I was driving last night, and came up to a lotus elise, decided to give him a run. I feathered off the line and then laid into it, spun until I hit second and it broke loose again. When I pulled up to the next light and went to accelerate my car started making a thumping sound almost like I had a flat front tire on the passanger side, so I pulled over, no flats. Got back in and same thing, it does it everytime I press the gas, any gear, any speed, only on acceleration though. So that rules out bearings and brakes. My cousin whos a machanic at dodge seems to think I messed up the drive shaft, but he hasn't had a chance to look at it. Dealership says they can't squeeze me in till Friday.

 

?? motor mount or the shocks maybe

is there something in the tire itsself, i had a HUGE nail that sounded like a boulder was stuck in the tread

 

Is it the other side of the tire? Check and see if anything's wrong there.

 

May be related, but my friend had a similar sound after racing his prelude. It turned out being a rip on the sidewall of his tire. A huge flap was sticking out and thumping in his fender. Tire kept pressure and everything so it was pretty amazing it never popped.

 

I second the motor mount....You say you only hear/feel "thumping" when pressing the accelerator. I think if it was something with your tires, shocks or anything else in the suspension it would be all the time not just during acceleration.

Also I believe the motor mounts going bad are fairly common with the CLS. Right??

 

Not really, during acceleration it caused my friends flapping sidewall to hit the fenderwell. When not accelerating the flapping rubber stayed close to the tire. Centrifugal force?

 

Is there a noticable thump when you put the car in drive from reverse and back? I heard and felt a noticable one when my motor mounts were busted.

 

when motor mounts break, the motor actually slides back and forth slightly. Do you feel a slight shift before the car actually starts accelerating?

 

I checked both front tires thoroughly, nothing in them, no sidewall issues, nothing hitting them. It's not a noise, there is no noise to be honest, it's a thumping, or bump, bump, bump sensation in the front end, it increases when I accelerate while turning the wheel to the right, and goes away when I'm turning left and accelerating. I'm thinking maybe the right axle.

 

Yeah, you probably blew the axle.

 

When I broke the right axle on my CRX, I was experiencing similar symptoms.

Doesn't sound like anything major - good luck on getting her fixed.

 

My buddy took out his modified Type-R to the drag strip for the first time ever (well, for the car) and got some horrendous wheel hop off the line. Stupid kid kept the pedal buried, and half way down the track, we could feel the vibrations.

First run ever at the track, and he blew the axle. He was scared to drive it home, so I had to. I told him to take it to the shop the following day, but he kept driving it around... Two days later, he called me and said come get me from this gas station... the axle completely popped out of the transmission.

Just felt like sharing... and so that you don't delay taking it in to have it checked out.

 

Sounds about right, I've had quite a bit of wheel hop since the install of my bolt ons on the s/c'r, but I try to control it, I don't sit there WOT off the line, but I'm pretty sure that's what's wrong. I have it sitting right now, it happened monday, and I called the dealer monday, but they told me they can't even get me in till Friday!! so I've been driving the Firehawk around most of the time, except today when it rained for the obvious reasons (lack of traction)... Thanks for the responses.