Rear differential is shot. Help?

[Philly758]

I wouldn't drive on a rear end that you know is making noise. If the pinion gear goes into the rear end you will lock the axle up. One of the guys I work with had his truck lock up at about 70kph and was lucky not to have a crash.

You can get a rear axle up here from the pick a part for $90.

Yeah, not to mention its very annoying.

If I can get an axle that is cheap/convenient to pick up and find the time to replace it, I will. Otherwise I'll continue to drive it as is.

[Philly758]

I met up with dunedog yesterday to look at the differential he had and got to talking. After putting about 1200 miles on the van since my original post, I think the issue may just be the pinion bearing, or as dunedog said, maybe the pinion crush sleeve needs to be tightened a tad. What are your thoughts?

Also, I was thinking this morning... Would a 2003-2005 rear axle fit on my van? And if so, would it be easy enough to make the switch from rear drums to the discs? If I am going to go through the trouble of swapping the axle, I mine as well upgrade at the same time right.

[mdmead]

Swapping to the newer axle will change your rear bolt pattern. You will probably run into proportioning issues too going from drum to disk. These issues can be overcome, but it won't be a quick & simple swap in.

[Philly758]

Swapping to the newer axle will change your rear bolt pattern. You will probably run into proportioning issues too going from drum to disk. These issues can be overcome, but it won't be a quick & simple swap in.

Fair enough, I want to keep the cost of the swap down while keeping it quick and easy... So I don't think I will be exploring this option.

As always, thanks for the quick feedback.

[Philly758]

This appears to be a useful link that I found elsewhere on these forums: http://www.4x4now.com/gt0699.htm

Worn pinion bearings can cause whirring noises at all speeds, under deceleration and/or acceleration. Pinion bearings tend to whir, rather than rumble because the pinion is turning several times faster (depending on gear ratio) that the carrier. Badly worn bearings can also cause howl if they do not support the gears correctly.

This seems to describe my problem best. The noise is greater during acceleration/deceleration, but lets up a bit when I take my foot off the gas to coast.

[LiftedAWDAstro]

If the pinion bearing is shot, you will be able to feel the play in the pinion. Remove the rear drive shaft and grab hold of the pinion. If it is loose, you can try to tighten it up but I would pull the diff cover first and check for any metal filings and/or pieces. There is a magnet on the inside of the cover.

As has been mentioned, swapping to a 2003-2005 axle will require a new master cylinder (probably) and definitely a new set of wheels for the rear. The rear will be 6 x 5.5" bolt pattern while the front will remain 5 x 5" bolt pattern. Really no strength reason to swap and if you are looking for better rear brakes, do the 11" drum swap.

[Philly758]

Well, 7k miles after the noise started I finally picked up a rear axle for my van! Its out of a 2000 Astro, 90k, 3:73 and it has only been sitting in the yard for a week. I got it for $300 out the door (including drums) which I think is fair, they even loaded it into the van for me. The yard has a standard 30 day warranty, so if things don't seem right once I get into things I should be able to bring it back.

I plan on popping the cover off to clean and inspect the gears. Any recommendations on trans fluid/weight? Is it worth it to pop out the axle shaft while I'm in there and the fluid is drained to inspect and possibly replace the bearings?

Pictures to follow in the next month when I get around to the install. As always thank you for the help and support.

If the pinion bearing is shot, you will be able to feel the play in the pinion. Remove the rear drive shaft and grab hold of the pinion. If it is loose, you can try to tighten it up but I would pull the diff cover first and check for any metal filings and/or pieces. There is a magnet on the inside of the cover.

As follow-up, I looked into this and there was little to no play. That is why I decided to do a full rearend swap.

[Philly758]

Do you need new u-bolts for an axle swap? Someone told me this today:

"they are torque to yield, so once they are stretched, not supposed to reuse, they can break"

[LiftedAWDAstro]

Yeah you are supposed to replace them. I have re-used them with no problem. If they are real rusty you may want to have 2 new ones made.

[Philly758]

Yeah you are supposed to replace them. I have re-used them with no problem. If they are real rusty you may want to have 2 new ones made.

Thanks for the response.

Another question... I have read that you should mark the drive shaft and pinion flange before you remove the u-joint, so it can be installed with the same alignment and balance. Since I am replacing the entire axle, there will be a different pinion flange and nothing to line up. Should I just ignore this step?

[LiftedAWDAstro]

Yeah...the drive shaft is already balanced.

[Philly758]

Since I don't do a lot of work on cars (or any), I figured I would ask if you think this setup is safe.

- 2-ton jack stand on each side, under the front leaf spring/bolt.
- Van/borrowed jacks under the body next to the stands, as a precautionary measure.
- Wheels stacked in the rear under hitch.
- Wheel chocks in front of front tires, wood blocks behind front tires.

If I'm going to do the axle swap I mine as well do it safe.

Thanks again. I hope to do the swap on Saturday. Pictures will follow.

[LiftedAWDAstro]

Looks good to me. Give it shake sideways to make sure it is secure and stable.

[Philly758]

Well... Today I finally got around to do my axle swap.

THE GOOD: The new axle is in and the terrible noise has gone away. Fresh mobil 1 syn gear oil. Brakes bled and they work better than they did before.

THE BAD: I don't think the rear axle is aligned properly. On my test drive I noticed the steering wheel was slightly turned to the left on straights. I know I took special care to not move the clamps on the leaves and install the axle exactly where the old one was. I will take some measurements tomorrow to see if I really screwed up, if something is obviously out of line I will try to fix it. If everything looks good but it still tracks funny, should I just pay for a 4 wheel alignment?

And once again. Thank you all for your help. I never could have gotten this far without your knowledge and support.

Everyone loves pictures. So...

U-joint disconnected, drive shaft tied up out of the way.


New gears.


Old axle out. (Note: I put some bigger jack stands in before I started the job, the little crappy ones were terrifying and weren't really tall enough even when they were maxed out).


New axle, lawn chief, wheels, old axle (in order).


New axle up and in.


Almost there.


Old gears. They look like they are in great shape, only a couple specs of metal on magnet over the last 3000 miles. I blame a bearing for my noise.




DONE.

[LiftedAWDAstro]

Looks good! You can adjust the forward - rearward movement of the axle as you tighten up the clamshell bolts. You will probably find the right side wheel closer to the front of the wheel well than the passenger side. You can adjust it.