Front axle clunk

[Bad137]

My front axle (’77) is making a heavy clunk / clank noise. I can’t locate the source of the sound, but it may be the front differential. It started less than 2 miles ago and was initially only when turning. It then progressed to louder and more often, and as I got close to home it would also clunk when driving straight. Almost like it was a death spiral of something getting knocked loose, which made it looser and looser.

It is driveline / speed related, but I didn’t notice it being on every axle rotation. I locked the front hubs and it still did it, also cycled through 4L N 4H (didn’t drive it in 4WD; was on the street) and didn’t notice any correction.

I’ll put it on jacks tomorrow and start spinning things. Any idea where to start looking? I’ve never opened a differential before and don’t know what to look for. I’m not wanting to drive it until I figure out the cause. The quickness of the escalation and the severity of the clunk has me concerned to put it back on the road. None of the previous "clunk" threads I found on the forum matched my symptoms.

Thanks for the help!

Brett

 

[.94 OR]

Check the u-joints in the axle and the drive lines.

 

[Jdgephar]

In 2 wheel, nothing should be rotating, except the hubs. I would check the hubs.

Could be a dust shield hitting on the rotor, or a rock got in there...

Sent from my SM-G981U using Tapatalk

 

[DirtDonk]

All of the above. You can even remove the hub lockouts and drive it again to see if the noise disappears. The locking mechanism is not necessary for driving. Only the wheel bearings are, so make sure they are not failing before you drive it.
And if you do drive without the lockouts be sure to cover the open hole with a plastic bag, or tape.

Make sure you can turn the front drive shaft by hand, which is a sure fire way to verify that the transfer case is in 2 Wheel Dr.
As mentioned, in 2wd with the hubs unlocked nothing inside the differential should be turning.

 

[Broncobowsher]

Loose lugnuts

 

[Rustytruck]

we once had a womp, womp, womp sound didn't find it until disassembly of the knuckle it was the needle bearing inside the rear of the spindle they were muddied up. it was all repacked the month before by a paid mechanic we paid 300 to a professional mechanic to do the job and we were screwed. so we had to do it right ourselves. missing parts and chisel removal of the spindle nuts what a mess the professional did.

 

[carter2772]

Loose lugnuts

I found this out the hard way back in the day.

 

[Bad137]

And the culprit is…





Loose lug nuts (embarrassingly). I did’t even look hard here before jacking, but as soon as the front wheels were off the ground it was obvious the front passenger wheel was loose. 2 nuts were backed off enough to not make contact, two more were in contact when the wheel would wobble, and only one was “tight,” although I could still remove it with my hand. While I’m thankful for the easy find and fix, I’m irritated that I can only assume my own negligence would have caused this.

Worse, there is damage to the rim. Only one hole is clean. The others have degrees of wallowing or burnished edges, one pretty bad.

I tightened everything back up again and it seems there is enough there that the lug nuts still have something to purchase. I’m not sure where this falls on the risk scale of “never drive a damaged wheel” to “it can drive just fine with deformations like that.” It’s not too easy to just replace since they are custom backspace rims from Wheel Smith and then powder coated, but not enough of a barrier to keep me from getting a new rim made.

Thanks for the help guys, and I’m going to 125 ft/lbs now instead of 100!

Brett

 

[Bad137]

Pics…

 

[DirtDonk]

I’m sure glad you found that!
Maybe there’s a tapered reamer somewhere to re-profile the holes?

I don’t think it was lack of torque between 100 and 125 pounds. I’ve never had a wheel come loose even at 70 pounds.
Perhaps the original powder coating was too thick and it gave a false torque, then chipped away a bit. It doesn’t actually look that way, but it seems like a possibility.

 

[DirtDonk]

Another possibility is if the studs were recently replaced they may not have been pulled all the way tight. Then once the Lugnuts were torqued and some miles accrued, they started to work loose.
I’ve seen that happen before.

 

[Bad137]

Paul, I thought you had nailed it with a replaced stud until I went back and looked at my notes. It was the passenger rear that had a stripped stud that I had to replace when I mounted these wheels. Current dilemma is passenger front. Maybe I just never had the nut's taper fully seated and got false torque on a flat spot on the rim. I've always worried about a nut not centering so I pay attention to it, but it seems fairly easy to miss, particularly if rushed.

 

[Broncobowsher]

I once had a set of wheels where the lugnut would bottom out on the stud before the taper was fully seated in the wheel. Fresh disk brake conversion. Wheel spacers for the save.

 

[BradGP]

And the culprit is…





Loose lug nuts (embarrassingly). I did’t even look hard here before jacking, but as soon as the front wheels were off the ground it was obvious the front passenger wheel was loose. 2 nuts were backed off enough to not make contact, two more were in contact when the wheel would wobble, and only one was “tight,” although I could still remove it with my hand. While I’m thankful for the easy find and fix, I’m irritated that I can only assume my own negligence would have caused this.

Worse, there is damage to the rim. Only one hole is clean. The others have degrees of wallowing or burnished edges, one pretty bad.

I tightened everything back up again and it seems there is enough there that the lug nuts still have something to purchase. I’m not sure where this falls on the risk scale of “never drive a damaged wheel” to “it can drive just fine with deformations like that.” It’s not too easy to just replace since they are custom backspace rims from Wheel Smith and then powder coated, but not enough of a barrier to keep me from getting a new rim made.

Thanks for the help guys, and I’m going to 125 ft/lbs now instead of 100!

Brett

Good to hear you found it. My friend got this '71 Bronco with clunk noise coming from the front passenger side. He ordered a set of tires from 4Wheelonline so everything will be checked while we are there.

 

[Slednut10]

And the culprit is…





Loose lug nuts (embarrassingly). I did’t even look hard here before jacking, but as soon as the front wheels were off the ground it was obvious the front passenger wheel was loose. 2 nuts were backed off enough to not make contact, two more were in contact when the wheel would wobble, and only one was “tight,” although I could still remove it with my hand. While I’m thankful for the easy find and fix, I’m irritated that I can only assume my own negligence would have caused this.

Worse, there is damage to the rim. Only one hole is clean. The others have degrees of wallowing or burnished edges, one pretty bad.

I tightened everything back up again and it seems there is enough there that the lug nuts still have something to purchase. I’m not sure where this falls on the risk scale of “never drive a damaged wheel” to “it can drive just fine with deformations like that.” It’s not too easy to just replace since they are custom backspace rims from Wheel Smith and then powder coated, but not enough of a barrier to keep me from getting a new rim made.

Thanks for the help guys, and I’m going to 125 ft/lbs now instead of 100!

Brett

If you torqued to 100ft-lb and they loosened up, you (or someone else with an overzealous impact gun) have likely stretched the studs. The recommended torque for a 7/16wheel stud is around 75-80.

 

[Broncobowsher]

If you torqued to 100ft-lb and they loosened up, you (or someone else with an overzealous impact gun) have likely stretched the studs. The recommended torque for a 7/16wheel stud is around 75-80.

7/16" is GM car studs.
1/2" is the size for Bronco wheel studs.

 

[DirtDonk]

GM six bolt truck studs as well.
I was always amazed at just how many six bolt Chevy trucks would come into our shops with loose or busted off lugnuts, when we’ve never had that problem with five lug Fords and their half inch studs.

 

[Rustytruck]

Take that tire to a wheel shop check the balence and wheel run out. there is a reason they loosened. were the wheel studs clean and dry of lube like they are supposed to be? Glad you found it before it found you.