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2002 Crown Victoria front vibrates at 55-65 mph, else fine

I love this car. It’s a CNG vehicle and has saved me many hours of sanity in commute traffic. I’ve only had it for a year. It’s past life was a taxi car. It currently have close to 395k miles, and does have a few other issues (no engine light now).

The problem I have now is the front of the car starts to shake when I get the car running somewhere in the 60MPH to 65MPH range. This problem is more announce when I let go of or step the accleration and it transitions into that speed range. The problem is dampen or less when I’m stepping on the accleration, inside that speed range. It’s incrementally less when I’m above or below that range (+/- 5mph). The shaking and vibration sounds is almost as close to the sound that’s generated if you’re running the car’s tire on the freeway shoulder’s (california) or having a helicopter hover ontop of your car (but faster).

Possibilities include worn bushings, ball joints, CV joints, tie rod ends, and on & on. With 395K on the chassis, anything could be worn out, busted, or rotted. Or it could be the tires.

Sorry, but a good mechanic has to get under the car to tell you what’s wrong. And with that many miles as a taxicab, I’ll bet the list will be long.

The only cheap fix is to check that the front tires and wheels are balanced.

it could be anything from tire balance to bad bushings and almost anything inbetween

I am going to bet on one bad tire. There is an internal tread separation. You can test this yourself before turning your bank account over to a mechanic. Rotate the tires, front to rear. See if that changes the vibration pattern.

In some cases on these tranmissions, that rumble strip effect can be caused by a torque converter and/or aged transmission fluid. In a nutshell, it could be a converter shudder so a fluid change might help.

My memory is a bit fuzzy on this but I think this car may have a converter drain plug on it too which makes a more thorough fluid change much easier.

At near 400k miles though, I could think of a number of possibilities related to steering, tires, and suspension.

Just want to update this thread. I have recently replaced the right and left (both inside and outside) tie rods, checked the tire balance, and have also swapped the front with the back and the back with the front tires. The problem is still there. I did bring the car to Firestone(auto mechanic), and had a full inspection. They commented the engine mount thread is slightly worn. Could this be the cause of the problem I’m having?

I want to root cause this issue. Any other ideas on where I can/should start looking into? Could this issue be related to the transmission?

I also noticed the vibration window has widen and is now any where from 50-70 mph range. I don’t have any problems inside this window, as long as I am stepping on the gas peddle. However as soon as I let go and start coasting for a second or two, the vibration would start. I’m not sure where the vibration is coming from(either from the front or on the bottom of the car). I’m certain the problem is not caused by the brakes, because the noise isn’t there when I step on the brakes.

Three suggestions:

Have all four wheels checked on a machine that does “road force balancing”. If there is any anomolie, that’ll find it.

Have the CV joints checked. Sensitiviity to the application of or removal of torque on the axles could indicate a bad CV joint.

When the engine is cold, try physically shaking it and see how the mounts act. If you do have a bad mount, it’ll show.

Check all of the bushings and joints on the rear of the car also.

Okay, that’s four not three. But try them anyway.

OK, I was going for tire balance until you posted more info. Now I would check the universal joints in the driveshaft. Just grab the driveshaft and rotate back and forth and look and listen for play in the joints

“Have the CV joints checked. Sensitiviity to the application of or removal of torque on the axles could indicate a bad CV joint.”

Mountainbike–I think that you perhaps did not get enough sleep last night.
This is a RWD car, thus, no CV joints.
;-))

Personally, I think that the problem is most likely to be a defective or out-of-balance tire, but…with almost 400k on the odometer, the possibilities are actually a fairly long list, and the OP has seen all of those possibilities listed already.

Oops. You’re right. I didn’t. I stayed up to watch Joe Bonamasa “An Acoustics Evening at the Vienna Opera House”.

Make that the U-joints!

@ok4450 “In some cases on these tranmissions, that rumble strip effect can be caused by a torque converter and/or aged transmission fluid”

Liked it, Let us know the answer @garyz21 when you find it.

Take a look at the driveshaft and it’s U-joints…

Thanks for the comments. When I brought the vehicle into Firestone, they claimed all the tires were balance checked and were all set to the right tire pressure. I’ll try the other suggestions and update this after this weekend.

Thanks,

Just for clarification, “balance checked” isn;t the same as “road force balanced”. “Balance checked” usually means they put it back on the spin balancer for a recheck. “Road force Balanced” means it was spun balanced with the addition of a simulated roadforce. This is done by pressing the tire against a spinning drum while it’s being balanced. This can detect internal tire anomolies that regular spin balancing cannot. They may have done this, but I wanted to be sure there was clarity in case they didn’t.

I had a ujoint of a rwd car, in need a replacement. It did start out as a vibration…but it was in the butt. Of course the radio was playing disco music…but, I’m betting on front end components…tie rod or wheels etc. including rim and or tires. I would do a simple rotation first to eliminate that wheel possibility…if not done already.
@Same
You know you were really watching Jersey Shore reruns.

not all rwd cars have u joints do have cv joints but this c.vic has u joints

I don’t think this is a tire issue - crowding the throttle shouldn’t change a tire vibration. So I think it’s u joints.

But there is a simple test. Swap the tires front to rear. If it’s tires, the vibration will change.