Steering column assembly
The cars > Developments and changes
A new steering column assembly
Over the years since we built Insanity Too there have been several iterators of steering column design. All of these have involved the use of a standard D1 steering column. Initially without a steering quickner and then a number of versions with a Howes 1.5-1 quickner in place.
The introduction of the steering quickner provided a massive improvement in steering response etc. it also brought with it some compromises. The the lower steering shaft became very complex and the Steering UJ angles are on the limits of acceptability and the location in the engine area meant it would collect a lot of dirt and debris.
The plan is to build a new steering column assembly that will be robust and easy to source spare parts, using off the shelf bearings. I also want the new column to house the steering quickener moving it to be inline with the input and output shafts and inside the vehicle.
The hope is that it will remove a lot of the lateral loads on the quickner bearings, this also has the effect of moving a few grams of weight toward st he middle of the car :-) .
In this case I started with a Quick Release Splined Steering Hub and the 6 Hole Adaptor Plate from McGill Motorsport and a set of simple Miniature Oval Housings & bearing assemblies from a bearing supplier.
The next step was to have a friend machine some steel bar to size to accept the spline drive for the steering wheel and a second splined drive for the steering quickener. The bar size has been calculated to be large enough so that when the two drive couplings are welded in place the bearings can still pass over the shaft to enable bearing replacement. this was also the determining factor to size the bearings.
Once I get the machined shaft the couplings are welded to each end and the excessive weld bead ground back to create the main shaft that will support the steering wheel and connect directly to the steering quickener. Up until this point I had been "practising" with lengths of 30mm tube planning the general assembly and layouts. one of the complications that had to be considered is the input and output shafts of the steering quickener are not inline, there is a small offset so it is not a simple case of aligning all three bearings along a shaft.
The image on the right shows Steering shaft with the coupler's in place after welding, however you may notice that where the weld has been ground back the shape of the shaft has removed a little to much and the bearing lock collar was difficult to fit, so later I built this up again with some weld and carefully reshaped it so it is more "round" under the bearing lock collar.
The next step is to start fabricating the frame that will support everything. I decided to try folding sheet steel and creating walls to support the bearings and steering qickener. This took a lot of CAD (Cardboard Aided Design) and at least three versions before I got it even close. Working out the angles and dimensions for each part so that the entire steering column is kept straight and aligned.
The bearing assemblies on the shaft and column housing walls before assembling the next step.
Next the steering quickener brackets and location are created, at this point I also start to assemble the lower steering shaft and another bearing bracket that supports the lower shaft as it passes through the bulkhead. The lower shaft has been made up from 19mm CDS steel tube and some 30mm steel tube to create a sleeve.
The sleeve at the bottom of the shaft has two purposes;
- It creates an additional level of strength over the welded join between the 19mm tube and a section of standard splined shaft onto which the steering uj will fit.
- Enables the use of the same bearing used on the top of the shaft to help standardise parts.
The complete column is assembled (several times) and tacked together, finally the complete assembly is located in place in the car to check (and adjust) the location and length of the bottom shaft.
At this point I recognise that a modification is required as the bottom of the assembly presents edges towards the drivers knees, ther is sufficient clearance but I feel this needs correction, so the bottom of the assembly is adjusted folding the edges in across the bottom. this has the additional benefit of increasing the stiffness of the entire assembly.
After more tweaks and adjustments to get everything "just so" the frame is tacked into the car. The assembly id disassembled before fully welding in place.
