Quite a lot of work has been carried out on the hanger since my last update. The initial design wasn't working out that well due to the top rose joint allowing the whole assembly to pivot upwards affecting the chain tension.
The next few pictures will show the evolution of what I hope to be the final solution. The real test will be installing everything in the car but so far it's working out well.
The original idea
As seen in this picture, I had the top mount linked to the main frame via a double, adjustable length rose joint. The theory being I could simply turn the link bar to tension or slacken the chain. However, the practice was the whole hanger could pivot on the rose joint resulting in the chain line moving all over the place.
I played around with a few ideas and finally settled on what follows.
The New DEsign
So what I have done?
A piece of steel square section was cut into a bird mouth so that it could be welded to the main backbone of the engine cradle whilst keeping it horizontal relative to the engine.
Next I cut a hole and welded a round tube to the other end. I actually used a 10mm weldable insert for the tube as the wall thickness was much thicker than any of the steel tube I have.
The threads were drilled out to make a hollow tube for the large M10 Hex bolt to pass through.
Tensioning the chain
The large hex bolt is connected to the hanger via a rose joint. This allows the hanger to pivot bot the fixed position of the hex bolt prevents the whole assembly moving. Tension is applied to the chain by simply raising or lower the hex bolt achieved by turning the two nuts either side of the tube it passes through. The desired position can be locked off by tightening the two bolts.
I've played around with lots of rose joint configurations and have finally settled on having two male M8 rose joints with left and right-hand threads. I will be making a link bar with opposite threads so the position can be adjusted by turning the link.
I wanted to make a substantially stronger mount point for the rose joints than pieces of drilled flat bar welded to the frame, so I made some custom mounts out of box section.
I started out with some box section and drilled a pilot hole where I wanted the rose joint to mount. I then cut and shaped the box section into a mount that the rose joint would sit inside.
Here you can see the parts of one side of the lower mounts.
Here is a closer view of how the parts all come together to mount the differential hanger to the engine cradle.
Spacing between the rose joint and the box section is achieved using nylon washers. The Rose joint can no longer pivot side to side which was the desired effect and can now only pivot up and down.