I did some searching and didn't see anything relevant. Hopefully I didn't miss it.

2003 E350 Extended with V10, 83,xxx miles. Not sure if it is relevant, but it has towed at least 75% of the miles since I got it at 19,000.

On a long trip in late January (not towing), I noticed a minor vibration when you coast down a hill. It took a while to isolate it, but it seems to do it in either 3rd gear or OD.

I assumed it was u-joints, so I replaced them and it did not make a difference. The original ones were a little stiff but not really worn or damaged. It does not have a carrier bearing.

We just got back from a long towing trip and it is still doing it, and it is worse, though that just might be because of the trailer weight.

It doesn't seem to matter hot or cold, windy or not. I played with the air bag and hitch height several times on this trip and this doesn't seem to make any difference. We blew out a rear tire on the trip and putting a new rear tire did not make a difference.

It only does it on deceleration. Acceleration and up shifts are normal. Also, it doesn't do it immediately when you lift, rather it takes a little bit of time before it vibrates.

Any ideas?

Thanks,

DaveW

 

U Joint center bearing - check for wear.

Next, pinion gear / possible internal bearings issue depending on how hard you towed.

Is the differential filled with correct fluid? Changed regularly?

 

Doesn't have a center/carrier bearing, just a straight driveshaft.

Yes, differential is filled with correct fluid and has been changed regularly. Barring any new ideas, I will check bearing here next.

Nothing seemed odd when I gave it a spin with the d-s out, but I didn't exhaustively check anything. How do you check a pinion bearing?

Tow load has been the same for the entire life of the van, 24' enclosed in the 5-7000# range.

Thanks for the help,

DaveW

 

If it is only vibrating on deceleration, the next step that I would think about is checking two things. The first is driveline angles. Both the top ujoint and bottom ujoint must be at equal angles. On deceleration the pinion will be forced to drop upsetting the angles enough to induce vibration. Factory springs have a tendancy to settle over time and when you said that you have all those miles of towing regardless of airbags your springs may have settled enough to throw those angles off. How do the rear springs look? If sagging you may want to replace/rebuild. An easy check is to have someone that you trust get behind the wheel as you LAY DOWN A SAFE DISTANCE AWAY next to the vehicle but close enough to watch the lower pinion ujoint and with the brakes firmly applied load the drive train with power alternating between drive and reverse. My bet is that you will see significant movement from the springs and the pinion will drop in reverse. Driveshafts are balanced by small weights spot welder on someplace. look for signs that you may have chucked a weight.
It may also reveal worn motor/trans mounts so safely look for that as well. Is it 2wd or has it been converted to 4wd? Does it have a block of any kind in the rear? Shims to correct pinion angle are widely available in a range of degrees from 2 degrees to 8 degrees or more. The bolt on steel shims are by far the best but they do require full disassembly of the leaf pack on order to replace the center pin. Beware of aluminum shims as they tend to break over time. Does your rear driveshaft have a slip built in or a slip yoke in the tailshaft of the trans? Both go bad and can cause vibration. Also the ujoints need to fit snug in the yokes and if they don't, replace them with a new quality part such as Dana Spicer and not some overseas cheap crap. This is assuming that your tires and both balanced and not going out of round. You can also do a speed test by safely putting the vehicle on jack stands supporting the axle tubes but this in my opinion will not load the drivetrain enough to make a difference.

Good luck, hope you find it.

 

It is 2wd. The driveshaft has a slip yoke that goes into the transmission.

The new U-joints are Spicer and fit the flages properly.

I think I will do the brake torque test you suggested and see if something is moving around down there. I can see where a broken spring or something could allow pinion angle change which could do wierd stuff. Ditto with a soft trans/motor mount.

If that looks OK, I guess I will dive into the rear end and start checking stuff there. I have never had a failed pinion or differential bearing before, I'll have to read up on that.

Thanks again for the help and suggestions!

DaveW

 

sportsmobile has all the bases covered... do as he say.

 

I know its been a while since you have had this problem. My 700,000 miles of experience with the E vans might help. They are extremely sensitive to out of roundness in the wheels. They will balance okay and be smooth at 55 but above that they will shake the van, many times under acceleration the out of roundness is dampened by the power on the tires, but under deacceleration the tire returns to its free running shape and it will shake the van. I have had multiple sets of tires and rims on my vans and they are a real pain, and the metal wheels bend easy. Jack it up and run it in drive at idle and look at the wheels, you will see them going up and down on the top edge of the tire and its often the wheel, sometimes remounting the tire will fix it, but they have zero tollerance for any hop in the wheel. Easy to check and doesn't cost a lot at all to check. Many times the balancing machine at the tire shop hasn't been calibrated in years and I have had the best balance on a brand new machine the self calibrates. AE

 

I still haven't found it, but your thoughts do make sense.

I put new brakes, rotors and wheel bearings (front only) on all four corners. If found one front wheel bearing which was extremely loose and repaired that. Everything else checkout out fine. I was hoping that would fix it, but it did not.

I put all new tires on it over the past year also, including fronts right after the brakes. This also did not entirely eliminate it, though it did get better.

I do think the front wheels/tires are out of balance currently, the wheel shakes very hard at 45mph but it goes away as you go faster. I have not had time to get that fixed, but will soon.

Whatever the problem is, it does not seem to be something like a transmission or rear axle bearing as it really has not changed much over 20,000 miles, many of them towing. I would think that an axle or trans problem would have gotten a lot worse and finally failed given the miles and load this van sees.

I think I will get an appointment somewhere with a good balancer or road force machine and also have them check the wheels for runout (or watch myself)

Thanks,

DaveW