Loud Thud under car during hard acceleration

[Stangdriver13]

I took my car out over the weekend and heard a loud thump from under the car during a 1-2 shift. This is not a one time occurrence as I've heard it before just didn't think much of it. It feels as if the car is hitting a bump as a I make the 1-2 shift. Feels as if the source is coming from directly under the center console/arm rest. Could this be cause by the aluminum ds and not having a upper control arm to re-adjust the pinion angle? I've been meaning to change out the control arms but haven't got around to it yet. Maybe Van has an answer?

 

[spitin venom]

I have read that if the pinion angle is off it can cause a loud thud.

 

[enormous]

I would like to know also since I have the same after going to an aluminum DS.
Strange thing is I don't have a single witness mark on the DS.

 

[betiwin]

What type of driveshaft, DSS?

 

[Stangdriver13]

What type of driveshaft, DSS?

I'm not sure. Previous owner had it installed and I haven't looked into it.

 

[stkjock]

could be the DS hitting the tunnel from your description

 

[Robert M]

could be the DS hitting the tunnel from your description

^^^+1, those are my thoughts also.








R

 

[Iceman5000]

Another possibility is your LCA'S bushings are shot.

 

[Stangdriver13]

Car only has 4k miles so while not likely I will check them out this weekend.

 

[lawdude]

More negative pinion angle should take care of the problem - requires adjustable rear upper control arm

 

[Robert M]

Car only has 4k miles so while not likely I will check them out this weekend.

Did you also go over a bump during the sprint when the "thump" happened?





R

 

[Stangdriver13]

Did you also go over a bump during the sprint when the "thump" happened?





R

That is what I thought was originally causing the noise but it occurred more than once and I know I did not hit a bump when a felt it over the weekend. I really think it has to do with the pinion angle. Guess its time to order some control arms.

 

[lawdude]

To verify, look at your drive shaft. If it's hitting the tunnel, there will be some scoring around the diameter of the shaft where it hits. Very easy to spot.

 

[Robert M]

That is what I thought was originally causing the noise but it occurred more than once and I know I did not hit a bump when a felt it over the weekend. I really think it has to do with the pinion angle. Guess its time to order some control arms.

Mine did this once when the back end was squatting under harder acceleration, and the pavement changed with a small bump/step in the road. That is the only time I have had that happen.




R

 

[Nick13]

I had this issue, it turned out that my UCA bracket was destroyed. It was also causing my driveshaft to hit the tunnel during acceleration.

 

[Robert M]

I had this issue, it turned out that my UCA bracket was destroyed. It was also causing my driveshaft to hit the tunnel during acceleration.

^^^^^OUCH!!! That is Broke!

What caused that??





R

 

[Nick13]

^^^^^OUCH!!! That is Broke!

What caused that??





R

I'm not 100% sure what caused it. It was only launched 10 times with it installed, 7 of which were on street tires. It was a clunking noise that I gradually noticed getting worse. I figured it was just because of the aftermarket suspension on the car. Then one day the driveshaft hit the tunnel. I parked it, and pulled it out. It was little over a year old when taken out of the car. That is the Evolution UCA. The car only made 603/606 at the time.

 

[Stangdriver13]

Was that the stock bracket or an aftermarket part? I'm going to buy the BMR adj upper with bracket this week.

 

[cjgt500]

Happened to me a few times. Checked everything closely that has been mentioned....nada. Determined it slammed onto the bump stops. It scares you at first but happens only in certain situations such as existing bumps while under hard acceleration.

 

[zporta]

Do you have stock UCA bracket? They are pretty thin. Also if you don't have the aftermarket bracket torqued down right it will clunk