So, after much pondering I have come up with this
I want to use the crossmember as I can always revert to the original set up without having cut holes in the base unit. My original thoughts were just to control the diff movement with two struts which would try to push the crossmember forwards. This didn't work too well, so I tried to toughen it up so it would take the pressure.
After much thinking, it occurs to me that the way I am doing it transfers a lot of the torque to the crossmember. If you imagine a circle with the centre being the centre of the driveshaft, the torque of the diff is trying to turn around that centre. My set up has the full torque going to a point 12cm away from the centre and pushing forward. If I can make that point of control further away, I would need less strength to control it.
So, I thought I could bolt a steel plate to the original rubber bush in the middle of the crossmember, then redesign the lower part of the cage to connect to this, so I would have a control point 72cm or so from the diff centre so only 1/6th of the pressure would be needed to control diff movement, and use the crossmember in the way it was designed, controlling upwards movement as per the original Rover diff.
If it doesn't work, I'm blaming Mark
All I need to do is recut the hole that I had welded up in the crossmember, then the two bolt holes, refit the rubber mount and weld up the holes where the tubes went through, and refit it......... Or just fit the spare one
I found a couple of these hefty looking brackets in the warehouse and welded a bolt through one of them to fit into the bush.
The propshaft runs over the top of this and is quite close so I filed the head down a bit to get a bit of extra clearance, then refitted the crossmember into the car. Problem is, I couldn't remove the bracket as the propshaft was now in the way. I didn't want to be in the position where I couldn't remove it without removing the rear suspension, so I tried removing the prop from the diff to see if I could get some wiggle room.
Two things
1/. There wasn't enough wiggle room to lift the whole bracket up high enough, so I have had to remove the welded in bolt and file a square hole and use a coach bolt instead. There is enough room with the prop undone to lift the bolt out
2/. I was underneath the rear of the prop when I took it off and all of the oil in the little void at the end of the prop and in the end of the pinion, dropped straight into my ear. It actually filled my ear!!
Berating myself for being so daft as to lie right under a bit filled with oil and cussing a bit, it took me a minutes or so to realise that there shouldn't be any oil in there
A year or so ago, when I had just finished installation, I wrote this - "Other noises are a whirring noise from the back, possibly the diff. I do wonder if it's been sitting around for some years and just needs to be driven around to quieten down (I hope it's this one), or a bearing, or even the new prop? Not sure yet but I'll find it. It's only audible with the radio off, all windows closed and above 60mph."
More pondering. Diff has a noise, albeit a very quiet one, and now it leaks...... Not only that, but the driveshafts are out, De-Dion is out, and the diff is only held in with three bolts, brake pipe and handbrake cable. Is it worthwhile actually dropping it out and getting an expert to have a look at it as it's very nearly out anyway?
I had a chat with a local diff man and he did say that driving it around would "possibly" quieten it down but as it did need a front seal and was very nearly out, it would be best to give it a good check over. Here is one of the bearings
My credit card was in tears for two weeks! and my wallet is still in therapy!
Anyhoo, diff is back, all rebuilt and set up like a proper job
Put the brakes back on, all dressed up, and popped it back in.
Now I'm back to where I was when I dropped the prop off.