Definately, I like the idea that there is potentially a lot of adjustability available, incidentially I found out the other day that E39 BMW's had the same type of suspension at the rear. Will be a while before I get to it, just about to start making a two engine stand rotisserie.
Hello, I am new to this forum and to be honest, I don't even have a Datsun, but I do have a car with a semi-trailing arm rear suspension, a Ford Sierra based Merkur XR4Ti. I stumbled upon this discussion when searching for different ways to modify and improve the basic semi-trailing arm suspension.
Coincidentally, I had seriously considered modifying my suspension to look like the Bluebird pictures in this thread. You are correct that several BMW's have this type of suspension, namely the E36 and E46 3 series. The E39 5 series does NOT. But, I joined the forum just to give you a heads up that it does have a problem in that the concept inherently causes a lot of toe change and if one is not careful with the angles of the lateral links it could even toe out under compression which is bad. If one does the calculations, you will find out that it actually has more toe change then a semi-trailing arm with a smaller sweep angle like the E30 BMW's. If you want to do some reading, look at the toe change that the C2 and C3 Corvettes have, as they basically also have the same suspension layout with one of the links being the drive shafts.
Even though it does provide the easy ability to adjust the camber curve and roll center, I decided against this configuration in my car due to the toe change.
I am not quite sure which direction to go yet. The stock Sierra sweep angle is 18 degress, less then the 25 degress of the 510 but still way to much by modern standards. As mentioned in a previous post, I common mod for a the Sierra is to modify the rear beam to change the sweep angle to 6 degrees. This seems a bit low to me, but it is proven. I could easily do that, but it would not fix the other problem, which is the lack of anti-squat and the resultant low roll center. To fix the anti-squat in my application I would need to raise the pivot points about 4inches (100mm) which of course fouls the floor
Lately my thinking has been to simply replace it with a double A arm setup of either my own design or from another car like a 350Z.