Bump/Jerk at 40 to 45mph

[wilto]

I did post this in the tranny bypass thread but I should probably get a thread of my own.

I recently bought my 2007 PF SE with 61k miles.

Coolant is as green as can be, I haven't checked the ATF yet and the bypass will be performed later on in the week.

I've noticed a bump/jerk at around 40 to 45 mph.
If I have no feet on the pedals and lightly press the gas, I hear the tranny give a good thud as it goes into gear.

Now if i'm just accelarating normally everything seems fine but if I'm coasting at the above speed I can't help but hear the thud and it just doesn't sound good.

Any ideas?

If I were to have a cross contamination issue, the extended warranty would help me out correct?

[pandarturo88]

It's normal it has to do something with the gear ratios' and the overdrive system. it's completely normal and there are other threads on this issue.