Transmission

Transmission

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With the race coming up the next weekend, I started installing and replacing the transmission for my 318i. It was going to take a lot of work and a lot of luck to make it to the races. I was not confident that I would succeed, but I buckled down, warned my girlfriend not to expect to see a lot of me, and cracked my well-worn Bentley bible to "Transmissions". I didn't begrudge the transmission for failing – after all, it had over 200,000 miles, including five thousand tough track and race miles. There aren't many transmissions that will put up with that kind of abuse! I was quite tired from spending the weekend racing, but I knew that I didn't want to miss the last race weekend of the year, so despite my misgivings, I started work.

The previous race weekend at Portland, the guy in the paddock spot next to me had a similarly tough project to do – in a lot less time. He had recently removed the mechanical fan from his ‘70’s Dodge Dart, but discovered that the car was overheating. When remounting the fan, he had poked a hole in his radiator. All his coolant leaked out in the morning practice session. As I’ve mentioned in the past, that's bad. Dart-guy spent the rest of the afternoon looking for somewhere that could weld his radiator, while two friends helped pull both of the heads. It turned out that the heads were warped, and had to be machined flat again. In classic race track fashion, they fixed the radiator, machined both heads, replaced the head gaskets and put it all back together again in time for him to make it out Sunday morning. Not very long ago I thought an oil change was challenging. If they could do all that in a day, I could do a transmission in a few evenings!

The first job was to get the car off the ground, as far as my jack stands would reach. It made me nervous, as I had never worked with my car this far off the ground, but this was necessary for there to be clearance under the car for both me and a transmission. I already had a headstart on the job, because the driveshaft had been pulled at the race track the day before.

I needed to confirm that there was a problem with the transmission and not the clutch. With the car off the ground, I started the engine, being careful not to jar the car on the stands. I don't advise that you do this! I peeked under the car so that I could see the output flange of the transmission. With the car in neutral, the flange still spun. This is normal, but when I reached up with a dowel to try and stop the flange, it just about ripped the dowel out of my hands. This isn't normal. When I depressed the clutch the flange slowly spun to a stop.

From what little I understood about clutches and transmissions, this meant that the clutch mechanism was working properly, in that it properly disengaged the engine torque from the transmission. The transmission, however, appeared to be stuck in first or second gear – i.e. it was busted. Rebuilding a transmission would cost about $1200, so I decided to go with a junkyard replacement for $275.

Following the directions in the Bentley manual, I began undoing the bolts that hold the transmission to the back of the engine. Most of them are relatively easy to get to, but several of them are quite difficult. One of them doubles as a fastener for the starter motor and is a big pain in the butt, as it requires three inhumanly flexible hands. Once the transmission was unbolted, it was simply a matter of sliding it off the engine output flange.

My neighbor Ted, an old Datsun roadster guy, came over and helped. Which was good, because I managed to drop the tranny – URKmmmpph – on my face. Luckily, BMW 318i transmissions aren't very heavy, and my face doesn't have much to recommend it anyway, so there was no expensive damage done. I gave the transmission a little shake, and it rattled – there were big chunks of loose metal in it! With the transmission off, the clutch mechanism was exposed. I inspected it for damage or wear. The racing clutch that had been installed in June looked barely worn. As I didn't really have the time or money to spend replacing the clutch, I was glad to see that it looked okay.

I had picked a new transmission up at Aurora Autowrecking. Neither Strictly BMW or the local dealership had the necessary front and rear transmission seals, so I ended up installing the "new" transmission without seals. This was not desirable, as replacing them on the car is a lot of work. On close examination I also discovered that the shift rod bushing, where the shifter enters the transmission, appeared to be very worn. So I swapped it with the original one from my car.

My neighbor Ted came over again and helped me lift the new transmission into place. I had purchased a fancy transmission lift tool, but it turned out to be complete overkill for the dinky little 318i tranny. We used a jack to get it most of the way up. Then, while I supported the tranny with my arm (and face), he slipped the transmission input shaft into the hole in the clutch mechanism. I wiggled the tranny output shaft a few times to get the ridges to match up properly and the transmission snicked home. I quickly got a few bolts started to hold it in place.

Assembly, as they say, is the reverse of disassembly. Or something like that. It was Thursday evening and I still hadn't even begun the normal prep work for the car to get it ready to race. I worked slowly and carefully bolting the transmission back into place. Because I'm not a well organized person, I double and triple checked my work to make sure I hadn't done something (obviously) stupid. Once the transmission was completely bolted to the engine, refilled with clean lubricant and the shifter properly mounted, I redid my dowel test from several days previously. This time when I held the dowel against the transmission output flange, I was able to get it to stop spinning without exerting much effort. From inside the car, I tested that I could shift into all gears. I was able to do so with no problems. This that the transmission worked.

I finished mounting the driveshaft and exhaust system Friday evening after work. Then it was a matter of bleeding the brakes, running through my normal pre-race weekend routine, packing my tools and safety gear and getting the car on the tow dolly. I was absolutely exhausted after working late every night that week. A part of me was looking forward to the off season as a chance to recuperate, but at the same time I was excited about the races Friday and Saturday. I slept like a log, and could barely drag myself out of bed Saturday morning. The uncertainty of the race weekend made me nervous – there were two more races to go before the season was over, and if there's one thing that I've learned, it's that anything can happen. Anything.

Saturday morning, October 5^th, dawned cool and with a light drizzle. Just a few miles from the house I heard a metallic rasping from the towed racecar. I knew immediately what it was. The shifter was too close to the re-installed driveshaft and was lightly scraping. I pulled off into the rain-soaked parking lot of a Safeway, grabbed a wrench and went to work under the racecar. What was easy in my lit, dry carport with the drive shaft removed was far more difficult in the parking lot. It took me close to an hour under the car, swearing and dropping the wrench on my face. Just as I finished up, a fellow who had parked next to me asked, "Hey, do you race that thing?"

"I try," was my response.

"I really appreciate what you do," he said. "I love motorsports, and I think that it's the amateur stuff that keeps it alive. It must be a lot of work."

Man, if only you knew!