Selecting parts

Hello. One of the popular aftermarket upgrades is the carbon fibre drive (prop?) shaft. In the Toyota 86/BRZ this replaces a two part stock steel with a one piece CF. For discussion sake, what could you expect from this? When would this be worth the outlay?

I am a proponent of selecting parts needed to solve a problem. If you don't know what problem you are solving, why would you ever consider spending money? The problems you might solve with a carbon fiber drive shaft would be reduced overall weight, reduced rotation mass, increased strength.

Not sure if your "aftermarket upgrade" would solve those problems or not.

What I do know -- I have a customer with a 700hp LS3 in a BRZ, when we added a 150 shot of Nitrous (measured 818 hp at the hubs on my Dynapack), it only made two passes down the drag strip before it broke the carbon fiber drive shaft. I'm very lucky that didn't happen while on the dyno just two applications of the Nitrous earlier.

As David said, it's a solution for a problem you may not have, and the money may be better spent elsewhere.

Advantages are less total mass, less inertia, less vibration/ noise - in theory, some dampening of shock loads on the transmission, possibly better traction/drive as the torsional flex helps dampen shock loads on the tyres, something to boast about having - which seems to be a big selling point, and as you point out, a single piece 'shaft can span greater distances so replace 2-piece 'shafts..

As David found out, while they can be excellent for some things, it HAS to be made for the torque and shock loads it will be subject to - overload them and they'll turn into a very expensive brush. They are also quite easily damaged, compared to steel and alloy, and that will be a failure point.

If I had the budget, or I was requiring replacement/a custom shaft, I'd maybe use one, but I'd regard it as a luxury item unless it was cheaper.

Forgot, there does seem to be some variation in quality, so do your research.