Programming Perfection: Running an Early Porsche Flywheel on Our Haas

Kallin from JB Racing takes you behind the scenes as we migrate an early Porsche flywheel program from our veteran Mazak to a newer Haas mill. The part fits early 911 and 914 applications, with versions tailored to clutch size and transmission packages. Moving a legacy program to a new platform is more than copy and paste. It means fresh code, new fixturing checks, careful first article runs, and a pile of small process upgrades that make the end product cleaner and more consistent.

From Mazak to Haas, with fresh code

This flywheel has a long history on our Mazak. To run it on the Haas, we rebuilt the workflow as four separate programs. Each one focuses on a single stage, so we can verify every feature before moving on.

1. Drilling and tapping
   We drill the center, friction surface pattern, clutch mount holes, and the ring gear circle. Tapping follows for the threads that require it. During the first article, Kallin runs slow rapids, stays on the feed hold, and visually checks alignment by jogging a drill into position. Early verification prevents surprises later.
2. Chamfering and deburring
   Every hole gets a clean chamfer to remove burrs and speed assembly. Threaded holes receive about a thirty thousandths chamfer, which makes starting bolts easy and keeps the first thread crisp. One of the trickiest moves is a half inch chamfer cutter reaching down into a five eighths hole. There is not much clearance, so the operator watches for rubbing, chatter, or smeared aluminum on the cutter.
3. Engraving
   Part numbers, JB Racing logos, and a clean date code go on next. The artwork has fine details, so this cycle is longer, but the results are sharp. The new coolant and tooling combination on the Haas leaves a brighter, cleaner mark than the older setup.
4. Date code
   We finish with a small, tight engraving near the clamp, which is why the clamp is relieved in that spot. It is a close operation, so we probe carefully before we run it.

Purpose built fixturing

We designed a Porsche flywheel fixture with a roll pin for clocking the clamp washer. That clocking ensures the engraving lands where it should, and that the clamp stays clear of the cutting paths. For BMW flywheels we already have two sided fixtures that allow us to deburr both faces in the machine. The Porsche version is in progress. Until it arrives, we deburr the back side by hand right at the bench after the machining pass.

Smarter automation for first article confidence

Once a first article proves out, we enable tool break detection at every tool change using the table probe. If a drill slips in its holder or a cutter breaks, the machine catches it before the next operation. That feature adds about a minute per part, but it saves taps, saves material, and keeps the process flowing without an operator hovering with a finger on feed hold.

We also use a spring loaded fan tool at the end of each program to blow chips and coolant off the part and table. It clears most of the bowl on these deep Porsche flywheels, which makes visual checks faster and keeps the work area cleaner.

Two clutch sizes, two personalities

You will see two variants on Kallin’s bench.

• 140 mm clutch
  More room inside the flywheel, so there is space for lightning holes. The internal pocket is shaped more like a bowl. This setup pairs with specific racing clutch packs and transmission packages.
• 184 mm clutch
  Larger diameter clutch, tighter interior, no extra room for lightning holes. The walls are more vertical to provide the necessary clearance. Even without the lightning holes, it is still far lighter than the factory flywheel.

Both share the same overall offset. Each version aligns with different power levels, classes, and driveline choices. For Porsche applications, these friction surfaces are race only, not street. If you are choosing between them, your class rules and clutch package will guide the decision.

Hardware and fit checks that matter on a Porsche

Space behind the flywheel is tight on early Porsche cases. We size clutch hardware so bolt tips do not protrude out the back. During inspection Kallin runs a clutch bolt into tapped holes to verify depth and feel, then checks a long bolt in the friction surface pattern to confirm clean thread engagement. The goal is simple. Zero weirdness, smooth starts, proper depth, and no hardware sticking out where it could touch the case.

We also test fit the friction surface itself. The lip inside the flywheel is turned so the plate slips in snug, centers itself, and stays put. The bolts secure it, but the geometry does the locating. That tight slip fit keeps runout low and makes assembly feel precise.

First good part, then steady production

After drilling, tapping, chamfering, engraving, and date coding, the part comes out looking clean on the front face. Until the two sided fixture is ready, we deburr the back by hand, wipe it down, and inspect threads and features. With the first good part approved, we move the run into production and start building inventory.

What the move buys you

Rebuilding the program on the Haas gives us a few wins.

• Cleaner engraving with better coolant and toolpaths
• Automated tool break checks between cycles
• Repeatable chamfers that make assembly painless
• Faster blow off and cleaner work area with the fan tool
• A fixturing plan that soon eliminates hand deburr on the back face

The end result is the same promise we make on every JB Racing flywheel. Precise machining, smart process control, and a balanced, lightweight part that bolts in cleanly and performs on track. If you have an early 911 or 914 package and want to talk clutch size, transmission details, or class rules, reach out. We will help you land on the version that fits your build and your goals.