Car Shudders

You guys have helped me so much in the past. I’m hoping you can help me figure this one out, too.

I don’t know if these 2 problems are related. A week ago a friend thought my right front tire looked a little low. It was hard to tell. I live in Maryland, where we just got through 2 huge blizzards, so I wasn’t driving anyway. There was no way I could even check the air in it.

Yesterday I discovered it was almost completely flat. I drove it 1 block to a tire shop and they put air in it. Obviously the best thing to do was to have them take it off and check it, but I was on the way to the doctor 1.5 hrs away and they couldn’t get to it for 2 hrs. I had to take the chance that it would be okay, and drove in the right-hand lane with care.

The trip there was perfectly fine, but just as I turned right into the parking lot the car shuddered/vibrated quite noticeably. I had to circle the lot for a space several times. It didn’t shudder every time-- it was intermittent-- but it seemed to increase in frequency over those 15 minutes. It also did it while turning left a few times.

The tire looked fine. After my appt, I decided to drive it a little and see if I could pin down the problem/noise better. But the noise was gone. I headed for the highway, since the Subaru dealership was on my way home. No noise.

I drove 80 miles home and it never did it again. Any ideas?

1999 Subaru Legacy sedan, 140,000 miles, auto trans. Tires have about 10,000 miles on them.

The Subaru AWD system is very sensitive to differences in tire diameter, and driving the car with a tire with low pressure can lead to very expensive damage to the viscous coupling/variable transfer clutch (the exact nature of the device varies with different transmissions and different models).

I would suggest first verifying that the tires are all inflated properly. If you don’t have a tire pressure gauge, you need to buy one. Then, have a mechanic who is very familiar with Subarus check the viscous coupling/variable transfer clutch.

Thanks for replying! I’ll definitely check the tire pressures. Could it have the AWD problem you described even if it drove fine for 80 miles on the way home?