knocking noise when launched

[bullysteve]

i have a knocking sound from underneath that i can not track down when i start to move forward anybody have this problem and a fix for it , it sounds like its coming from the drive train but everything looks and feels tight .

[D4x4Fish]

Check the rear drive shaft u-joints

[bullysteve]

i did they seem fine .

[happycamper]

maybe your exhaust, mine did that, passenger side between trans and long arm bracket

[bullysteve]

its more of a knock with a thump like the u joint , i'll pull the transfer case skid plate and see if the transfer case is loose some were , the drive shafts seem tight . a guy at the shop said it might be a loose heim joint but they all seem fine also

[red rubi]

check your rear track bar : and make sure all your johnny joints are stright ; cv joint : just to name a few of my cluncks in the past lol

[bullysteve]

thanks for the help guys i'll check tommorrow , you might have something with the rear track bar i noticed the heim joints are shinny from moving around alot when everything else is dirty ......

[IPSteeler]

When checking the U-Joints did u have it in neutral with the parking brake on in 2-high?
I know it sounds kinda amateur but i have seen alot of people check the U-Joint's for slack when the vehicle is in gear with the E-Brake on and that doesnt work unless the U-Joint is completely gone.
Also i had a click noise from the front end a while back and it was my track bar so i just took the front and back off.
Also are you sure it is coming from the underneath?
It could be motor mount's.

[bullysteve]

thanks red rubi , it looks like it was the rear track bar i straighten the joints and tighten the LOOSE nuts and everything seems fine

[97sahara]

check your transfercase shifter linkage, most tjs have this problem, its normally the linkage hitting against the body, skyjacker makes a bracket to fix this

[bullysteve]

97sahara , do you have a part # or name of part

[Shadly1]

"I hear you knockin'...

but you can't come in"

[97sahara]

http://www.quadratec.com/products/12521_901.htm

[4point]

Mine was doing that, turned out to be a bad Unit Bearing.

[bullysteve]

mine was the aftermarket rear track bar....