I have a 2006 X-type with 106,000 miles. I have changed the transmission fluid once with Castrol Import, changed the transfer case fluid (boy was that fun), changed the rear diff fluid.

At highway speeds when I go into overdrive (pedal to the floor), the car shifts down very hard. It almost feels like the roughness is in the rear. All other shifting is fine.

I'm thinking I will change the Tranny fluid again as the first time I just did a drain and fill which I read only gets about half the fluid out. I've read some other people using a transmission additive, but I'm real leary of that.

Is there any way that it could be mount related? It almost feels like the sudden increase in force moves the transmission from the mounts to cause a hard body movement (that's just what I am feeling anyway).

Let me know if anyone has any ideas/thoughts.

Thank you!

 

You actually mean "pedal to the floor" shifting FROM overdrive to a lower gear is giving you the jolt?

 

Overdrive, passing gear, downshift, whatever you call it. When you press the pedal down into the indention. That's the gear.

 

https://www.jaguarforums.com/forum/x...ar-help-55161/

Other option that sometimes works is doing a "hard reset". This is disconnecting the battery leads, touching them together, leave disconnected for a hour or so, then hooking them back up (don't forget to reprogram auto windows, etc.).