{Chrysler 300} A Power Steering Box Commentary on Rebuilding

Hi All,

This email to the list is more of an editorial commentary on steering box rebuilds than anything else. Just something to ponder.

I have been collecting up as many NOS or NORS parts that I can to send in with my steering box with an end goal of having a steering box that is at factory specification.

I have written the usual suspects about a couple of parts that I have not been able to find. Even after searching all the usual and some not so usual suspects.

Some of the thrust bearings and their races that are used in the worm head are proving to be hard to get. I have been advised that the wear in these steering boxes is often a result of wear in the worm bearings.

When I asked a couple of the rebuilders if they had a stock of those part number or manufactured them the reply was that they reuse the bearing and races. Presumably, they crank down on the adjusting nut and then stake it to reset the end play.

I am not thrilled about that.

Several of us ran into similar issues with the Jaguar E-Type IRS wishbone fulcrum bearings and races. Over time what happens is the races wear and once you get to a certain point the hardening is worn off and you can get accelerated bearing wear and IRS movement for and aft.

What was interesting was that we tested the races and found that 50% of them from the factory did not meet the Torrington specification for hardness. The ones that just barely did wore much better, the ones that did not were in bad shape.

We purchased new ones and, on a lark, had them tested. All failed. All did not even register on the Rockwell Scale. We ended up having to send out a new batch of the races and have them hardened to the Rockwell Specification.

What does this have to do with the MOPAR steering boxes? For a car that is only to get a thousand miles a year probably nothing. But if you plan on using the car extensively, what I can see happening is something like…

After a reputable rebuild in 25K to 50K miles the steering starts to get a little loose feeling. This can be due to the hardening being worn off the thrust races and the thrust bearings start to dig in which causes more endplay on the worm-piston assembly. This then makes it all but impossible to use factory service method to take up wear. That method is for wear in the teeth of the worm and sector shaft. It will do nothing for worm bearings that lose their specific end play.

The only cure would be to pull the box and replace the bearings and races or try to move the staked nut to take up the play this driving the bearings further into already failing races. All bad choices as it requires removal and disassembly of the steering box.

What I personally fear is that the shops doing the steering are doing good enough rebuilds that would last a car that is not driven much indefinitely. But, for a car that is going to be used extensively, down the road one would be back into a steering box.

Assuming the rebuilder I choose will work with me, one can take most of the thrust washers (races) that have worn and send them out to an Industrial Hard Chrome shop, and they can build back up both sides to specification and the hard chrome will provide a 66 to 70 Rockwell C hardness. This is a tad higher than the Torrington specification upper limit of 62, but since it is bathed in fluid and is not a high RPM use, I do not think it will cause a bearing life issue and the bearings seem easier to get than the races in any event.

Doing a rebuild one way or another is not better or worse or “correct” or not. A rebuild should be done for the intended mission of the car.

Now that said, if the mission is a 100% restoration, then all parts large and small should meet factory specifications. When it comes to the steering box, one would have to do a lot more work than just ship a steering box out to one of the usual suspects. Same thing if one plans on driving the car daily for the next 20 years.

Like I said, just something to ponder.

James