Rear axle shafts

2000 Ford Crown Victoria, 221K miles

For a time now I’ve had a noise coming from the car that sounded an awful lot like worn out front wheel bearings, so considering the mileage I replaced those. That wasn’t it, the noise continues. It’s consistent with vehicle speed and is like a gentle roaring/whirring. It can’t be heard at 30mph or less, but gets louder with higher speed. It definitely sounds like a wheel bearing, so I wonder if it’s the rear axle bearings. I recently replaced my rear brake pads and rotors, and in the process I checked the wheel hubs for play: I could wiggle both of them up and down, side to side perhaps a couple millimeters. How tight are these things supposed to be in the axle? Is that enough play to consider them or the bearings worn?

I plan to remove and inspect the axle shafts this weekend. If they are worn, has anyone has luck with aftermarket axle shafts (I.E. Dorman)? How about repair bearings? I’ve read some places that they can have a tendency to leak. Personal experiences?

Used axle shafts with good bearings is what I used to use on rear wheel drive Chrysler products. They were pretty cheap at the junkyard. Don’t know if Ford uses the same setup. Nobody in the family ever had one I needed to work on.

Axle saver bearings have been around quite a while and they often solve problems like yours

You might check with your parts store for availability on your car.

It most likely is the rear axle bearings you’re hearing. The Ford rear end is a popular one for aftermarket and perfomance use, and you’ll find a plethora of parts for it just about everywhere. I’m pretty certain you’ll only need to replace the bearings. The axle and the bearings are held onto the rearend housing using retainers. In fact, a very popular conversion for GM rearends is changing to a Ford system of axle retention.

If it is the rear bearing, I’m pretty certain the associated seal has been compromised, and you’ll probably find evidence of this on the backside of your rear tires. You’ll probably be able to smell the rearend lube as well. (Nasty stuff, that.)

Don’t wait too much longer. If it is the rear bearings, that probably means the axle is low on grease, not a good thing.

If you can detect any up and down slop in the axle flange, the bearing is shot…if you use an axle-saver repair bearing, the seal is incorporated in the bearing. I have found these to provide service equal to the original parts…On my Vic, I placed a neodymium magnet (hard-drive salvage) inside the back cover to positively trap any debris created by the failing bearing…I also intentionally over-filled the real axle a little to insure that oil gets down the tubes to the bearings…If the oil in that gear-case is a little low, the wheel bearings get very little oil, a major cause of failure in this type of axle…

There is no oil leakage whatsoever from anywhere on the rear end, I checked when servicing the rear brakes. I changed out the gear oil about 70K ago and filled with Mobil 1 synthetic. The noise has been fairly steady for a while, hasn’t suddenly gotten worse or anything.

Autozone stocks repair bearings for my car, and there’s one within walking distance. If I find the axles in good shape when I inspect them, I’ll probably just walk over and get the bearings, rent the tools I need, and call it a day.

I’ve heard a couple people say that the pinion shaft lock bolt should not be reused, and that they occasionally snap off? Why would that happen when it spends its entire life in a sealed, lubricated environment?

Pinion shaft lock bolt? NOT…When you remove the cover, between the two axles, is a steel block that hold the axles snug in their spider gears…You must remove this block from between the axles to provide enough room to push the axle in far enough so the horseshoe clips on the end of the axle that retain the axle in the housing can be removed. The guys over on are going over the details on this repair right now…The limited-slip rear ends are similar but as I recall, have a couple of “S” shaped springs getting in the way…But you do not have to remove these springs to remove and replace the axles…Check to be sure the sender for any anti-lock brake system does not interfere with axle removal or installation…

Yes sir, there is a lock bolt for the pinion shaft, which is the part that holds the axles snug up against the spiders. You remove the lock bolt, and only then can you slide the pinion shaft out of the carrier, which then allows the axle shafts to be pushed inwards for C-clip removal. I have a similar thread going on…you might be looking at my thread, actually. :slight_smile:

