is FWD better than 4wd in mud, sand....
08-22-08, 10:52 AM
#1
Lexus Champion
Thread Starter
is FWD better than 4wd in mud, sand....
a thought popped in my mind after my dad's LX 470 been stuck countless times at the beach with loose sand, decent mud after raining....
Is FWD better???
I use to own a 96' ES300 186hp and it has NEVER been stuck in any of the similar situations as above...
Is it just an isolated observation since the 6500lbs LX is only rated at 230hp, distributing only 57.5hp to each wheels??
any thoughts??
Is FWD better???
I use to own a 96' ES300 186hp and it has NEVER been stuck in any of the similar situations as above...
Is it just an isolated observation since the 6500lbs LX is only rated at 230hp, distributing only 57.5hp to each wheels??
any thoughts??
08-22-08, 11:08 AM
#2
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No way is Front wheel drive better than 4 wheel drive in those situations. If your dad was on the beach with his LX did he air-down his tires? He needs to let the air out of the tires to about 15-18 psi. After that, he should have no problems on the beach.
I go surf fishing a lot, in Delaware you are allowed to drive your 4WD vehicles on to the beach with proper gear and permits. I've seen even the littlest SUV's navigate over and around deep dunes, as long as they have aired-down
I go surf fishing a lot, in Delaware you are allowed to drive your 4WD vehicles on to the beach with proper gear and permits. I've seen even the littlest SUV's navigate over and around deep dunes, as long as they have aired-down
08-22-08, 11:23 AM
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Yet another too long post. If you look at vehicle dynamics, you have three situations, accelerating, decelerating, and coasting (for lack of a better word). Getting the vehicle to accelerate is based on the ability to put power from the engine through the contact patch of the tire to the ground. The amount of power applied would be the next thing to look at. When looking at traction in low traction environments, you typically are not going to try to put a lot of power down. If you do, the weight naturally transfers to the rear wheels which increases their ability to put power down, ala dragsters. Of course on decelerating, the weight transfers back to the front which increases front tire grip and the reason why racers will drag the brake going into turns - transfer weight to the front and make the steering tires work better.
FWD is of the most help accelerating in a car with a decidedly heavier front end, which isn't hard to get in a front engine car. That extra weight up front gives them better traction on the front, drive tires. AWD doesn't care about weight distribution very much as the mechanics, and now electrics, vary power split ratios to give each tire as much power as it can put down. In a low traction environment, you aren't going to beat a well setup AWD with either FWD or RWD. It is possible that there are relatively primitive AWD setups that aren't very well setup but a modern AWD setup should win every time. Steering feel, frictional losses, costs, weight, etc., all complicate the issue but for real low traction environments, like mud or sand, I would be very surprised if FWD could ever do better than AWD.
FWD is of the most help accelerating in a car with a decidedly heavier front end, which isn't hard to get in a front engine car. That extra weight up front gives them better traction on the front, drive tires. AWD doesn't care about weight distribution very much as the mechanics, and now electrics, vary power split ratios to give each tire as much power as it can put down. In a low traction environment, you aren't going to beat a well setup AWD with either FWD or RWD. It is possible that there are relatively primitive AWD setups that aren't very well setup but a modern AWD setup should win every time. Steering feel, frictional losses, costs, weight, etc., all complicate the issue but for real low traction environments, like mud or sand, I would be very surprised if FWD could ever do better than AWD.
08-22-08, 12:14 PM
#4
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Maybe his tires needed replacing, the LX is a beast in mud conditions and is based on one of the greatest off road platforms ever. We have pics of guys in LXs here in some serious off road terrain.
FWD is best used for economical conditions. FWD is made b/c its cheaper to build and easier to package. They became popular during the fuel crunch 70s here.
FWD is best used for economical conditions. FWD is made b/c its cheaper to build and easier to package. They became popular during the fuel crunch 70s here.
08-22-08, 01:03 PM
#5
Lexus Champion
08-22-08, 01:31 PM
#6
Out of Warranty
Offroading is great fun, whether you do it just for the adventure of exploration, or as a means to a remote fishing or hunting camp. You'd be surprised just how much difficult terrain your present car can handle - if you are careful, observe a few rules, and prepare properly for your trip. You don't have to be a Baja contender to enjoy a little light "softroading".
