My girlfriend has a 07 Mazda 6, 4 banger. Automatic. Nice little car, runs great blah blah..

Problem is shifting.. Sounds like it would be a motor/tranny mount. Heres whats goin on..

Loud thud along with shudder of the car. Seems like it would be a mount right? Well heres what i dont get. I can hammer it ( as much as it can be..) and it WONT do this from 1st to 2nd or 2nd to 3rd. ONLY from 3rd to 4th and 4th to 5th. The 4th to 5th seems to be the worst.

Havent had a chance to get under and check it all out. But im just so puzzled since its only those gears. unless for whatever reason they cause a lot of torque on that mount that its doing that only in those shifts.

Ideas/opinions? Aside from selling the car.. she loves it.. lol

 

The higher the gear, the more stress is transferred to the motor and ransmission mounts. Also in higher gears the engine is under a heavier load (lugging) and this can cause misfires if the ignition or fuel delivery are below par. Both a misfiring engine and bad mounts can cause shuddering and vibration.

 

something like taking a hammer to the bottom though? It does this in 4th and 5th under almost any kind of acceleration. It probably is, i was more or less just checking to see if anybody had an idea other than what i have.

 

my bro had a similar problem with his trans. it was a torn trans mount. the stock rubber ones tend to rip. check that first. and if u can get a polyurthane trans mount to replace it and it wont happen again. but if it isnt that then it could be a bad tranny thats gonna cost u some money. other then that idk.

 

imports...

 

is it a manual or the tiptronic trans? a friend of mine had the tiptronic and it let go about 5 times in 30k miles. he eventually filed for lemon law and the mazda dealer bought him a new charger. but i would check the trans/engine mounts. get a big bar, put the car in neutral, and intelligently pry against the engine to see if there is excessive motion, just be careful of what you pry against. i dont think anything inside the trans would cause that kind of problem without effecting all the gears. however, if a bearing supporting either the counter shaft or output shaft went bad, that could cause it, but it it would also whine and cause hard shifting