So my wife called me this morning on her way to drop off our kids at high school (5 min away) and she said the truck felt like it had something wobbling and didnt want to move. Then a big clunk and it drove again but the 4wd light came on and she barely made it back home. When I got home I started to back it out the garage and it felt like the wheels were out of round when so I stopped and had my son look under and he said some metal pieces were hanging in the rear. I got out to look and to my surprise both rear lower control arms had rotted and snapped. I jacked it up and took the wheels off. What a pain to get the bolts off to remove them. Then I happened to look at the rear end and noticed...holy crap! No driveshaft!!! I quickly took a ride in my truck looking for it in the dark and luckily I found it on the side of the road!!

So long story short...check your lower control arms for rot. It's on a 99 Navigator with 106k, always garaged and washed and waxed, under carriage hosed down over the winter months to keep the salt off. I was shocked to see it like that! I might end up replacing the upper control arms and panhard bar too since they look pretty beat too.

 

It happens...
https://www.ford-trucks.com/forums/9...ml#post8653438

 

You forgot the "SH" there alloro.

Fortunately she was going slow, Just imagine the damage if she were going 70 mph.
Her experience is just about a worst case scenario that I could think of. How did the drive shaft come out? They are bolted to the pinion in the rear dif.

 

When the lower control arms broke the rear end shifted and the driveshaft mount snapped! I couldn't believe it myself! I just got everything back together...what a PIA doing it by myself. The front bolt on the driver side came out toward the gas tank...what a b*tch to get it out. I had to use a comealong to get the rear end back in place.

Anyone know where I can find the torque specs?

 

I hope these work for you.

Torque Specifications Description Nm Lb-Ft Lb-In
Differential bearing cap bolt 105 77 —
Differential pinion shaft lock bolt 30 22 —
Oil filler plug 30 22 —
Rear axle housing vent 11-24 8-18 —
Differential housing cover bolts 45 33 —
Driveshaft bolts 112 83 —
Ring gear bolts 150 111 —
Traction-Lok clutch gauge nut 6.7 — 60
Pinion bearing preload (used pinion bearing) 0.9-1.5 — 8-14
Pinion bearing preload (new pinion bearing) 1.8-3.3 — 16-29
Minimum breakaway torque — (Traction-Lok®) 27 20 —
Driver handle 2.2 — 20

 

This has been an issue as many of us have had this problem, I was lucky and caught mine before they broke and went with the complete PMT set up on my 01.

 

An incident like that can ruin your whole day, and now for some more bad news... the force of your driveshaft being whipped out of the truck can and often causes more damage than originally counted. I would check the drive shaft for run out even if there is no clearly visible sign of a bend. Also check everything close to the attatching points for impact and any damage, hopefully there is no additional damage. A bent driveshaft will make for a miserable driving experience. Don't ask how I know....

 

Moto Mel..I was worried about the driveshaft too...visibly there appears to be no damage. According to her she had to stop after she took a right hand turn bc the truck felt like something was stuck in the wheels. She put it in reverse and then felt like it came out...my guess is that's when it bound up and snapped. I found the drive shaft less than 100ft from where she said it happened. I'll know shortly how it runs (crossing fingers). Only thing I can see under there is some tranny fluid must have leaked out.

Thank you for the dif torque specs. Would you happen to know the control arms torque's?

Thanks again!

 

Make sure you top off the fluids in the T-case and check the trans. If there is any vibration while driving the driveshaft may be bent and need replacing. Get one from a bone yard, you really don't want to know how much Ford wants for one.

The torque specs for the fasteners on the arms and track bar is 125-170 lbs. ft. according to my manual.

 

I don't know if you just mis-spoke, but just in case you didn't, it's not the tranny fluid level you need to check, it's the transfer case fluid level. With a 4WD the rear driveshaft goes into the t-case, not the tranny.

Oh and when the '4wd light came on', it was because there was no rear driveshaft turning. The A4WD system kicked in power to the front axle and that's how the truck was able to keep driving.

 

T-case for certain and the trans just because it is an often overlooked part of the drivetrain.

 

i just had the same problem... i found the lower control arm on ebay for $125 for both of them, where the dealer charges about $250 each now im trying to locate the yoke that is mounted on the differential cause i dont need the whole drive shaft and the auto parts dont sell it separate... i just dont understand why ford dont have a recall for this problem... some one can really get hurt.

 

Almost any salvage yard will have the yoke for about $25.00.

 

Because if Ford has a voluntary recall, then they're admitting to it being a problem. Once they admit to the problem and someone ends up hurt, then they are automatically liable. It's that plus the fact that it's less expensive to deal with the few complainer out there, instead of volunteering to change them all.

 

It's only a problem in regions prone to rust!