steering box work

What are the differences between the steering boxes fitted to a pre 1932 trike, a later trike, a Series 1 Scout and the Series 4, 5 and 6 Scouts?
Over the ten years that the cars were produced at Small Heath a number of changes were made to the steering boxes fitted to both the trikes and Scouts.
Some of the changes are quite fundamental and effect which boxes should be fitted to individual vehicles. This article sets out to review the various differences uncovered by examining individual steering boxes and various drawings supplied by Tony Meade. The information contained in this article reflects my current knowledge and it may not therefore be complete.
The most obvious difference between the steering boxes fitted to the early vehicles and the Series 4, 5 and 6 Scouts is that the former are fitted with an aluminium cover while the latter use a cast iron cover.
The aluminium cover is fitted with a bronze bush in which the steering quadrant runs.
In those boxes fitted with a cast iron cover the steering quadrant runs directly on the iron surface. The change to the cover also resulted in a change to the steering drop arm.
Those fitted to the later Scouts have a raised lip that runs in a groove machined into the iron cover. The effect of this change is to reduce the load exerted by the steering quadrant on the cover and therefore reduce wear on the bearing surface. Examining the level of wear in the various boxes I have stripped, this appears to be the case. This change removed the need for a bronze bush, replaced an aluminium component with a cast iron one and, I assume, reduced BSA's manufacturing costs.
The other obvious change is to the steering gear ratio. The majority of the boxes I have seen are stamped 12T on the top surface of the pressed steel box. This indicates that the box is fitted with a pinion manufactured with 12 teeth.
The corresponding steering quadrant is manufactured with 58 teeth, giving a ratio of 4.83:1. The early trikes, pre chassis No 1850 (according to the 1932 parts list) are fitted with a pinion and steering quadrant containing 14 and 56 teeth respectively, giving a ratio of 4:1. Trikes manufactured after chassis No 1850 were manufactured with pinions and quadrants containing 13 and 57 teeth.
This intermediate arrangement appears to have been fitted to a limited number of trikes from chassis No 1850. The change to 12 and 58 teeth gearing appears to have occurred sometime in 1933 or 34. I cannot be absolute sure about this as I lack a number of parts lists.
Other minor differences include changes to the thrust washers fitted to the input pinion. The 1932 part list shows that the boxes were fitted with two washers, part number 35- 5526. These are fitted under the head of the pinion and between the top of the box and the column. Both run on the surface of the white metal bearing fitted to all the steering boxes. The later trikes and Scouts are fitted two different washers. The one under the head of the pinion, ref number 35-5527, was increased in thickness to 0.190ms while the original thinner washer was retained between the column and the box.
I have noted some of these changes in stripping down various boxes in recent years. What I had however failed to notice was a more significant change that first appeared on the Series 4 and possible the Series 3 Scout. On these boxes the location of the pinion housing on the steering box was moved. I had rebuilt a steering box for the Series 4 and changed this, or should I say attempted to change this, on the Sunday after the AGM. The box was fitted with a nylon bush to replace the standard bronze item. Everything was stripped down and I offered up the new steering box. I could not get the steering column to engage with the pinion. The layout of the box and column looked wrong. The column appeared to be out of line by 10°. I took the new box off the car and had a good look at this, the original box and that fitted to my Series 5. The difference was now obvious.
On the steering box fitted to the Series 4 the pinion input housing is rotated clockwise by 60 degrees (looking down from the steering wheel). On the earlier cars the housing is in the 9 o'clock position adjacent to the steering box mounting. The effect of this change was to raise the position of the column at the steering box end, move the column away from the chassis and to lower the steering wheel very slightly. All the boxes with cast iron covers have the modified pinion input location.
The other discovery I made was that the wrong steering box was fitted to my Series 5 when I acquired the car in 1965 and it is still wrong. I now know why the steering column locking bolt catches on the chassis frame. This goes to show you can still leam something new about BSAs, even after 35 years of ownership.

The various steering boxes fitted to the cars are detailed below:

Trike - pre chassis number 1850	35-9158 14 and 56 teeth
Trike - post chassis Number 1850	35-9159 12 and 58 teeth
Trike - 1933 & 34	35-9159 13 and 57 teeth
(Change from 13 to 12 appear to have occurred at this point)
Trike - 1935	35-9815 12 and 58 teeth
Scout Series 1	35-9815 12 and 58 teeth
Scout Series 4	38-9621 12 and 5 8 teeth
Scout Series 5 & 6	38-9624 12 and 58 teeth

The aluminium cover is part number 35-9162 and the cast iron cover is 38-6207.
There are some gaps in my knowledge and no doubt other minor changes will show up when I examine the drawings on order from Tony Meade. One further piece of information that I found interesting. The layout of the trike and Scout steering box is identical to that found on the 1920s rear wheel drive BSA light cars The detail design is quite different but the concept is based on an input pinion and output quadrant which look similar to those on the trikes and Scouts.
From the parts list I hold for a L16 and TA & Bll I cannot identify the number of teeth on either item but it would not surprise me to find these are 14 and 56! I hope that Mike Scott- Coomber will be able to confirm this.Peter Cook

The various steering boxes fitted to the cars are detailed below:

(Change from 13 to 12 appear to have occurred at this point)