I've just bought a new scion tC 07 three weeks ago. I noticed a thump noise coming from the rear whenever going over the speed bump at low speed. I'm not talking about rattling noise caused by loose parts that were mentioned in some other posts at SL. I'm talking about the noise that sounds like something big bouncing up and down in the trunk ( I already checked and there was nothing in the trunk. I even removed the spare tire to make sure that it's not causing this). I noticed that this thump noise is produced when the rear wheels start rolling off the speed bump. I brought my tC to the dealer and one of the mechanics there told me that the thump noise is normal. He said he already checked the suspension and everthing and nothing is wrong.

Does your tC make any thump noise when going over speed bump?

I also noticed that when the mechanic guy sitting in the back seat, it's harder to produce the thump noise than when he is sitting in the front passenger seat. I was thinking that when he's sitting in the back, he's putting more weight on the rear wheels (suspension etc...). And that's probably why the car the doesn't bounce as much. Do you know if this noise is normal or not? Thanks

 

haven't heard of this before. I just bought an 07 tC and I don't have that problem at all and I go over a lot of speed bumps! I wouldn't let the dealer off that easy.

 

I think I know what you mean, I experience it too, kinda like someone is slamming down the hatch almost...I'm guessing(hoping) it is normal. I take the speedbumps slow, if i go a little faster than extremely slow, that is when the thump/thud occurs.

 

Doesn't happen to me. Doubt that it is normal, but what do I know.

 

Its probably the body just hitting suspension... it happens unless you go under 5 MPH

 

I hear the sound like hatch or hatch window is bouncing or shaking when I go over the bumps. I don't know where it's from tho. I started hear that after 1500miles (or maybe before that, I couldn't hear that b/c of loud music) I'm just too lazy to go to dealer and check it

 

That's exactly what happen. If I take the speedbumps at about 8 mph or slower, then the thump doesn't occur. I guess I'm not the only one with this problem. I don't mind the noise at all as long as nothing from the car hits the ground and gets damage. I'm sure the stock car is not low enough for that to happen. I guess I just have to take the speedbumps slow and wait for the TSB for this...

Have you brought your car to the dealer to have it fixed?

 

I definitely hear and feel thumps when I go over speed bumps, usually because I don't slow down enough.

 

yeah i hear the same think when im going around 5mph over speed bumps, i just assume it's normal.. or so i hope

 

have you tried putting foam tape on the bumper stops of the hatch? maybe there is too much clearance between the stoppers and the body, causing it to bounce and make this thumping noise you're hearing. And since there is less weight in the back than when the mechanic sat back there, it's lighter and more prone to bounce more.. more bounce = more movement = hatch moving = thump noise..

it's worth a try.. i think it's the hatch moving on you when you flex the body going over these speed bumps..

 

do you have an exhaust system ?? if so it might be the sound of your pipping hitting the lower cross member .... because i hear the same thing over speed bumps ...

 

No, I dont have an exhaust system.

 

caboy.. check my post.. 2 up.. see if that's your noise problem

 

Thanks sciontc_mich. I will try to put some foam tape at the bumper stop to see if I still hear the thump.