For clutches with non-sprung hubs like the Mcleod, sitting in neutral with the clutch engaged (foot off the pedal) can often generate gear rattle in the transmission that is then carried up through the shift handle. The non-sprung clutch hubs don’t absorb any vibration from the engine firing events and the gears “knock” back and forth against each other. A bigger cam with a lopey idle exacerbates this issue. Gear rattle is a big reason why OEMs like to use dual mass flywheels, they smooth out the torque delivery to the transmission especially at lower RPM and cut down on NVH. (Of course, a dual mass flywheel presents another can of worms if/when the moving elements inside it decide not to move anymore or the springs break.)
The transmission gear rattle with a solid hub clutch may also be audible while driving at lower RPMs as the solid hubs won’t dampen the pulsations from the engine. Accelerating in overdrive gears at lower RPM tend to be the worst for this as the torque requirements are higher and engine RPM is lower.
If it’s gear rattle, you can always try isolating the shift handle like the OEMs do, often with a rubber isolator in the handle itself. That will help cut down on the amount of gear rattle carried into the car. A buddy has a 2006 GTO with a Monster dual disc clutch with solid hubs. The gear rattle was barely detectable with the stock shifter and handle which had some rubber isolators, but when we put in a Ripshift shifter, a bronze shift bushing, and a solid mounted steel hurst shift handle the gear rattle at idle and at low RPM in 5th and 6th became much more noticeable.
With a dual disc clutch like the Mcleod, any noise with the clutch depressed while sitting stopped is usually the floater plate in the clutch moving around a bit.
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1969 Chevelle
Old setup: Procharged/intercooled/EFI 353 SBC, TKO, ATS/SPC/Global West suspension, C6 brakes & hydroboost.
In progress: LS2, 3.0 Whipple, T56 Magnum, torque arm & watts link, Wilwood Aero6/4 brakes, Mk60 ABS, Vaporworx, floater 9" rear, etc.
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