Wheel bearing adjustment - another mod?

[Thymeclock]

I was driving my wife's 2009 Aveo the other day, and I realized something was different between this new car and the 20 year old others that we have. I try to coast as much as possible (even with the automatic in 'drive') and I occurred to me that when I take my foot off the gas on the new car it doesn't glide as well as my other old beaters do. I'd attribute this to the wheel bearings (and other components) being new and tighter by comparison. (It might also be the nature of the transmission, but my perception is that it just seems to not roll quite as easily.)

I've heard it said (in the case of the Aveo) that the gas mileage will improve as the car gets older. (We're currently getting a disappointing 22.5 MPG in all city driving, and that's with using the scan gauge and driving conservatively.) I find it hard to believe that mileage or anything else will get any better as a car ages, but in thinking about it, it seems possible that worn and looser parts might exhibit less rolling resistance. Also this might explain another factor as to why cold weather operation reduces FE: the colder the temperature, the less viscous grease and lubricant becomes, and the resistance is increased.

If I'm correct, you might want to add this to the list of suggested modifications. Not that we should want want sloppy steering or suspension, but if wheel bearings or brake components are adjusted too tight or there is any increased resistance in the rolling ability of the wheels, it's not going to help FE any.

[Frank Lee]

Bearings are normally credited with a really, really small portion of the various kinds of drag vehicles face. Your car's lack of coasting prowess is due to other things. That said, yeah, most anything that moves against anything else will do better after break-in.

[Thymeclock]

Originally Posted by Frank Lee

Bearings are normally credited with a really, really small portion of the various kinds of drag vehicles face. Your car's lack of coasting prowess is due to other things. That said, yeah, most anything that moves against anything else will do better after break-in.

Older cars remind me of wearing a favorite old pair of slippers that have loosened up: they don't pinch anymore, you know what they can and can't do, and you know why they are comfortable. And you probably won't wanna give 'em up until they are all worn out.

[NeilBlanchard]

Check the tire pressure -- and new OEM tires can be pretty janky. If you pump 'em up to close to the sidewall maximum, you should see an improvement in coasting. You might also have dragging drum brakes (or one of 'em), or the handbrake is not releasing properly. You might have an alignment issue.

[McTimson]

Try coasting in neutral, the car may just be engine braking when it's in drive.

[Christ]

Originally Posted by Thymeclock

Older cars remind me of wearing a favorite old pair of slippers that have loosened up: they don't pinch anymore, you know what they can and can't do, and you know why they are comfortable. And you probably won't wanna give 'em up until they are all worn out.

Don't wanna give 'em up until they're worn out hell!

I just got a pair of boots back from the boot store next door - I paid $14 to get a $40 pair of Wally World boots fixed because they're comfortable!

I ain't lettin 'em die!

As far as bearings, there isn't really much you can do besides let them wear in on their own. It's the same with engine bearings, rings, etc... the engine will run better once it's loosened up a bit.

If you're replacing bearings, I tend to be a bit conservative with torquing them all the way to factory specs for the first 50-100 miles. I'll usually back the castle nut off by one "tooth", then put the pin in, then after about 50-100 miles, I'll pull the pin again, re-torque to factory specs, and reinstall the pin.

This has more to do with my strange habits than anything, but I believe that the bearing needs a little "wiggle room" to properly seat. Same deal with new lug studs, except you have to retorque those because they stretch ever so slightly with torsional load.

[Thymeclock]

Originally Posted by NeilBlanchard

Check the tire pressure -- and new OEM tires can be pretty janky. If you pump 'em up to close to the sidewall maximum, you should see an improvement in coasting. You might also have dragging drum brakes (or one of 'em), or the handbrake is not releasing properly. You might have an alignment issue.

The car is practically new (2 months old.) I'm not about to start disassembling everything on it.

1000 miles down and 99,000 to go... then we'll see if looser is better.

[user removed]

Most of the new cars today do not have adjustable wheel bearings. They are sealed units and much more expensive than the old ones.

regards
Mech

[Hankinator]

I agree with the other posters and their suggestions with this addition. Could the something else causing less coasting be attributed to the vehicle weight? Your older/other vehicle is surely heavier than the Aveo. Less weight...less inertia...less coasting ability. Something to consider.

I have also wondered if it would be worth repacking wheel bearings with synthetic grease and "adjusting" the tightness of the spindle nut for better coasting.

Thanks,

Hank

[tasdrouille]

I've seen a reference crediting 12% of rolling resistance to bearings and seals, 82% to the tires and 6% to the brakes.