2000 V70R - AWD Rear Sub-frame replacement

[scot850]

I have started this new thread as I may add to my original plan of doing a rear e-brake write up and also attempt a write up on the rear sub-frame swap.

I have ordered a (hopefully) good sub-frame from Chapman Motors as I know they will find the best the have. If I planned to keep the car long term I may have considered having the frame powder-coated prior to install to try to prevent a repeat, but don't plan to keep the car. Also, the old one lasted 14 years (Canada winters and 265,000km) so maybe not worth it. Wondering if the issue is that new liquid anti-ice stuff they spray on the roads? Anyone know what it is made of?

I've copied over the questions I asked on the corrosion thread hoping after the large proportion of our follow correspondents in the US are basking in the after glow of Turkey dinner you may find time to help! Have a wonderful Thanksgiving!

So I am going to have to pull the sub-frame and replace it. I have never done this before, and need some advice from anyone who has dropped the frame.

Does the fuel tank have to be dropped? I don't need to access the tank for any reason, and it is full of premium fuel, so I don't really want to drain it down if there is no need (I have no where to store it).
Most of the info I have read about dropping the rear sub-frame is to do with accessing the fuel pump, but currently I don't have any issue with that or evap. issues. (I will now answer this myself to a point). Having had a good crawl under the car, wire brushing all bolts and nuts I could see and spraying liberally with Deep Creep, I can see the rear of the 2 halves of the fuel tank are supported by hoop straps that are hung at the front of the sub-frame. I still don't think I will have drop the tanks to remove them, but I will have to support the tanks with some bracing to stop them moving as the sub-frame is lowered.

If the tank does need to get dropped, then I may take a chance and run the car until the tank is nearly empty before commencing the strip down.

Looking at the whole rear axle area it seems to me that by removing the inner bolt of each of the lower swing axle support, it may mean I don't have to actually undo anything attached to that. It is probably too good to be true.

Questions:

1) I notice what looks like a slight leak from the rear axle seals at the differential. These have a great big old nut like the front axles at the rear hub. How does one prevent the rear axles from moving while undoing the nuts? Is it best to refit the wheels and drop the car back on the ground to undo the nuts?

2) I was also hoping to not have to remove the muffler from the axle back as it is getting crusty. Anyone know if this is a must to access any fasteners?

3) Is the rear diff actually bolted to the sub-frame by its rear cover plate? I was hoping again to support the front end of the diff housing and not have to undo any of the drive line. Thoughts?

Thanks folks!

Neil.