Rear end apart question

[Abbottgod]

My rear end lost power all of a sudden. The transmission would spin freely in any gear but no power to the rear end. When i would shift it back to park it made a grinding sound. I had a friend come try to pull me home with a strap and the passenger side tire came off with a rod attached. I called a flat bed tow truck and have it home now. My question is from looking at the pictures do I need a whole new rear end? Can this one be salvaged? And any ideas on what exactly happened? Thankyou in advance and it is a 1975 buick regal with a 350.

Edited May 16, 2021 by Abbottgod (see edit history)

[c49er]

That axle bearing was making some noise!

[Abbottgod]

It never made a noise before. I had came 50 miles driving home and yes the last 3 miles I drove at 25 mph it made a slight clunk. Not very loud. Then what I described happened on that last 3 miles. Do you think I need just new bearings?

[Bloo]

You broke an axle. You did not mention make, model and year. Designs vary widely.

 

It looks like a GM car, and probably has a c-clip style rear axle. The axles are held in by clips at the center. After the axle broke, it could simply come out.

 

I don't know if it is salvageable. Depending on availability, it would probably be cheaper to buy a whole assembly used. Recognizing that parts like this are not just laying around everywhere these days, the next things to do would be:

 

1) Take the brake backing plate off, remove the old bearing and seal, and figure out how damaged the axle housing is. This type of axle oils the bearing from the rear axle oil, so the seal is on the outside. It will have to be undamaged enough that you can have a new seal out there, and have it press in properly and seal.

 

2) Take the pan off. CHECK AND WRITE DOWN THE HOW MUCH BACKLASH on the ring gear. Take the differential and ring gear assembly out and look inside at what broke (it's likely in the middle with the spider gears). EDIT: If the rearend has not ground up any metal, don't take the ring gear and diff out yet. See if you can just get the piece(s) out and ascertain the condition of the gears in there without taking that out. Maybe. If the axle broke out in the middle somewhere away from all the gears, this is actually a good possibility. If the ring gear and differential assembly has to come out, the other axle has to come out too. The shop manual will show you how. Any tutorial for a "c clip rearend" should show you how that comes apart. You will need to do that regardless.

 

4) See how much broken metal got loose. Look closely at the ring and pinion for damage. If only the axle broke and you found all the pieces, and they did not get ground up by anything else, it might not be too bad to fix.

 

5) If there is ground up metal in there, it will need all new bearings, including the ones on the pinion, and the housing cleaned out. It is probably possible to do this under the car but I do NOT recommend it. Take it out of the car and put it on the bench. If it has this sort of damage it is NOT a good beginner project. The pinion probably has a crush sleeve. You will need a big torque wrench and you will likely need to make a tool (steel plate, pipe, holes drilled or machined, welded) to hold the yoke, and then a tiny torque wrench to check bearing preload. In my opinion if it is bad like this you need professional help. I know what to do and I would still take it to some guy who sets rear ends up all day.

 

6) If it wasn't that bad you will still need to clean the housing out really good and reassemble, replacing the axle, the wheel bearing, the seal (consider replacing the wheel bearing and seal on the other side too as preventative maintenance), and anything that got broken or damaged in the center (the spider gear area) when the axle broke.

 

7) Put it all back together and set the ring gear backlash the same as you found it. It is tough to get pans to seal. It is tough to get anything to seal gear oil. Get everything real clean and buy some silicone that is made for this exact purpose. The parts store should have it. If not, Ford and Chrysler dealers do. Fill with fresh GL-5 gear oil to the bottom of the plug, assuming this is some 70s or 80s American car (you didn't tell us what it is!).

 

Good luck.

 

Edited May 16, 2021 by Bloo (see edit history)

[plymouthcranbrook]

And if I my paraphrase for Bloo, he is suggesting you try to find a good used differential set up. Most likely cheaper and you have to take the damaged one off anyway. At least that is where I would start if it were me.

[Angelfish]

I must agree with the above two posts.   I did the same thing with an old truck, snapped an axle at an intersection and there I sat.   Bought a complete used rear axle/differential from a wrecking yard and still drive it today.  
 

In another truck I stripped the differential ring gear, the symptoms sound closer to what you describe, but the fix was the same. 

Edited May 17, 2021 by Angelfish (see edit history)