I’m not so sure that this is not important, during a recent visit to REDLINE to discuss new rear shocks and springs I pointed out I had the ‘brace less’ type frame, apparently they were only fitted to De Dion cars for about a year around 1990.
John explained it to me like this, under acceleration the De Dion tube trys to twist/rotate and the ‘A’ frame prevents/minimises this, however without the brace bar when the trailing bars are pushed forward they bend outwards allowing the DD tube to twist and putting stress on the chassis points and bushes. Apparently if you could hold one whilst accelerating you would be able to feel it bending.
I’m not sure about “torque seen by the back axle is after the gearbox so only 1st gear causes problem" etc. torque is torque so if you increase the power/torque of your engine the ‘problem’ must get worse. My car started life as a 135bhp (optimistic) Supersprint, it’s now a 200bhp+ ZETEC.
Anyhow I hold Mick & John of REDLINE in high regard so I decided to take their advice and do it! It was a very simple and inexpensive job, I used a metre of 19mm O.D. seamless steel tube, two new bushes, powder coating and a friendly welder (no we didn't braze it),
I cut the tube to length, John said it should be fitted as near the bushes as possible, I filed the ends of the tube to suit the profile of the existing tubes then, with plenty of spark shields, tacked the new tube in place, removed the frame from the car and finished the welding on a flat bench. Re powder coated it and pressed in new bushes.
I have posted some pictures HERE
Guy