dukedave5200

So, I recently bought a 2005 FX4. It is in pretty good shape body wise but it had a number of more or less minor mechanical issues that I've been working through. But this last one has me a little stumped.

The rear end, particularly the driver side, seems to bounce or shake about an inch or so up and down rapidly over bumps and you can feel it while accelerating and if the road isn't completely smooth you can feel it. I already replaced the shocks, the old ones appeared original but didn't seem totally gone. It got a little better, but I think it is just masking the issue - and/or this is normal for this truck.

I read issues about the emergency break rubbing and eventually causing violent shaking. When I replaced the rear rotors I gutted the e-break for now to try and eliminate that from being a possibility.

The bushings in the leaf springs appear to be ok, visually and with a crowbar, but I am not an expert with this so they could be bad. But, I really can't think of what else could be causing this extra bounce in the rear. Is this normal for this truck? If not the bushings what else could it be? The shackle appears unbroken, no springs appear cracked or broken. Lots of rust, but everything seems solid back there from a visual inspection and again with a crowbar.

Here are some of the other things I had done so far: All new tires, new breaks/rotors all around (they were trashed), plugs and COPs, wheel alignment (once at a shop and then I fine tuned it myself with string and my eyeballs), oil, differential fluids, transfer case. I also did a bunch of other minor things, tightening bolts, replaced some missing screws, etc.

Any thoughts or things I might need to look into?

screamineagle

Have you replaced the shocks?

dukedave5200

Yes, as mentioned in my post, it helped a little, but the it still does the same thing.

Rick's 06

There really isn't that much back there that could cause that. You've replaced the shocks, so it's not that. E-brake gone, so it's not that. I don't know if you can really check a leaf spring bushing without taking it out. My money would still be on those being bad. Take a look at your sway bar bushings too. I'd also put your E-brake back on as well.

primalurges

The bed is supposed to shake a bit while going over bumps. If it's not happening on a smooth road if say you don't really have a problem.

dukedave5200

Thanks for the reply guys.

I think I am pretty convinced now it's bad bushings. I agree that the bed is going to shake a bit going over bumps, etc, but my bed is shaking a bit more than I think it should. I've had a few other trucks in my life and they all had solid rear axles and a bit of shaking going over bumps, etc, but this does seem not normal. Where I live there really aren't any really smooth roads, so it kind of happens all the time. Any little bump makes the bed shake and you can feel it throughout the truck - it's subtle but noticeable to me.

Going to get some new bushings. Not sure I want to tackle that job myself but I may give it a try if my air hammer still works (haven't used it in 10 years) - if it's not working and/or I need any expensive tools to do the job I may just take it into the shop and have them do it.

My biggest worry is that the rear differential is somehow causing this - because I can feel it shaking some while just accelerating. But a differential shaking like my truck does really doesn't make sense.

Anyway, thanks again. I'll try and reply back to this thread after the work is done.