Damaged tranmission due to two-mile on mismatched tires?

My 2002 Ford Explorer (with about 85,000 miles on it) has what seems to be a peculiar transmission, transfer case, or traction-control module problem, but I?m not sure. The vehicle is equipped with an automatic transmission and all-wheel drive, but it can be manually shifted into locked, full-time four-wheel drive.

Here are the symptoms:

The vehicle behaves flawlessly when it?s cold, but after a warm-up of 5-10 miles of driving, a thumping-bumping-shuddering phenomenon occurs beneath the vehicle during acceleration after the transmission shifts into second gear. The problem persists after the vehicle shifts into third gear, but it?s subtler when the vehicle?s moving at a higher speeds. I CAN MAKE THE PROBLEM GO AWAY ENTIRELY BY MANUALLY SHIFTING INTO FULL-TIME FOUR-WHEEL DRIVE, but it?s inadvisable to drive around on dry roads in four-wheel drive, so that?s not a good solution.

Here?s the history:

The problem developed immediately after I went to a tire shop to get my four studded snow tires mounted and installed in early December. Halfway through the job the installer noted a cut through the bead on one tire?s sidewall, rendering the tire unusable. (Perhaps he himself made the cut while attempting to mount the tire on the rim, but I?ll never know.) The shop had no suitable tire to replace the damaged one, so the shop manager suggested that I leave the two already-installed studded tires on the rear of the vehicle, put my regular tires back on the front, and drive a mile or two to the next tire shop to try to obtain suitable replacement studded tires for the front. This strategy seemed reasonable to me, but as soon as I pulled out of the shop the thumping-bumping-shuddering phenomenon beneath the vehicle began. I thought perhaps a tire was way out of balance, so I turned around and drove right back to the shop. They put the vehicle on the hoist, checked the tires, and said nothing was wrong. So off I went again, thumping-bumping-shuddering down the road to the next tire shop. There, they advised me that it was a poor idea to put new studded tires on the front and keep my old studded tires on the rear, so they sold me a full set of new studded tires (about $700 worth) and off I drove with new rubber on all four wheels. The thumping-bumping-shuddering wasn?t as bad then, but the problem has never gone away. On the other hand, the problem hasn?t grown worse. Is it possible that by driving just a mile or two with a mismatched set of tires I damaged my transmission, transfer case, or traction-control module?

Your post indicates the concern was noticeable as soon as you left the first shop, as I read your post (and it is hard to follow) no mileage was put on the truck before the noise showed up.

Get a pro.to confirm that the drivetrain is damaged,then we can start to figure out how it happened.

Elaborate on the “poor idea” issue,poor idea as in causing damage or poor idea in some other way.

just curious: how many miles have been driven on it since the tire change, swap and replacement?

and the thing that makes me wonder is the assertion that the problem disappears in 4wd.

one would think if the thing operates in one mode correctly, then the tranmission is OK. so what is different in AWD? traction control? does your manual state whether traction control shuts off in 4WD? if traction control is ON in 4wd, then that is further confusing.

when you left the first shop was it REALLY just a short time till you returned? how many miles?
I don’t know your vehicle transmission, but you state it has AWD, does it have full time AWD, or is this only selected when the traction control senses slippage in the rear wheels? this may even be the abs sensor or the speed sensor may be involved. but too many guesses is too expensive.

Thanks for your interest in this. Here are some answers to your queries:

I’ve driven the vehicle only about 500 miles since the tire change and the onset of the problem.
The default drivetrain mode for the vehicle is AWD, but I’m not sure how that system really works. It has some type of traction control, which presumably shuts off when the vehicle’s in 4WD, but I’m not really certain of that, either. My manual contains no relevant information on this.
I truly drove less than 1 mile before returning to the shop when I first noticed the problem.
I think what I need as a starting point is simply a clear understanding of how the AWD and 4WD systems on the vehicle really work, but I’ve been unable to find useful information on the internet or anywhere else. I hate to go to the Ford dealer, where they’ll charge me an arm and leg just to touch the vehicle.

It sounds like to me that the drivetrain is the problem. As far as Ford says they recommend changing all 4 tires a once (per owners manual). The problem being that a 4wd/Awd vehicle with 1 or more odd tires make the center differential work in a way it shouldn’t for more than a few seconds. Basically bronze bushings melt and seize the center diff. It sounds like your is currently half way there. Your best bet is to bring it in to get fixed before something breaks and its Found On Road Dead