Q: My 1969 Roadrunner has a new diaphragm-style clutch. While shifting at high rpm, the clutch pedal sticks to the floor. When the engine speed decreases, the pedal comes back up. Can you help me out?

A: Remove the clutch pedal’s over-center/assist spring. While it was originally installed to help with heavier Borg and Beck clutches, it can hinder diaphragm clutch operation. Next, inspect the clutch linkage and adjust the pedal free-play per the manufacturer’s recommendations. You should also check your engine mounts — clutch linkage can bind if your engine is lifting under load. Finally, you may need to fabricate an adjustable stop to limit clutch pedal travel and prevent pressure plate over-extension.



This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all

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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.