ok guys i have been experiencing this issue as well, and i have been thinking about posting it for a few months but i haven't. I consider myself fairly experienced/knowledgable, and here is usually where i come first to help if i can when i log on. So here is my dealing with this issue and ideas.
Ok, I am going to describe my issue in detail even though i am 99% sure you are experiencing the exact same thing. Upon acceleration in any gear, the car starts to shudder at 60 then stops around 68 or so. It does not shudder under deceleration. Note: my car did not do this when i bought it, and it has progressively gotten worse and worse. it began as only slight vibration at 60 and has progressed to very noticeable shudder that starts at 60 peaks at about 63~ and tapers off until its gone about 68. This has taken approximately 3 months.
I am owner number 2 of my 04. The first owner said the only collision that happened ended in a bumper replacement, that was performed by Acura. Car tracks perfectly straight. So collision is not the issue. I have had warped rotors before, and it is only doing it under acceleration not deceleration or braking. My rotors on my TSX are not warped, so they dont have anything to do with it. I have had bad wheel bearings before, there is no metal on metal squeaking, and that would shudder at a constant speed not under accel, decel, braking or turning. I have stock wheels. So it isnt the center ring thing. I have not touched the wheels nor hit anything major that would dislodge a weight on the wheel. However i have not checked the balance. But i have had this issue before as well. It has been my experience that this would cause a big vibration at low speed and taper off as speed increases because the centrifugal force of the wheel will eventually balance it out enough for the suspension to absorb all or most of the vibration and you wont feel it. I don't think it is flat spots in the tire, because we have abs, i haven't engaged abs, i dont have uneven tire wear, and i rotate my wheels anyway. Not to mention i drive spirited enough that the turns would take care of my uneven tire wear if i did have any. Do not think it is transmission related because i would think it would do this at a certain rpm level in each gear. I have no CELs or Sensor lights (ABS, VSA, etc.).
Ok (i already see this is a long one i apologize), Axles... potentially yes, as it makes sense since they are behind the output shaft of the transmission so they will be rotating at a speed relative to the speed of the car, so that makes sense. but how? Granted I do drive very spirited several times a week, to include catching second, third, and sometimes fourth (on a good day LOL). But, I just don't see a stock clutch clamping enough torque to bend/warp/unbalance the axles... thoughts please?
EDIT: when i drive in a spirited manner, i do not launch from a dig. I roll into first then get on it.
/2 cents
just a lot of experience, Dan.
