7 June 2013

After much correspondence with the very helpful people at Competition Clutch, the following (with the advantage of hindsight) is now clear:

1. There was nothing wrong with the clutch. However, pulling it out did allow confirming that the pilot bushing was present (there was some question at to whether there was one.) Also, upgrading to the lighter diaphragm spring greatly lightened pedal effort.

2. Once they learned how how light my car was, they said that a better choice would have been one of their mid-range single-disc units. The weight of the car is the important factor when considering a clutch, and 1600 lbs doesn’t warrant a twin-disc clutch. The clutch will simply never see a huge amount of torque – the tires will spin first. They said that it should basically last forever – good!

3. Twin-disc clutches engages near the top of pedal travel (requiring only about 1″ of travel to do so.) However, to <em>completely</em> disengage the clutch requires several additional inches of pedal travel due to air-drag between the spinning and non-spinning components. And, a dog box is more likely to exhibit grinding gears due to no synchronizers masking a slowly spinning input shaft.

3. My clutch master cylinder was too small. While it resulted in very light pedal effort, it wasn’t moving the clutch enough to fully disengage it. Moving to a proper size master cylinder resulted in an “OMG Gezzus Christ” level of pedal pressure, heavy enough that when I’d push it in, I’d raise up out of the seat, probably around 150 lbs of pedal pressure… not acceptable, even if correct. So I backed off to a 13/16″ cylinder  which seems perfect. Not too heavy, and even after heat-soaking, there’s no grinding. I’m just going to have to get used to the fact that when leaving a stop, nothing happens until the pedal is very nearly completely released. As it is now, after the light goes green I sit there like a goof because I’m not used to releasing the clutch pedal so far before it bites. Give me time.

I’ve began tentatively experimenting with heel-and-toe shifting, and the transmission works great… when done right of course. I worry that there may be some embarrassing grinding episodes on upcoming videos… and NOW I understand why I sometimes hear 18-wheel drivers struggling to shift. Anyway, this should be the last post regarding the transmission issue.

Regarding the search for a generic hood scoop, the first inquiry went about as expected. A Chinese-made part that looked like it might fit was found, but since the sides are curved, it seemed wise to confirm with the mfg whether it would cover the rectangular hole in my engine cover. I sent a question saying that I had a custom car and wanted to know if it would cover a hole of size X. The “answer” was, “our scoops fit practically all cars. If it doesn’t fit, contact us, and we may ask for pictures, and we’ll remove your car off our list if it doesn’t and you get to keep it.” Sigh… So I sent back a slightly testy response, saying that it was a custom car so it’s not on any mfg’s “list”. Can’t they just answer the question?” The reply came back, “it won’t fit.” Wonder if it’s true or whether I worried them…