it while my exhaust is loud I'm pretty sure I would have heard something hit it hard enough to crack it.


Heard it? Cracka', you'd have felt it!

:D

'specially going that fast in reverse :p

I have snapped a ring gear and crumbled a pinion gear inside of a casing once before on a Ford Torino and nothing happened to the casing.

well there is a HUGE difference in durability of a 9 inch ford Nodular case and that wimpy little aluminum 8.8 diff cover.

hell 9 inch fords dont even HAVE a rear cover...lol

So part two the soap opera story this is becoming. This morning I had no choice but to drive the Ls and it has seemed to do fine even under highway speed loads. Not today it didn't. It blew a whole new hole in a different spot of the cover. I'm way beyond confused, befuddled, and staight up like DUH! I can't for the life of my figure out what is causing this but I think now I screwed up the internals again. I don't get how it can run fine and make no noise and then all the sudden be blowing holes in the cover. I will hopefully get to take everything apart tomorrow and find out the bad news. Everything in there is fricking new so I guess I'm a retard or this is just beyond my level of comprehension. It just makes me sick though, $600 and way more time than it should have taken in the first place now it may all be lost. Any ideas anyone? Could there be a compression problem in the diff? Maybe the vent hole is plugged?

sorry to hear.

I bet you'll find edges of teeth knocked off.... and the, flying off the diff spinning at 60mph punched out of the diff cover.

Good thought Quik, well it's not good but it makes sense. That just makes me sick to think of that. Ring and pinion gear are not cheap. Any idea what would have caused it to chew teeth off? Especially when it was running great for the last three weeks?

I should have just done the damn full swap to 8.8 casing, carrier, and a 4:10

Did you refill with 80/90 and the friction additive for LSD's? Not that i know if that makes a difference, but it was recommended to me to not use the 75/140 that the open diffs use.

What was your backlash set at?

Again, just throwing these out there. I have no idea how bad of an effect either one could have.

Well I used the 75/140 and the additive. What is the backlash supposed to be set at? Idid this with a buddy of mine who runs a local mechanic shop. I trusted he knew what he was doing because he rebuilds a least one diesel rig diff a day. I know it's a little different but the concept in about the same and i know he's rebuilt other diffs.

LOL...don't feel bad, dude. This was my old 87 LSC's 8.8 after a romp down the 1/4 mile track...

Wasn't as newly done as yours, but still sucked that I had to re-do it all...the next time with stronger axles, girdle, aluminum driveshaft, etc...

Sh*t happens, man. That's about all I can say to ya. You'll get it sorted out.

If you did the work with a mechanic with knowledge of diff's, backlash SHOULD be fine. The shop manual calls for .008" to .012". I didn't see this when I did my diff swap, so I'm running like .005" right now. Just making sure you didn't have like a .000 backlash or something.

Thanks for the info. I'm pretty sure we were with in that range. I will tear into it tonight and see what actually happened. I just can't imagine what went wrong. I purposely spent two days going through it to ensure I wasn't missing anything. Think it's possible I got a defective Ring gear or something and it just broke?

LOL...don't feel bad, dude. This was my old 87 LSC's 8.8 after a romp down the 1/4 mile track...

Wasn't as newly done as yours, but still sucked that I had to re-do it all...the next time with stronger axles, girdle, aluminum driveshaft, etc...

Sh*t happens, man. That's about all I can say to ya. You'll get it sorted out.

holy hell!! bet you felt that!