Q – I want my 88 Carrera to sound better. I can barely hear the engine. Some of my buddies took their cat convertors off and they sound better than mine but I want to keep the cat since I don’t like the way their cars smell. I am thinking about a Dansk stainless steel muffler with dual tips. It looks simple with only three bolts and two big clamps holding it on. I am pretty handy and I was thinking about doing this myself. Got any tips? – Steve
A—I am familiar with the Dansk products and they are very nice indeed…top quality, great finish and they fit like factory parts. Installation should be fairly straightforward but there are a few issues that you need to be aware of.
Since the new muffler has two tips and your rear valence panel only has one cut out, the panel will need to be removed and modified if you decide to bolt it back on. I use the word “if” because some folks prefer to leave it off and look at that shiny stainless steel muffler. To get the valence off, there are a few Phillips head machine screws that you will need to remove. These steel screws in the aluminum bumper do not come out without persuasion. My method of removing them involves heating with an oxy/acetylene torch. As you judiciously warm up the bumper, the aluminum heats up and expands much more rapidly than the steel screw. The difference between the rates of expansion breaks the rust bond. Using a pair of mini vise grips on the shaft of the Phillips screw driver will give you just the right amount of leverage to unscrew them without a fuss. You will need to have the vise grips set tight enough that they are actually “digging in” to the metal of the screw, or they will simply slide around on the screw head.
Caution: Whether you are using a torch, map gas or a Bic lighter, flames, fuel and cars do not mix so have a fire extinguisher near by and a helpful friend to make sure you do not catch your hair (or your car) on fire!
With the valence off, prepare to unscrew the giant stainless steel band clamps that hold the muffler to the rear engine bracket. These clamps have a captive nut on the top and an Allen head bolt coming up from the bottom. They are very expensive and worth saving if you can. You should expect the bolts and nuts to be frozen from age and rust. I have seen some ugly attempts to loosen these. This next bit of advice can save you some grief and money.
Spray penetrating oil on the three cat-to-muffler bolts and the two band clamp nuts and bolts. Next chase the threads on the exposed part of the clamping bolt that sticks out of the clamp. If you don’t clean the threads, when you try to unscrew the bolt from the captive nut, it may seize and twist the clamp as you try to remove it.
The next surprise to the unwary is that the captive nut tends to spin in the band clamp as you try to unscrew it. This negates your effort to save the clamp! You can prevent this by gripping the captive nut with baby vise-grips. Now if you think you can unscrew that Allen bolt…Surprise! It is seized tight! So take the vise-grips off, light up the trusty oxy/acetylene “heat wrench” (Map gas will also get the job done) and apply enough heat to warm the captive nut cherry red. Then take a break and give it some time to cool a little, five minutes or so. Spray it with penetrating oil again. Be ready for the comment “what’s on fire” because it will smoke as it evaporates. This process is another method to break a rust bond.
Get hold of those captive nuts with the vise grips again, and then after a few small hits with an impact wrench the bolt should spin right out. Once the bolt is out, clean the threads of it and the captive nut so you can screw them in and out by hand and they are ready for reassembly.
Now you can remove the muffler: Caution: Before you try to unscrew the next three bolts, support the muffler by temporarily re-attaching those two bands to keep it from dropping on your foot. The muffler is secured to the cat convertor by three bolts and I guarantee that these bolts will not resemble bolts if you simply try to unscrew them. This is where the budding back yard mechanic earns his stripes (and learns a few new cuss words if he is merely assisting). Generally most under car exhaust components are attached with rusty bolts.
The easiest and cost effective way to remove them is by cutting the head off the bolt or the nut off the bolt depending on how easily you can access them. Even when you cut them, they will not come out of the holes without a fight. For this, I recommend an air chisel. Now I realize that you might not have an air chisel in your arsenal of tools but if you are going to work on your own car, it would be a good investment. Hobby quality tools are inexpensive and readily available at local tool stores. The action of the air chisel is two fold. It is an irresistible force that can push bolts through rust as it vibrates the components to turn rust into powder. As you get the last bolt out, it is time to celebrate. The hardest parts are over. As you sort through the pile of debris you can take stock of what you will need to put it all back together. You will need a new muffler gasket, three new bolts, six flat washers, and three nuts…all stainless steel if you can predict the future and live in Michigan.
So you are ready to install you new shiny cool muffler. Get two muscular friends to hold the muffler in position while you install the band clamps. You want the band clamps loose so you can position the muffler and wiggle it around as you install the three bolts to the cat. So just get the Allen bolts screwed into the captive nuts only four or five threads. I then usually install the easiest to reach bolt first (to see if I get lucky) then remove that first bolt and install the hardest to reach one. You notice that the Dansk muffler flange has oval shaped holes? Now you understand why! Due to production variations, lining them up is no problem. So now you have the three bolts started, the muffler roughly in position and it is time to align the tail pipes. Since the original muffler had only one pipe, alignment was not critical but now with two, if you don’t get them lined up, the tail pipes will be crooked.
With the new muffler on, your two beefy buds holding it in the best possible position, does it line up? No chance. What lousy luck…but you are not done yet. The cat is adjustable! Joy. That is, until you realize that you have SIX MORE RUSTY bolts to remove and replace in order to do it. In case you were wondering why it is so cockeyed, remember that your original muffler was hanging from just one three bolt flange for all those years and now it needs an “adjustment.” If you got this far, you are on the home stretch! So if you are willing to buy some tools, go through the work and do it well, it is a thing of beauty and your Porsche will sound like a Porsche should! The added benefit is that you will acquire new friends when they discover that you did it yourself and might have some tools they can borrow. With the money you save doing this yourself you can take your better half out to a number of very nice dinners as well.