With the cooling department completed in part 9 (et 2/09s), our engine is ready for more power. But before we get into new components, there's one last thing to take care of - the clutch. After all, we don't want it to slip on our next test and skew the results. And with 145000 miles on the clock, it was probably a good time to change it anyway.
Several companies have played a vital role in this project and will continue to do so. One of them is BimmerWorld, from where we ordered the company's clutch and flywheel package. It features a factory pressure plate modified by ClutchMasters with beefier straps and a fulcrum-point change in the fingers. The result is a minimal increase in pedal effort with a much greater tolerance for high RPM and torque. It also has the benefit of being a perfect fit.
BimmerWorld owner and racer, James Clay, advised we use the CM stage 2 Kevlar clutch. While it can work with the factory flywheel, the company also sent us a JB Racing 10.5 lb lightweight aluminum flywheel (stock weighs 25 lb). To reduce any potential clutch chatter (common to lightweight flywheels at idle), we received a CM clutch disc with a sprung hub as well.
With the transmission removed, we knew it would also be a good time to do a short shifter install. Having enjoyed UUC short shifters on numerous BMWs, we ordered its new Evo3 shifter.
UUC reports this third generation shifter features near-stock effort with very little notchiness. Unlike the factory pivot bushing cup, which gets exposed to road dirt, UUC's new bearing system isn't open to outside contamination, keeping the shifter lubricated and properly aligned over time.
We also went with UUC's optional Double Sheer Selector Rod (DSSR), which eliminates extra movement from the factory selector rod, leaving only the play left by the transmission itself. The end result is firm shifter feel with minimal play in-gear.
We even decided to replace the starter at this time. Ours had been giving us problems over the last year, and it sounded as if the solenoid wouldn't move the starter gear to catch the teeth on the flywheel. At first, this happened once in a while, but within a week of our clutch install it did it every time, sometimes taking several tries to fire her up.
It was perfect timing to order a Bosch unit from Bavarian Autosport. These guys carry virtually every OE replacement part for BMWs at prices much lower than the dealer and have been our OE supplier throughout this project.
The Bosch starter is remanufactured, as opposed to rebuilt. Bavarian claims "a remanufactured unit is stripped down to the most basic parts. Everything is then cleaned and inspected, and all wearable parts are replaced, regardless of condition. In effect, the unit becomes a brand new starter, only re-using the core castings and machined parts."
By contrast, "a typical rebuild can be anything from a quick clean and test, to minimal disassembly and replacement of only the common failure points." What's more, you can generally only purchase a remanufactured starter from the dealer.
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