Last week, I had removed Louie’s rusty resonator and muffler and was about to hang my pretty new ANSA “standard” exhaust when I realized that with the resonator out, I really should drop the driveshaft and giubo and replace the leaking transmission selector-shaft seal. I did that—but then the transmission rear seal wanted in on the action. It teased me. It mocked me. “How do you know I’m not leaking too?” it taunted. “You’re going to wake up at 2:00 a.m. obsessing about me. Come on, you know you want to. Do me. DO ME! You’re totally going to regret it IF YOU DON’T DO ME! A real man would!”

What, your seals don’t troll you? Must just be me.

The seal was right, however. With the back of the transmission wet, and the differential and giubo already out, even if you think that all the leakage is coming from the selector-shaft seal above it, it really is silly not to just replace the rear seal as well.

Yeah, sure, my own personal devil’s advocate interjects, provided that the parts are inexpensive and won’t take forever to get here.

There’s a metal lock ring for the output flange, the seal, and the gasket underneath the plate the seal sits in. While it was true that it would never be easier to replace the seal than right now, there was also no evidence that it was leaking. So what’s your peace of mind worth to you, bub? How much of your time and money is it worth to prophylactically replace a transmission rear seal that you have no evidence is leaking, just because you happen to be in the neighborhood?

Let’s be clear about something: I am not cheap. Heaven knows, I spend money like water on all sorts of car-related things. But I can’t afford to let every loquacious seal sweet-talk me like this. I can’t let every repair on every car mission-creep its way into a restoration, even a modest mechanical one of a single component. I’d bankrupt my family into the year 2525 if I did that.

If you’re like me—and a truly frightening number of you appear to be—sometimes a number just pops into your head: Twenty-five bucks. Absent any evidence the thing is actually leaking, the peace of mind is worth twenty-five bucks.

Hey, at least it’s an answer.

I looked online. The seal was as low as $14 and the lock plate as low as $2.50 at mail-order dealerships like GetBMWParts, but the dealer cost of the gasket was a surprisingly high $24—all of that plus shipping. An aftermarket gasket is available for as low as $4, but many of my usual vendors didn’t have the aftermarket gasket, or had it but didn’t have the seal. The only one who had the magic set of all three, including the inexpensive aftermarket seal, was Pelican Parts. Adding the cost of USPS Priority Mail, their total was $33.50.

Close enough.

Pelican has one of the best websites in the business, giving you several delivery options and showing you visually, on a calendar, when the item will ship and when it will arrive. It was currently Thursday. Pelican is in California; using USPS Priority Mail, delivery would be the following Tuesday. Faster delivery options were expensive. Drat—I really wanted to get it buttoned up over the weekend.

Although Amazon is spotty as a car-parts vendor, they will sometimes surprise you. They had the gasket for about $6, with free shipping. Great, I thought. However, Amazon did not have the seal or the locking plate for a decent price.

I thought, okay, I’ll order the aftermarket gasket from Amazon, and order the seal and the lock plate from my local dealer (Herb Chambers). Their discount isn’t as good as GetBMWParts, but these are inexpensive items; the difference is just a few dollars, and they typically get stuff in two days. There’s no shipping charge, although I do need to drive into Boston to pick the parts up. I called them up and placed the order.

Then I went to finalize the Amazon order for the gasket and noticed that Amazon itself didn’t have the gasket—an “Amazon Merchant” did. This meant that the shipping wasn’t part of the highly predictable Amazon structure, where it’s free two-day shipping with Amazon Prime, and you pay a small premium for next-day delivery. With an Amazon Merchants, items shipped for free are often quoted as a week to ten days for delivery, and upgrading it to two-day or next day, if possible, is often very expensive.

Well, I thought, this is actually pretty simple. You want to pay $25? That’s your magic number? You’ve found a path to being able to do that, but you have to accept that you have to wait for the gasket. Louie isn’t going anywhere. It’s not really a big deal.

So I put in the order.

In the meantime, I pulled out the old seal. It’s pretty straightforward; you pry the lock plate out of the output flange, put a thin-wall 30-mm socket (I already own one) on the impact wrench, and whacketa-whacketa-WHEEEEE the output flange comes off.

Undo five 10-mm bolts holding on the seal plate, and off it comes.

I said, off it comes.

Well, maybe with a little prying, off it comes.

