Nasty-soundin' noise on weight shifts

[JarredH]

2WD, Manual, HF35 Axel code. No lift-kit I can see.

So, I got my 1991 Hardbody back in October, and not long after, noticed that somewhere in the rear, and I wanna say the driver's side, makes this hollow-sounding, metallic grind when I had to brake hard. Like, any more force and I'd be losing traction, hard. At first, I though maybe my shoes were bad, so I went and got new pads and shoes for all four corners. They were all good, besides the few hairline cracks in them. The drums on back were good, no irregular wear or grooves at all. I replaced them, adjusted the clearence, and went along my merry way, except that the noise still persisted on hard braking. I didn't think about it any more, as I only had it do the noise to me three times since I've owned it, and one was on purpose.


This is how she was untill I replaced the shocks last weekend. The old ones took a lot of force to compress, and when they did, took a good twenty-five seconds to extend back to rest. No bueno, truck rode like a brick. New ones on, and she's nice and comfy again. But now, when I go over the speed bumps at my campus at anything over two or three, I hear that sound in the split second the rear reaches it's furthest lift in the bounce over the bump. I haven't gotten under the truck to see if I can find any rub marks because it's been raining and I don't feel like going out and freezing my cheeks off.


At first I thought brakes. But after the bumps doing it, I've realized it must have something to do with weight coming off the rear end, as that's the moment the sound happens. I'm at a loss as to what it could be. It's not brakes, as it's only happening with weight change, and I don't have them engaged going over the bumps. I know nothing's scraping. I'm just confused.

It's gotta be somewhere in the drive-train, as it's in tune with wheel speed. When it happens on the hard braking, there's no lead in, just one second it's quiet, then it pops up with increased brake force. Just some loud, hollow, metallic scraping/grinding sound, in-tune with the wheel speed, and only on weight shifts.


Anyone have any clues? Everything I think of, I find reasons why it can't be it. I'm also going to drain the diff lube and replace it soon-ish, but I can't see why it would be diff related. Granted, I'm no expert, but I know how it all works, and I can't imagine how it'd be diff related. Still, nice to take a look, eh?

[themadscientist]

Leaves in the spring pack grinding against each other?

Does it sound linear or rotational?

[JarredH]

It's defiantly rotational, grinding slows as the truck stops. It's the same sound going over bumps, just only a split second, so I can't say for sure it's also rotational, but I'd imagine it also is.

[whomadewho]

Try greasing the splines on the drive shaft - check the hanger bearing

[JarredH]

I'll look at it tomorrow or Saturday when I get back to my tools.

[JarredH]

Found the problem, driveshaft running on the cross member sure to bad shackles on the leaf. Will post some pics later, possibly. Perhaps I'll document the work for future back-yard mechanics to use.

[JarredH]

https://www.dropbox.com/sc/gn088eol2glc ... l_1845ZKUa#/


There she is, all fixed with junkyard bushings. Apparently there are no parts stores around here than can get them to me any earlier than the nineteenth, so I figured it's only gotta last until August before I leave, why not just slap good used ones on.