Downshifting to 2nd in an automatic while going 75 mph? Not fatal, but not recommended.

Dear Car Talk

Dear Car Talk | Mar 01, 1993

Dear Tom and Ray:

We drive a 1989 Ford Aerostar minivan. The gear shift is on the floor between the driver and the passenger seat. It's an automatic transmission. The problem is, my husband drives when we go through the mountains, and he likes to let the car accelerate to about 70 mph on the downward slope in order to not have to press the accelerator so hard to make it to the top of the next hill. One time I woke up in the passenger seat, and he was going too fast, so I asked him to apply the brake. He refused, so I pulled the gear lever from D into 2, which slowed us down. 300 miles later, we pull into a service station, and he noticed that transmission fluid was leaking. The fluid was not leaking much, but we took it to our garage and they told us we needed a whole new transmission. He says it's my fault for downshifting at 75 mph. Is he right, or is it something that can just happen at 78,000 miles?

RAY: It's probably not your fault, Annie. I wouldn't say what you did is GOOD for the car, but shifting to second gear once at 75 mph is not going to ruin the transmission.

TOM: And the reason is that the transmission has built-in protection that prevents it from ruining itself if you shift into a lower gear when your going too fast. It's really to protect the ENGINE from being revved too high.

RAY: If you had shifted to FIRST gear at 75, the transmission wouldn't have done it. It would have shifted to second and waited until the car had slowed down enough to make the shift to first gear safely.

TOM: But even though you didn't ruin the transmission, Annie, you shouldn't do that again. It's dangerous to interfere with the driver's controls when you're sitting in the passenger seat. The appropriate way to protest your husband's driving is to sit quietly until you get home...and then call your mother and invite her to come visit for a month.

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