Rear suspension bottoms out on dips

[Reed Young]

I have read numerous threads discussing “suspension bottoms out”, but all seem to talk about leaking blocks, valves, or bags. I have 2 ‘07 LR3s and have replaced the air suspension on both with Arnot replacements. Neither vehicle show signs of leaking overnight. I have not done anything with either of the compressors. My problem is, on both vehicles, when driving at slower speeds through dips in the road, speed bumps, *** holes, or pulling out of a parking lot onto the street, the rear end thumps quit harshly as if it is bottoming out on the strut. The trucks raise and lower normally with no faults or codes to be read. Any thoughts besides “don’t hit the dip any faster than 10mph?”

 

[Houm_WA]

Hmmmm...I have an '06 that does this, or at least, what I think sounds like your description except only on harsher bumps like off-road. I had the rear swaybar bushings changed. That didn't help. It could be the swaybar itself. The tech took photos and it is pretty worn out in spots.

I'd changed the fronts out for Arnotts but not the rear. Also, the clunking noise was happening before the new front shocks.

Just a theory. I'm not sure at all. My '06 has 206k on it.

 

[jaamrode]

I would check the upper rear control arm bushings. Mine are worn and clunk going over bumps.

 

[Houm_WA]

Maybe I should check mine too!

 

[Mx468]

Mine are all worn out as well. I need to replace them. I could see the rubber bushings splitting. My Lr3 has 190,000 miles.

 

[remember5]

I had a clunking like that going over speed humps. Replaced upper and lower control arm bushings (its been several years but I think I replaced the whole control arms, sway bar links, ball joints, and it improved the front end 100%. That was back when I could take Genuine parts to Goodyear and they would replace them for labor, now they won't install any customer supplied parts. I don't have any issues with the rear at this point but probably am due to replace some of the components back there.

 

[Houm_WA]

Right...the fronts are much more common And recurring, and easy to recognize/diagnose. The OP is specifically talking about a more mysterious "clunk" from the rear.

 

[remember5]

Lotta stuff back there, attached is a .pdf.

 

[Reed Young]

Remember5, this is very helpful. I’ll give it a read. Thanks.

 

[bbyer]

Lotta stuff back there, attached is a .pdf.

I appreciate the pdf. The "bushings" are hollow pieces of rubber filled with silicone. I guess over the years, the rubber splits and the silicone leaks out.

I have probably had those rear bushings replaced on my 3 about 4 times now over the past 15 years. I regard it as a maintenance thing so to speak.

I note in the parts diagram pdf, page 1/10, the arrow pointing to the bushing shows the number 36 but on the listing on page 2/10, it is called up as item 37, Bush (Rearward Lower Control Arm).

Regardless, you will not be wasting your money by replacing the two of them.