Popping Noise - Axle Bushing?

[natenkiki2004]

For a while now, I've noticed a popping noise in the front end. The sound is easily created when backing up and hitting the brakes, especially while turning or on a bumpy gravel road. However, flat pavement, turning, acceleration, braking while moving forward, none of those cause it.

What I know;
The radius arm bushings were replaced, they look and feel great. None of the steering joints have been replaced. The drivers side lower ball joint needs replacing but has very little play and doesn't quite make the same noise.

While crawling underneath to do battery cables recently, I noticed the driver's side (the half with the differential, bushing on the passenger side) axle bushing looked a little funny, like it's sitting at an angle. Take a look:
https://dl.dropboxusercontent.com/u/464376/vehicles/1991 Explorer/Pictures/2014-06-18 15.33.39.jpg
https://dl.dropboxusercontent.com/u/464376/vehicles/1991 Explorer/Pictures/2014-06-18 15.34.15.jpg

In this picture it looks like it has quite a bit of cracking:
https://dl.dropboxusercontent.com/u/464376/vehicles/1991 Explorer/Pictures/2014-06-18 15.36.42.jpg

The passenger half has a bushing completely soaked in oil due to a leaking oil pan, it's difficult to see what's going on with it:
https://dl.dropboxusercontent.com/u/464376/vehicles/1991 Explorer/Pictures/2014-06-18 15.37.39.jpg



My question is to you experts out there, does this look/sound like the culprit? I know the Chilton and various forum posts say you have to drop the axle. I don't have the tools or mechanical ability to do that, nor do I have the funds to pay a shop to do it. Looking at how things are setup, it almost looks like if the front end was properly supported, I could get a jack (or 2?) underneath the axle to hold the weight and undo that bolt, slowly lower it down and replace the bushing. Does that sound reasonable? Thanks.

 

[Anime]

The popping noise might still be the radius arm bushings, if they aren't snug. It's possible that the big nut holding them on is 'bottomed out' on the threads, meaning it's threaded all the way on, but there isn't any more thread for it to go on tighter to make the bushings snug. The 'fix' for this is to add a big washer on both radius arms, which spaces the nut out and lets it be tightened to spec.

A popping noise can also be the brakes. It's possible for the slide pins that let the brake caliper slide side to side to get dry if they aren't regularly greased, and so the popping noise would be the caliper moving, ungreased, when the brakes are applied and it needs to move. The brake pads also have shims, and the shim for the inner pad can wind up sliding foward and leading to a loose pad that causes noise when braking. Same thing with the retainer clip for the inner brake pad, if that breaks or gets loose, the inner pad can move around.

You might also want to really check the lower ball joints, by jacking up the axles and sticking a long stick tool under the tire and prying up to see how much the ball joint moves. Chances are good that it is REALLY loose and both lower joints on both sides need to be replaced.

I doubt the pivot bushings are causing the noise. You can replace them, but it's a bear of a job to do with the axles still on the vehicle.

You would need to remove the coil spring and have the axle supported to have a shot at moving the axle down enough to get access to the bushings - but then you have to figure out how to get all the tools needed to push out the bushing in there, and cut out the metal sleeve, AND press in the new bushing.

It CAN be done, sure, but I'd say you're better off looking to the ball joints and checking out the brakes for any popping noise, and perhaps double-checking the radius arm bushings and/or throwing on an extra washer to be sure.

 

[natenkiki2004]

Thanks for the thorough reply. I'm not sure that the brakes could be causing the issue. It has to be something in the front end that's moving. It doesn't always happen when I'm braking. It also happens when going down a bumpy gravel driveway, it's something that's moving with the suspension.

For the radius arm nuts, I can just take those off and throw a washer on and re-torque? No need for special tools or anything? What's the torque spec for those bad boys? I'll probably start there since that sounds the easiest.

*EDIT* The torque spec for the bushing bolt is 80-120ft lbs as per the Chilton manual.

For the ball joints, both sides could be bad but from my inexperienced hands, only the drivers side feels sloppy. I just don't really have the proper tools to do the job, nor the confidence to do them right, nor the money to have them done

 

[Anime]

You can try the washers as a fix to see if that helps, but I would guess it's the ball joints, especially if they are original. They never get greased, and so they wear out and just get so loose that they slop around. You can at least check them out by lifting up the axles and sticking a long stick tool under the tire to pry it up and look from the front to see how much play the lower joints really have. You may even just be able to pull on the lower part of the tire and notice how much play they have.

You can go for a pretty long time on bad ball joints. The lowers on mine were bad for years before I got around to fixing them. It's apparently even possible to align the front end so the tires wear pretty evenly, even with the bad lower joints.

That said, it's not too hard of a job, and can be done with some basic hand tools, and specialty tools that are free to rent at auto parts stores.

Here's a walkthrough with images to show you what's involved:

http://www.explorerforum.com/forums/showthread.php?t=218254

 

[natenkiki2004]

I haven't done anything yet as far as this goes but I did happen to come across the exact procedure I had in my mind to remove the axle bushing without removing coils or the whole front end. It's explained here:
http://www.rmftc.com/howtos/ttbaxlepivot/ttbaxlepivot.html

 

[Anime]

Yeah, you can do it that way - but if/when you do, I strongly suggest you at least jack up the frame a tiny bit on the side of the wheel that's attached to the beam you're working on - and put a jackstand under the frame and have the frame rest on the jackstand so the suspension and tire does not have much of the vehicle weight on it.

Working on it with no jackstand, just yanking down the beam, is actually possible - but could have dire consequences if a body part is between the beam and the pivot bracket/crossmember and the weight of the vehicle shifts, causing the beam to go back up into the bracket/crossmember.

With the radius arm bushings loose, and the frame slightly up and most or all the weight off the wheel/tire, it should be even easier to pull the beam down far enough to get a press in there to remove the old bushing and install a new one.