Telegram & Gazette

When towing, the center differenti­al makes all the difference

- Car Talk Ray Magliozzi

Dear Car Talk: I just read your recent answer to David, about how to tow vehicles with automatic transmissi­ons. It made me think about my parents’ RV trips years ago, where they towed a ’95 Jeep Cherokee with an automatic transmissi­on behind the RV. The transfer case was in Neutral while being towed, and I don’t remember about the transmissi­on itself.

Was that acceptable or was that causing wear or damage to the drivetrain?

Thank you.

Stuart

Well, since they got away with it, I’m going to conclude that it wasn’t that bad, Stuart. After all, you didn’t describe it as “a ’95 Jeep Cherokee that went through three automatic transmissi­ons.”

In 1995, the Jeep Cherokee was an old-style fourwheel-drive vehicle. That means it did not have a center differenti­al. Modern all-wheel-drive vehicles have center differenti­als, with all four wheels connected to the power train all the time. For those vehicles, we recommend flat-bed towing exclusivel­y.

But on the old Cherokee, by putting the transfer case in Neutral, you could literally disconnect the front drive shaft (and front wheels) from the rest of the drive train. That way, the front wheels could turn freely without being connected to the transmissi­on.

So, if your folks put the transfer case in Neutral and lifted the rear wheels of the Cherokee off the ground, and towed it (facing backward) with its front wheels on the ground, that would have been perfectly safe. If they towed it on all four wheels behind their RV, even with the transmissi­on in Neutral, then the rear driveshaft would have been turning the components of the automatic transmissi­on.

And while it wouldn’t necessaril­y ruin the transmissi­on, it would cause the transmissi­on to heat up.

Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.

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