When I drive over large street cracks I hear a thump from the rear

[Rancho5]

02 Sport with 160,000.

I noticed the sound most dramatically when I was in Mexico recently. There were four people in the rig, and we were full of luggage in the back. Also had the tray carrier with a couple of small suitcases on it. The roads in Mexico are pretty bad, and every time we hit a bump in the road there was a loud thump in the back.

When we got home and unpacked, the car looked level at rest so I did not think it was the rear springs. When we were packed to the rafters it did sag in the rear, but we were loaded down so I figured that was normal. The rear shocks looked original so I replaced them as well as the rear lower control arms, whose rubber was pretty shot. None of this has helped.

I do keep a large crate in the back, and I mean large, that weighs about 150 pounds. It holds all of my emergency gear. Maybe that’s contributing?

I’ve read that one of the signs of bad rear springs is if the car drives squirrley. I haven’t had the car that long and I’ve never driven another 3rd Gen before so I’m not too sure what squirrley feels like.

I’m suspecting that it needs new rear springs so any input is appreciated. Also, if it does need new springs I’d appreciate some clarification on the types of springs to get. The car is not lifted and I don’t want to lift it. I like the stock height but I see people buying 99 springs etc. and it can I’ll be a bit confusing.

Any help much appreciated

 

[rickmum]

Spare tire underneath? Rear sway bar bushings gone bad? Rear sway bar end links broken? Junk in your trunk?

 

[00Spork]

I have had some rear thumping before. It would be the most obvious if I was driving over washboard, and it would thump-thump-thump.

I did a body lift and the thumping never came back.

What I would suggest is first take all of your gear out that could bounce around and cause a thump. Try to replicate the thump sound with your gear out.

Next, check all of your body mounts, especially the rear two. Make sure they are tight and try to replicate the thumping after tightening. Report back with your results.

If you don't know where your body mounts are, google a body lift install for a 3rd gen.

 

[BrianK14]

My thump was due to a missing bolt in the drivers side rear upper control arm. So, the loose end was banging against the gas tank. All around not a good situation. I would start with a good visual inspection under the truck. Look closely for anything loose, broken, worn, etc. Also, sometimes its hard to tell where the noise is coming from. Check the front as well

 

[MStudt]

What rear shocks are you running? I had the same issue with some Bilstein shocks I was running a couple years ago. Mine would always come loose, and make a metal on metal sound when going over bumps.

Mike

 

[zoombyu86]

I would check your upper mounting bolt for the rear shocks. When I did my lift, I didn't torque them because I couldn't get a torque bar in there and apparently it jiggled loose and when it would extend it would back the nut off and slam down over bumps.

 

[4runnerfiend]

If you were weighted down and your sagging. maybe you are just hitting your bumpstops. This is very common and most likely what you had with all that weight.

Start with the easy stuff.. just get under there and look around. Check that the spare tire is secure. I've had it not seated all the way and it would swing back and forth creating a thump.

Just grab every link possible and yank on it. panhard, lower control arms. sway bar, shocks. and a visual. most likely is is something simple.

Good luck

Springs.. you can get 99's they are 1" taller. however they are expensive to get new OEM. You can use 5th gen rear springs, and usually are pretty cheap because everyone lifts their rigs. the 5th gen springs will give you 1.5 to 2" in rear. however if you are already sagging a lot this may be more. I know there are aftermarket ones IE Moog and Ac Delco. but I can't speak for the quality.

It really depends on you application and preference. do you constantly have weight in the rear? do you not mind a little rake? what is your budget?
Lots of things can cause "squirrley" bad shocks are one. Your springs are probably not "bad" I don't think springs go bad, but they sag really bad over time on this generation.
Squirrley is most likely something in the front IE steering, related. Alignment or brake related. depending on when is is happening.

 

[Jidaran]

stand on the bumper and jump up and down to see if you can replicate the thump. if you can, have a friend do the same while you crawl under the back and see if you can locate the source of the sound.

 

[96RedRunner]

3rd Gen 4Runner Lift Information and FAQ's - Toyota 4Runner Forum - Largest 4Runner Forum

With 160k mi loaded you were probably hitting bump stops.
Where bumps contact axle, center of spring and outboard bumps is paint worn off from contact?
Suspension has seen better days at 160k mi.