Loud bang when going over bumps

[4D7]

Hello!

I have an 03 V8 runner with a toytec 3/2 spacer and coil lift. When going over speed bumps in a parking lot at slow speeds (5 mph ish - not slowing down for the bump), there is a loud bang when the rear axle goes over the bump. The front does not do this, it absorbs the drop just fine. It was doing this prior to my coils being installed.

Any ideas?

 

[RCs4Runner]

Loose shock, bad swaybar bushings and or endlinks?

 

[kevinpt]

i would get under the thing and take a rubber mallet and tap things and see if you can hear anything moving

 

[4D7]

The shocks were inspected during the install of the rear coils, they were in good shape. It sounds like I am missing bump stops or something (bump stops are there) , or the shocks are bottoming out. I'll tap around with a mallet and see what I can find.

 

[chaz]

did you install lifting coils & a spacer in the rear & reused the old shocks? you have xreas?

 

[4D7]

2" coil in the rear on stock shock - but the loud thump/bang was there prior to the coil upgrade. No xreas.

 

[chaz]

so you have an 03 with stock tokico (black) shocks, then you installed 2in. rear lift coils, right? OME, toytec, or what? even tho you say the bang was there before the new coils, are you sure the shocks are still good? either way, the coils maybe too much for them & they are not long enough, you should of gotten new, longer shocks, 5100's maybe.

 

[4D7]

so you have an 03 with stock tokico (black) shocks, then you installed 2in. rear lift coils, right? even tho you say the bang was there before the new coils, are you sure the shocks are still good? either way, imo, you should of gotten new, longer shocks, 5100's maybe.

You are correct sir. Stock shocks as far as I can tell, I am the 2nd owner and bought it last year. They may have been replaced with factory shocks but there is no paper work. The coils are the 2" superflex coils from Toytech. It still handles great on and off the road, no floating. Maybe they are shot? Is there an easy way to tell ?

 

[NJshadow93]

You are correct sir. Stock shocks as far as I can tell, I am the 2nd owner and bought it last year. They may have been replaced with factory shocks but there is no paper work. The coils are the 2" superflex coils from Toytech. It still handles great on and off the road, no floating. Maybe they are shot? Is there an easy way to tell ?

I'd recommend getting 5100s regardless. As it sits now, the stock shocks are extended, which is fine - until you flex. Shocks such as Bilstein 5100s are made to accommodate the 2" lifts we put on the rear of the trucks. How are the sway bar end links?

 

[4D7]

I'd recommend getting 5100s regardless. As it sits now, the stock shocks are extended, which is fine - until you flex. Shocks such as Bilstein 5100s are made to accommodate the 2" lifts we put on the rear of the trucks. How are the sway bar end links?

The end links look good. They are tight and the bushing aren't cracked. May have to spring for some 5100s. Still, I don't know what the bang is coming from.. The best I can describe it is it sounds like it is bottoming out, but the impact feels normal - like going over a speed bump in a pickup, it's stiff. It in no way sounds quality, which is why it bothers me lol.

 

[4Evr4RunN3R]

This may sound stupid but it may be your muffler that rotted out? I had a similar problem on my old 3rd gen. Every time i would hit a bump or pot hole, it sounded like a loud bang. I couldnt figure it out till it got louder and took it to my mechanic. Put it on the lift and what do you know, it was just hanging there on one of the cross members causing it to bounce around and hit the underside of the truck.

 

[4D7]

This may sound stupid but it may be your muffler that rotted out? I had a similar problem on my old 3rd gen. Every time i would hit a bump or pot hole, it sounded like a loud bang. I couldnt figure it out till it got louder and took it to my mechanic. Put it on the lift and what do you know, it was just hanging there on one of the cross members causing it to bounce around and hit the underside of the truck.

Haha! Thats actually a great thought, but the exhaust is solid. I was pressure washing the undercarriage recently and decided to check the pipes and muffler underneath. The bang is pretty big, almost like a boom. It's something heavy hitting something solid would be my thoughts - just don't know what it is. I had the same sound when a strut went out on my Solara.

 

[having fun]

Not to sound stupid here and it sounds like you know what to look for on working components. By any chance you look in the rear compartments in the back and see if something is bouncing around in there, like stock jack on one side or a hitch on the other. Come to think of it, if you have a hitch in the rear, it sometimes bangs do to not a tight fit.

And on a side note, you adding a 2" lift/coil in the back, you will need longer shocks for it also as others have stated.

 

[Bskelton]

I had similar issues with my rear and it turned out to be my panhard bar. I tightened all of the mounting bolts and it went away. I was able to grab the bar and it moved very slightly. Worth checking. Look at all the bushings while you are under there too.