Auto Repair Service

Free repair service information and advice.

Four Wheel Drive Problem

    

Four Wheel Drives and All Wheel Drives

A lot of people get confused over the difference between a 4wd car and an all wheel drive car. When it comes to it, the differences may be subtle but they make a massive difference on what you can do with the vehicle. You will find vehicles that are AWD tend to be smaller in size, and they have less clearance.

Basically an AWD vehicle is able to go off road, but is not able to do anything too severe. They may be able to drive on the beach, but if it gets soft then they will struggle. A 4wd car distributes the power evenly across all four wheels, or more to the wheels that have less traction. AWD cars function differently, and they also lack low range. AWD vehicles are always in that mode, whereas most four wheel drive vehicles are used mainly in 2wd for when you are on the bitumen, and then four wheel drive is selected when you want it. What this means is that for any serious four wheel driving you are unable to drive slowly, which is a huge problem for descents down hills and crawling over rocks.

All Wheel Drive cars tend to be less strong as well, which means that if you give them a flogging off road then they are more likely to break. Basically it comes down to what you want to do with the vehicle. If you want it primarily for driving around town with a bit of light four wheel driving every now and again then an all wheel drive vehicle may suit you. If however you want to go touring or more serious four wheel driving then get something which has low range and is a true 4wd.

What Are Difference Between Two Wheel Drive And Four wheel Drive ?

The two wheel drive are cars in which only two wheels receive the power from the engine. On the other hand four wheel drive receive the power from the engine for all four wheels at same time. Hands the varied names cars .i.e. four wheel drive, all 4 wheel drive, or 4×4. The phrase 4×4 is self explaintory.

The four wheel drive has system to direct power to all four wheels. On four wheel drive is an add-on system that works in conjunction with two wheel drive components.

The Transfer Case 4×4

The latest vehicles are equipped with transfer case, is attached directly to the rear of the transmission. The transfer case function is to transmits the drive power to both, the front and rear differentials though two other drive shafts front and the rear.

The front differential is mounted below the engine and connected to the front wheels by two drive-axles which turn the wheels when your car is in the four wheel drive mode.

The Hubs 

There free running hubs are used when are unlocked allow the front wheels to spin while your vehicle is in the two wheel drive mode without rotating the drive-axles and the front differentials, thus reducing wear in these components.

When your car is switched to the four wheel mode, the hubs should then be locked to engage the wheels with the drive axles. The new models cars today comes with an automatic-locking front hubs, eliminating the need to jump out and manually lock the hubs when the transfer case is engaged in four wheel drive mode. Is no difference between the rear differential and the axle assembly you can find in the two wheel drive.

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29/09/2011 Posted by | Uncategorized | , , , , | Comments Off on Four Wheel Drive Problem

Parts Rear Axle

   

How Do Differentials Work?

A differential is the gadget that separates the torque of the engine in two ways so that each output can spin at a different speed. You can usually find this in a lot of all-wheel-drive & full four-wheel-drive cars today.

You’re probably thinking, “Well why do I need this on my car?” Technically speaking, all of the wheels on your car spin at different speeds. Let’s say you’re making a right turn at a light; the inside wheels (the ones closest to the curb) have a much less shorter distance to travel than the ones on the opposite side. See what I’m saying? The formula to calculate speed is the distance that is traveled divided by the time it takes to travel that distance. If you happen to have either Rear-Wheel-Drive or Front-Wheel-Drive, then you don’t have to worry about it. Since they spin independently, there is no connection between them.

The wheels that are driven are connected: the engine & the transmission can spin both wheels at the same time. If your car doesn’t have differentials, this would cause for the wheels that are driven to be locked together. This means the wheels would have to spin at the same time, causing you to have difficulties when you turn into driveways, corners, et cetera.

The most common differential is called the “open differential”. There’s a lot of terminology to learn, so I’m just going to try to explain it while I go on. Ready? Pretend you’re just driving straight with no where else to turn, both of your drive wheels are obviously rotating at the same speed, right? There’s something called the Input Pinion that is spinning the cage & the ring gear. This pinion is smaller than the ring gear & the cage, which means it’s the only gear reduction in your vehicle. When you’re wheel needs to make a turn, the pinion gears start moving in the cage whereas when you’re going straight, the pinions moves with the case.

Even though the wheels may be spinning at different speeds, the open differential never hesitates to apply the same amount of torque to each individual wheel. When you’re driving in dry conditions where the traction is abundant, the quantity of torque applied is restricted by the engine & gearing in the vehicle; but when you’re driving in the mountains, in the snow, or in climates like that, the torque will give just enough quantity so that your wheels won’t end up slipping. So say you’re driving on thin ice (hopefully you’re not), you’re going to want to start in either second or third gear so that the gearing in your transmission will limit the amount of torque available to your vehicles. Even when you’re going off-roading, you’re differentials may cause you some trouble. When you have a truck that’s four-wheel-drive with an open differential in the front and the back, you can get stuck. To me, it’s pretty funny; but it may not be so funny when I’m in that situation. See, when you’re going off of those cliffs & one of the back tires comes off the ground, they will keep on spinning in the air so you really won’t be able to stop…

There is something called LSD (Limited Slip Differential), or positraction, that works by giving more torque to the non-slipping wheel; that way, you’ll be perfectly fine when you go off-roading.
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29/09/2011 Posted by | Uncategorized | , , , , , , | Comments Off on Parts Rear Axle

   

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