May 19 2008

Rear end.

I started disassembly from rear end which is easier to access. But the main reason is, I can get clearer idea about rear differential - a challenging point as I'll have to find something suitable with desired ratio and that will fit. While I'll search for it fit, I can work on the front end.

Disassembling something put together by someone else is easy part - easier than create something no one has done before. Anyway, taking parts off won't take very long time. The key is to prepare good information what's where and necessary tools. Regarding information: I ordered Audi factory manual from Bentley publishers. It is by far the most complete source of info, but it isn't meant for garage mechanics never dealt with Audi before. It is for service technicians to remind them what the sequence of actions is to achieve certain tasks, but who have done removing/installing things before, and got some training. For instance manual will specify in the sequence to remove engine: remove oil cooler, remove A/C compressor, remove generator. It won't get to specifics *how* to do it. They assume you know, and just may not remember which unit goes first. Sure you can search for removing/installing of A/C compressor separately, but it will be the same story - unplug gray connector from evaporator, remove oil cooler, drain ATF fluid. Where is that gray connector? What is the dash going to complain about if I don't plug it back? How evaporator works (what kind of signal is being sensed so I can mimic it)? The manual won't tell. IT will tell you how to unbolt one, not educate you what the unit you're unbolting is for. Nevertheless, without this manual my work would be more difficult and investment is well worth it.

So, I wanted to clean up rear end from unnecessary components: gas tank, heat shields, all pipes and tubes to the filler neck, and remove fuel system related canister in the spare tire cavity with all its tubing The gas tank is above everything - rear differential and shields. To remove the tank I also have to remove parking brake cables as they won't allow lowering the tank. Here is what I did:

This is what rear suspension look like. Note fancy gas tank with cutout in the middle.
The differential is supported by wood blocks.
Rear half shafts flanges are unbolted from the differential and set aside.
Side and rear of the diff unbolted from the cross member and it's free to lower.
Another view. You can see threaded holes for 3 bolts holding rear of the diff.
Now I can lower it.
Nice room for a new diff.
This is what stock unit look like. The R&P ratio of this one is 4.11:1. I wish Audi made 5.7:1 or so.
Wonder now much does it weigh - I have to keep balance of things removed an things installed. 24kg.

Next one is gas tank. There is something especially satisfying in freeing the car forever from nasty chemicals.

Supported tank. The straps holding it underbody now can be removed.
But first - brake cables which are on the way. Removing ends of cables on the wheel side
Now - the straps.
Rear frame carrying whole suspension has to be unbolted from the body as the tank couldn't be removed otherwise. The frame is hanging on the shock absorbers.
The moment of truth...
The gas tank on the floor. Huge.
The space in front of the tank toward drive shaft tunnel. Just enough room to fit the motor. Bottom of the motor, as measured it is flush with the car underbody Nice!