Dodge Cummins Diesel Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 12 of 12 Posts

·
Registered
Joined
·
128 Posts
Discussion Starter · #1 ·
I recently had to replace my front hubs. The first units I went with were NAPA hubs. Cleaned all the gunk from the knuckle, axle shaft and all bolts. Greased the hub surfaces and anti seized the bolts. Reinstalled torquing the mounting bolts to 150 ft lbs and the axle nut to 260 ft lbs. I've read those torque specs numerous places. I did however see the write up here say 185 ft lbs for the axle nut. Everything went in easy, straight and smooth. Those lasted all of 300 miles. I returned them under warranty and upgraded to the SKF like I originally wanted. Followed the same procedure to install the SKF units. I haven't driven the truck since I've installed these because while the truck is still on jack stands the wheels wobble like the bearings are loose even after the mounting bolts and axle nut is torqued. I can't see anything else really moving when I shake the tire from the sides and top and bottom, but it's hard to tell doing it on my own. It's not a large amount of play but it still plays. Is there something else that could cause this? U joints, ball joints or steering components? Truck has 248,000 miles and I'm not sure what the previous owner has done or replaced. No death wobble on the original or previously replaced hubs, just the low speed groan and grind sound that went away after changing but came back with the NAPA units. I'd like to find the issue before I destroy the new SKF units. Thanks in advance.
 

·
Registered
Joined
·
1,565 Posts
That must be a record for quick bearing failure! I'd check the ball joints really good.

You forgot to put baling wire in your sig.!
 
  • Like
Reactions: krs

·
Registered
Joined
·
128 Posts
Discussion Starter · #3 ·
HA! Yeah, I sure did forget bailing wire. I'll be sure to check the ball joints. I really want a set of EMFs but they're all on back order. I like the fact that I can rebuild them with out having to continually press them out. Might have to look into Carli or DynaTrac.
 

·
Premium Member
Joined
·
1,135 Posts
Wait, this is odd. If the ball joints are bad, I wouldn't expect to see any wobble at all while the truck is jacked or while headed down the road straight and level. Under steady load, the ball joints will displace and you'll be out of alignment, but there's nothing in them that allows a cyclic load or cyclic play. This just doesn't sound right.

Did you FEEL a wobble when the bad unit bearings hubs were on? Did the wobble go away and then come back when the NAPA bearings went bad?

A 3rd gen... I don't know your truck.... are the axles turning all the time? Are there locking hubs?

Something cyclic with wheel rotation has to be loading the unit bearings. They're hairy edge design... so it doesn't take much to make them go bad, especially since the replacements probably aren't even as good as the OEMs.

A bent rim?

A damaged u-joint?

Bent axle?

I'm not saying you don't have play. But I think that might be a separate issue.

Tell us about your wheels and tires. If you're running on oversize tires with the offset flipped to give the tires room to move, AND if you've got a bent rim, I could see that killing the unit bearings FAST.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #5 ·
The wobble is when I shake the tire with the new skf bearings while jacked up. I heard the same grinding groan like when the original bearings went out so I changed the napa units to the SKF units. Stock rims 33x12 tires. Yeah, bad bearings had a wobble while on stands, went away with the new napa units and came back. Axles turn all the time, no locking hubs. No bent rims. That's what I'm trying to find is if someone came across this same issue.
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #6 ·
This seems strange to me as well. Did I miss something when I replaced the bearings? Over torque?
 

·
Premium Member
Joined
·
1,135 Posts
This seems strange to me as well. Did I miss something when I replaced the bearings? Over torque?
OK, so you don't have a wobble while it's spinning. That's what I was picturing. Just play when you shake it.

You can't overtorque the unit bearings. You could overtorque the bolts that hold the unit bearing hub to the knuckle, but that wouldn't stress the unit bearing. It would only damage those bolts and maybe the threads in the forging. If you overtorque the axle nut, worst that could happen would be you damage the axle end. The axle slides out and won't load the unit bearing axially and torqueing the nut doesn't load the bearing. If the knuckle weren't flat across the mounting face, you could conceivably damage the bearing, but that would take tons of weird force or impact and would likely damage something else badly, like the wheels, if maybe you skidded sideways into a curb or something. I can't believe the knuckle isn't square.

If your alignment is WAY off it could be loading the bearings axially or in torsion across the axis of rotation, but that would chew up tires too. You'd see it. And it should take a lot of that to damage the bearings. In the meantime the truck would drive like poo. You'd notice that.

Your stock wheels are providing factory offset. So no crazy super wide wheels and tires that stick out and overload the bearings in side moment.

There was a recent thread about the random and sometimes abysmally poor quality of aftermarket unit bearing assemblies. There was a comment to the effect that sometimes what you buy at the parts shops are OEM supplier rejects.

