Lucky me, I thought ahead eight months earlier and I ordered all 17 hoses, a thermostat, gaskets, o-rings, etc.. including a new water pump. Now all I had to do was swap out some parts!

Needing a daily driver, I proceeded to rent a car: a top of the line Hyundai Accent. Bright blue. I figured at worst I’d only have to suffer three days in this car but I figured wrong. The next day the coldest weather in the last decade hit Houston and put the project on hold for a week. I decided to make use of this time and powder coat the coolant manifolds:

All said and done I think the project turned out pretty well. Everything is nice and clean, no more seeping coolant. I’d dare say the system is ready for another 100,000 miles and when I replace it then it will be much easier without busted bolts and corroded aluminum!

Remove material where it affects the moment of inertia (MOI) the most. Removing material near the crank hub is unnecessary and likely dangerous. This area of the flywheel is under the greatest stress, why remove material from there and risk the part failing? Removing material near the ring gear is best and will give you the greatest effect.

Generous radii, no sharp corners. Corners are stress risers and you want to minimize stress concentrations. Doing so will result in a stronger, more robust part.

Flywheel material composition. Beware that cast flywheels typically have voids in them. This is why minimum thickness rules cannot be applied across all different flywheels. Never say “I’ve seen this done on other flywheels,” every flywheel design and manufacture should be evaluated individually. The material quality is vastly different between Fiat and BMW flywheels, even between different model flywheels of the same company.

Balance. After any lightening procedure the flywheel should be dynamically balanced (aka zero balance). Even though a flywheel is lightened on a lathe and is dimensionally symmetrical, this does not imply that it is balanced. Cast materials are not a consistent density throughout and will affect the balance. Preferably, flywheels should be balanced with the whole rotating assembly (crankshaft, crank pulley, flywheel, and clutch) but this is only possible if the engine is disassembled.

Grind friction surface. It may be hard to believe but after you lighten a flywheel, it is possible for the whole part to warp due to the removal of material and internal stresses. This can make the friction surface uneven and it should be checked and reground. Sometimes the friction surface does not warp and this is not a necessary step. Do not “turn” the friction surface on a lathe. The proper procedure is to blanchard grind it. Turning creates tiny grooves parallel to the clutch’s direction of travel, this makes it difficult for the clutch material to “bed-in” to the flywheel and create friction. A blanchard grind, however, makes lines perpendicular to the direction of travel, this encourages “bed-in” and friction, which is what we want! In addition, turning will not be consistent over hard spots. See the picture below. The shiny spots are hard spots, and the dull spots are the normal material. All hard spots must be removed, because they will cause uneven ware and are very slippery (we don’t want slippage). All cracks must also be removed.

Check for bolt embedding: Loose flywheel to crank bolts can create all kinds of havoc. One result is that the bold heads can “embed” themselves into the flywheel material, resulting in a surface that is no longer smooth and ideal for carrying the bolt’s load. The solution is to “clean-up” the surface by skimming with a lathe or grinder to make it smooth again.

Detail work: When reconditioning a flywheel it is nice to see the other small details like the clutch mounting threads nice and clean, sharp edges deburred.  A dye penetrant or magnaflux check for cracks is also recommended for peace of mind.

We can evaluate any flywheel for lightening and race preparation. Our prices are as follows:

Evaluate crack check, clean: $40
Flywheel lightening: $60
Balance (flywheel only): $40
Regrind friction surface: $40
Fiat dowel pinning: $30

We can also supply the appropriate ARP mounting hardware for flywheels and clutches. See parts pages for more details.

How I can make this claim? Well first of all, I am not in the business of selling clutches! Second, just think about what a clutch does: a clutch is a switch for torque. Turn it on and apply torque to the wheels, turn it off no more power is transmitted.

Similar to the amperage ratings for electrical switches, clutches have ratings for switching torque. Some aftermarket companies can give you these numbers but they are impossible to come by for a stock clutch. Not having the numbers makes it difficult to compare your choices to eachother. On top of that, how much torque is your engine producing anyway? How much does your new clutch need to handle? I’ll try shed some light on this with some numbers for Fiats from my own experience:

Stock 2 liter Valeo clutch:
+  Organic single disk
+  Cast steel pressure plate
+  Stamped steel housing
+  Measured torque rating: ~180ft-lbs

Stock 2 liter engine:
+  Fiat torque rating:  ~110ft-lbs at crank

Worked 2 liter:
+  Torque: ~145ft-lbs at crank

All-Out 2 liter engine:
+  Torque: ~170ft-lbs at crank

***It is important to note that a clutch’s rating should be specified in units of torque (lb-ft or N-m) and not units of power (hp, bhp etc..) That is always the first clue, if a clutch is rated at a given horsepower, it is being hyped, and it is quite possible the the seller knows nothing about their product.

Referencing the above numbers, it is only in the most extreme cases that a clutch upgrade is deemed necessary to switch the required torque. So if your clutch is not slipping, or just falling apart, why go with anything other than stock? The best part is that it is about $120 and you know stock parts will fit perfectly without extra modification!

Introductory pricing set at $40.
Add up to four more ports for $10 each.

We can supply gaskets, bolts, and pipe plugs to get you from start to finish with installation.