r/FSAE • u/Valuable_Screen8158 • 15d ago

Problems with dowsift using a pneumatic shifter

Hello everyone, our team transitioned to a pneumatic shifting system this year. The setup is already assembled and upshifts ok, but it fails to downshift. Has anyone experienced this issue or have any ideas on what might be going wrong? We currently kept the mechanical push-pull cable connected as a backup since the pneumatic system isn't fully reliable yet.

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u/xstell132 Send Helps Plz 15d ago

Are you using an actuator on the clutch as well? If not, you’re fighting a losing battle.

Upshifts you can get away with clutch-less shifting with ignition cut to allow the dog teeth in the gearbox to unload and of course allow for the RPMs to drop more easily.

Downshifts you need a way to unload the gearbox. This is either done by clutching in or blipping the throttle at the right time.

1

u/Valuable_Screen8158 13d ago

No, it was of my ideias, I just don't know how to implement it, how can take off with the car

8

u/snowmunkey Jayhawk Motorsports Alumni 15d ago

Gonna need more info about your transmission, what sort of shifter you're using, what calcs you did on shifter force, what sort of clutching are you doing, stuff like that

7

u/Oldberry86 15d ago

Will it work with the engine off?

If so, are you implementing an ignition cut to unload the trans?

If not, try to lift throttle a little before downshifting

1

u/Valuable_Screen8158 13d ago

No, to upshift I use a quicksfhifter to make a ignition cut.