CAR TALK: When faced with a pricey estimate, consider experimenting

Dear Car Talk:

I have a 2003 Chevy Trailblazer 4.2L. The front differential is shot. I bought it not knowing that. I have talked to shops around my area, and it’s going to be around $5,000 to replace, if they can find me one.

My question: Can I just remove the front CV axle shafts and drive it? I know I won’t have 4WD, but I can live with that.

Please let me know. Thanks. — Travis

I have good news for you, Travis: This is the perfect vehicle on which to find out.

It’s time for an experiment. I think you can turn your Trailblazer into a rear-wheel-drive vehicle. As you say, you’d have to start by removing both front axles.

That’ll prevent the front wheels from turning the differential gears when the car is moving. I don’t remember how the axles are connected to the front differential on this truck. Sometimes there’s a flange, sometimes they go right into the differential itself. If your axles go inside the differential, then when you remove the axles, the differential oil will leak out. But who cares? You’re not going to be using it anyway. And it’s already shot. So, it’s just a matter of draining the oil and disposing of it properly.

Once the front wheels are free of the axles and can turn freely and independently, they have no need for a differential, so steering and turning won’t be affected.

Next, you could try to remove the front drive shaft. That’ll prevent the transfer case from turning the front differential gears if you (or someone else) accidentally put it in 4WD. If you can do that without making the transfer case leak, I’d do that, too.

If not, just leave the transfer case in 2WD, so the front driveshaft never turns. At that point, you have a rear-drive-only vehicle, and you’re just carrying the differential around with you — as if it were your favorite bowling ball.

This stuff is probably beyond the scope of your average DIYer, Travis. So, I’d have a shop do it for you and test it out. It’s not a big job but it requires some tools you probably don’t have.

Then save the parts, just in case the experiment fails. I don’t think it will. But even if it does, you’ll be no worse off than you are now — needing a new front differential. Or a different car.