When I floor my '02 HLSD 6 speed in 1st, and the wheels slip, there is a very loud knocking noise that sounds like it is coming from right around the shifter. It only happens under wheel slip (as 1st gear can do very easily).. It sounds like someone punching it pretty hard.. and is pretty quick..

Ideas?

Motor/transmission mount gone? I checked the lower front, and the passanger side mount and they "looked" ok.

On second thought.. it sounds like its coming from the right tire itself...

Video: http://vtwireless.com/maxima.wmv (right click, save as.. i dont have the mime types set right)

 

if the wheels are breakin loose, it could be caused by the wheel hop...or my guess is the lower motor mount...i had that before i swapped mounts for the energy suspension set from cattman performance. brian will take care of you. just to make sure, jack the car up and crawl under and check the rear lower mount near the y-pipe. you'll see either fluid, if it just happened or the tear in the damper will be noticable. that's my take. do you have an STB? maybe bangin on the bar if you have a bad mount too.

 

Whats a 'STB'? I'll jack her up and take a look...

 

Mine does the same thing. I hope it stops after I get the energy mounts changed on my whole front suspension and motor mounts.

 

Its actually your y-pipe knocking around the bracing/chassis area.

I have all ES bushings + coilovers and have the same noise. You'll have to loosen the bolts on your exhaust system and try to realign everything.