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Sunbeam Alpine Series III-V: Excessive play at the steering wheel

Discussion in 'Featured Articles & How To's' started by Tim R, Nov 12, 2021.

  1. Barry

    Barry Platinum Level Sponsor

    In most recirculating ball steering boxes, the ball nut (the gizmo that surrounds the worm gear and moves axially when the worm gear rotates) has a rack gear that engages a sector gear that rotates a Pitman arm. The Series Alpine steering box is weird in that the ball nut does not have a rack gear that engages a sector gear, but instead has a "tapered pin" that engages a "fork" that rotates the Pitman shaft. Weirdness aside, I am struggling to understand how ball bearings can be split in the Burman box. As with other recirculating ball steering boxes, the ball bearings in the Series Alpine steering box serve to reduce friction and "slop" between the worm gear and the ball nut. The purpose of having many small ball bearings is to distribute the mechanical load among many bearings. It seems to me that ball bearings can only be split by the application of an extreme point load force on only a few balls (maybe only one) rather than being more or less equally distributed among many balls. It also seems to me that the only way that the force can be concentrated on only a few (maybe only one) balls is if the worm gear is worn in spots or if some (maybe only one) of the balls are larger in diameter than others.

    I am also struggling to understand what (if anything) that power steering has to do with ball bearing failure. Again, it seems to me that the same amount of torque is applied to the steering shaft whether or not there is any power assist.

    Don't claim to have the answer(s), just trying to think logically about the process.
     
    DanR likes this.
  2. Tim R

    Tim R Silver Level Sponsor

    I am still waiting for a response from one of the guys here in the UK that re-condition our steering boxes but I have found out some interesting things.

    The article attached below as a pdf is by Chris Barker (author of The Essential Guide to The Sunbeam Alpine and editor/compiler of The Alpine Guide V3) he was a Rootes Student Apprentice and started working at Rootes in the 1960s, he has owned his own Alpine since the early 1970s and knows these cars inside out, few have his level of expertise.

    Some Alfa Romeos use a very similar Burman steering box and there are multiple reports on the internet of these cases and columns splitting

    https://www.alfabb.com/threads/cracked-burman-steering-box.175568/

    A lot of the failures are attributed to steering the car when it is not moving and/or using radial and larger width tyres causing excessive strain.

    There are at least two different companies who are making heavily strengthened Burman steering box cases that are machined rather than cast that apparently overcome the problems of cracking (see photo).

    There are a couple of UK suppliers who sell Alpine power steering systems (Vauxhall derived) and there are several owners who have converted their Alpines to use manual rack and pinion steering (which might actually be a good way to incorporate p.a.s. on an Alpine?).

    My own take on this is that I would love to have p.a.s. on Alpi if someone can work out a way to do it reliably without any risk of damage to any components and if DanR (or anyone else) has managed to achieve this, that is great. My 'gut feeling' is that even when steered manually the Burman steering box is a weak spot on the car and that even minor increases of pressure on it (like wider radial tyres) might make either the case or the internals fail. If someone can actually solve the problems and deliver this it could be a very popular modification.

    On the up side the UK Owner's Club are on the verge of securing the manufacture of brand new worms and nuts so that boxes will be able to be fully re-conditioned to 'as new' standard again.

    Tim R
    steering_box2606s.jpg
     

    Attached Files:

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