Did you inspect the outboard u-joints for play and wear? I can picture a situation where badly damaged u-joints can load up the bearing, but again, I'd think you'd hear or feel that from minute one on the roll. Any chance at all the unit bearing hub bolted on cockeyed? It was seated flat at all four corners? Kinda obvious, but I gotta ask to rule it out. On your truck, is the pattern symmetrical top to bottom? Any chance it was out 180? And there's no right and left? Again, just trying to rule out obvious stuff.

If the ball joints are obviously loose, go ahead and replace them. Adjust toe yourself to near neutral and dial in symmetrical positive camber. A little too much won't hurt any. That should eliminate any weird wear attributable to alignment.

I'm betting you got a bad pair of unit hubs. Bad surface induction treat. No lube. Something.

Was it an older NAPA parts guy, and was he surprised at all?
 

·
Registered
Joined
·
128 Posts
Discussion Starter · #8 ·
There wasn't a great deal of play in the u joints that I could tell. The unit hub slid on easily and flat. I started and ran the bolts about a quarter way in before I put the ratchet on it. I didn't have to use the bolts to pull it flat either. Also thinking about it now,, the first set when I changed them, the axle shaft slid out and I had to put it back in on both sides. I did however make sure that it turned the drive shaft after. I didn't open up the front diff though. Both part numbers were the same so I don't think there's a left and right. But what would the odds be that I got two bad bearings from different part houses? Theu had to ship and go pick them up to get the pair from two separate places. All of this is asking, not arguing the point. I'm working blind as far as previous repair and maintenance on the truck. The previous owner was a friends relative that passed away. I purchased the truck from the family and all they could tell me was that it was well maintained. It's got 248,000 on the clock and I'm not sure if the u joints have ever been changed. It was a middle aged man behind the counter at napa that's been there as long as I can remember and he was surprised the first pair I changed went out so soon. The box was actual SKF bearings. Do you think they would be bad from the start? Would bad u joints that you couldn't notice slop in them cause it to be able to be shaken back and forth? Also just to clarify, when the tire is off, I can't shake the bearing at all. It feels solid. It's only when the tire and rim is bolted up that I can feel the top and bottom, back and forth play. I did however have the alignment shop tell me that my passenger side upper ball joint was on its way out when I replaced the tires 3,000 miles ago. This isn't a daily driver, so it takes a little longer for these problems to surface.
 

·
Premium Member
Joined
·
1,135 Posts
More than likely the unit bearing hubs at the two NAPAs that had them, relatively near to one another, came from the same warehouse and the same lot. So if it was a bad lot, you could have gotten two bad ones. But do you know that both went bad again? Or do you know that there was noise, and maybe it was coming from only one side?

The u-joints weren't transferring any torque, so if they were reasonably tight, there shouldn't be any issues. They'd have to be far out of alignment -- loose -- to load up the bearings.

I'm betting on one bad, new bearing, or a weak lot. I can't think of anything else it could be, unless you've got a bent wheel... but you'd see and feel that.

But all of this is just more justification for a freespin hub conversion. I don't think we'd see crud like this happen with real wheel bearings.
 

·
Registered
Joined
·
532 Posts
Your thread reminds me how long its been since I've had to replace wheel bearings and/or ball joints.

In spite of every thing going on in the world today...About ball joints and wheel bearings I feel better.

Free spin hubs and EMF balls joints make life better for a long long time. Cost some bucks to convert but do it right the first time and you don't have to worry about it or put up with the hassle. EDIT Carry on.....
 
  • Like
Reactions: 5.7 Hemi

·
Registered
Joined
·
128 Posts
Discussion Starter · #11 ·
Yeah, even though they came from two different shops, it was the same distribution warehouse. That could be the issue. They guy actually went back to the warehouse to get the part that the truck forgot. So that may be the problem. I'm working, so I can't really check into all that at the moment. I was trying to get some direction for when I can actually get it done, it's not my daily driver. As I said earlier, I heard that grinding groan again so that's what made me look. Put brand new skf bearings and they wobbled in and out, back and forth with out ever even rolling on them. From what I understand of these unit bearings is that they shouldn't have any play in them.
So because I can't swing $2000 for a free spin kit, (which yes, I've looked into it and would LOVE to go with that much better option, but have responsibilities) and wait at least a month or better for ball joints, I'm wrong headed and cheaping out? I LITERALLY just dropped over a grand in just the brakes alone. I really don't think it's cheaping out trying to fix a problem with the best parts you can afford. Thanks, appreciate the help dude. I'm happy that you're doing well.
 
  • Like
Reactions: Barefootdog

·
Registered
Joined
·
532 Posts
Re reading may comment it sounded terrible...not intended. Changed it. Apologies.

You're facing what everyone else who owns these trucks have faced. Poorly designed and built front ends (among other things). Before I changed out to the free spins Timken front hubs from Amazon or Ebay were the go to replacement part for many.
 
1 - 12 of 12 Posts
Top