Rear Bearing Shim?

shew01

shew01

Well-known member
I’m still new to Model As, and my current discovery is the internal working of the rear wheels.

I took one of the rear wheels apart yesterday to grease the wheel bearings and found a surprise. It looks like there was some sort of bearing shim (I suppose—I’ve never seen anything like this). It is a thin, conical piece of metal that was wrapped around the spindle, but had a gap for what I think is the axle key.

When I had the drum off it learned I needed to remove a grease seal to remove the roller bearing. I didn’t have a spare grease seal in case I messed up the seal trying to remove it. So, I dabbed some grease on the roller bearing and tried to put everything back in place until I can locate a proper grease seal. When I tried to put the drum back on the spindle, it balked. Ultimately, I wrinkled the “shim.”

Can anyone identify if this is a shim of some sort? What is its purpose? I took it out because it was wrinkled after my initial failed attempt to put the drum back on the spindle? Should I order a replacement? If so, what should I search for?

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It is an axle shim for the rear hub. Over time the rear hub will wear and become loose on the axle resulting in the brake drum rubbing against the backing plate. The shim is used to take up the wear on the hub. Sometimes it takes more than one axle shim to take up the slop. It is a common fix for worn hubs. I would also replace the axle key, axle nut, snap ring, and outer grease seal/washer when replacing the bearing seal. You will probably destroy the bearing grease seal when you remove it. Also, drive the new seal in just past the snap ring groove. The bearing should have a slight amount of back and forth movement...

All of the above parts are relatively inexpensive and are readily available at Model A suppliers....
 
Should the axle key be “pushed” inward (toward the backing plate) as far as it will go? It shifted toward the end of the spindle when I pulled the drum off initially, which is why the drum hung on reassembly.

Also, what torque should I put on the axle nut? Les Andrews says 125 ft/lbs, but I’ve seen a value of 100 ft/lbs in Google. I don’t want to break the nut.


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If the bearing and seal looked good then you can add some grease to the bearing if you don't want to remove it by squirting some grease into the the bearing with a grease needle.

You could try installing the hub without the shim and see if the hub turns freely. If it doesn't then a new shim or two is needed. Mind how the key is installed, they can be persnickity.

The axle/hub nut should be 125#, but, I take them to 100# and then just enough more to install the cotter.
 
Thanks Dick and Patrick. I think I have enough information to move forward. I appreciate your help.


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When I have removed and then re-installed a hub, I tighten the nut but don't put the cotter pin in until I have driven the car a few miles and re-tightened the nut, they often will move a little. I have only seen shims when hydraulic brakes have been installed, to keep the drums from rubbing on the backers. I have sometimes made shims out of tin cans, not aluminum. This is not rocket science.
 
The rear axle taper is exactly that - a taper. Friction holds the parts of a true taper together. So you want to maximize friction - hence no lubricant.

Another school of the machine tool taper background hold that the taper can't come apart until the air can fill the space - so they tend to put a light film of oil on machine tapers - mostly to help exclude the air. Also to aid in removal once the taper is "started."

For my machine tools I do the latter. For the Model A axles I do the former.

Joe K
 
I did mine yesterday. The seals and snap rings were around $6 a side from Brattons. I had one side rub once done but it was because the brake plate was slightly bent. Was able to drive a chisel between the drum and plate to tune it.

Also per the grease, the zerk behind the brake plate greases the wheel bearing.
 
The grease fitting does grease the bearing, but, it has its problems. Over the years one doesn't know exactly what you're pushing into that bearing. Plus some don't know when to stop pumping and fill the brake drum or axle housing, kinda like greasing the u-joint and all of a sudden the transmission is fill of grease.
 
As Patrick says, plus the inner seal is often installed backwards, so not pushing the grease into the wheel bearing but allowing it into the diff area.
 
I don't know the history of my chassis, however it was all painted yellow during a previous "restoration". When I popped the hubs off the bearings were slightly oiled from seals leaking but had no grease. I purged the zerk and it pushed some grey grease out that didn't smell horrible before the new stuff showed up. I have a new to me rear with the original chassis' hubs. What I thought was neat was that once full any excess grease that pushes by the outside seal should get slung into the catcher and then seep out of the 1/2" drain port at the bottom of the axle. Either that or it'll get mixed in with the axle lube if the inner seal is toast.
 
I am also new to maintaining a Model A. So I am looking for guidance on my first major lubrication job as I reassemble the rear brakes. I have Les Andrews book but could not find the details about lubrication that would help a newbie get started.

1. I understand reading this thread that taper on axle and hub should have no lubricant. What other parts of the brake assembly should not be lubricated?
2. What type of grease should I use - synthetic or non-synthetic?
3. Do I need a special grease for packing the wheel bearings? I took the bearing out, cleaned them and have got new seals.
4. For adjusting wedge and adjusting shaft, should I use grease or use the white lithium spray?

Thanks in advance.
 
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