I get a clunk/thud sound when I hit the gas pedal, but only starting at 3rd, and only really at speed. Nothing when starting in 1st and nothing in 2nd that I can notice.

If I let off the gas, then just touch the pedal in 3rd+, I get a thump (not loud, but noticeable without the radio on). From the searches, it seems like it could be suspension or engine mount related. It sounds like it could be the initial stress on the drivetrain when I go from no-load to load though?

I also didn't notice this when it was warm out either. Also, just put snow tires on it, and was hoping it doesn't have to do with an improper fit (265/35R-18 rears, 225/40R-18 fronts) messing up the diff.

Any ideas? Should I not be worried about it since it could just be caused by it getting colder out?

 

Would you descibe it as excess driveline backlash? I had that at one point and tightened things up with new transmission mounts (cracked), the rubber coupling in the driveshaft that goes to the front of the car (cracked) and new rear CV joints (worn) - it took all of this to tighten the car back up to like new...

 

Yeah, that seems to be the general consensus from searching too... The fact that it's only at higher gears and doesn't happen on deceleration/letting off is what I thought what was weird.

 

Sounds like backlash....Do you have a similar experience under hard acceleration in the lower gears?

 

No, that's the weird part. I'd think it would be more prevalent in lower gears, but in 1-2 there's nothing.

 

When I had the excess backlash, I felt it the most in 3rd gear when going from no throttle to slight throttle.

 

Yep...that's about right. I guess I'll have my indy check out the tranny mount and CV joints on the next visit. It's nothing major right? Just wear and tear that needs fixing _eventually_?

 

Yea, I had it quite a while before I decided to get into it...

 

K. I'm a car hypochondriac at times...

Love your car btw...mine's yellow too. Once I get around to it, I'm getting your 3.0 exhaust too

 

Thanks.

Cool! I'll be happy to help you with the 3.0 whenever you are ready...

 

Check the thread depth on your snowtires- my X3 has driveline clunk when I had the staggered summer tires on and I realized it was worst when the rear tires got worn more than the fronts-hope this helps

 

Yeah, I was afraid I'd have the wrong rolling diameter; I saw threads about chewing up diffs by putting the wrong ones on there. All 4 are brand new though...