Best Panther site for tech?

[EW]

My grandmother has a '99 Grand Marquis that has an intermittent driveline vibration especially if driving under load uphill. It does it with overdrive on or off. 75K miles.

[Aceman85turbo]

the only panther specific forum i am aware of is crownvic.net

[dee]

Put some limited slip additive in the trans. Are you sure it isn't a miss?

[Skidonenko]

If it happens when the torque converter clutch is coming on its time for a mercon V fluid and filter change. Sometimes the converter can be bad enough that it needs to be replaced but generally this cures it if it has not been happening too long.

[ELVIS]

panther = crown vics???

god bless.

[Damnittsteve]

panther = crown vics???

god bless.

panther is to crown vics, grand marquis as is fox is to mustang.

[76 Maverick]

Crownvic.net is where i got all my cv info....

[EW]

Put some limited slip additive in the trans. Are you sure it isn't a miss?

Pretty sure. The vibration is jarring and feels like it is coming from the rear tires. Driving is normal and then bam,bam,bam,bam then normal for 1/4 mile, 1/2 mile then same pattern bam,bam,bam,bam. It is not very loud but strong low frequecy vibration. On a smooth, uphill road, it is really obvious. On a rough road, it is a little harder to pick out but once I knew what I was looking for, it became easy to identify. Car seems to idle and rev ok. My guess was transmission related. Hopefully a fluid change will do it.

[EW]

If it happens when the torque converter clutch is coming on its time for a mercon V fluid and filter change. Sometimes the converter can be bad enough that it needs to be replaced but generally this cures it if it has not been happening too long.

Thanks!

[shumpertdavid]

Converter shudder is common in the ford overdrive transmissions. Easiest way to tell is 2 ways depending on when it happens. Pay attention if it's doing it as the converter locks up, or if it's while locked up and pulling a load. If it's as it locks up there's not really any other diagnosing that I remember. If it's while pulling a load, like up a big long hill, then simulate the problem and while it's acting up use your left foot to apply the brake pedal just enough to turn on the brake lamps, this will also command the converter to unlock. If it instantly quits at unlock then it's torque converter shudder. The fluid change is typically a bandaid from what I understand. The repair is a converter or something in the valve body from what I remember the trans guys saying.

[Skidonenko]

Pretty sure. The vibration is jarring and feels like it is coming from the rear tires. Driving is normal and then bam,bam,bam,bam then normal for 1/4 mile, 1/2 mile then same pattern bam,bam,bam,bam. It is not very loud but strong low frequecy vibration. On a smooth, uphill road, it is really obvious. On a rough road, it is a little harder to pick out but once I knew what I was looking for, it became easy to identify. Car seems to idle and rev ok. My guess was transmission related. Hopefully a fluid change will do it.

Converter=running over rumble strips

That sounds more like rear axle, I would check your u-joints, diff gears/ring/pinion. If anything feels funny pop the cover.

If the axle checks out ok drop the trans pan and look for metal as you probably lost a bearing in the planetary and its locking up. If this is the case it may be intermittent but can lock the trans up permanently.

http://www.tccoa.com/articles/tranny/transmission/page1.shtml

Could it be a missfire?torque brake it with the parking brake set for 5-10 seconds, it will buck if you have a miss.

[EW]

It is kind of like rumble strips. So the torque converter makes a thud when it locks up? If driving around 60 or so on a flat road holding the gas constant then press the gas smoothly to accellerate, there will be a thud. It is not a downshift.

[Skidonenko]

Does the instrument cluster have a tach? I know some did and some did not, like stated above if you are on that road just hold a steady speed and tap the brake pedal for a second enough to kick the lights on but not enough to slow the car down and the converter will release, (default stopping strategy so you dont get a clunk when coming to a stop/downshifts) rpm's will go up 500rpm or so, after a second or two the converter will reapply and you'll feel the shudder/rumble as the rpm's fall.

If the fluid/filter are old I would most definitely change it with mercon V or SP (Ive know people to run it in ther E4OD's and 4R100's with great success.

*FLUID EXCHANGE ONLY RECOMMENDED IF THE FLUID IS NOT BLACK/BURNT

[One zero]

Sell it to dammitsteve. He'll pay 7 grand for the pleasure of ownership...

[LS1Goat]

I had the same thing happen in my '00 GT. Felt like running over train tracks. Torque converter shudder right was around 40-45 under load, when the clutch locks up. I solved the problem by simply changing the fluid/filter and then installing a B&M trans cooler. Did no permanent damage to the trans and it never happened again. It's all heat related breakdown of the trans fluid.

This is extremely common with the 4R70w. If you catch it time, it won't hurt anything.