First and foremost: speed is the enemy. You don't want things coming at you any faster than you are prepared to deal with them. Slow down. If you can't see over the next dune, or if you are unsure the surface will support your car, GET OUT AND WALK IT. It may seem kinda wimpy at the time, but it is a LOT less so than sitting there with your oil pan impaled on a rock or buried up to the door handles cursing your own foolishness.
In a low traction situation, your priorities look like this 4WD>AWD>FWD>RWD. No matter which wheels you are driving, it is important to get the power to the ground smoothly. Breaking traction results in wheelspin and burial on a soft surface. Ron is correct as usual, in really soft conditions let some air out of your tires to enlarge your footprint to distribute the weight of the vehicle over a larger area. At the same time you will increase the area of your "contact patches" to apply more tractive force over that larger area.
A word of warning here: as you approach 20 psi, you reach a point where it is possible to rotate the rim inside the tire, which often results in the tire coming off the rim - at which point you are thoroughly hosed. At 17-18 psi, you are almost guaranteed of it. Carry a good tire gauge and a portable compressor onboard to restore your tires to full inflation once you reach firm ground.
Now, as to getting your vehicle to move over soft ground: the key is slow and smooth. Wheelspin is death. Spinning the wheels may send up a rooster tail of sand or mud, but it is simultaneously digging its way to China. At the first sign of wheelspin, STOP. An old friend down in Ft. Meyers who built swamp buggies taught me why an automatic transmission is best on soft surfaces. He showed me how to use that torque converter to apply power veeeeerrrrryyyy slowly to the drive axles. Engine idling, put the vehicle in gear and very, very, slowly advance the throttle until you reach 12-1400 rpm (depending on load, YMMV), Hold the throttle at this position and allow the torque converter to apply pressure to the driveline.
It will produce loads of tractive power in this stalled condition, more so with every passing second, so you may have to wait as long as 15 seconds or more to see results. If not pickup a couple hundred more rpm and watch the ground next to your door sill. At some point you should see the ground begin to move very slowly, indicating your progress. Slowly squeeze in just a little more power - maybe a hundred or two rpm, and let the momentum build slowly. You can get an amazing amount of "grunt" out of even a passenger car with this technique. I've hauled some pretty large loads up slippery or icy boat ramps with no problem at all, when other folks couldn't pull 1/5 of my load. This works every time. Just don't get in a hurry.
Don't employ this procedure for too long because your transmission will be converting al of that frustrated stall torque into heat, and you can really roast a tranny with a few minutes of power-on stall.
If do you manage to get stuck, shift to reverse, don't move the steering wheel, and back out slowly exactly the way you got in. If you can stay in your own wheel ruts, you will be on ground you've already compacted, and will not have to break trail - saving a lot of power and traction.
A word on maintenance: if your 4wd vehicle has automatic locking hubs, and most do these days, have them disassembled and serviced BY AN EXPERIENCED 4WD MECHANIC every time you pull the front wheels for brake or bearing maintnence. It's relatively cheap at that point, and can save you a world of trouble. Those dog clutches in the hub are subject to seizing and can cause a world of trouble if ignored. I emphasize having them done by an experienced 4wd specialist because I had a set installed by a moron who got the dogs in backwards. Only after bogging down in a foot and a half of mud did I find I was driving a 2WD Suburban, my front axle essentially useless in applying power to the ground.
Finally, preparation is everything. If you are well and truly buried, a good tow strap and a shovel are invaluable - as are a good jack and a few broad planks. Here's where good maps and/or a GPS can be a big help. Cell phones may be useless in the back country, but you should carry yours if only in faint hope of getting a tower. If you want to communicate between cars, an FRS radio is cheap, handy, and effective. Check your county highway office for the really good maps (usually published in big folders) that detail every road, and literally every building in the area. They are pretty expensive, but you only need to buy the coverage for the specific area of the county you will be visiting.
Before you venture offroad for the first time, find a copy of "The Jeeper's Handbook" or a similar offroading instruction manual like "Shifting into 4WD: The SUV Owner's 4WD Handbook" or "**** Cepek Off-Road Handbook", and read it before you go. They is filled with excellent information on gear and driving techniques that will pay for themselves many times over. If you are venturing into an area where there are no other vehicles, travel with a buddy to help spot for you. It's always best to travel with friends in a second vehicle also - just in case you need a tow.
Have fun and be careful - there's a lot of adventure out there off the pavement.
