hey whats going on guys....i got a 2004 blazer 4x4 auto and yesterday when i got on the highway i felt the car jerk when i got to about 55mph and backed off the throttle...it continued to do it about 10-12 more times throughout my 45min drive home...the transmission shifted fine off the highway no jerks or slips...and it seemed like it down shifted fine as well when i gave it more gas...any clues to what could be causing this...had a transmission flush about 15k miles ago...Thanks Steve

 

oh and i just took my rims off for the winter and it was my first trip on the highway didnt know if that could have contributed in any way

 

When you say jerk, is it shifting out of od into 3rd? Are you sure it was the transmission and not a misfire (remember during lockup/OD there's no trans slip so a misfire/backfire/other engine event may translate directly to the wheels and cause a jerk like feeling).

 

im not sure if it actually leaving od...it feels like a pretty descent jerk when i back off the throttle

 

when you back off the throttle, there's a key influence....check motor and trans mounts, any banging?

 

no banging and checked the mounts earlier...drives perfect around town...only seems to happen over 55mph...and like i said it only did it about 10-12 times not everytime i backed off...it even happened two or three times while using cruise control

 

I'm stumped....maybe somoene who's had this problem can add some info.

 

I had a similar problem on my 2000 blazer, jerky rocking at speeds at about 50 to 70 KPH, turned out to be a worn out distributer shaft. The gears were worn out and caused the problem.