4wd hi question

Hey guys something i'm not supper familiar with but a few weeks ago we had some pretty big rains and was going to run through a good sized puddle (its rare for so cal). I figured what the hell and hadn't put the truck in 4wd in about a year so I put it in 4wd hi and took of for the puddle. At about 30 the truck made a pop noise and I felt the whole truck shake from it. Didn't feel right so I took it to the dealer and even took the service tech on a test drive and showed him what it was doing. The tech just called me and told me it was because it was on the street and not offroad that is the reason it made the noise and shake. I have put it in 4x4 going up mtns and on hard pack dirt and never have had this issue. Is this street excuse correct or are they trying to give me the run around.

What year truck? Did you turn at all in the puddle or towards the puddle? Why did it need to be in 4wd? Truck 'lifted' at all?

I ask year because the '12 and newer trucks came with a Torsen front diff it's similar to a rear posi/locker. Consider it a traction aid. It will not allow the wheels to spin freely of each other when engaged. So just like the rear locker being engaged, the tires will make all sorts of noise around a turn because the tires cannot turn at different rates because the turn radius

Turn towards puddle or while in it? See first response. The pop and shaking could be the tires across the pavement.

Its a puddle in So Cal, 4wd does 0. I've only used 4wd to get unstuck in sand, across ice, and thru a silt bed in the Oregon desert.

4wd on dirt, the dirt allows "slip" under the tires. You have to remember when turning, the outside wheels need to travel a greater distance, so they need to make more revolutions. When the rear locker is engaged on the street you can hear and feel the rear end skipping across the pavement. I def don't recommend driving like that. In 4wd, the Raptors with a Torsen, 4wd on dry pavement (or even wet pavement for that matter) is a bad idea. The front tires are now just about locked together not allowing the front tires to rotate independently.

The dealer may be correct saying that 4wd on the street was your problem.

'10-'11 trucks with the open front diff wouldn't be as bad, it'll only power 1 of the front wheels. I still don't recommend it.

If you're concerned, put it in 4hi and drive in a straight line, if no noise, then I would say you're okay. Just try not to turn. The pop could even be the IWE broke. Pull both wheels and front axles to look and the IWE. Go out to the desert and put it in 4hi and see how it performs. If no noise, you're okay.

If truck is 'lifted', IE with more preload on whatever aftermarket front setup you're running, the front axles could be in a serious bind, and the pop was a front axle making unhappy sounds. Again, why 4wd thru a puddle?

IMO, 4wd should really only be used if there is a problem.

I run 2wd everywhere unless I'm in the sand and about to get stuck.

If you're running on the street in a straight line, no issues. Even on wet pavement, there should be enough 'slip'. No way a loud bang is normal under any circumstances. I'd get another opinion from another dealership that knows what they are talking about. It's true, the 4 wheel drive shouldn't be used on dry pavement, and definitely not while turning hard. But again, loud pops and the truck shaking, shouldn't be happening at all.

Good luck and keep us posted.

I run in 4HI on the street quite a few times a week, it's only way I can run hard without doing the one tire burnout wonder and the nannies kicking in.
I do however avoid turning hard but weaving in and out of traffic is no problem.

Year of the truck does not matter, if only 4HI, the front locking diff does not engage in 4HI, only 4L

4x4 are not supposed to be driven on surfaces that don't have a little bit of slip. Especially these raptors with the fragile IWE.

Don't do it. You WILL break things.

Haven't had a problem in 6 years!
Knock on wood!!!

I'm told that my 2010 1/2 have different IWE than the 2011-2014.
I never confirm that but I've been told that by several techs.

I wonder how the Gen2 does with it being AWD

i test drove my truck after they fixed my 4wd. i was doing 80 on the freeway. finally after 97,000 miles i finally have a working 4wd system. the excuse that it can be used on street is not right. hard turns will cause that issue you are talking about, but not slight turns or highway speeds

The front Torsion diff is NOT a locker. A torsion diff does not lock both front axles causing both front wheels to turn evenly like a locker would.

EricM said:

The front Torsion diff is NOT a locker. A torsion diff does not lock both front axles causing both front wheels to turn evenly like a locker would.

Click to expand...

Correct, it's not a E-locker like the rear.
But they use the same term when talking about it.
In 4L the 2 IWE stay locked and with the Raptor's TC this makes the Torsen act like a locker.



Behaviour of Torsen differentials[edit]

The Torsen differential works just like a conventional differential, but can lock up if a torque imbalance occurs, the maximum ratio of torque imbalance being defined by the Torque Bias Ratio (TBR).[3] When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to 75% while the other side would have to only handle 25% of applied torque. During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher percentage of applied torque, no relative wheelspin will occur. When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential.

An excerpt from the manual concerning 4wd...