Violent Kick around 30k and then some...

[Falcon51]

Hi everyone

 

Sorry to start another thread.

Just thought I'd write up my own as a search doesn't seem to reveal any similar topics to what I'm experiencing at the moment.

 

My 07 BF XR6 AUTO, driven as my daily on highways constantly. It has a very cruisy life and is always babied (although with the $ it's currently stealing from me, it doesn't deserve it 😂).

 

When travelling around and between 30-35K (and often 50-55K also, although not as violent), its almost as if it loses all drive momentarily and then suddenly engages very roughly, creating a heavy jerk throughout the car and then a grinding noise can be heard coming from the rear.

Also when accelerating out of a corner, the grinding at the rear noise occurs again.

 

The Diff Bushes; both L&R front/upper ball joints, L&R Sway Bars, both front wheel bearings and diff oil were replaced less than 5k ago and in the past couple of days, I had the transmission serviced and the driveshaft repaired and balanced. This seems to have somewhat very slightly (barely at all) helped the issue but it's still extremely noticable and uncomfortable while driving.

 

TIA

[MaStars]

wow you must have one special Barra in there, revs up to 55,000 RPM? No wonder the gear changes are so violent.

 

are you sure the factory Barra hasn't been replaced with a Pratt & Whitney JT8D? If so I'm sure the stock auto doesn't like the extra RPM that is supplied from a Jet engine

 

😲

[k31th]

based on the symptoms, I'd suspect it's your diff bush bolt/mount has broken in some way... but could also be the trailing arm bushes or the tailshaft centre bearing... or could be the diff itself has a bit of lash in it's CV joint or the gears themselves.