Harmonic Balancer

under acceleration the engine will knock loudly as you accelerate harder. the balancer is advancing the timing. look for an oil leak in the front seal area as this deteriorates the rubber in the balancer. eventually this will lead to the balancer coming apart as it did on my 95 gt

I asked the question as I noticed a slight vibration while on a recent long drive at speed. (you can feel it in the floor pan) Very slight but nevertheless there and it appears to be throttle sensitive. Trying to rule out certain items of the many that could be the cause.

You can put matchmarks on the hub and pulley of the damper. (BTW, on the 5.0L it's a harmonic damper; the engine is internally balanced.)

If the rubber is deteriorating you will probably notice the matchmarks getting further apart as you put mileage on the car.

M dad's '96 GT developed a shake noticeable only on the highway too. It turned out to be the driveshaft being out of balance. $120 to balance and get new U-joints and the car was smooooth after that!

BTW, I notice in your sig that you have under drive pulleys. Most of the UDPs I've seen eliminate the rubber-isolated harmonic damper.

On Tue, 30 Aug 2005 16:09:03 -0700, scromwell2 rearranged some electrons to form:

No, it isn't.

Did you break that too while abusing the car?

Huh. I had a Ford truck w/ 302 and it had a plain round damper and flywheel. I wonder if they were incorrectly in there?

(BTW, today is the first day I drove my dad's car. 10 years and 125k miles gave him plenty of time to wear it out.)

New aluminum drive shaft with u-joints installed last year

UDP's have been on the car for 4 years.

I'm beginning to think that maybe it's not driveline related. As I've only had the car for 4 years and the mufflers are stock,I'm now wondering if the vibration could be comimg from a muffler whose inards are coming apart. I've had to weld the tail pipes back on twice (one each side) this past year.