how to test 4wd?

[filterway]

Hello all,

today i had to use 4wd system on the snow (automatic hub, automatic transmission). It engaged hard enough that i suspect something is wrong.

How can i test the 4wd system to see if everything work fine? If not, what are the symptoms?

Here is what i did today: Jack the van (4 wheels) and see how the wheels respond.

What i observed, with the 4wd system engaged: the front right wheel turned as i push on gas pedal. The front left wheel did some kind of erratic rotation.

Does the 2 front wheel are supposed to turn in the same time, or just one of the 2?

So i need help to see if something is wrong, how to diagnose and what to do if something is wrong..

thanks

Jerome

[Jlhollowx13]

it sounds like it is fine. both wheels will not turn unless you have locked differentials. having only 1 wheel spin is normal for non locking differentials.

if you were to turn one wheel by hand, whether the front or back doesnt matter, the wheel on the opposite side will turn the OPPOSITE way (this is if the wheels are off the ground), i.e. if you turn the drivers side wheel clockwise, the drivers side passenger wheel will turn counterclockwise from your point of view at the drivers side wheel.. if you had a locking differential they would turn the SAME way(both forwards or backwards)

[filterway]

it sounds like it is fine. both wheels will not turn unless you have locked differentials. having only 1 wheel spin is normal for non locking differentials.

if you were to turn one wheel by hand, whether the front or back doesnt matter, the wheel on the opposite side will turn the OPPOSITE way (this is if the wheels are off the ground), i.e. if you turn the drivers side wheel clockwise, the drivers side passenger wheel will turn counterclockwise from your point of view at the drivers side wheel.. if you had a locking differential they would turn the SAME way(both forwards or backwards)

Ok so the maximum wheels with traction on the van is 3 because it don't have front diff. lock? I'm wondering why it's the right front wheel is moving instead of the front left wheel? who decide which front wheel will move?!!

I'm not familiar with this sytem. The front left wheel had no or little rotation while front right wheel moved fully. So i'm asking how can i do to move the front left wheel instead of the front right wheel? (i want to check that left hub work fine, now i know right hub work fine)

Jerome

[filterway]

it sounds like it is fine. both wheels will not turn unless you have locked differentials. having only 1 wheel spin is normal for non locking differentials.

if you were to turn one wheel by hand, whether the front or back doesnt matter, the wheel on the opposite side will turn the OPPOSITE way (this is if the wheels are off the ground), i.e. if you turn the drivers side wheel clockwise, the drivers side passenger wheel will turn counterclockwise from your point of view at the drivers side wheel.. if you had a locking differential they would turn the SAME way(both forwards or backwards)

I forgot to mention, i just jacked the 2 front wheel. The front right wheel turn freely. The front left wheel is hard to turn, i need my 2 hands on it to make it turn. It sounds not normal.

Also you said when one wheel turn clockwise, the other one turn counterclockwise. This not happened while the 2 front wheel were off the ground.

Jerome

[Jonny]

Have you checked the brake caliper on the left side to make sure it's not dragging?

[Jlhollowx13]

Ok so the maximum wheels with traction on the van is 3 because it don't have front diff. lock? I'm wondering why it's the right front wheel is moving instead of the front left wheel? who decide which front wheel will move?!!

I'm not familiar with this sytem. The front left wheel had no or little rotation while front right wheel moved fully. So i'm asking how can i do to move the front left wheel instead of the front right wheel? (i want to check that left hub work fine, now i know right hub work fine)

Jerome


no, the maximum traction is not 3 wheels, its actually only 2 with a 4x4, 1 with a 2wd, unless there are lockers involved which is another story and will gain more traction to more tires. i would also check that you arent having brake drag. you cant control which wheel the engine turns, its just a matter of which one has less resistance in a 4x4 system like this. you should probably also jack all 4 wheels off the ground while troubleshooting, the resistance your experiencing could be from the rear wheels preventing the rest of the 4x4 system from moving freely as its all connected when your 4x4 is engaged, which is another point, make sure you are actually engaged in 4x4.

To really test it, i would go somewhere that has a dirt hill that you cant get up in 2wd but can in 4wd. if you put it in 4wd and it gets up fine, then all is good, you might just be overthinking it, especially since you dont actually know how the system works. more research on a non locking 4x4 system might give you some more insight.

the thing about 4wd in most vehicles, especially non locked vehicles, is that not all 4 wheels get the same power at the same time, so seeing 1 wheel spin and not the others doesnt really mean much. From my experience i would assume all is fine since the way it works is the power is transferred to the wheel with the least resistance.

another way to test it is jack it up, turn one wheel at a time, if your related drive shaft turns (front driveshaft for front wheels, rear driveshaft for rear wheels) then all is good.

[Jlhollowx13]

look up some youtube videos on how a 4x4 with limited slip differentials work, then compare to locking differentials. i think that will help alot to explain how these systems work. its imperative that you understand how it works before you assume something is wrong or start troubleshooting a problem that may not actually exist.

if in fact something is wrong its most likely in your hubs, which are easy to take apart and check out.

[filterway]

Have you checked the brake caliper on the left side to make sure it's not dragging?

yes i thought about calliper but what can i do if it's dragging? Is there simple thing i could check if the problem is on the caliper and not inside the hub?

[filterway]

Have you checked the brake caliper on the left side to make sure it's not dragging?

Finally it's the calliper the problem. after removing it, the disc is turning free.

one piston is squeezable (left) , the other one cannot move, stuck. Full of rust.

3473

I'm relieved it's not the automatic locking hub.:dance2:

Thank everyone for your help! :thmbup: