Are 4WD and AWD the same things?

Question

I know that 4WD can be turned on whenever needed on my Ford truck, but my dad is thinking about buying and AWD 1997 Chevy Astro and he wants to know if the AWD can be turned off and not stay on all the time.

Answer 1

4WD is usually a manually actuated system whether turning hubs in and pulling a lever or pressing a button on the dash. These systems are the best and only system I would use. Plus they have a low range position available also.

AWD is just that AWD there isn't a 2WD position, and usually with most systems there isn't a 4WD Lo position available either. Most systems have some sort of torque percentage split that allows the system to transfer power between the front and rear axles depending on traction conditions.

Answer 2

True 4wd locks the front and rear driveshafts together so you don't want to use it on the street. In a turn, each tire wants to turn a different speed so 4wd has to be part-time otherwise there'd be a lot of tire and driveline wear. 4WD usually also comes with a low-range ratio in the transfer case to give you those "granny gears".

AWD is full-time. You can't turn it off. It usually consists of a limited slip differential between the front and rear axles. Other variations include electronic or mechanical, variable-slip differentials in the center. There are situations where the limited slip won't send enough power to the other axle and you can get stuck. 4wd is superior in this regard.

The awd in Astros and Safari's is a mechanical, viscous coupling system that works well in snow, mud, dirt and sand. You do feel the differential slipping when you make a tight turn, but you don't notice it otherwise. The viscous coupling tightens with wheelspin so sometimes you have to spin the rear tires a little bit before the fronts will engage enough to pull you through. Sometimes the center differential can get noisy and chatter. The dealer will usually replace the fluid in the coupling to remedy this, but the fluid is very expensive...about $100/quart. You don't need to do this unless the noise annoys you to death.

The Safari/Astro's are very difficult to drive in slippery conditions without the awd so I recommend it if you get one. They are heavy in the front, light in the back, are rear-wheel-drive and have quite a bit of power. This is a bad combination in snow, etc. Awd on these vans is almost essential for backing up-hill on anything but pavement!

Answer 3

The astro AWD system is full time.We have a lady in our service office that drives a astro AWD to work every day.She has over 260.00 miles and had no major problems with it.This system puts 60% power to the rear wheels and 40% to the front wheels.Hope this helps

Answer 4

4wd you turn on, awd is always on