Decided to tidy up my 73 RHD steering box. Input shaft was tight and notchy. Thought I would take some pictures which may be of use to others. This is in essence a simple worm and wheel box. I think this is how it works. Please correct me if I'm wrong. The worm is supported by two angular contact ball bearings. One outer race is pressed into the casting. The other slides in a bore. A retaining plate presses on a domed washer which preloads the whole shaft assembly . A shim between the case and plate controls the preload. The inner races are machined onto the worm shaft. The bearings are marked SKF 355927 but SKF does not list them. I'm guessing they might be bespoke. So if the outer races, inner races, balls or ball retainer sare damaged, there is little you can do yourself. The wheel shaft is supported by plain bearings. It can move axially and is retained by an adjustment screw which protrudes through the end plate. When this screw is turned, the whole shaft assembly moves axially and comes into contact with the worm shaft. The more you turn, the more you preload the shafts. I have a feeling some people may overload this adjustment to try and fix steering problems that are due to something else. The oil in mine contained swarf and there is some pitting showing on one of the worm shaft races. With the whole assembly cleaned, relubed and assembled with the correct preload it feels much better. I understand these boxes can be refurbished and I would be interested to know how the bearings are replaced? Are the shaft and casing machined to accept a different bearing design? I also see that Heritage is selling new ones: for a price. The two things that are standard are the oil seals which I have replaced. ps. Just noticed, in the picture of the worm shaft the domed washer should be on the other side of the bearing race. Here is a video of the wheel shaft moving when the adjustment screw is turned.: http://s190.photobucket.com/user/jonbarrettbucket/media/IMG_2984_zps5b4abd2f.mp4.html
Very nice pics. I think fritt on here may have located some bearings in the past. I'd doubt that "refurbished" boxes have very much actually refurbished inside: unlikely there's any money in it for the low volume. I bought one of the Heritage NOS boxes a few years ago, and they are the real deal: early 80s spares from ZF. Lovely . I wonder how many boxes are just chucked out as no good, when with a bit of work like you've done, they're as good as new.
I bought a refurb but I kept my old one. It had two of the mounting bolts sheared off and was only attached to the van by the other two so it was moving when you turn the steering wheel. I'd planned to get some new seals, remove the sheared off bolts and put it back together. It looked fine inside to my untrained eyes. Obviously someone had tried to get it off in the past for whatever reason, and I hope that as you mention misguided, problem elsewhere. My steering is good at the moment anyway.
