Join Date: Apr 2008
Location: Proctor, VT, USA
Freeplay in the lever needs to be checked when installing any aftermarket lever. Properly adjusted, there should be a small (5% – 10%) dead-band of the full lever movement before there is pull resistance felt at the lever.
What's happened is that the mispositioned master cylinder piston is obstructing the vent port preventing fluid return to the reservoir.
When you apply the brakes the calipers get hot and the fluid heats up and expands. If it can't return to the reservoir to prevent a fluid pressure increase caused by the expansion, it expands the other way and pushes on the caliper pistons and applies the brakes. After the fluid cools the brakes release.
Similarly, if the vent port in the clutch master cylinder is plugged or covered, as the clutch fluid heats-up from engine heat the fluid expands and instead of returning to the reservoir, it pushes on the slave to separate the plates and cause slippage. After it cools the clutch will function normally until it heats up again.
Last edited by Strega; Sep 11th, 2019 at 9:41 am.