I may not be the Brightest button in the box but I aint thick.
So why the shell am I struggling with simple measurements.
I've made the steering rack support brackets mounted them and they are all spot on measurements. So why is the height from the top of the base tube 5mm low.
And don't get me started on the column support bracket. Nothing in the book makes sense to me. I've cut every tube spot on tacked it in place but not hi g corresponds with the check measurements in the book.
Can you get Bluetooth steering.
I'm fully expecting to shim my rack to minimise bump steer anyway so wouldn't worry about the precise height of the mount, especially if it is a bit under height.
I had to shim up my rack as well. Think I used 1/4" plate so just a little over 5mm so it'll be fine.
I know the feeling when everything looks to be wrong or seems not to make any sense in the book. Just leave it for a while, breathe, and come back on it later, you'll figure out what you haven't seen with a fresh mind.
Regarding the steering rack support, there is an alternative to the book's one. A member of the Haynes Forum, Madis, designed years ago a stronger steering rack support, which is also corrected to reduce (avoid?) bump steer. That is the one I have on my car and I'm very happy with it. You can find the plans, drawings, and measurements, on the documents I share (with his agreement) on my Google drive at this link:
Even if you don't make and use the same steering rack support, perhaps the informations on the measurements of the part he designed and its installation on the chassis you will find in these documents will help you figure out the problem you have.
Regarding the steering column, if your problem is related to the steering wheel frame tubes (SW tubes), I don't understand what the problem could be. Measurements of SW tubes in the book are correct. I suggest you double check the measurements and cuts of your steering wheel support tubes (SW) and your transmission tunnel tubes (TT).
However, if your problem is related to the steering column brackets CP15, the book says nothing about the distance between the 2 brackets CP15. This distance will obviously be given by the distance of your steering column fitting points.
It also does not say where these two CP15 brackets should be welded on the steering wheel frame top tube (SW2). But the middle plan should be aligned with CP16a hole centre. So tack CP16/CP16a in place first, and you'll figure out where to weld the 2 brackets CP15, especially if you already have your steering column. You can even use your steering column as a jig to place CP15 once CP16/CP16a are in place.
Hope that will help