The decision was made not to make a suspension jig for the rear brackets.
It was slow work and I have burnt fingers, but I’m pretty chuffed.
I was going to make a suspension jig on the bench, where I could carefully measure, then re-measure every bolt hole, bracket and angle, once twice and three times in 3 dimensions. However, whether it was over enthusiasm or just the fact the the chassis table is fairly low to the floor or an array of other excuses, I skipped this stage and went to weld the brackets directly to the chassis.
Every bracket was carefully made and placed in position with clamps and grips. The bolt holes were measured against several datums; including my master datum (centre punch mark) on the bottom front cross member; then tack welded in place. Every bracket on this Kit Car is unique due to chassis triangulation and the anti-squat geometry.
Once I had the front and rear brackets tack welded, I placed a 12mm bar through these holes, with the remaining brackets already threaded on. This bar not only allowed me to guarantee that the were true and straight, it also gave me something else to grip & clamp, giving better access the the edges of the brackets for welding.
The bar also gave me a solid edge to rest the micrometre against, speeding up the measuring process.
After tack welding, I was pretty pleased with the results. I measured all the hole centres against my central datum. Of the 12 brackets only 3 require a light tap with my ‘adjusting hammer’.
With the rod removed I welded the brackets more solidly and fairly amazing the bar just poked through again with virtually no resistance.
In conclusion, it might not work well for every builder, but for a ‘one off job’, I would use this method again. If I had 10 chassis to make, then I would definitely look at a gig solution. Measuring from a single datum works but it is frustrating and slow.