This post is to log my attempt to fix my daughter's transmission on her '01 Audi A4 Quattro with 01V transmission (ZF 5HP19FLA.) I will be updating with photos and info as I go.
Reverse gear does not work after the transmission has warmed up. I googled that, and found a common problem is an o-ring in the valve body popping out. That seems to be the case for her transmission. Pic below:
The clip is broken, and the o-ring is popping out. In fact, the piece of o-ring you can see fell off when I removed the broken clip.
Pic of the good clip on the left and the bad clip on the right below.
I found the broken piece in the transmission pan.
The part for the o-ring is 0734 313 190. I found it at https://cobratransmission.com/
The part for the clip is 1060 327 119 but so far I can't find anybody that sells it.
I thought about making my own clip, but I want to be careful that it's not going to fall apart. On my first attempt at bending one, a piece broke off from metal fatigue while shaping it. So I thought of something else.
Below is a pic of how the other cylinders are retained.
Note the inverted "T" on the left. The one on the right is the same, but the "T" is hidden. There are several more like that. The "T" is toward the center layer of the valve body so it can't fall out when it's assembled.
The reverse cylinder, and the other one the same size to the left of it, also have slots at the top and bottom, but there's no room for a "T" head because one side is blocked. There is, however, room for an "L". So I came up with this:
(The scoring on the piston is from the old clip.)
16ga steel. About 34mm tall. Stem of "L" 8mm wide. Lower part of "L" about 13mm wide. Thickness of lower "L" about 3mm. Give or take. This was rough-sawn with a hacksaw and filed to shape in a vise.
Not sure yet whether I'll just use this, or keep trying to find the "official" clip. I think my solution might even be sturdier than the original. No wire to break, just solid metal. It doesn't block any passages. The slot toward the bottom of the "L" is up against solid metal in the spacer, for both cylinders. It's at minimum a backup in case I can't find the clip anywhere.
To be continued.