Yes, a single bolt locks that spacer block in place, and it can be reused…The “Pinion Shaft” is the part the rear U-joint connects to and becomes the hypoid gear that meshes with the ring-gear. The axles can be removed and replaced without disturbing the “Pinion Shaft” at all…It is possible someone has used incorrect terminology in describing these parts. I would call this part the “axle locating block”…

Take care when you remove the axles, especially if you do them both at the same time…Once the axles are removed, the spider gears can roll around anywhere they want to and if the carrier (ring gear is free to turn (transmission in neutral) things can get interesting in a hurry as the spiders go their separate ways… You may have to place the transmission in neutral to rotate the carrier into a position where you can remove the locking bolt…Fine…But remember to put it back in park before you pull the axles out of the housing so the carrier can not change position…

Yeah, I think it’s a terminology confusion. I only used that term because my Haynes manual does, and it’s called that on the Autozone and Rockauto websites as well. The part it holds in place is actually called the cross pin (as listed on those same parts sites), so why it’s called a pinion shaft lock bolt escapes me.

Ford calls that shaft a “pinion shaft” and the two gears on it that mate with the axle shaft end gears “pinion gears”.

What do they call the Pinion gear? The part that connects to the driveshaft and meshes with the ring gear?? Those small gears (there are 4 or them, two drive the axles) we always called the “Spider gears”

In the service manuals the vehicle manufactures call them differential pinion gears (4), the other is called a drive pinion gear. You can look up the parts on one of the Ford online catalogs.

The threaded pin holding the “spider” gear shaft rarely breaks. If it does break removing it might be difficult for a DIYer working on the ground. It is advisable to always use a non permanent thread lock on the pin when reinstalling it. For years I used “Indian Head” gasket shellac as a thread lock.

Auto Zone and the other McParts stores offer the slide hammer needed to remove axle bearings.

If patient and fastidious, with no unexpected broken pieces, replacing the axle bearing successfully should be a manageable job. If the axle shafts are gauled, and they usually are, the axle saver bearing is worthwhile.

there is a repair bearning for your cv


I performed the surgery on the Vic today. Both rear bearings were obviously worn out, the rollers were pitted and losing their outer layers. The axle shafts themselves were fine, a little bit of visible wear on both, but no really major grooves worn into them so the axles are being reused.

I got bearings from Carquest and rented the tools from Autozone, but hit a snag when installing the passenger side bearing. I’d missed where the instructions said to lubricate the outside of the bearing and inside the axle housing with grease, to help the new bearing slide into place. The thing only went in about half as far as it was supposed to, and refused to go any further, and I was using a proper sized bearing driver too. I had to slide hammer the thing back out, which I knew would probably destroy it, and it did. So I walked down the block to Autozone to get another repair bearing (FYI, even though it’s labeled Timken, it was EXACTLY the same bearing as the Carquest one I got, right down to the blue grease on the rollers), and that one got properly greased and installed.

Put everything back together, filled her up with fresh Mobil 1 synthetic 75W-140, took her for a test drive, and everything’s looking good. The roaring noises I had before are gone.

Thanks to everyone for the tips. This was actually pretty easy.

Edit: I see you got it solved. Good on you! And I see you indeed used the Mobil 1 gear oil.

Just double checking. When you say you replaced the gear oil with" Mobil 1 synthetic", do you mean you used Mobil 1 synthetic gear oil? i.e. 90 W Mobil 1? Gear oil is usually a higher weight than engine oil, and if you used Mobil 1 designed for the engine, that could be a problem. Did this problem start when you replaced the gear oil?

Of course I used gear oil. I’ve been working on cars for a long time, I’m not so dumb as to use engine oil in the rear end. :slight_smile:

This Crown Vic happens to be an ex-police cruiser, and they are spec’ed to get 75W-140 in the rear end. That’s what I put in there, Mobil 1 Synthetic 75W-140.

Glad to see you got everything worked out @budd. But don’t take offense at George’s question. A lot of people come here for advice who don’t know how to open the hood on their car. Like myself, he may think it’s better to be safe than sorry… for you. Stick around. You may have some good advice for a troubled car owner on occasion. Obviously you can handle more than most car owners these days.