First and foremost: speed is the enemy. You don't want things coming at you any faster than you are prepared to deal with them. Slow down. If you can't see over the next dune, or if you are unsure the surface will support your car, GET OUT AND WALK IT. It may seem kinda wimpy at the time, but it is a LOT less so than sitting there with your oil pan impaled on a rock or buried up to the door handles cursing your own foolishness.
In a low traction situation, your priorities look like this 4WD>AWD>FWD>RWD. No matter which wheels you are driving, it is important to get the power to the ground smoothly. Breaking traction results in wheelspin and burial on a soft surface. Ron is correct as usual, in really soft conditions let some air out of your tires to enlarge your footprint to distribute the weight of the vehicle over a larger area. At the same time you will increase the area of your "contact patches" to apply more tractive force over that larger area.
A word of warning here: as you approach 20 psi, you reach a point where it is possible to rotate the rim inside the tire, which often results in the tire coming off the rim - at which point you are thoroughly hosed. At 17-18 psi, you are almost guaranteed of it. Carry a good tire gauge and a portable compressor onboard to restore your tires to full inflation once you reach firm ground.
Now, as to getting your vehicle to move over soft ground: the key is slow and smooth. Wheelspin is death. Spinning the wheels may send up a rooster tail of sand or mud, but it is simultaneously digging its way to China. At the first sign of wheelspin, STOP. An old friend down in Ft. Meyers who built swamp buggies taught me why an automatic transmission is best on soft surfaces. He showed me how to use that torque converter to apply power veeeeerrrrryyyy slowly to the drive axles. Engine idling, put the vehicle in gear and very, very, slowly advance the throttle until you reach 12-1400 rpm (depending on load, YMMV), Hold the throttle at this position and allow the torque converter to apply pressure to the driveline.
It will produce loads of tractive power in this stalled condition, more so with every passing second, so you may have to wait as long as 15 seconds or more to see results. If not pickup a couple hundred more rpm and watch the ground next to your door sill. At some point you should see the ground begin to move very slowly, indicating your progress. Slowly squeeze in just a little more power - maybe a hundred or two rpm, and let the momentum build slowly. You can get an amazing amount of "grunt" out of even a passenger car with this technique. I've hauled some pretty large loads up slippery or icy boat ramps with no problem at all, when other folks couldn't pull 1/5 of my load. This works every time. Just don't get in a hurry.
Don't employ this procedure for too long because your transmission will be converting al of that frustrated stall torque into heat, and you can really roast a tranny with a few minutes of power-on stall.
If do you manage to get stuck, shift to reverse, don't move the steering wheel, and back out slowly exactly the way you got in. If you can stay in your own wheel ruts, you will be on ground you've already compacted, and will not have to break trail - saving a lot of power and traction.
A word on maintenance: if your 4wd vehicle has automatic locking hubs, and most do these days, have them disassembled and serviced BY AN EXPERIENCED 4WD MECHANIC every time you pull the front wheels for brake or bearing maintnence. It's relatively cheap at that point, and can save you a world of trouble. Those dog clutches in the hub are subject to seizing and can cause a world of trouble if ignored. I emphasize having them done by an experienced 4wd specialist because I had a set installed by a moron who got the dogs in backwards. Only after bogging down in a foot and a half of mud did I find I was driving a 2WD Suburban, my front axle essentially useless in applying power to the ground.
Finally, preparation is everything. If you are well and truly buried, a good tow strap and a shovel are invaluable - as are a good jack and a few broad planks. Here's where good maps and/or a GPS can be a big help. Cell phones may be useless in the back country, but you should carry yours if only in faint hope of getting a tower. If you want to communicate between cars, an FRS radio is cheap, handy, and effective. Check your county highway office for the really good maps (usually published in big folders) that detail every road, and literally every building in the area. They are pretty expensive, but you only need to buy the coverage for the specific area of the county you will be visiting.
Before you venture offroad for the first time, find a copy of "The Jeeper's Handbook" or a similar offroading instruction manual like "Shifting into 4WD: The SUV Owner's 4WD Handbook" or "**** Cepek Off-Road Handbook", and read it before you go. They is filled with excellent information on gear and driving techniques that will pay for themselves many times over. If you are venturing into an area where there are no other vehicles, travel with a buddy to help spot for you. It's always best to travel with friends in a second vehicle also - just in case you need a tow.
Have fun and be careful - there's a lot of adventure out there off the pavement.
Last edited by Lil4X; 08-22-08 at 01:43 PM.
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