The first stage since I have the dash out for wiring is to mount the bracket for the clutch master cylinder on the firewall and cut the access hole.
I was unable to get a bracket from the dealer so I cut one out of a parts car. The bracket is spot welded into the firewall. Either there was a welding inspector standing by or the guy doing the welding was pushing for a promotion because the bracket is welded at one inch intervals - over kill even by Porsche standards.
I purchased a spot weld drill from Eastwood Products but a drill works just fine. At first I tried to drill the bracket out from inside of the car, but this becomes labor intensive in a hurry and there are a few welds that cannot be reached. So I took a Milwaukee Saws All (always use the best tools) and a long bi-metal blade and cut a corner off the body. (Its a parts car - right!) With the part off the car it is much easier to work with.
Some must die for others to live
Once the part is off the car it was easier to back drill the spot welds. This works best because there are then no holes in the part you are attempting to save. I used a die grinder with a wire wheel to remove the body shutz that is sprayed everywhere. This makes it easier to see the spot welds.
The bracket for the clutch master wraps around the side of the pedal support. While difficult to drill out the welds, the bend in the bracket makes a perfect alignment spot for positioning the bracket when installing it. There is a temptation to just cut this lip off to save time, but without it the final position will be difficult to guarantee. Positioning of the clutch master is very important as a bad angle can cause the cylinder to fail prematurely. There is probably no job that I hate more on a 928 than replacing the Clutch Master Cylinder.
Spot welds are strong so even one missed weld makes it almost impossible to get the bracket separated. Once all the welds are drilled the bracket separates easily with no damage. A little tapping, grinding and bead blasting and it ends up "like new".
Success
Making a template - Before the mounting bracket for the clutch master can be installed an access hold has to be cut in the fire wall. I was concerned about the difficulty of this task and the degree of accuracy that would be required. The hole in the firewall is fairly big to allow clearance for the cylinder. So back to the part I cut off. This time I used a jig saw to cut out the part of the fire wall for the hole and the portion of the firewall that goes over the brake booster bolts. The template can be attached to the bolts that hold the brake booster insuring a correct placement of the hole. I attached the temple and cinched it down with a couple of nuts. Then I used some spray paint and an awl to mark the area.
Cutting the hole - At first this seemed like it was going to be a difficult task, but the corners are round so I just used a hole saw and made a couple of overlapping holes. This I finished off with the jig saw and a die grinder. Total time about ten minutes. End result a hole that looks factory. Without the template this would have been difficult. There was some insulation left on the outside of the firewall that was easy to cut with a utility knife.
Mounting the Bracket - Once the hole is located installing the bracket is a snap. The bottom of the lip on the bracket lines up with the bottom of the brake bracket. There are a couple of spot welds that also help with the alignment. I used a outside caliper to further verify the position in relation to the donor firewall. With the bracket held in place with Vice Grips I drilled two locator holes for pop rivets.
To secure the bracket I used JB Weld and pop rivets. With the two locator holes and the wet JB Weld it is easy to install the bracket and then drill the rest of the holes for the pop rivets. Since Porsche went over board with spot welds I did the same with pop rivets. Between the JB Weld and pop rivets this thing is never coming out of there. I will finish the rest off with a little body sealer and paint before the insulation goes back in.
At this point the worst is done and the rest is down hill. The pedal installation is a bolt up. Total time about a half hour. The clutch pedal goes on the same shaft as the automatic brake pedal. There is a plastic spacer that has to be removed from the mounting shaft. The spacer is replaced with the clutch pedal. There is room for the automatic pedal but that just looks weird. The brake pedal shaft and brake light switch has to be adjusted back to be even with the clutch pedal.
There are a few other items worth noting.