Just a quick word about acid corrosion...the best way to deal with this is to prevent it from happening or catch it before it gets too far along. There are two products I've seen that are specifically for battery acid neutralization and corrosion prevention...both available in a spray form from Pep Boys and other fine retailers (just check out the battery sections). The first product is a foaming cleaner that neutralizes the acid (baking soda?). Spray in all over the tray area, the rad fan shroud/switch (if your's hasn't yet dissolved!) and over all the electrical connectors nearby. Let is do it's thing for a few mintues then hose it off. Repeat if you're as paranoid as me! Let everything dry out (now is a good time to take your other car to the shops to by the Optima!). Then decide if you want the corrosion inhibitor...this stuff is really just an oil based spray (much like linseed oil used for chassis/under body rust proofing back in Canada) but they've dressed it up a bit with some purple colouring (matches my car's paint!). It's great to creeping into all the little nooks and crannies where acid and rust like to live. And it doesn't seem to drip off the surfaces. However it does attract grit and grime...so don't put it everywhere. Alternatively, you could go the wire-brush, primer and paint route (but hey, it's just the battery tray!).
On to the install. The posts on the Optima are located at the front to back midpoint of the battery top, unlike the stock VW battery with the posts at the rear corners. For the positive cable, this present on real problem as there is enough slack to still reach the new position. However, the negative cable doesn't reach. The reason is this cable has a metal "tang" crimped onto it about 8 inches from the clamp. The tang has an eyelet on it and mounts to a stud at the back of the battery tray.This provides for chassis grounding. The cable then continues on unbroken to the engine block ground point. The effect is that the clamp to chassis ground has virtually no slack, while the chassis to engine ground points have a fair amount of slack. As a temporary solution (it was late on a Saturday when this was done and I'm lazy about going to shops on Sundays!) I rigged up a short (2-3") piece of 12 gauge wire to serve as a chassis ground. I put a crimp-on eyelet on either end of this wire and bolted one end to the stud on the battery tray. The other end was lined up with the negative cable tang eyelet and a nut & bolt was used to hold it all together. This provided the necessary slack for the clamp to reach the post and also made for an adequate chassis ground. However, I prefer a more stock like setup so when I get the time I will make up a new cable (4 gauge multistrand) without the tang arrangement. I've made up complete main cables for my Rabbit GTi before and it was dead easy and cheap ($15 in parts). Also, New Dimensions can make up very professional cables to your specifications (I think they even put gold terminals on those suckers!). For the more cost-restricted among us, most readily available aftermarket battery cables have additional lines welded/crimped to the main clamp for the purpose of chassis grounds. You just need to find one of the right length and with a low gauge number ground line (the corrado likes lots of chassis current to run those fancy seatbelts etc.).
Another point to mention is the battery hold down clamp. Most North American batteries I've come across have a clamping ledge that is too low/thin for the stock VW clamps (same is true on my '84 GTi Rabbit). The Optima is no exception here. Trying to hold the battery with the clamp is not adequate and you'll likely end up with the rad damaged when you make a tight left turn at speed and the battery slides free. The Optima has a curved surface right where the clamp makes contact and this can create a stress point on the plastic battery casing. So, I took a curved file (grinder will also do) and files a concave edge on the clamp metal (easy, soft material). Then to provide better grip, I cut a short pice of 1/4" fuel injector hose along it's length and sliped over the newly curved edge of the clamp. I also put a second length of hose along the rear hold down bracket. Dropping the battery in place I immediately felt the rubber hose cushioning it front and back. Torquing the clamp down made for a very secure battery.
Michael Dobbs
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