Steering Box Drop Arm

[kevin50]

Just fitted mt steering box to my rebuild,  No steering wheel fitted yet but I can turn it freely by hand, what position does it need to be before putting arm back on ?

Thanks

[David Sparkes]

56 minutes ago, kevin50 said:

Just fitted my steering box to my rebuild,  No steering wheel fitted yet but I can turn it freely by hand, what position does it need to be before putting arm back on ?

Central.

Turn the shaft fully clockwise until it stops. Put aligning marks on the column and the shaft to show the end of travel.
Turn the shaft fully anticlockwise until it stops, counting the number of times the mark on the shaft passes the mark on the column.
When the shaft stops, put a second mark on the column to align with the mark on the shaft.
Put a third mark on the column midway between the 1st & 2nd marks.
Count the number of turns the shaft made between column mark 1 and 2; this might be in the region of 4.75 (I haven't checked again).
Turn the shaft clockwise around half the 4.75, until the shaft mark meets the third column mark. That's the centre.
Double check the number of rotations from the centre to each side is the same, adjust the column mark as required to ensure the number of turns in each direction is the same.

When confirmed, make the shaft mark and the final column mark more obvious, as these will be the reference point, until the box is rebuilt.

Mount the drop arm so that it hangs vertically downwards, assuming the chassis is level fore and aft.
Remember the arm will swing forwards and backwards MORE than when the steering links are in place, because it's not until then that the swivel steering lock stops come into play. Those stops will prevent the box travelling to its limits, which is how it should be.

It you test the box without the swivel lock stops in play the drop arm may strike the bulkhead. Ignore this, because when completed the swivel lock stops will stop the drop arm moving so far.

When you  come to fit the steering wheel, ensure the shaft is in its central position, then fit the wheel where you want to, then mark the wheel centre and the shaft so you can repeat the positioning. If, in service, the wheel appears misaligned, DO NOT move the wheel, correct the steering link lengths until the wheel alignment is correct.

Regards.

[Snagger]

I think the arm hangs slightly forward of vertical with the box centred to allow enough aft movement before contacting the foot well.  That is why the top and bottom arms on the relay are set 81 degrees apart - so the top arm is forward of perpendicular by the same amount as the drop arm, maintaining a parallelogram (albeit twisted around the axis of the longitudinal rod connecting both arms).

[David Sparkes]

I strongly disagree.

I have already explained why the arm MAY touch the bulkhead before the rest of the steering linkage is installed and correctly adjusted.
'May touch' depends on the fitting discrepancies of the bulkhead and steering box to the chassis.

The figure of 81 degrees is impossible to achieve, 81 is a clerical error.
When the offset is applied on later Series 2A, and the Series 3 models, the offset is 'one spline' on the shaft of the steering relay.
Examination will show there are 44 splines on both ends of the relay shaft and, unless the shaft is in failure mode, and has twisted prior to snapping, the splines are in the same register at each end of the shaft.
Divide 44 into 360 and you will never get the angularity of a single spline to be 9 degrees.

Regards.

[Snagger]

Well, it limited left lock on mine when I fit the drop arm vertically.  Not by a huge amount, but noticeable.

Regardless, if you fit the drop arm vertical and the relay top arm “one spline” forward of perpendicular, you will have a trapezium formed by the arms and longitudinal rod which will make the steering ratios uneven left and right, whereas if you fit the drop arm inclined a little forward, similar to the relay top, then you have a parallelogram which will give steering that is more consistent left to right.