05 LS8 drivetrain vibration

just bought this car at a auction, has a vibration that starts about 40mph, feel like drive shaft u joints like the old days, i put transmission in nutural doesn't change, rotated tires front to rear no change, everything looks good, drive shaft, rear axels, any ideas thanks

Could it be a symptom of a bad torgue converter?

Try shifting out of "5" and to "4" to see if the vibration changes or goes away. I think if you shift from "5" the locking torque converter will unlock. If it's a u-joint, bearing, or wheel balancing issue the vibration shouldn't change.

-Rod

i'll try that when i get the car back from lincoln dealer, it's in there for coil recall, i'll keep you posted thanks mslv 1320

All of the problems with Lincoln LS were weeded out befor 2005, the dealer should know if there is any recalls.

How about a free inspection at CarMax, they might do a better job of inspection.
I bet, they would do a free CarFax too.

Tires
Drive shaft
broken mounts

ok i'm the original post, this vibration comes in like clockwork at 40 mph, it is a pretty good vibration between 40-45, gradually smoothes out by 60, don't feel it much at all after 60, putting transmission in nutural at the peak (40mph) doesn't change a thing, i don't hear any noise in the drivetrain, i'm no dummy when it comes to cars, i don't think it's torque converter, or internal transmission, the transmission shifts fine, i think it's the center carrier bearing in the driveshaft or u joint, , but can't confirm it. any other ideas thanks

I'm trusting that you feel it primarily in the body of the vehicle and not in the steering wheel, and when you rotated the wheels/tires, the vibration remained in the body and not in the steering wheel. I'll also assume that when you rotated the wheels/tires that you inspect all suspension and steering components for wear and they are all fine.

Were any of the tires wearing poorly or cupping? You might try to find a shop that has an alignment rack and is willing to put your car on it, get all four wheels off the rack but supported by the suspension (so the ride height is about normal) and slowly bring the car up to 40 mph. If the vibration is still present you'll know it's in the rear of the vehicle and if there's someone under the vehicle they may be able to tell if it's driveshaft or half shaft. You could also index, then remove the various pieces of the driveshaft and take them to a driveline shop to have them balanced. It would be easy to check the carrier bearing at that time too.

-Rod

There's a TSB (S204-07ammended) for a S Type Jaguar, that had simular problems.
The forward front mounting bushes with a new/updated unit.
Part# JLM21535 , eccentric bolts, and align suspenshion.

thanks for the info, you assumed right, the vibration you feel in your seat not the steering wheel, i talked to my tire shop this morning, he is going to check tire balance, check for bent wheel or axle, and than check driveshaft if needed thanks mslv1320

Since the vibration was never apparent in the steering wheel as you rotated the tires I don't think it will be a balance issue. As you're probably aware, a balance issue on the front of the car will usually cause a shudder in the steering wheel.

-Rod

I've got the same exact vibration! Let me know what you find. It's definetely not from the front. I was thinking driveshaft, rear axle shafts, tranny or wheel bearings. I have no idea and it could cost some serious cash to pin point where it's coming from.

i'm the original post guy again, reply to kcobra, i am in the car business so i'm no dummy, i've had almost everyone i do business try to pinpoint this vibration, can't say for sure, but we are about 99% sure it is the center carrier bearing in the driveshaft, i gave the car to my wife, we've driven it app 1000 miles, the vibration hasn't changed a bit, that i can tell, wouldn't be suprised if this car hasn't been like this for sometime, i sort have got used to it, still bug's me though, i plan on buying a used driveshaft including both rubber ends, out of a 43,000 car and replace mine, just haven't done it yet, it's about 1.5 hours labor to replace, plus whatever you pay for the shaft, so if that's it a fairly cheap fix, i'll let you know when i do it and results , if you do this before i do let me know results thanks

Thanks, will do.