11-02-09 

We are rebuilding a set of Audi dual piston calipers for our Tornado red Corrado G60. We are taking this build to the max like we do with everything. We will even be employing our EPMtuned custom Stainless Steel Audi dual Girling G60 piston set. It will consist of 4 SS pistons and seals to do a complete rebuild on both front calipers.  

11-09-09

Got all the parts cleaned up ready for painting with our caliper paint. By the way the color will be red. Also forgot to mention that these calipers are salvage yard items and were not in the best shape but are worth rebuilding. There was some corrosion pitting in the cylinder bore. A little corrosion pitting will not affect anything, to much and your calipers could start leaking. We did mention that we were going to use our SS pistons but we are not, our calipers pistons have no corrosion non at all so we threw them in our vibratory polisher and they look awesome so we decided to reuse them.

At this point we are ready to paint but we have to wait for the rear MKIV calipers to be ready also. All we lack is to blast the original Corrado G60 caliper carriers.  

11-13-09

We ran into a little problem here but nothing we can't handle. The Audi dual piston calipers use a male end at the caliper. Our Corrado is a 1990 model and was manufactured with the front brake lines having female ends on both ends of the line as the caliper has a nicely engineered hard line and support bracket, this hard line turns to face the female end of the brake line and uses the dimpled bracket for support. This bracket is dimpled and keys to the dimples on the caliper for even more support and is attached to the caliper with a single bolt, the Audi caliper has no dimples and no bolt hole for this bracket. 

It appears that there was a caliper brake line update for the later 1990 G60's and on. The new line has a female on one end and a male on the other. We did some research and found that the late 1990 Corrados have a different part # for their brake line. The change went all the way thru to the VR6 brake line as the Late 1990 Corrado G60 and later Corrado VR6 brake lines have the same part #. We like the old way VW did the brake lines. It looks like VW realized they could shorten the parts count here with only a brake line change.

We played around with all three brake lines for the best possible setup, the early set up that our Corrado came with that we found out we can make work but leaves the short hard line without the small support bracket that the Audi Dual calipers will not readily accept. We can make it work but were not about to reengineer the system here there is no need it has already been done we are just looking for the best setup for our Corrado. The second set up is the late Corrado brake line which seams to be too long for our liking but will work. The third is the Audi brake line that we like the best and is less than 2" longer than our original. When we do our install we will know for sure.

Stay tuned.    

11-14-09

Problem #2

This problem turned out to be a bigger one than we first thought. We blasted our iron calipers and stripped them clean of everything exposing the raw metal. In this state iron is very prone to corrosion. Our biggest concern is the caliper piston bore, as brake fluid is also very corrosive, combine the two raw iron and brake fluid and your asking for trouble. Were not concerned about the carriers for three reasons one they are not in constant contact with the brake fluid and two we will be able to see any corrosion starting to happen and three they will be protected by the caliper paint.

In a later write up we will detail our plating efforts using an industrial quality at home plating kit from Caswell. 

So how do we solve this problem now.... We are buying brand new Audi Dual piston calipers and carriers and they come corrosion plated from the manufacturer for this same reason. 

On the rear calipers there is no concern since they are aluminum. In fact we took a piston out to replace the seals and the highly polished piston bore looks brand new.    

12-09-09

We did a little research on our Audi calipers and consulted with experienced builders. So our decision to go ahead with this build was solely based on what we learned from  fellow experienced builders. We were going to purchase brand new calipers and corrosion plate our used ones. It has been determined that the brake fluid is not corrosive to metal in the absence of oxygen and water moisture. While it may still react with the caliper metal it will not corrode but will form sludge inside the caliper from use and the heat cycles from braking. Also minute amounts of  moisture and oxygen will be present thru seepage from the seals and also by adding contaminated brake fluid. Brake fluid is hygroscopic meaning it likes to absorb water moisture. This is why it is manufacturer recommend to replace the brake fluid (Flush) in the brake system every 2 to 4 years.

What this all means for us is that it will be ok to continue with our Audi dual caliper rebuild. More pics coming and we will be finishing up or brake upgrade.