986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - When I change between P, D and R gears.. car jerks just a little.

jakeru · 10-08-2016, 02:07 PM

A small jerk is normal when changing an automatic transmission's shifter between forward-neutral-reverse while braking the car still. You should also never be applying any throttle when shifting from neutral into forward or reverse (and engine should be at idle speed).

Basically, the drive axles are applying a bit of torque, which will cause the engine and transaxle to rock in an opposite direction against the engine/transaxle mounts a small bit. An abnormally delayed jerk, (longer than about 1 second) or too strong of a jerk, could be a transmission problem.

When switching the automatic transmission into "park", there is a lock in the transmission that engages. The car could still however, rock back and forth a small bit due to the rotational slop in driveline components, such as the CV joints. When you use your parking brake, it brakes the rear wheels directly, eliminating this driveline slop. The parking brake is also highly recommended as a redundant safety feature whenever parking the vehicle on an incline.

10-08-2016, 02:07 PM	#3
jakeru Registered User Join Date: May 2015 Location: Greater Seattle, WA Posts: 534	A small jerk is normal when changing an automatic transmission's shifter between forward-neutral-reverse while braking the car still. You should also never be applying any throttle when shifting from neutral into forward or reverse (and engine should be at idle speed). Basically, the drive axles are applying a bit of torque, which will cause the engine and transaxle to rock in an opposite direction against the engine/transaxle mounts a small bit. An abnormally delayed jerk, (longer than about 1 second) or too strong of a jerk, could be a transmission problem. When switching the automatic transmission into "park", there is a lock in the transmission that engages. The car could still however, rock back and forth a small bit due to the rotational slop in driveline components, such as the CV joints. When you use your parking brake, it brakes the rear wheels directly, eliminating this driveline slop. The parking brake is also highly recommended as a redundant safety feature whenever parking the vehicle on an incline. __________________ 2001 Boxster Last edited by jakeru; 10-08-2016 at 02:18 PM.