So I finally forced myself to make a decision and buy a clutch/flywheel setup.
The stock flywheel had to go for multiple reasons:
Its actually counterbalanced to offset the internals of the ICE motor. (If spun by itself it would be horribly out of balance)
It attaches to the crank with a giant keyed shaft and must use a giant 2 1/8″ nut to mount. (No bolt pattern like 99.9% of other vehicles use)
Its really… really heavy
Now the flywheel was an area I could have cheaped out on, but I wanted to go with a good brand on this one to reduce the rotational inertia, ensure it was perfectly balanced even to 10,000rpm, and the simple fact that I really don’t want to have to pull it all back apart at some later point to replace it.
The stock clutch also had to go:
- With the pure increase in torque from 159 lb-ft to 221 lb-ft (~40% increase) the clutch simply needs to have more gripping strength
- There is a huge reduction in rotational inertia from the ICE motor to the EV motor so the system should be able to react and climb rpm much faster and this alone could slip the stock clutch
- Combined with the reduced rotational inertia, the electric motor has the ability to ramp in massive amounts of torque almost instantly, and this would surely cause a stock clutch to slip
I ended up going with a stage 3 clutch and HD pressure plate. The stage 3 clutch uses a 6 puck design to increase the clamping pressure (psi) on the clutch surface. This upgrade also does away with the standard organic clutch material and replaces it with copper ceramic pucks. This is usually used exclusively in race applications because it results in a very short and aggressive clutch engagement. Luckily for me though, I could care less how harsh the clutch engagement is because I don’t need to slip the clutch at launch. The clutch will only be needed for slight rpm matching between gear shifts, and a mechanical fuse in the system incase an electronic bug/failure causes an undesired driveline torque.
And now once I have the clutch and flywheel in hand I can start to measure and calculate the offset distance needed for the adapter to mount the motor casing to the transmission bell housing. This distance will be absolutely critical because if I get it wrong the clutch will either permanently slip, or never fully disengage. The current plan is to rapid prototype the adapter on my new 3D printer and make sure I have it right before I send it off to machining.