I'm hoping you guys can help me out. I've been reading the forum for several months and this place is great.

I noticed about 2 weeks ago when the first snow finally made it down to town that when I clicked the switch into 4wheel drive, there is a wierd vibration from about 15-30 mph. I have had the truck since last spring and have never felt this from the truck before. I had it into a local ford dealer that I feel I trust and they were unable to find anything wrong with the front end. They did find the rear U-joint on the rear axle was bad and also put a new set of brake pads on the back end also.

A little more history.

I had the truck serviced this summer by another ford dealer when I was having difficulty getting the hubs to fully disengage from 4wheel drive. I have used it a handful of times since then and everything has worked great, goes in and comes out of 4x4 quickly and easily, no problems. Now I have this vibration and everything on the front end checked out according to their Tech.

Any advise on what I should have checked from here?


To me it feels like a bad U-joint and they did find the rear was bad, but I am still feeling this and only in 4x4, it comes on instantly and goes away just as soon as the hubs unlock. It does seem perhaps a tiny bit reduced from what it was last week but not sure, I know I still feel it without a doubt.

Any ideas?

Truck is an '02 F-350 Super Duty 4x4 V-10 with a leveling kit, 285/75/R16 BFG A/T K/Os

I am planning to take the truck up to the mountains to go snowmobiling and am planning to just watch and see what happens... The roads are clear and dry in town now so I can't really test under identical conditions till Saturday.

Thanks

 

Try this and report back.

Manually turn the hubs to the locked position and drive the truck.

Do not turn the switch.

Still have the vibration?

 

Check the Cardan joint on the front drive shaft as well. I just replaced one on an '02 F350. Had a vibration and rumbling noise when in 4x4.

 

Great idea.

 

I will give that a try tomorrow and report back



What is a Cardan joint? Is that a fancy new name for the U-joint?

Thanks for the ideas so far.

 

The front driveshaft has a typical u-joint on the front end where it connects to the front diff. The back of the driveshaft where it connects to the transfer case uses a Cardan joint, which is sorta like two u-joints connected together.

If the joint is bad, it can be rebuilt by a driveshaft/drivetrain shop.

 

I wish this forum had the "THANKS" button option, lol


Thanks for the info, that's good to know, I never knew what those were called.

 

It does, upper right hand corner of the individual. Just after the thread number. It is called reps. Hit that and you can even leave a comment.

It it ends up being that joint, be sure to mark the driveshaft before removal. Want to put it back in the same way.

When you remove it drive the truck to confirm.

 

Well we went sledding yesterday and I had the chance to use the 4x4 on snow and ice. On the already bumpy road it was very hard to notice, but I think I still felt the vibration to a MUCH reduced degree than it was a couple weeks ago before the rear joint replacement. I manually locked the hubs in this afternoon when running around town and I can barely feel anything, if I didn't know to look for it, I would not know it was there so it is really minor, perhaps to the point of being accepted as 'normal' not sure.

I guess until I feel it to a more significant degree I'm not gonna worry bout it for now. When we get more snow in town I will pay attention for it again and post if I feel I still have a problem.

Thanks....

A pic of myself from yesterday just for fun.....

 

Great photo, looks like alot of fun.

I agree, just drive the truck for now.

 

This forum is GREAT!

We have same problem on a 99 F-250 SD SC 4X4. In addition we know that we have a vacuum link someplace.

Vibration that is felt and visible on steering wheel with hubs manually locked and SOF ON!

Tests:

1. Hubs manually locked and SOF OFF running on smooth highway all 20 to 60 MPH - NO Problem!

2. Hubs manually locked and SOF ON vibration in steering wheel starting around 20 MPH all the way up to 60 MPH.

3. Unlock hubs, NO Problem at any speed with SOF ON or OFF.

4. Had truck on 2-post lift and we have just enough vacuum to "lock" into 4X4 mode (hubs NOT manually locked) with front axle but not enough vacuum for hubs to lock and hold when on the ground (new snow over gravel driveway). Rear wheels slipping but fronts just rolled along, multiple tests with out turning 4X4 OFF.

5. While on lift, turned SOF OFF, put truck in reverse to drop 4X4, Hubs unlocked when trans put back into drive.

6. Checked all u-joints and Cardan joint for bad bearing, did not see or feel any problems, YET! (hand rotated drive shafts and looked for bearing play or binding).

From info on this thread it looks like we have a bad u-joint bearing someplace or the Cardan joint.

Truck is on way to college (130 miles) with 18 year old son. He will be back in 10 days after his finals.

Thanks for any additional help.

Ron - Former STM (Shade Tree Mechanic), Shade Tree blow down so built a 25 X 32 ft shop with a 10,000 lb two post lift.

 

In regards to your vacuum leak, that was my problem last spring.

I would use the 4x4, then disengage... after about 10-15 miles I would feel a grinding vibration and have to pull over... the hubs turned out to try to re-engage. I had new axle seals put in and it now disengages properly, no grinding vibration. Since you mention a possible vacuum leak, I would do a smoke test to figure out if you have a bad axle seal.... that was my initial problem with some of the symptoms that you have described.

Good luck with yours

 

Thanks, it really is a total blast... and your sled always comes home cleaner than when you left

Thanks for the idea on the Cardan joint... if I feel it more in the future, that will be the first thing I check

 

Ever service your transfer case?