Car still vibrates under load.

[brugg125er]

So my 02 GTP had the typical vibration at about 35-45 mph because the axles were bad. It also had vibration at highway speed 60+mph under light load and would dissipate to barely nothing once the cruise was set or I let off and coasted. Today I got both front axles replaced along with both rear hubs/bearings. It took care of the vibration that was happening at 35-45 mph but not the highway speed vibration. Anything under highway speed the car drives smooth.

Anybody have ideas on what it could be? Lower motor mount?

Thanks in advance.

[FordMan77]

Have you had the tires balanced?

[idrivejunk]

Tie rod ends? Any tire wear issues to report? If your tie rod ends are greaseable, try lubing those. You've probably already checked, just an idea.

[brugg125er]

Have you had the tires balanced?

Yeah the tires are balanced. Or at least I think they are (Walmart installed them). I forgot to mention they were. It vibrated with the last set of tires I had on, they were balanced as well.

Tie rod ends? Any tire wear issues to report? If your tie rod ends are greaseable, try lubing those. You've probably already checked, just an idea.

I actually did not check the tie rod ends. I will tomorrow though. Tires are almost new (about 2000 miles on them). No odd wear spots.

[dezebe1]

Not just having the tire balanced but take the vehicle to a place that has a balance machine that can measure roadforce variation, dealers are your best choice. Your tire may be balanced fine but excessive roadforce can cause it also.

[Mirraco]

I would check the tie rods, and ball joints. Also what dezebe1 said, you can always bring it to a dealer, and more times than not, they can find the issue, and want to charge you 200-300$ for a 20$ job.

[NotEnoughGPs]

I have driven some GP's in the past with high mileage, currently have one with 224K miles. In almost every case of vibrations, it was due to the tires not being balanced correctly. I know you said the tires are ok, but try rotating the rear tires to the front and see if you still have the problem. Since your tires are new, it is unlikely they are cupped. So, that will not be the issue.

Since you have new tires, get a good 4 wheel alignment. I have all my alignments done at a local shop with Bear alignment equipment. Also, I heard that Hunter equipment is good. Be sure to tell the shop that you are experiencing vibrations at highway speeds, and have new tires and new axles. A skilled shop worker will be able to advise you as he is doing the alignment as to what problems you have that are causing the vibrations. As mentioned by the other GPF members, it could be tie rods, ball joints, motor mount or even wheel bearings, lower control arms, worn strut parts or front end accident damage. It is possible, however unlikely, that one of the new axles is bad. Also, I have had new wheel bearings installed and had one of them go bad in less than 10,000 miles. Something is causing the vibration at highway speeds.

After the shop does a proper alignment, they should tell you to drive the car right away at speeds above 50mph to see if you are still getting vibrations. What I am saying is that a good alignment shop can help sniff out drivability issues since they deal with cars everyday.

The shop I go to is in Butler, PA (right off RT 422) and they have helped me in the past. Their prices for complete 4 wheel alignments is not bad. They pointed out problems with wear issues with the car and I got those items replaced. My GP with 224K runs very smooth at all speeds. Also, this shop has told me that GP's are a quality built car. Hmmm

[brugg125er]

I have driven some GP's in the past with high mileage, currently have one with 224K miles. In almost every case of vibrations, it was due to the tires not being balanced correctly. I know you said the tires are ok, but try rotating the rear tires to the front and see if you still have the problem. Since your tires are new, it is unlikely they are cupped. So, that will not be the issue.

Since you have new tires, get a good 4 wheel alignment. I have all my alignments done at a local shop with Bear alignment equipment. Also, I heard that Hunter equipment is good. Be sure to tell the shop that you are experiencing vibrations at highway speeds, and have new tires and new axles. A skilled shop worker will be able to advise you as he is doing the alignment as to what problems you have that are causing the vibrations. As mentioned by the other GPF members, it could be tie rods, ball joints, motor mount or even wheel bearings, lower control arms, worn strut parts or front end accident damage. It is possible, however unlikely, that one of the new axles is bad. Also, I have had new wheel bearings installed and had one of them go bad in less than 10,000 miles. Something is causing the vibration at highway speeds.

After the shop does a proper alignment, they should tell you to drive the car right away at speeds above 50mph to see if you are still getting vibrations. What I am saying is that a good alignment shop can help sniff out drivability issues since they deal with cars everyday.

The shop I go to is in Butler, PA (right off RT 422) and they have helped me in the past. Their prices for complete 4 wheel alignments is not bad. They pointed out problems with wear issues with the car and I got those items replaced. My GP with 224K runs very smooth at all speeds. Also, this shop has told me that GP's are a quality built car. Hmmm

Thanks for the detailed reply. I actually forgot, it was in a front end accident with the previous owner(s). So that could be the problem. But wouldnt it continue to vibrate after i set my cruise or left off the gas? It is only vibrating when i put load on to accelerate even the slightess amount.

[00Daytona]

motor and trans mounts. I had this problem on a few 3800 fwd cars. you can replace EVERYTHING; axles, ball joints, balance wheels, new tires, strut mounts, and it will vibrate/shake under load if the motor and trans mounts are bad. drivers side trans mount is super easy. Passenger side lower motor mount not so much.

[Casper00693]

Need to bump this post... Ive done what 00 daytona said.. However i also have the throttle vibration also at idle... Did you fix it?

Ive changed, dog bone mounts, ttans mount, new lca's, ball joints, tie rod ends, subframe bushings (im at 271k).

I just ordered strut mounts and engine mount once i do those ill see... Hoping for the best cause om going nuts oh... Even changed harmonic balancer.