Bad shuddering on acceleration... I'm thinking CV Joints or Motor Mounts

[Dr. Tweak]

First of all, my (front?) motor mount broke the other day, so I know for sure that it's bad. Whether or not it's causing this new problem is the question here.

My front brakes are also getting done in a couple days.

I was exiting the interstate and I was going around one of those 120* cloverleaf thingamabobs at high RPM and well over the suggested speed. When I leveled out at the stretch, I found that my SHO has developed a serious shudder. It only happens on acceleration (even minor acceleration) and is worst around 50 mph. The car shakes like one of the rims is bent badly.

After doing a bunch of searches, I'm thinking that's either the motor mount has gotten REALLY bad, maybe due to that hard corner, or the cv joints are going.

I haven't heard any clicking when making turns, but the car has had a pretty good shudder over the past several weeks on hard acceleration.

Thoughts, comments, cheesefries?

 

[93nighthawk]

Do you hear a clicking noise while driving normally? If not I seriously doubt CV joints. Sounds more like a wheel bearing/ball joint/end link situation. also with the broken motor mount, that might be throwing the geometry out of aliagnment causing the shudder (sense it happens under hard acceleration.) I would first replace the motor mount and see if the shudder goes away.

 

[Dr. Tweak]

Thanks. No clicking at all.

A couple more things I noticed:

It happens both when accelerating and engine braking, but when the car is maintaining speed (ie, I'm just pressing on the gas a little, no serious accel or engine braking) the shudder stops completely.

It is very bad at 50 mph, not bad above or below that speed.

Could this be caused by something going wrong with one of the tires? Both front tires are worn.

Whatever is causing this definetely started right after that hard right hand curve.

 

[93nighthawk]

It happens both when accelerating and engine braking, but when the car is maintaining speed (ie, I'm just pressing on the gas a little, no serious accel or engine braking) the shudder stops completely.

That definitely sounds like the engine has shifted due to the broken motor mount. With the HP & Torque this engine puts out it is not to hard to see how this would cause the shudder even under light acceleration/engine braking when the engine is moving the most (compared to a constant speed).

It is very bad at 50 mph, not bad above or below that speed.

Could this be caused by something going wrong with one of the tires? Both front tires are worn.

Whatever is causing this definetely started right after that hard right hand curve.

As said before, replace the motor mount first (sense you know it is bad), then start throwing other parts at the car. The hard right hand turn was probably enough to shift the engine/tranny out of geometry big time with the subframe which would be similiar to having your tires out of aliagnment. Tires might be the problem, but I doubt that is what is causing your problem.

[Edit]- Also you want to check your other engine/tranny mounts, They could have been damaged by the hard right turn.

 

[Dr. Tweak]

I changed the brakes today with new rotors and pads, problem is gone.

Wierd.

 

[Dr. Tweak]

Nevermind, I guess I just didn't get it up to speed when I test-drove it. It's just as bad as before.

 

[ghostrider]

When you did your brakes, did you happen to check out your tires. A slipped belt would act very similar to that. I would though start with that motor mount first. Since like you said, you know it is bad.

 

[Dr. Tweak]

Maybe I'll switch the tires around and see what happens?

 

[ghostrider]

If you jack up the the front end, just spin the wheels a look for any flat spots, or a buldge. A slipped belt is very noticeable with a visual inspection.