jrhendo A question you might be able to help with. I’m currently doing the Peking Paris rally again and the steering shaft kept moving down to the extent it threatened to disengage the safety joint. I ended up locking the joint with 2 bolts to stop it happening but I’m concerned that’s putting stress into the steering box. I can’t see what stops the shaft moving down normally. Any ideas?
Ideas only, yes.... but only ideas. Referring to picture below -
I presume you've replaced the upper collapsible coupling bushes with bolts, shown by the two red lines?
I'm guessing the column is sliding downwards (towards the front of the car) due to a combination of
(1) missing / damaged springs / seats / ball bearings at one (or both) ends of the steering shaft,
(2) the pair of shear-off bolts (indicated by the upwards-pointing red arrows) working their way loose from the lower half of the ignition lock [61], in combination with
(3) the white plastic U-shaped brackets on the lower dash support plate being worn, broken, or otherwise damaged.
These shear bolts pass though the underside of the lower dash support plate and sit in those white plastic U-shaped brackets fixed to that support plate. The operation theory being - when forward pressure is applied to the steering wheel (like, with the driver's body hitting it as a result of collision), the column collapses forward, the shear bolts allow the column to slide forwards about an inch or so in the U-shaped plastic brackets, and then the upper collapsible coupling bushes on joint [41] let go and disconnect the steering box so the driver doesn't cop the full force of a steering wheel in the chest.
Seems to me that the 50 year old white plastic u-brackets would not be particularly resilient when faced with hard driving over rough / un-made roads and they may have worn or broken, &/or the shear bolts going through them may have worked loose, which would result in an unwanted semi-collasping forward motion of the column rod towards the front of the car.
IIRC, BigAl and @1971_144GL did a repair job on BigAl's 1974 145 years ago, which involved drilling out the shear bolts and replacing them due to the forward movement of the column, so repairs are possible.
