The spring semester is almost over and during that time, Blipshift made another run of the Gutentight shirts. Thank you to everyone that bought a shirt, that money helps purchase more car parts! And while it wasn’t enough to by a Carbon Fiber Driveshaft outright, it did provide a steep discount. 😉
Installation was pretty easy. I had to drop the mid-pipe when I did the install on my 2005 STi, however, on the Bugeye, it wasn’t necessary. Your mileage may vary.
I only jacked up the rear of the car. The hope was to minimize transmission fluid leaks from the tail shaft (gear oil stinks!) and also because I’m lazy.
Starting from the differential, there are six 14mm bolts holding the diff cover in place. Penetrating oil and a breaker bar are strongly recommended here. The cover won’t fit the CF driveshaft without modifications so you can either mod it or toss it. I plan to modify it by removing the weight near the end of the cover.
Next, remove the four 12mm bolts from the differential/driveshaft. You will need to rotate the driveshaft to access all. Remember to release the parking brake so you can rotate the driveshaft.
Next, remove the two carrier bearing bolts. These are 12mm, IIRC. Push the driveshaft into the trans to clear the lip on the differential flange and then remove the driveshaft from the car.
Just holding the two driveshafts back to back is astonishing how much ~10 lbs feels like. The stock driveshaft weighs approximately 22lbs, and I forgot to weigh the CF driveshaft in my excitement, but DSS claims it weighs 12lbs; which isn’t too difficult to believe.
Installing the CF driveshaft is easier since there are only the four bolts at the differential to install. I would recommend getting longer bolts; I had to remove the lock washers on the stock bolts to get full engagement on the nuts. I will be ordering new bolts shortly.
Driving around, throttle response is noticeably improved. Accelerating from a stop is also easier, and the bucking tendency in low-speed situations is reduced. It’s still there due to the play in the differential, transmission, and the springs in the clutch. Overall, acceleration is smoother.
At speed, the need to downshift is reduced. However, while cruising in fourth, anything more than a quarter throttle I would recommend downshifting on an equal-length header EJ207 with the USDM WRX 5MT transmission. Fourth gear is slightly overdriven (0.972) and ELH EJ207s don’t have a ton of torque below 3,000-RPM, which could lead to LSPI.
The overall effect feels similar to adding stiffer bushings to a component that moves around a lot; like transmission or subframe bushings. Making a more direct connection which reduces the delay in response. However, this is also coupled with adding lightweight components like lighter wheels, which also aids in response.
NVH increased a bit at highway speeds. I have many aftermarket bushings so it’s kind of hard to nail down whether it is the driveshaft is the cause of NVH, or that it is bringing out previously hidden NVH. Sometimes rotating the mounting points to the differential will make the NVH go away, however, it didn’t change a thing in my situation. And it seems to go away at higher speeds so maybe its a weird resonance frequency thing.
Handling feels better, especially at speed; although my steering feels heavier (almost like torque steer). Initially, I was thinking this might be due to the weight balance shifting back to the front but now I think that might be due to my center diff failing. I took it to the Dragon and it handled great. In all honesty, I could just add brakes and a faster steering rack and call this project a success.
On the other hand, we could see what the rest of the planned mods bring to the table. 🙂
Coming up soon, K&N Typhoon Intake Install/Review.