Recirculating ball steering
 

Most cars have rack and pinion steering. But as a kid, my family had a couple Benz's from the 70s and 80s, and they came with recirculating ball steering. Recently I looked into it and heard/read that recirc ball is a steering system mainly used by trucks. Why is that? I understand the mechanical differences between recirculating ball vs rack and pinion steering. But why would one be preferable to another? The recirc ball system seems more complicated and Rube Goldbergish. Why would Mercedes put that into their cars whereas every other passenger car manufacturer used rack and pinion?

Longevity.

Racks get worn in the middle (where the majority of steering input happens)

The recirc ball system is more complicated and Rube Goldbergish, but doesn't have that wear problem.

I think it offers better leverage as well by allowing more turns lock to lock.

Load / leverage is the key. Some heavy-duty trucks, like fire engines have dual steering boxes to distribute the diagonal load on both front frame rails....

I rebuilt a GM recirc ball steering box when I restored my '64 Corvair Turbo. No longer own the car, but the rebuild was an exercise in counting balls LOL. It worked great when done. I think in my case the corkscrew shaft was worn and pitted, as a result the adjuster had been maxed out and could not longer keep the mechanism tight. I bought 3 steering boxes to salvage parts as much was NLA other than balls and seals. Once everything was packed w/ new balls there were various shim thicknesses to get the rotational tension to spec. You had to reinstall the rack and use a fishing weight scale on the steering wheel to set the tension to spec w/ the front wheels off the ground. Originally these were packed w/ oil...guaranteed leaking. I packed mine w/ a mix of synthetic grease and STP, as recommended by others. The car was and continues to be a 95 point concours winner, the new owner shows it much more than I did. I sold it in around 2016, have posted about it here before.

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I always feel so old when I read something like this.

Every car I ever had growing up had recirc ball. Also, every car I had growing up was old and well used, and one of the joys of wrenching on old cars was being able to tighten up sloppy steering on a recirc ball steering box. So satisfying!

I would not say that every other car manufacturer uses rack and Pinion, BMW also used recerc ball in many of their cars, pretty sure my 1971 2002 was recirculating ball and 1987 535i also is. They used rack and pinion in the 2004 530i and the rack in mine was replaced in 2010.