Header install and removal of stock differential (Originally posted 5/31/10)

As noted in the previous post, I aquired a used Goodwin Racing header for the car.  Since I'd already pulled out the stock header, the install of the new one only took about 10 minutes.  It will certainly be a good starting point for the car.  I still will need to get a different midpipe.  I'm inclined to go with Goodwin Racing here as well due to the cat, but it's not absolutely necessary.  Since DP is a non street legal class, I don't have to worry about any emissions items.  That said, no matter what I do, I'll need to have bungs for the oxygen sensors. 

I'm going to start with a Torsen in the car since I already had one.  Ultimately I'm going to go with either the OS Giken or the Mazdaspeed clutch type diff.  The OS Giken sure sounds like it is probably the way to go, but I have bigger fish to fry to get the car out on course, so that will have to wait.

So, today involved pulling out the stock diff on the car.  This is not a simple process, as you have to pull off both rear hubs in order to get the axles out of the diff.  I've done this a few times before, but I've done it on cars that were essentially brand new.  After 96k miles of use, the press fits of the multilinks and axle shaft in the hub were a little more challenging than I'm used to.  In any case, nothing a BFH and air hammer couldn't take care of.

In doing this work, I came across a couple of other items that will have to be purchased unforunately.  The bottom front lower link on both sides have a bend in them.  I'm not sure how this happened, but they certainly are the smallest of the links so it could just be that something as simple as hitting a curb when parallel parking could have done it.  On the plus side, these are also very inexpensive, so overall not too big of a deal.  What is a bigger deal is that the aluminum piece that the diff bolts to which then bolts into the car is apparently different between a manual and automatic.  I'm assuming that the difference lies in how far forward or backward the diff actually sits in the car.  Unfortunately, the list price on this about $280.  Obviously I'll get better pricing through Mazda Motorsports, but this is still something that I wasn't expecting.  I wish I had a manual one to compare to.  If it's a small difference, it might still be workable. 

While I was under the car, I drilled out the rivets for the heat shield that goes above the muffler.  This looks to be aluminum, but was heavier than I expected.  It's a little over a pound and a half, and every bit counts.