"Thud" in start/stop traffic?

[Sitt]

In start/stop traffic (around 25 kmph) I'm getting a "thud" for a brief secound which sounds like its coming from below the car somewhere. I can actual feel the "thud" when it happens. Could it be play in the drive shaft or something which causes this? I have had the car in to the local dealer who says they can't find any issues.

[marcthelegend]

is it an auto?? mine does it when im slowly driving.. let off the accelerator and then press it again .. normally it would just ease on, but this is like the transmission is in neutral and then when you accelerate it slams into gear... mine surges forward a bit too, but not very violently .. just mildly, I imagine its just normal??

Marc

[Sitt]

Yes, its an auto. You described the symptoms exactly. Maybe it is normal then?

[marcthelegend]

I though it was normal.. and now that there are 2 pajs with the same thing kinda makes me think it is normal.. would be interesting to get other peoples input though.

It is kind of annoying, but I worry if it does any damage.. the feel and sound of it makes me think it is putting stress on the driveline components (transmission, diffs, etc.)

Marc

[jace]

My 2000 MN has the same issue. Quick acceleration from coasting causes a thud from the somewhere under the car. There have been other posts on this but no real resolution.

The only thing that seems to help is to keep the accelerator cable nice and tight (even slightly over tight). The issue will happen much less often. The adjustment is on the bracket on top of the air intake manifold - a few minutes and a pair of spanners should do the trick.

[marcthelegend]

mines a 3.8l .. with fy-by-wire.. cant really do much adjustment, but it does it even if i ease the accelerator on.. as in very very slowly, anyone know if this causes damage??

Marc

[icysyrup]

Dont know if this will apply to you all but mine was doing that and I replaced the bushings in the crossmember that hold the diff, 2 of them total and they were fairly cheap and it helped me. There is a lot more movement of the drivetrain under there than most people realize.

[Stinky]

i would be checking g/box mount/s. mine doesnt do it, but test drove one that did it so i know the noise & thud u r talking about. def felt like a mount on its way out.

[brianwanless]

The first thing I thought when I read the post was mountings. Try putting it in drive and with your foot hard on the brake, accelerate a bit then back off. Try this in drive and then in reverse. If it's a mounting you should hear or feel the thud when you back off. Drive will test the mounts on one side then reverse will test the other side.

[gaz1]

Dont know if this will apply to you all but mine was doing that and I replaced the bushings in the crossmember that hold the diff, 2 of them total and they were fairly cheap and it helped me. There is a lot more movement of the drivetrain under there than most people realize.

How difficult a job was it? Do the bushings need to be pressed out & in, does the crossmember need to come out?

Gaz

[baldyjoe327]

check the mount on the transfer case to the chassi rial on the passanger side or the cover under the transfer case might be bent out of shape and hitting the case .

[icysyrup]

I did mine with the crossmember in and the rear diff in there. Rigged up a 3 finger bearing puller to get them out. They are a bit of a pain and stubborn but they are press fit in there. Its prob lots easier to just take the diff out and then you will have more room to work in there.

[sheaquinn]

I get a random thud like whats described in my paj but not when driving, it normally happens when I change from Reverse to Drive or Park to go down to Drive. At first I thought it might have been because we parked on steep hills, but i'm finding it does it when on flat surfaces as well.

[Sitt]

I get a random thud like whats described in my paj but not when driving, it normally happens when I change from Reverse to Drive or Park to go down to Drive. At first I thought it might have been because we parked on steep hills, but i'm finding it does it when on flat surfaces as well.

Just an update on my problem.
I persisted with my complaints and yesterday saw the Mistsubishi rep based in Adelaide who pays a visit to the local dealers once a month or so.
He noted my problem after a quick drive around the block, he also did exactly the same as what Sheaquinn mentioned above, moving from drive to park whilst stationary. He said that the problem is caused by play in the gears on the drive shaft (can't remember the exact term he used). He did say that the play would be within tolerance if the play was up to 5mm, they measured the play in my gears and apparently I have 4mm of play which is within tolerance.
So, my car is within tolerance which means that I have to live with the noise or buy a new car.
I imagine that if i should keep the car and the play gets worse which I imagine it will with time, then in another 18 months or so just when the car is out of warranty the whole rear diff will need replacing at my expense.
I must admit that I didn't expect anything to come of my complaints as everything else that I have complained about regarding my car Mitsubishi have always seemed to be able to get out of the complaint without doing any repairs. Maybe this is how they offer a 5 year warranty as nothing ever seems to get fixed!

[icysyrup]

Thanks for the update....that sucks that u cant get it to go away.