1 During July, 2000 I purchased a used set of Unorthodox Racing underdrive pulleys from the same person I had previously bought the Hamann pedal covers. He had a 1998 M Roadster and was planning to install a supercharger. The underdrive pulleys are incompatible with supercharging and he was forced to remove them after only 4 months of use. His loss was going to be my gain, or so I thought. The pulley set is part #0402003-03, the red anodized pulleys that are supposed to fit all late-model 3-series, according to the Unorthodox website. The chart said the pulleys should fit my 2000 2.5L Z3, but I double-checked with a technician at Unorthodox just to make sure.
2 I received the pulley set and the shortened belts from the 1998 M Roadster a couple of weeks later. Everything looked to be in order.
3 I decided to use Last Minute Racing in Stratford, CT to perform the install. They are a team of BMW's competing in the SCCA SpeedVision World Challenge Series. Next year, they will be moving up to the GT series in Porsche's. They do not advertise and do performance upgrades on a referral basis only. The owner and lead driver is Alain Chebeir, who came highly recommended from Unorthodox and several other sources. I talked with Alain on the phone to setup the appointment and he was the consummate professional, just the person I wanted to work on my baby. Being the engineer that I am, I also arranged with Alain to do a before and after dyno run. LMR does not have an in-house dyno (yet!), but uses Action Engine Machine in Bridgeport, CT.I showed up at Last Minute Racing's well-hidden garage at 9:45 in the morning. All was suspiciously quiet and empty. I was about to head out for a coffee when Alain showed up in his Porsche twin-turbo, delayed by traffic on I-95. He climbed into the passenger seat and we headed over to the dyno facility in Bridgeport for the "before" run.
4 Waiting to go into the dyno bay at Action Engine Machine.
5 The green RPM pickup cable, clipped to the coil on cylinder #1.
6 The technician on the left verifies that the car is instrumented properly, while Alain Chebeir oversees on the right.
7 The car is strapped down onto the dynomometer by 4 belts. 2 lower belts go straight, and the upper 2 angle in to keep the car from moving. Alain is in the drivers seat, doing a run in 3rd gear. The technician is holding the control panel for the dyno as he signals with Alain. Once Alain hits the rev limiter, he puts in the clutch to let the car coast to a stop. This serves 3 purposes. First, there is no airflow over the brakes to cool them down as there would be in a normal driving situation. Second, the street brake setup could never absorb the heat of stopping the wheels and the massive dyno. Third, the coasting gives the dyno a chance to measure the drivetrain losses rearwards of the clutch.
8 Here are the dyno results of my stock 2000 Z3 2.5L roadster done in 3rd gear showing horsepower and torque plotted against RPM. After we unhitched my car from the dynomometer at Action Engine Machine, Alain and I drove back to Last Minute Racing's garage to begin installation of the underdrive pulleys.
9 Back at Last Minute Racing's secret facility, it was now time to begin installing the Unorthodox pulley set...A customer's silver M3 had to be taken off the lift to make room for my topaz blue Z3. It is probably hard to tell from the photo, but that is a Remus carbon-fiber exhaust on the M3. It also has lots of other (very expensive) goodies from Last Minute Racing, not the least of which is LMR's own custom-built supercharger. The whole dash pod has had custom aluminum faceplates made for the dials and the headlight housings have been retrofitted with Xenon HID bulbs. The suspension system has also been reworked from the ground up.
10 Two of Alain Chebeir's techs, removing the factory pulleys from my car. I wish I could remember their names, but they were very thorough and very professional. Well... they did curse alot because the engine and manifold were so hot from the just-completed dyno runs!
11 With the OEM pulleys removed, installation of the Unorthodox pulleys began. Unfortunately, nothing was lining up properly. The Unorthodox power-steering pulley seemed to have a completely different offset than the factory pulley. I agreed with the techs that not underdriving the power steering wasn't the end of the world, we would just leave the OEM pulley in place. They then removed the main crankcase pulley and it became obvious that the Unorthodox replacement was not going to work here either. The Unorthodox crankcase pulley does not come with its own vibration dampener ring. On earlier 3-series vehicles, the factory crank pulley is a 2-piece unit. The pulley can be easilly separated from the vibration dampener and the dampener can then be attached to the underdrive pulley. This is apparently not the case for late-1999 and later Z3's which have a crank pulley and vibration dampener ring that are a single, inseparable unit.Alain Chebeir, in the foreground, surveying the situation.
12 The offset incompatibility is obvious between the Unorthodox power-steering pulley on the left, and the OEM pulley from my MY2000 Z3 on the right.
13 As of mid-1999, the Z3's main crankcase pulley (at the right) is a single piece unit with the surrounding vibration dampener ring (the wide diameter section at the bottom). The dampener cannot be removed and installed on the Unorthodox pulley.Alain then telephoned an engineer at Unorthodox Racing to relay our findings and determine if they had any solutions. It immediately became obvious that when the head driver of an SCCA race team telephones an aftermarket supplier, the level of cooperation is much higher than when I had called several weeks earlier. As best as I can determine, it seems that Unorthodox had some awareness that the pulley arrangement in the Z3 had changed in mid-1999. However, they had never received any real fitment complaints and had never formally tested their pulleys on a MY2000 vehicle, despite their prior assurances to me that the application worked. In fact, the Unorthodox engineer talking with Alain seemed surprised at first that the vibration dampener could not be separated from the factory crankcase pulley. The engineer then suggested to Alain that the Unorthodox crankcase pulley should be installed bare, with no vibration dampener.After the phone conversation with Unorthodox, Alain and I spent several minutes going over the possibilities. He was extremely dubious about installing a main crank pulley with no vibration dampener in the front. Admittedly, I would still have the flywheel at the rear of the engine to absorb vibration. From experience, Alain told me that no matter how well balanced the engine and crankshaft may be, there would still be a noticeable loss in smoothness to the engine and there would be additional stress placed on a crankshaft that is not designed for flexibility. The bad news would be that my crankshaft might last 10-20K miles and then snap. The good news would be that BMW would probably buy me a new engine. Ultimately, the decision was up to me based on the facts.
14 The other side of the Unorthodox crankcase pulley and the integrated vibration dampener on the Z3's factory pulley.It didn't take me long to decide that this was a game that I did not want to play, and Alain and his techs seemed visibly relieved. They then started the process of re-installing the OEM pulleys and belts, while I headed out for a quick bite of lunch. I intend to sell the Unorthodox pulley set to someone with an earlier model Z3, where the fitment is correct. I can then use the money (and education) towards my next upgrade. So, the upshot is that I spent a bit of money needlessly. On the other hand, I learned alot, obtained dyno charts for my stock setup, and found a wonderful installer and guru who I would not hesitate to use for any major upgrades in the future.
