Quote:
Originally Posted by Robin Lawrence
Since I have raced clutch cars for most of my racing career I am always interested in the discussion. I still have a lot to learn.
In the 2000 to 2006 time frame I raced NMRA Factory Stock then Real Street classes. Both had limited rules around the clutch specs. I had a Autometer Data Logger in the car during testing as it wasn't allowed in the class.
We were limited to a 10.5" to 11" Diaphragm clutch. the Factory Stock car was a high 11 second NA car on BFG Radials at the time. the Real Street car was a Supercharged on a 26x10 M/T slick. Transmission ratios were regulated to standard offerings on OE and Street (Tremec) style boxes that could be face plated or Dog Ring style modifications.
Factory Stock was not hard , a normal rag style clutch offered enough "slip" that we had decent 60' and control of the wheel speed at the hit.
When i changed to Real Street it got interesting. I actually ran that same rag disc at first. It slipped and engaged well but it only lasted about 6 passes. I was fortunate at the time to have a clutch sponsor. Clutchmasters and Fidanza were in the import side and wanted to get deeper into the Domestic market.
They built me some very cool Diaphragm clutch plates and we experimented with various materials on the discs. Kevlar, Bronze pucks, Sintered Iron Pucks, and some weird Carbon material. They also built me a Diaphragm pressure plate that had a billet aluminum pressure ring with a steel face friction surface. That deal saved us 9 pounds on the assembly. Yes we were already using a aluminum flywheel as well.
I remember when some racers in NMRA started using the "Screen Door Closers". A good friend of mine refused to use one. After watching racers with what he thought was less ability than his he tried one. He said he will never go back. My point here is in a limited restricted clutch rule class these type of products have merit. My buddy is a super tester. Has probably 5 different pressure plates with different base pressures. He now believes.
I have tried the diaphragm discs with the weight to apply more pressure as RPM goes up. I had never seen any difference.
I currently run a twin 7" Billet clutch in my Stocker. I can tune the engagement curve with the adjustable base pressure and counter weight. It works very well.
I would think that if I was allowed to attach a hydraulic cylinder to my clutch pedal I would have a solenoid to allow it to hold the pedal on the floor so I could release a button rather than my left leg. LOL
I really hate to feed the rumor mill but I was told that there is a Stock racer who is doing that.
Interesting stuff.
To answer the OP's question. Above peak torque and below peak power.
Robin
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The idea of using a solenoid to release the clutch pedal and regulate the engagement of the clutch was pretty much exactly what I proposed to Jerry Valentine several years ago, he cut me off before I even finished explaining my idea and said that absolutely there was to be nothing electronically connecting the clutch pedal to the clutch. Jerry was pretty high up the NHRA food chain so I took him at his word and didn't do it.