Part Time 4wd

[C5Drvr]

Does anyone know if there is a speed limit associated w/ the P.T. 4wd system? My Durango is limited to 55mph which is pretty inconvient if I want it on going down the rainslick highway. I have determined that the Dodge D-go is to go and I will be replacing it with an FJ. Just gotta get the funds together.

 

[FirstToy]

No, you can go as fast as you like in 4wd mode.

If you want to change from 2wd to 4wd (or back) it is limited to below approx. 50mph (check the manual).

 

[tnegiet]

Does anyone know if there is a speed limit associated w/ the P.T. 4wd system? My Durango is limited to 55mph which is pretty inconvient if I want it on going down the rainslick highway. I have determined that the Dodge D-go is to go and I will be replacing it with an FJ. Just gotta get the funds together.

Are you sure there is a speed limit on 4wd for your Dodge...I'm sure the speed limit is only for shifting from 2wd to 4wd.

 

[C5Drvr]

Yup, manual says limit 4wd ops to below 55. I have been above 60 with it engaged, and you can feel it start to hum.

 

[Lt1FJ40]

Yup, manual says limit 4wd ops to below 55. I have been above 60 with it engaged, and you can feel it start to hum.

I thought chevys were the same?

 

[chriscruiser]

Yup, manual says limit 4wd ops to below 55. I have been above 60 with it engaged, and you can feel it start to hum.

4H/4L is limited to *slippery conditions* going from 4H to 2H you can be at any speed and you're fine and from 2H to 4H I believe you're supposed to be below 40mph. When going to or from 4L you need to be stopped and have the tranny in "neutral"

Careful with binding when in 4H or 4L, if the surface has grip you want to be in 2H. Also, your turning radius is affected so no u-turns or sharp turns while in 4H or 4L since your diffs are locked in the front when you're in 4H or 4L.

Hope that helps!

 

[Beowulf]

...your diffs are locked in the front when you're in 4H or 4L.

Nope. Not unless you've installed an ARB locking diff up front.

-B-

 

[chriscruiser]

Nope. Not unless you've installed an ARB locking diff up front.

-B-

They are not locked? Could you explain why we get binding when in 4H or 4L? I figured if they were not locked, the tires could rotate at different speeds and avoid binding, when in 4H or 4L I can feel binding when I turn the wheel too sharp.

Thanks for your help in clearing this up!

 

[TLCgrappler]

Remember that there is no center differential in the automatic versions.

Consequently, even though the front differential is never locked (A trac is used to simulate the effect of a locked differential), a hard turn will wind up the drive shafts, and something will have to give. I suspect that is the reason for the binding. Of course, if the rear diff is locked, that would cause binding all by itself.

 

[rusty_tlc]

I thought chevys were the same?

No upper limit on 4H in my GMC. They recomend not shifting into or out of 4H at speeds above 35MPH.

Base on my experience driving on snow and ice I think using 4WD will just get you in trouble on the highway. If you lose control you don't know which wheel will gain traction first. In 2WD you narrow it down to one of the rear wheels. IMHO it's a lot easier to recover from a skid on a hard surface in 2WD.

That said, if your slogging over a pass in the snow at low speed (ie chain up conditions) 4WD is great.

 

[Beowulf]

Remember that there is no center differential in the automatic versions.

Correct.

Chris,
If you drive a vehicle with a fully locked front diff then you will be able to tell the difference between drive-line windup (which you are experiencing) and a locked diff.

-B-

 

[chriscruiser]

Correct.

Chris,
If you drive a vehicle with a fully locked front diff then you will be able to tell the difference between drive-line windup (which you are experiencing) and a locked diff.

-B-

Thanks, I appreciate the information!