Help me diagnose this!!

[Heavy87Chevy]

Yesterday I was driving & hit a pothole or some sort bump in the road at about 50km/h & all of a sudden something went wrong.. It started off sounding like a grinding/knocking noise coming from the rear left, so I figured it was something that was ready to go in my brake & it was seizing or something.. So I got it home & checked the rear brakes & they look fine, but if I try to spin the left tire a little bit, there is a knock in the rear diff. When I spin the right rear tire any amount, it spins fine.. So now I think the problem is in the diff, which I'm hopefully going to tear into tomorrow, but does anybody know what it might be causing the grinding noise in my rear diff, there is fluid in there!!?

[SoCalKris]

Hopefully just an axle bearing

[77 350 Shorty Wide]

Good Morning, could be a chipped or broken gear tooth. Don't drive it... untill you know what's going on. A friend found out the hard way what happens when there is a clunking in the rear differential and you don't look into it.

God Bless, Terry

[Heavy87Chevy]

Originally Posted by 77 350 Shorty Wide

Good Morning, could be a chipped or broken gear tooth. Don't drive it... untill you know what's going on. A friend found out the hard way what happens when there is a clunking in the rear differential and you don't look into it.

God Bless, Terry

Yeah I was about 25 mins from home when it happened & I decided to get it towed (free with CAA).. I'm going to take the cover off the diff & check it out right soon.

[J Knight]

Any noise in the rear end aint good. I agree, don't drive it till you fix it.

[Heavy87Chevy]

Got the cover off the diff & found a couple broken parts, couple broken teeth, there was definitely some grinding going on.. I was able to confirm what gears are in my truck though I saw 12 41 so they are 3.42s! Time to get my Haynes manual out (I'm a newb, but hey I'm only 20) & figure out wtf to do next..

[1LowToy]

I'm and old man. But what I do know is you were on the throttle when she broke. Right?

Sorry about that.

[Dunenutt]

Hard to tell from the pics, but it looks like the ring gear did a little munching on some part numbers! Good call on the tow!

[J Knight]

Looks to me the ring gear, spider gear, and peice of the carrier got chewed up, and I would bet the pinion gear got it too.

[77 350 Shorty Wide]

Good Morning, Here is my recommendation. Don't try to fix it yourself. Differentials seem at first to be easier and less complicated than engines... they're not! Unless you have the right tools to do the job and some experience in setting up rearends you'll be doing it again and again untill you become an expert. Here is what I would do. Go the pick & pull and get yourself a good used rear end. Find one with a posi unit, not a gov. lock differential out of the newer style trucks but and old fashioned limited slip. Then replace the whole thing. Or If your inclined... take it to a good reliable rear end mechanic and let them set it up with all new parts and a posi unit. Just my two cents.

God Bless, Terry

[SoCalKris]

I definately agree if you are not trained to rebuild Diff's DO NOT attempt it yourself. Backlash has to be measured in the thousands of an inch. If its wrong then they will explode. I speak from experiance having destroyed 4 rear ends.

[spudz]

guys.....its not rocket science.. If he gets a manual and borrows or rents the tools... He can fix it himself.... Don't try and cheat it. and as others said, You HAVE to have it right or it wont last. But you CAN do it yourself. BUT with that being said......... By the time you rebuild your rear end the right way... you can go buy 4 used ones. lol.

[Heavy87Chevy]

Originally Posted by spudz

guys.....its not rocket science.. If he gets a manual and borrows or rents the tools... He can fix it himself.... Don't try and cheat it. and as others said, You HAVE to have it right or it wont last. But you CAN do it yourself. BUT with that being said......... By the time you rebuild your rear end the right way... you can go buy 4 used ones. lol.

Yeah I have my Haynes manual & I'm somewhat mechanically inclined but I don't think I'm going to rebuild it, I'm going to buy a used one & just swap it in. Someday I hope to go to 3/4 ton axles (that will be when its no longer my daily driver) & I'll put the money into it then.

All of that being said, I am still trying to get the center shaft/spider gear shaft out so that the spider gears & everything will come apart & I can at least look at what all is wrecked & decide what to do, but it absolutely will not come out, I think its been worn which has caused some burrs, so still working on getting that out.

[motornut]

i had mine done at a local garage i trust
cost about $1200 things were welded in place.....
now 5-6 years later no probs,i wouldn't have bothered to try myself
it's just something i'd let the pro do
I got to watch it on the hoist two days....but i still wouldn't try it

[tucsonjwt]

I am about like you (except a factor of 3x older) and I would not do the rebuild myself, without a skilled adviser present.
I do have a 3/4 ton floater but I had lots of trouble with axle seals (properly called wheel seals) until I searched the web and found out the GM came out with new two piece seals to replace the one piece seals they used to have. Even my professional axle mechanic did not know that, and I went through two sets of seals until we put the new style in - ruined rear brake shoes and drums in the process. I mention this just to show how little issues like this are likely to ruin a repair effort when it comes to rear axles.
Having said this, I have never had any other issues with my other two 3/4 ton squares, so I guess floaters are more reliable than the 1/2 ton axles, but they are way heavier and don't help your gas mileage.