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Got The Shakes At High Speeds

At low speeds my Aerostar 3.0 engine doesn’t shake (at least I think it is the engine that is shaking). When I hit 50-55 and up it starts to shake-vibrate accept when I accelerate-then she stops momentarily. What is up with this?

Shake in this speed range generally indicates a bad front tire rather than engine shake. Check this idea by moving the front tires to the rear and see if there is a difference.

No, brand new tires on the front end. This was going on before I got the tires also. Thanks for trying to help.

The problem you describe sounds like it might be being caused by the tires being out of balance. And, it sounds like the rear tires are the ones out of balance. I learned this as a youngster working at a tire store. Can’t hurt to have them checked.

You’re right! I’ll do that tomorrow and see what happens.

The only thing that stops me for believing this is that when I excelerate the vibration stops and sometimes for a while then begins again. I don’t think its the tires.

I just went out and I am finding the car is even idling rough now.

I agree it’s not tires. The fact that acceleration changes it is a clue.

I think it’s U joints - especially the rear U joint. The pinion angle changes on acceleration and that’s why it disappears.

How old is the fuel filter? Plugs & wires? Air filter? I’m not saying not to worry about something in the driveline, but if it idles roughly it may be the engine after all.