Front end and 4WD

[NVPRIUS]

Just when you think your done- another issue.

I have an situation where when in 4wd the truck functions fine (mostly to pull my boat out of the water at the lake) no issues.

The problem is that if I turn either left or right while in 4wd the front end shudders pretty violently. When I straighten back up its fine.

I got the truck off the ground and ran it in 2wd and 4wd with the wheel straight ahead. All worked fine until in 4wd if I turned the wheel either right or left the front end began to shake as if something was out of balance but in a big way. I straighten back out and all is well.

Seems like something is majorly wrong here. The front differential fluid is up tp the fill hole and nothing seems loose or broken. It goes in and out of 4wd easily with no issue.

If anyone has any ideas or has had this happen to them I would truly appreciate and help.

Thanks Neal



My truck details again:


2001 Dodge 3500 5.9 Diesel 4x4 Dually
Automatic Transmission
All Stock NO Mods 82,000mi

 

[Joe Mc]

I'm thinking axle to hub u-joints.

 

[NIsaacs]

The problem is that if I turn either left or right while in 4wd the front end shudders pretty violently. When I straighten back up its fine.

I got the truck off the ground and ran it in 2wd and 4wd with the wheel straight ahead. All worked fine until in 4wd if I turned the wheel either right or left the front end began to shake as if something was out of balance but in a big way. I straighten back out and all is well.

Try this again, off the ground, wheels straight ahead and step on the brakes slightly. If you get the shudder, check your t-case oil for level and contamination. Maybe the chain is jumping with front axle resistance.

 

[NVPRIUS]

Getting some great advice here and lots to investigate.
Looks like when I select 4H the right (passenger side) starts or try's to turn and then when I turn right or left it starts to shudder on that side and then when Its back to straight the shuddering stops.
If you look at the youtube video below it shows what its doing (sorry its so long) Thanks again Neal

 

[Cummins12V98]

Maybe I am crackin here but in 4wd it's going to grab/shudder when turning unless on soft ground.

 

[petersonj]

This video is also posted on the MoparMan1973 site under a different name. Here was my response on that site. I did not get a response from my response.

If this is happening on asphalt or concrete, what you are talking about could be quite normal. The front axle shafts do not have constant velocity u-joints (CV joints). Consequently, when the steering is turned sharply in either direction, each tire will speed up and slow down twice in one revolution due to the steep angle of each u-joint per axle shaft. With excellent traction on asphalt or concrete, the front tires develop severe wheel hop because something has to give. And furthermore, since the transfer does not have a differential, there is also binding between front and rear axles, just not as severe.

@NVPRIUS, what I see in your video does not show anything unusual. The front tires will never turn at the same speed. The differential will allow the tire with the least resistance to turn the fastest.

- John

 

[NVPRIUS]

Guess I don't get it but when the truck is on the lift with the wheels off the ground the front end shakes and bangs so loudly when turned to the right or left It just feels like something is going to break. I understand that if on a hard surface the outside wheel would have to turn more than the inner and something would have to give (wheel hop?) or... but with the wheels off the ground I'm just not understanding why so much shake. So, do to my curiosity today I drained the front case and removed the cover expecting to see a bunch of metal or busted off gears only to see it is so pristine and clean in there I'm even more baffled.
John, I thought that the front was indeed a differential it's a DANA 60 49492 1 maybe I'm just over thinking this thing.
Thanks Neal (I love these forums)

 

[petersonj]

@NVPRIUS, I am not saying for sure that you don't have a problem. I am just saying from what you wrote and what you showed, everything that I am reading and seeing could be normal. It is not the different speed for each front tire that causes wheel hop. The differential takes care of that.

It is when you engage four wheel drive that triggers that action. Each axle shaft will now be driving the tire. Each axle shaft input into the u-joint is turning at a constant velocity, but the output of the u-joint speeds up twice and slows down twice in one revolution when the u-joint angle is sharp (not constant velocity). Since your tire is connected to the output of the u-joint, the tire is also going to speed up and slow down twice in one revolution. Each front tire is tracking at a different speed during a sharp turn. This put each tire out of phase with each other. These combined actions are what causes wheel hop when traction is excellent - such as on pavement or concrete. In slippery conditions such as packed snow or ice, the wheel hop may barely be noticeable.

Smaller vehicles such as one-half ton pickups and SUV's use constant velocity u-joints, so you will not experience wheel hop.

- John

 

[Timd32]

Not a boat person, so could be off track.

Agree on the man its pretty impossible to not lock up the front end making tight turns in 4WD with traction available. Especially when you have like a fully loaded hay wagon and you miss judge the gate and have to take a second shot.

I dont know anything about boat ramps, would a 2-low kit help in this situation?

I know it would help me in my situations where I need 4WD then need to make tight turns for a short period of time.

https://www.genosgarage.com/product/bd-1030703/differential-accessories

 

[petersonj]

I think a 2-Low would help a lot. Use 4-Low to get the boat and trailer up the ramp, back off the throttle and go to 2-Lo while truck is still moving straight, and then there will be no binding when you steer hard either way - the best of both worlds. I installed my own version of a 2-Low kit when my truck was new back in 2001 - one of the best mods I ever did.

- John