NEVER drive a 4X4 on dry pavement as you will bind up the system. Try turning the truck on dry ground and you'll feel it dragging.
Clint
Clint
dispute over 4x4
1 - 20 of 27 Posts
Consider it luck.HudsonValleyTitan said:
I've witnessed an outer u-joint fail on a vehicle by driving it in 4wd in a dirt parking lot, then out on the street to make a u-turn (on pavement) and *BAM* busted joint.
Seeing that our transfer-cases are chain driven, not gear, any unnecessary stress put on it due to the difference in speed between the front and rear will cause the chain to stretch.
As was said above, the binding isn't caused because the left and right sides turn at different speeds, the issue is because the front and rear need to run at different speeds. When you make a turn, all 4 tires take a different path. Since the paths are all a different distance to the same point, the tires will turn at different speeds, both side to side (there are diffs in the axles to compensate for this) and front to rear (In 4wd the front and rear driveshafts are locked together, they MUST rotate at the same speed). Forces build up and most of the time this energy is released through chirping, bucking tires. However, sometimes the tires have more traction and that energy will find another way out. Path of least resistance...which may end up being the t-case, u-joint, CV joint, differential...
Also, our trucks (and most others without front hubs) don't really need to have the 4wd engaged regularly. The entire drivetrain is in motion while driving, even while in 2wd. Engaging 4wd will engage the front output shaft in the t-case, 2wd disengages this but the front driveshaft, diff, and axles will keep rotating.
Basic rule of thumb is don't use 4wd when you don't need it. Work proactively so you don't get stuck, but don't engage it just because it's raining.
You'd have to do quite a bit of on pavement driving to kill a drivetrain though. I found that out first hand. But I've always used 4WD on all my trucks in very bad rainy weather over the years and have never had a problem. Sounds like the friend you're talking about may have done more damage while offroading and the dry pavement finally did it in. Now I don't say anyone should drive in 4WD on dry pavement....there's no reason to and it kills fuel mileage but, hitting a dry patch while driving in the snow or rain shouldn't be the death of a drivetrain. And I agree that doing this on a regular basis just causes premature wear of all parts involved.Yahooligan said:Consider it luck.
I've witnessed an outer u-joint fail on a vehicle by driving it in 4wd in a dirt parking lot, then out on the street to make a u-turn (on pavement) and *BAM* busted joint.
Seeing that our transfer-cases are chain driven, not gear, any unnecessary stress put on it due to the difference in speed between the front and rear will cause the chain to stretch.
As was said above, the binding isn't caused because the left and right sides turn at different speeds, the issue is because the front and rear need to run at different speeds. When you make a turn, all 4 tires take a different path. Since the paths are all a different distance to the same point, the tires will turn at different speeds, both side to side (there are diffs in the axles to compensate for this) and front to rear (In 4wd the front and rear driveshafts are locked together, they MUST rotate at the same speed). Forces build up and most of the time this energy is released through chirping, bucking tires. However, sometimes the tires have more traction and that energy will find another way out. Path of least resistance...which may end up being the t-case, u-joint, CV joint, differential...
Also, our trucks (and most others without front hubs) don't really need to have the 4wd engaged regularly. The entire drivetrain is in motion while driving, even while in 2wd. Engaging 4wd will engage the front output shaft in the t-case, 2wd disengages this but the front driveshaft, diff, and axles will keep rotating.
Basic rule of thumb is don't use 4wd when you don't need it. Work proactively so you don't get stuck, but don't engage it just because it's raining.
HudsonValleyTitan said:
I have agree with Yahooligan on this one and with the explanation. HVT, you are correct as well, in that you have to drive quite a bit to kill the drivetrain. However, the reason that is so is not because it doesn't hurt... It's because of design safety factors.Yahooligan said:Consider it luck.
The bottomline is that no one fully understands the concept of safety factors in design more than Engineers. The world and it's inhabitants have forced "those who would be blamed for manufactured parts failures due to individual stupidity" have had to design for excessive stress in manufactured parts because they know that someone, somewhere is going to push the part, and the vehicle way beyond what is normal. In order to build something that doesn't fail on a daily basis, it is somewhat overdesigned to compensate for human mental lapses.
There is a point of diminishing returns, as would be expected, where the cost of hyper-overstrengthening a part does not provide an economical solution, and someone will push the parts past even this raised level of performance.
So no, it is not a good idea to run a 4WD on dry pavement, and no, it won't necessarily fail right away, but yes, one day it will tell you that you have exceeded it's capacity to tolerate humanity's deficiencies. Count on it.
Don't do it... The C-Clips on our front drive axles are already insufficient and proned to break the way it is, no reason to instigate them into self-destructing because it may just wear just enough to decide to break later when at 62k miles and out of warranty. If one breaks, your front axle will slide out of the Diff and the only fix is to have the entire front Diff assembly replaced. Ouch!!!!
Exactly!!!!Yahooligan said:
I've ridden with a first time 4x4 owner who had about 40k on the clock and I caught him using 4HI in the rain when I was riding with him. He'd been complaining about what a POS his Chevy was and all the problems he'd been having. When I asked, he told me he always used 4HI in any bad weather so I had to explain it to him. His continuous problems were excessive drivetrain slack and U-Joint popping. Although it can be disputable, I have no doubt that it was caused from using 4HI while on pavement in the rain.
As for the second statement, I would've ruined every 4x4 I've ever owned if that were the cause. That's like saying your Rear Diff will blowout from burning rubber with only one tire spinning all the time, I have yet to see that be a cause.
1 - 20 of 27 Posts
