4 wheel drive - brakes

Uncle Turbo described it well.

Contrary to popular belief, ABS is not designed to shorten stopping distance. It’s designed to prevent loss of control during stopping. It does this by comparing the speed of the wheels and, if one is turning dramatically slower than the others indicating that it’s sliding, interfering with that wheels braking hydraulics in a pulsating action to allow it to somewhat keep rolling. Yes, the grinding sound is common. And ABS is inactivated on most systems below a designated low speed.

Unless you’re familiar with the feel of ABS it will feel to you as if the brakes are not stopping properly. Personally, I don’t like the feel of ABS.

It may seem to be hapening only in 4WD becasue the added drag from the drivetrain when you take your foot off the gas to apply the brakes conbined with the application of the brakes is causing the front wheels to slide more readily than then do when their freewheeling in 2WD.

Uncle T had it right. The only real solution is to be sure you have as good a tread set as possible. Good tires with lots of rubber left. And leave yourself lots of room to brake gingerly. And use 2WD unless you really need the added traction of the 4WD.

Any vehicle with full-time 4wd mode is the equivalent of AWD. It allows the slippage of front and rear wheels speed to a certain degree

MOST SUV’s and pickups are NOT full-time 4wd. They are part-time. Means you shift them into 4wd when needed…And when in 4wd there is ZERO…NADA…NONE slippage. Your experience seems to be only limited to AWD systems.

MOST SUV’s are Explorers and Grand Cherokee’s beyond trailblazer which all have full-time selectable 4wd. Those group compose the majority of SUV’s.

Maybe you own a primitive system and your limited experience is there?

Toyota, Nissan, GM, Ford, Jeep/Dodge…they are all part-time 4wd…So who makes full-time 4wd systems you say. People who buy these trucks do NOT want the front or rear wheels slipping while in 4wd. ESPECIALLY if they take their vehicle off-road. That is why you’ll NEVER see a AWD system off-road (unless it’s stuck). The trucks were designed to be taken off-road.

Here’s a nice article that explains it.

I have a 2003 Toyota 4Runner with the V-6. On this model, the ABS is not turned off when the vehicle is in 4 wheel drive. This system is different than part time 4 wheel drive on other vehicles. The vehicle can be run in 2 wheel drive or 4 wheel drive high all the time. There is also a 4 wheel drive low, which is really a low gearing. There is also a button that can be pushed that will lock the differentials. The V-8 of the same year as mine is always in 4 wheel drive, but does have a 4 wheel drive low. (If one has to go into 4 wheel drive low and lock the differentials and is still stuck, Toyota packs a bottle of brandy in the glove compartment. This was the first thing I tested). I don’t know about earlier or later Toyota 4Runners. I do know that I have had the ABS activate while in 4 wheel drive high.

I think you missed the entire boat.

Jeep/Dodge, upper end Toyota, Infiniti and Ford all have a selectable full-time 4wd(for pavement) along with a 4wd mode(part-time not for dry pavement eg off road).

Our company fleet car 2000ish 4runner limited is full time 4wd btw.

My 05 4runner the ABS is NOT turned off when in 4wd. Truck also has traction control which uses the ABS system to control braking the individual wheels.

The Grand Cherokee has several different 4wd systems. Their select-track (used for off-road) has a Full time 4wd AND can be switched to part-time 4wd for off-road or extreme snow. As I’ve said many many times…MOST people don’t need the part-time 4wd system…but it is the BEST system in the snow and off-road.

The Explorer was NEVER designed to go off-road. It’s fine for 95% of the time…but in extreme snow country like Upstate NY’s snow belt or NE’s white mountains during snow season it’s NOT a good vehicle to have. I have a cousin who owns a cabin near Mt Washington that we use to visit a couple times during ski season…Road is NOT maintained by the town or country…AWD system will NOT make it to this cabin. It’s tough enough with a true 4wd system.

Jeep/Dodge, upper end Toyota, Infiniti and Ford all have a selectable full-time 4wd(for pavement) along with a 4wd mode(part-time not for dry pavement eg off road).

Our company fleet car 2000ish 4runner limited is full time 4wd btw.

And those vehicles were NOT designed to be driven off-road. If you want to go off-road or drive in extreme snow…these vehicles are NOT the ones you want.

Did you compare braking in 2wd and 4wd under very similar conditions? Unless you are very confident that you did, please go to an empty, slippery (snow-covered) parking lot and experiment. At the same speed in both 2 and 4wd, put the brakes on hard. Report back.