Guys,
I have an 02 F350 SRW crew cab, 8ft box, and had the Center Support Bearing replaced in June. Truck had around 200K miles at that replacement. I am now at 210K miles, and the bearing has failed again.

I would like a few opinions on this, here are a few details:

• Original failure occurred the day after hauling my 36' fifth wheel for about 100 miles. (but at 200K miles, probably ready to be replaced anyway)
• Second failure occurs 6 weeks later, right when I got home from a 7 hour pull through N. Alabama mountains and hills.(Could excessive load increase chance of bearing failure?)
• Could the problem have been related to poor installation (perhaps the mechanic beat on the outer race, or could the bearing have been flipped when installed?)
• Truck has load leveling bags (could this somehow be contributing to the problem)
• Truck was apparently wrecked badly by previous owner, as the rear end was discovered to be damaged and replaced at 50K, and I see evidence that the box is not original. (is it possible that some drive train alignment problem exists which only becomes a problem with heavy loads?) I have not had any re-occurring drive train or alignment issues until now.
• Could I have a bad motor or trans mount that is contributing to this problem?
• Back when the rear end was changed, is it possible that the rear end is not positioned properly (what defines the forward/aft positioning?) and could it be ramming the drive line forwards when the truck and trailer pivot over road buckles and bumps? In other words, when the trailer weight is pushing down on the bed as the springs compress when hitting a bad bump (like at every overpass between Meridian MS, and Laurel MS.), could there be some forward axial displacement which could be jamming the bearing and possibly the transmission tail shaft and yoke?

I am afraid of having a problem on the road with this camper. If any of you read my "90 degree turns with fifth wheel" post in the towing forum, you will know that I am already a bit intimidated with towing this trailer. My fear is that this problem will keep happening every time I use the camper.

Any help will be greatly appreciated. I have always had great responses from the FTE gang!

 

Suggest you just get a new bearing. The current bearing may have been rough from the start, and installation damage is always possible. Unless a 3rd unit fails too then I would not jump to any conclusion. I would carefully inspect all the U-joints and grease the slip yoke this time. Basically a full drive line inspection.

 

Just got off the phone with a cousin of mine who's worked on these trucks for years. He seems to agree that the rear end may not be properly installed. There was an issue I had in the past with the tail shaft being jammed against the front yoke too. These problems are probably made worse with the extra bed weight when towing.

Both bearings had been pushed forward through the bushing too.

 

is the driveshaft straight? Are the U-Joints still doing okay?

 

No u joint issues. I wondered about the shafts. The first bearing didn't fail for 200K miles, which makes me think the shaft is OK, plus there wasn't any vibration noticed.

Hoping to find a good driveline shop in the New Orleans area.

 

Why is it that you assume the driveshaft is good simply because it lasted 200K miles, when your axle has been there for 150K at the time? Would it make sense to you that the driveshaft WAS the problem and is what caused the first and second bearings to go out?

I don't think the driveshaft is a rigid, fixed unit. I think that's what the slip joint is for, to allow for expansion and contraction along the shaft. The driveline geometry is going to change constantly every time you go over a bump, and it makes sense that the shaft would be normally capable of adjusting to that. Now, maybe your slip joint is frozen up. That may cause bearing failure...

 

Did you change the driveshaft angles with your leveling system, sort of like adding a lift kit but not shimming down the carrier bearing, causing a weird angle and driveline stress.
Is this a new trailer, have you ever had this much weight on it before the failures.

 

What is the failure? Is the rubber isolator broken, or is the bearing case broken or the bearing rough?

If the bearing is pushed through the rubber isolator, then the driveshaft could be hanging up and pushing forward. I find it hard to believe the axle could be installed so improperly that it affects the alignment of the driveshaft or the axle to the back of the trans. it would be really evident if this was the case. I think you really need to check the rest of the driveshaft to make sure nothing else is hanging up or the driveshaft isn't out of balance.

 

Well, first Crazy101, I guess I figured that the driveshaft is a pretty stable piece of equipment and short of hitting it on something, that it would not be easily damaged, but I see your point. Frankly I have to admit that there could be events that I am not aware of that could damage a driveshaft and that could be the problem. It is possible too that it was damaged in the original accident as well.

It appears that they sprayed the splines in the split with a dry film lube back in June when they replaced the first bearing. And I have not dropped it to see if it is currently frozen, so that could be a problem.

Ehchvac, I would not think that I am changing angles, the air bags were the solution to some serious sagging that this 5th wheel caused. It was putting me on the overload springs on bumps and I figured the air bags were necessary at that point. I usually ride around with the minimum air pressure, and still grit my teeth on bumps. Even when I hook up the camper, I only put about 40 PSI in the bags, just enough to level the truck.

And yes, it is a new trailer, January this year. This trip was the 5th time we had it out, and the longest trip by a factor of 4. Prior to that, I hauled a 4wheeler in the bed and a tractor off the bumper, but never really sagged the bed, even with that load.

aldridgec, Both bearings came apart through the front of the bushing. And your thinking is along Crazy101, so yes, I will be getting the shaft looked at, in fact the whole drive line. I've been told that there is a centering bolt on the springs that would have saddled the axle in the right spot, plus nothing looks abnormal (but then again, I have an untrained eye). There is a driveline shop I will be calling tomorrow. Hope they are still in business.

It is ironic, I was quite proud of my baby on this trip, hate seeing her limping!

 

I don't think it would be collision damage. You would have experienced failure much sooner. It lasted 150k, had a problem, and now the problem recurs after another 10k. Something happened around the 200k mark. You need to look for causes of binding or vibration. Could be worn u joints, could be another bearing gone bad leading to vibration that takes out the carrier bearing. You would probably feel this. Could be as others have stated, binding slip joint.

 

My first thought was that the first bearing failed (I don't know the gearing you have, nor your tire size, but you can do the math and find the # of revolutions that bearing whent through...

When you had the bearing changed, if somebody used a vise to hold the driveshaft, it's bent... no questions.

Of course, this would result in pinion bearing failure, too, and you'd probably be eating U-joints... unless you've got a vibrational dampner on your pinion (I don't know when they started putting those on, so you might)... That might save your U-Joints and pinion bearing.... Then again, it might be the problem...

 

What is the pin weight and the total trailer weight?

 

Just another thought, make sure they check the timing (phase) of the U-joints.

If someone assemble the slip-yoke spline with the u-joints out of phase, you might not feel the vibration but it could wear the support bearing. You can just lay under the truck and see if it is severly out of phase. This is why we always mark a drive shaft alignment before disassembling it, but sometime things happen.

I found this writeup on it:
http://www.pirate4x4.com/tech/billav...ft/index2.html

 

I spoke with the guy at the driveline shop, he was wondering about the pinion bearing too. Truck wont make the shop until Wednesday, I hope they can figure this out.

 

You were dead on about the splines. The guy I took it to discovered that to be the problem.