Help! Clunk at rear when accelerate!
 

Car is a Tip 996tt. I've been encountering a clunk or thump at the rear sometimes when I accelerate from a low speed (around 30 mph at 3rd gear). Mechanic said the engine/tranny mounts are tight. The subframe is ok. The sway bar and U/CV joints are all ok. The "thump" doesn't happen all the time. Mechanic was unable to find the problem. Any idea? could it be detonation? driveline backlash?

Did your wrench check your carriers and lugs? You could also get a clunk if you have a loose control arm or track rod..... I know from the front the drop link will cause this noise, it did on mine when the wrench forgot to tighten it.....

Good Luck!

-Eli

30 MPH in 3rd gear? Are you lugging it? What happens when you accelerate at 30 MPH in second gear?

Wondering if I've ever gone 30MPH in 3rd.... :) :D

It is a tipronic. It is the computer which decides to run the machine at 3rd gear at around 30-40mph. Are you suggesting that I should shift gear myself if the computer doesn't do it.

Sure, give it a try. Look at what Eli said above. I don’t know the gearing in your car, but 30 MPH in third in my car is somewhere around 2,000 RPM. That’s far, far too slow for any significant acceleration. If I were to hit the gas hard around 2,000, that would really be lugging my engine. It would complain loudly. Don’t know if that’s the clunk you’re referring to or not.

30 MPH in second is around 3,000. This is a much better RPM to accelerate from. My car is naturally aspirated and yours is a turbo, but I’m sure you need more than 2,000 RPM to get those turbos spooled up.

If you really want acceleration, you’d probably still be in first at 30 MPH.