When I accelerate, my car shudders around 20 mph. This vibration is felt mostly in the seat and floor, not the steering wheel. There is no vibration at any other speeds. Also, If I drive constantly at ~20 mph, its hard to feel the vibration - its really only apparent when I am acceleration. Any ideas?

 

Transmission slipping perhaps...

 

I shudder to think that you might be having tranny problems.

 

I don't think that its the tranny, since it will do the same thing whether I am in first, second or third gear (shudder is always at 20mph). I'm hoping that it is because I am slammed and have yet to get an alignment; I'm getting one tomorrow as well as getting a camber kit installed, because right now my rear camber is terrible.

 

bump.... going to the dealer tuesday to get it checked

 

My best guess would be the axle. I had a old Camry that used to shutter something horrid between 20-40mph. It got progressivly worse over time. Read up on possible causes and sure enough the front passenger axle was toast. Lost its grease packing. When I slightly pulled on it when I was getting it out, the boot broke and lots of rust inside. After I replaced it, no more shutter.

 

does it happen when accelerating slower than usual? I have in both the MDX and the TL and it is normal. The TL learns how you drive and changes shift points accordingly. If one day your racer then the next day fuel saving man, then the car takes about 100 miles to learn, hence harsh shifting, which occurs usually at 20MPH

 

Transmission mounts and/or motor mounts can cause a shuddering at certain speeds, what kind of mileage do you have on your car? It's not a really big deal, but not usually a DIY job.