Thread: bad vibration while accelerating help please!!!

check th enigine mounts. that can cause alot of vibrating. i know my old gtp used to have a really bad vibrating at around 1600 rpm's. im pretty sure it was the mounts

Your wheel bearing will not causing vibrating. The way you tell your wheel bearings are going out is when you turn your wheel all the way over and give the car gas from a still position, you will hear them make a popping noise indicating a problem with them.

The vibration I had in mine was from the Driver side half shaft literally wobbling when I get to 40+mph. And it would continue until I reached a good cruising speed. The best way to tell if your half shaft is wobbling is to put it on a lift and have a tech sit in the seat and give it gas. You will either see the shaft stay true or it will wobble. That is exactly how I discovered my issue. Once I replaced it, problem was gone.

Now if your car is lowered, and you have not done the spacer trick to equal out the half shafts, you will get vibration as well. Not quite severe as you mentioned, but you will feel it the steering wheel after you hit 60mph+

Examining your engine mounts and tranny mounts is not a bad idea as well. Check for wear, cracks, or even leaking hydrolic fluid from them if they are the stock ones.

I hope that helps steers you in the right direction.

Originally Posted by GeddyLee

Now if your car is lowered, and you have not done the spacer trick to equal out the half shafts, you will get vibration as well. Not quite severe as you mentioned, but you will feel it the steering wheel after you hit 60mph+

Geddy I just recently lowered my car and it vibrates when i accel but when i let off its fine but i was wondering what the "spacer trick" was.

you put spacers underneath the motor mounts so that it raises the engine and transmission back up so that the axle geometry is correct. that is the reason why it shakes when you lower the car. your other choice is to shorten the front dogbones about 3/4".

the spacers are the "right" way to fix it, but the dogbones work. ive got shortened dogbones on mine and it took away the majority of it to where i dont mind driving the car. before i shortened them it shook horribly.

yea i got shorter dogbones i mean its not bad like ya said were ya cant drive it but i yea i was just wondering thanks bro!

Originally Posted by b00stinGTX

Geddy I just recently lowered my car and it vibrates when i accel but when i let off its fine but i was wondering what the "spacer trick" was.

Well if you have not done the spacer trick, then yes your car is going to exihibit some vibration. I am running poly mounts for my motor mounts and the dogbones, those alone stopped most of my vibration. I am thinking I am going to have to break down and purchase a set of the spacer to truly put the engine/axel alignment right.

I am not a huge fan of the shortened Dogbones. Why? Well if you are running headers, not sure if the Plog would be susceptable to this as well, but when you use the shortened dogbones you pull your heads into the radiator fans. This is usually considered a BAD thing

Some folks who cant or dont wish to pay for polymounts will do the stock bushing flip to help alleviate some of the vibration by keeping a "frimer grip" on the engine thus illiminating "some" of the vibration caused when lowering your car.

Just another thought for ya.

my headers rest on the heat shield for my radiator fans and they are going strong for quite a while already.

Originally Posted by Bio248

my headers rest on the heat shield for my radiator fans and they are going strong for quite a while already.

I know Bio, I am just not a big fan of that. I am glad its worked for you no doubt, I would just perfer to avoid those potential issues down the road. Also it doesnt give you a great deal of wiggle room if you are trying to get into front area to work on anything.

We had a guy in local GP who we helped install his TOGs Extreme headers and he had the same problem, but his Dogbones on his 04 Comp G were stock and he was nailing the fan with them. If he had shortened Dogbones, it wouldn't have worked at all for him.

It was just a general observation

i think i would gain a little room if i were to switch to the 99+ fans as they are more slim line. mine are HUGE!

A friend of mine had a pretty bad vibration on his wife's GTP only under acceleration as you described. I drove it myself and noticed it right away. When you let off the gas, it went away. The problem turned out to be a bad CV joint. New axle assembly cured it immediately.

Ironically, it was a redfire metallic also. LOL! Doubt that had anything to do with it though.

speaking of bad CV joint I think I need to replace my driverside one that would pry help hah

Originally Posted by 01RedfireGT

Still havent gotten around to fixing it, but on another note, how do you guys go about changing the rear plugs on your 3.8's?

unhook the dogbones in the front. rock the car until the motor leans towards the front of the car and quickly engage the e-brake. you should be able to reach the rear plugs easier now. otherwise they arent that bad just normally.

Vibration under acceleration = bad CV joint.

Just for informational purposes I'm posting the link to the motor mount spacers but if you aren't lowered this won't be your problem solution:

http://www.grandprixforums.net/motor...tock-1107.html