OK, I'm still kind of new to the 4 wheelin aspect of life, but I was looking at some back posts and saw someone say that you should not run 4 wheel drive on dry pavement. Why is that, I know if I'm asking, someone else out there is asking too.

Thanks
Steve

 

Because the front axle runs at a slightly faster speed than the rear. You could tear things apart while making a turn.

 

Thanks bigred......

 

you can tear things up just going strait. the tcase is usually first to go in such situations.

 

The problem is mainly in turns since the difference between front and rear is only 0.01. What happens is that since in turns the wheels on one side travel more than the others, that will put some stress on the driveline that can build up if there's a good traction.

 

Even minor discrepancies in the driveline gearing go a long way when all four wheels are planted firmly on dry pavement no matter whether its straight line, 'round in circles, race weaving... the transfer case chain suffers the most since its the link between the front and rear driveshafts. S-T-R-E-T-C-H!!! and eventually SNAP!

 

Now my front and rear gears a slightly different. my rear is 3.70 and my fronts are 3.73 and my drivetrain buddy said that it wont make a different off of the pavement and maybe to let some air out of the fronts so the spin a lil faster. Does this sound right? Now what about the newer trucks that have full or part time awd and 4wd. How does that one work on dry pavement?

 

3:70 is an odd ratio. Also,yes off pavement doent make a difference hence the tires being able too slip a little. But, I wouldnt air down just the fronts, if you air down, do all 4.

 

the point of deflation would be too make up for the 0.03 ratio difference, thats it. the 3.70 is in my 9" if i was to do it all over, they would be 4.56 but who knew, save it for next rebuild.

 

Many newer cars with AWD or full time 4WD has a clutch, viscous coupling, or something else that allows minor rotational differences between the wheels without putting too much strain on the driveline.

 

so burning out on the road in 4 would do more then the obvius damage to the diff pins? does that do the same thing because the tires are slipping?

 

you must be a Kid

doesnt matter if they are slipping then because your gonna have to stop at some point and when they do grab . BAM, there goes the tcase chain or maybe more. you might get luck with just a broken ujoint though.

now if the hubs arent locked thats a different story of course

 

Even some of the older Range Rover and Jeep 4WD systems had another differential mounted in the driveline (mounted between front and rear driveshafts to allow for the discrepancy) to compensate for the possibility of one axle outrunning the other. The advent of reliable viscous couplers has made full-time 4WD much easier to achieve as aurgathor said.

The 4WD systems in many trucks are specifically listed as being "Part-time" systems that should only be engaged when the terrain or driving conditions warrant its usage. The really amusing fact as that many people with part-time systems have no idea that their 4WD has never been engaged or they have no idea how to engage it because they make the assumption that the vehicle is 4WD so it must always be. (Had to explain to a soccer mom how to put her Cherokee in 4WD after I watched her try to climb the same snow/slush covered hill three times. Her response, "Oh, well I just thought since it was snowing the Jeep knew I needed 4WD").

BTW, if you want to do "burnouts" in 4WD, go find a mud pit or a snow covered field. They look really cool but the potential for damage is just too great to try anywhere else.

 

Trying to do a burnout in 4WD is very stupid since you'd need roughly twice the torgue because you'd need to spin all 4 tires instead of just two. And you can damage more components.

If that's what you want to do, your best bet would be any long bed pickup truck, or some RWD cars. The Brono has a reasonbly good weight distribution making burnouts harder to do.

I know that full time 4WD was available for quite a while in a few selected vehicles, but they weren't particularly common in the US.

 

why do you say rwd cars for the burn outs? I have 21 tauruss and the will burn the tires all day. and yes i am a kid and if any one is wandering the best thing for burn outs is a 95 f-250 with no rear brakes and bald tires.