Forty-five-year-old asbestos gaskets can really have quite a death grip, particularly on aluminum. And they never seem to come off clean; they routinely shred. You have to scrape them off with a single-edged razor blade, wearing a mask because it is asbestos. Cleaning the gasket off the seal plate isn’t that bad, since you can hold it in your hand, but cleaning the sealing surface on the back of the transmission is tougher. Because the sealing surface is flanked by the sides of the transmission tunnel left and right and by the shift platform directly above, the number of good angles your hand and a single-edged razor blade can get are limited. An Xacto handle with a blade that lets you push it forward like a chisel is very useful on the vertical sections of the sealing face.

What I do is scrape what I can without risking gouging the aluminum, then switch to the Dremel tool with a little abrasive Scotch Brite-like wheel. I make frequent use of these for cleaning gasket surfaces. The Dremel part number is 511E, which is a set of two containing a coarse and a fine (180 and 280 grit) quick-release wheels. Be aware that these are consumables; buy a few packs.

The maneuverability of the Dremel tool was good enough that I could reach nearly the entire sealing surface. It cleaned up beautifully. But when you’re using these abrasive wheels on the remains of an old gasket that’s likely asbestos, seriously, wear a tight-fitting mask.

After I banged the old seal out of the sealing plate, there was nothing left to do but wait for the parts. On Saturday morning, I drove into Herb Chambers BMW in Boston to pick up the seal and the lock plate. When I arrived back home, I was delighted to find the gasket waiting on the porch, well ahead of the Amazon Merchant’s predicted arrival date.

Every once in a while, the universe likes me.

I pressed the new seal into the plate, coated the new gasket, and got everything installed in short order.

Oh, and I forgot last week to post the photo of the old, deteriorated, shrunken transmission mount next to the 320i mount I replaced it with. Dramatic, no?

Okay, now, back to the main event : the exhaust. I installed the used headpipe I had kicking around the garage, hung the new Ansa rear muffler, slid the end of the new Ansa resonator into it with one hand while holding up the front of the resonator with the other, slid the sealing ring between the flared faces of the headpipe and the resonator, and was about to start to bolt the flanges together when I noticed something—or, rather, I didn’t notice something: the sealing ring. It wasn’t peeking out between the flared ends of the pipes like it’s supposed to. Had I dropped it?

I separated the flared ends and verified that the sealing ring was inside. I again pulled the flared ends together, and again, rather than the sealing ring sitting between the flares, the flares engulfed it. What the—?!

On close inspection, although the mating flanges and the flares appeared to be the same size, the flare on the front of the Ansa resonator was deeper than the one at the end of the OEM headpipe, and the difference was enough that the sealing ring was completely swallowed, as opposed to being trapped between the flare faces—meaning that it couldn’t do its job of, you know, sealing.

I looked online. Ansa makes a headpipe for the 2002; was their exhaust not compatible with the stock headpipe? Was I supposed to buy their headpipe to go with the resonator and muffler? It seemed surprising. I also found that there is an Ansa part number for their sealing ring, but as with the issue I mentioned last week with the clamp required to attach the resonator to the muffler, these parts from Ansa appear to be NLA. At least they don’t show up on the sites that sell the muffler, resonator, and headpipe.

Well, I thought, there are two options. I can either grind down the flare until it’s the same depth as the one on the headpipe, or I can try a larger sealing ring. I elected to try the latter first, as I was concerned that I could ruin the resonator by grinding too much off the flare.

The stock sealing ring is 47 mm in diameter. I looked online and discovered that part number 18 11 1 723 721 is 48 mm—and thicker. Eight bucks and three days later, I had it in my possession. As you might imagine, being larger, it rode more on the front of the flare than inside it, but it seemed like it should work.

I tightened everything up, held my breath, and turned the key. Blissful quiet.

I put my gloved hand over the tailpipe. The exhaust was tight.

I’d recently completed some other necessary inspection repairs to Louie (low beams and horn), so I swung him by the local service station where I get my cars inspected. He’s now legal. So, after the gonzo thousand-mile drive from Louisville with a NASCAR-like exhaust, I can now tool around town in Louie in a more socially acceptable manner.

Unfortunately, all of this occurred just in time to put him back in the garage, because an April Fool’s day snowstorm is forecast.

Next week, the heater box. Which, with this crazy weather, I may actually need.—Rob Siegel

Rob’s first book, Memoirs of a Hack Mechanic, and his new book, The Hack Mechanic Guide to European Automotive Electrical Systems, are available through Bentley Publishers, Amazon, ECS Tuning, and Bavarian Autosport—or you can get personally inscribed copies through Rob’s website: www.robsiegel.com.